mirror of
https://github.com/MintCN/linux-insides-zh.git
synced 2026-02-03 10:33:28 +08:00
Modify all linkers about interrupts
This commit is contained in:
mudongliang
@@ -2,7 +2,7 @@
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=====================
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终结篇
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-------------------------
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本文是 Linux 内核[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html)的第十节。在[上一节](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-9.html)，我们了解了延后中断及其相关概念，如 `softirq`，`tasklet`，`workqueue`。本节我们继续深入这个主题，现在是见识真正的硬件驱动的时候了。
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本文是 Linux 内核[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html)的第十节。在[上一节](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-9.html)，我们了解了延后中断及其相关概念，如 `softirq`，`tasklet`，`workqueue`。本节我们继续深入这个主题，现在是见识真正的硬件驱动的时候了。
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以 [StringARM** SA-100/21285 评估板](http://netwinder.osuosl.org/pub/netwinder/docs/intel/datashts/27813501.pdf)串行驱动为例，我们来观察驱动程序如何请求一个 [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_%28PC_architecture%29) 线，一个中断被触发时会发生什么之类的。驱动程序代码位于 [drivers/tty/serial/21285.c](https://github.com/torvalds/linux/blob/master/drivers/tty/serial/21285.c) 源文件。好啦，源码在手，说走就走！
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@@ -297,7 +297,7 @@ if (new->thread_fn && !nested) {
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准备处理中断
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------------------------------
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通过上文，我们观察了为给定的中断描述符请求中断号，为给定的中断注册 `irqaction` 结构体的过程。我们已经知道，当一个中断事件发生时，中断控制器向处理器通知该事件，处理器尝试为这个中断找到一个合适的中断门。如果你已阅读本章[第八节](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-8.html)，你应该还记得 `native_init_IRQ` 函数。这个函数会初始化本地 [APIC](https://en.wikipedia.org/wiki/Advanced_Programmable_Interrupt_Controller)。这个函数的如下部分是我们现在最感兴趣的地方：
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通过上文，我们观察了为给定的中断描述符请求中断号，为给定的中断注册 `irqaction` 结构体的过程。我们已经知道，当一个中断事件发生时，中断控制器向处理器通知该事件，处理器尝试为这个中断找到一个合适的中断门。如果你已阅读本章[第八节](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-8.html)，你应该还记得 `native_init_IRQ` 函数。这个函数会初始化本地 [APIC](https://en.wikipedia.org/wiki/Advanced_Programmable_Interrupt_Controller)。这个函数的如下部分是我们现在最感兴趣的地方：
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```C
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for_each_clear_bit_from(i, used_vectors, first_system_vector) {
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@@ -444,7 +444,7 @@ native_irq_return_iret:
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总结
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--------------------------
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这里是[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html) 章节的第十节的结尾。如你在本节开头读到的那样，这是本章的最后一节。本章开篇阐述了中断理论，我们于是明白了什么是中断，中断的类型，然后也了解了异常以及对这种类型中断的处理，延后中断。最后在本节，我们考察了硬件中断和对这些中断的处理。当然，本节甚至本章都未能覆盖到 Linux 内核中断和中断处理的所有方面。这样并不现实，至少对我而言如此。这是一项浩大工程，不知你作何感想，对我来说，它确实浩大。这个主题远远超出本章讲述的内容，我不确定地球上能否找到一本书可以涵盖这个主题。我们漏掉了关于中断和中断处理的很多内容，但我相信，深入研究中断和中断处理相关的内核源码是个不错的点子。
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这里是[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html) 章节的第十节的结尾。如你在本节开头读到的那样，这是本章的最后一节。本章开篇阐述了中断理论，我们于是明白了什么是中断，中断的类型，然后也了解了异常以及对这种类型中断的处理，延后中断。最后在本节，我们考察了硬件中断和对这些中断的处理。当然，本节甚至本章都未能覆盖到 Linux 内核中断和中断处理的所有方面。这样并不现实，至少对我而言如此。这是一项浩大工程，不知你作何感想，对我来说，它确实浩大。这个主题远远超出本章讲述的内容，我不确定地球上能否找到一本书可以涵盖这个主题。我们漏掉了关于中断和中断处理的很多内容，但我相信，深入研究中断和中断处理相关的内核源码是个不错的点子。
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如果有任何疑问或者建议，撰写评论或者在 [twitter](https://twitter.com/0xAX) 上联系我。
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@@ -469,7 +469,7 @@ native_irq_return_iret:
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* [pid](https://en.wikipedia.org/wiki/Process_identifier)
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* [设备树](https://en.wikipedia.org/wiki/Device_tree)
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* [系统调用](https://en.wikipedia.org/wiki/System_call)
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* [上一节](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-9.html)
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* [上一节](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-9.html)
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@@ -4,7 +4,7 @@ Interrupts and Interrupt Handling. Part 2.
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Start to dive into interrupt and exceptions handling in the Linux kernel
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--------------------------------------------------------------------------------
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We saw some theory about interrupts and exception handling in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html) and as I already wrote in that part, we will start to dive into interrupts and exceptions in the Linux kernel source code in this part. As you already can note, the previous part mostly described theoretical aspects and in this part we will start to dive directly into the Linux kernel source code. We will start to do it as we did it in other chapters, from the very early places. We will not see the Linux kernel source code from the earliest [code lines](https://github.com/torvalds/linux/blob/master/arch/x86/boot/header.S#L292) as we saw it for example in the [Linux kernel booting process](http://0xax.gitbooks.io/linux-insides/content/Booting/index.html) chapter, but we will start from the earliest code which is related to the interrupts and exceptions. In this part we will try to go through the all interrupts and exceptions related stuff which we can find in the Linux kernel source code.
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We saw some theory about interrupts and exception handling in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html) and as I already wrote in that part, we will start to dive into interrupts and exceptions in the Linux kernel source code in this part. As you already can note, the previous part mostly described theoretical aspects and in this part we will start to dive directly into the Linux kernel source code. We will start to do it as we did it in other chapters, from the very early places. We will not see the Linux kernel source code from the earliest [code lines](https://github.com/torvalds/linux/blob/master/arch/x86/boot/header.S#L292) as we saw it for example in the [Linux kernel booting process](http://0xax.gitbooks.io/linux-insides/content/Booting/index.html) chapter, but we will start from the earliest code which is related to the interrupts and exceptions. In this part we will try to go through the all interrupts and exceptions related stuff which we can find in the Linux kernel source code.
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If you've read the previous parts, you can remember that the earliest place in the Linux kernel `x86_64` architecture-specific source code which is related to the interrupt is located in the [arch/x86/boot/pm.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/pm.c) source code file and represents the first setup of the [Interrupt Descriptor Table](http://en.wikipedia.org/wiki/Interrupt_descriptor_table). It occurs right before the transition into the [protected mode](http://en.wikipedia.org/wiki/Protected_mode) in the `go_to_protected_mode` function by the call of the `setup_idt`:
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@@ -109,7 +109,7 @@ movl initial_gs+4(%rip),%edx
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wrmsr
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```
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We already saw this code in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html). First of all pay attention on the last `wrmsr` instruction. This instruction writes data from the `edx:eax` registers to the [model specific register](http://en.wikipedia.org/wiki/Model-specific_register) specified by the `ecx` register. We can see that `ecx` contains `$MSR_GS_BASE` which is declared in the [arch/x86/include/uapi/asm/msr-index.h](https://github.com/torvalds/linux/blob/master/arch/x86/include/uapi/asm/msr-index.h) and looks like:
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We already saw this code in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html). First of all pay attention on the last `wrmsr` instruction. This instruction writes data from the `edx:eax` registers to the [model specific register](http://en.wikipedia.org/wiki/Model-specific_register) specified by the `ecx` register. We can see that `ecx` contains `$MSR_GS_BASE` which is declared in the [arch/x86/include/uapi/asm/msr-index.h](https://github.com/torvalds/linux/blob/master/arch/x86/include/uapi/asm/msr-index.h) and looks like:
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```C
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#define MSR_GS_BASE 0xc0000101
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@@ -253,7 +253,7 @@ If the `CONFIG_CC_STACKPROTECTOR` kernel configuration option is set, the `boot_
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#endif
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```
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As we can read in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html) the `irq_stack_union` represented by the following union:
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As we can read in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html) the `irq_stack_union` represented by the following union:
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```C
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union irq_stack_union {
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@@ -432,7 +432,7 @@ static inline void set_intr_gate_ist(int n, void *addr, unsigned ist)
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}
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```
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First of all we can see the check that `n` which is [vector number](http://en.wikipedia.org/wiki/Interrupt_vector_table) of the interrupt is not greater than `0xff` or 255. We need to check it because we remember from the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html) that vector number of an interrupt must be between `0` and `255`. In the next step we can see the call of the `_set_gate` function that sets a given interrupt gate to the `IDT` table:
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First of all we can see the check that `n` which is [vector number](http://en.wikipedia.org/wiki/Interrupt_vector_table) of the interrupt is not greater than `0xff` or 255. We need to check it because we remember from the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html) that vector number of an interrupt must be between `0` and `255`. In the next step we can see the call of the `_set_gate` function that sets a given interrupt gate to the `IDT` table:
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```C
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static inline void _set_gate(int gate, unsigned type, void *addr,
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@@ -544,4 +544,4 @@ Links
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* [vector number](http://en.wikipedia.org/wiki/Interrupt_vector_table)
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* [Interrupt Stack Table](https://www.kernel.org/doc/Documentation/x86/x86_64/kernel-stacks)
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* [Privilege level](http://en.wikipedia.org/wiki/Privilege_level)
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* [Previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html)
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* [Previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html)
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@@ -4,7 +4,7 @@ Interrupts and Interrupt Handling. Part 3.
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Exception Handling
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--------------------------------------------------------------------------------
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This is the third part of the [chapter](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) about an interrupts and an exceptions handling in the Linux kernel and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) we stopped at the `setup_arch` function from the [arch/x86/kernel/setup.c](https://github.com/torvalds/linux/blame/master/arch/x86/kernel/setup.c) source code file.
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This is the third part of the [chapter](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) about an interrupts and an exceptions handling in the Linux kernel and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) we stopped at the `setup_arch` function from the [arch/x86/kernel/setup.c](https://github.com/torvalds/linux/blame/master/arch/x86/kernel/setup.c) source code file.
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We already know that this function executes initialization of architecture-specfic stuff. In our case the `setup_arch` function does [x86_64](https://en.wikipedia.org/wiki/X86-64) architecture related initializations. The `setup_arch` is big function, and in the previous part we stopped on the setting of the two exceptions handlers for the two following exceptions:
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@@ -519,4 +519,4 @@ Links
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* [Per-CPU variables](http://0xax.gitbooks.io/linux-insides/content/Concepts/per-cpu.html)
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* [kgdb](https://en.wikipedia.org/wiki/KGDB)
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* [ACPI](https://en.wikipedia.org/wiki/Advanced_Configuration_and_Power_Interface)
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* [Previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html)
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* [Previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html)
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@@ -4,7 +4,7 @@ Interrupts and Interrupt Handling. Part 4.
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Initialization of non-early interrupt gates
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--------------------------------------------------------------------------------
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This is fourth part about an interrupts and exceptions handling in the Linux kernel and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html) we saw first early `#DB` and `#BP` exceptions handlers from the [arch/x86/kernel/traps.c](https://github.com/torvalds/linux/tree/master/arch/x86/kernel/traps.c). We stopped on the right after the `early_trap_init` function that called in the `setup_arch` function which defined in the [arch/x86/kernel/setup.c](https://github.com/torvalds/linux/tree/master/arch/x86/kernel/setup.c). In this part we will continue to dive into an interrupts and exceptions handling in the Linux kernel for `x86_64` and continue to do it from the place where we left off in the last part. First thing which is related to the interrupts and exceptions handling is the setup of the `#PF` or [page fault](https://en.wikipedia.org/wiki/Page_fault) handler with the `early_trap_pf_init` function. Let's start from it.
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This is fourth part about an interrupts and exceptions handling in the Linux kernel and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html) we saw first early `#DB` and `#BP` exceptions handlers from the [arch/x86/kernel/traps.c](https://github.com/torvalds/linux/tree/master/arch/x86/kernel/traps.c). We stopped on the right after the `early_trap_init` function that called in the `setup_arch` function which defined in the [arch/x86/kernel/setup.c](https://github.com/torvalds/linux/tree/master/arch/x86/kernel/setup.c). In this part we will continue to dive into an interrupts and exceptions handling in the Linux kernel for `x86_64` and continue to do it from the place where we left off in the last part. First thing which is related to the interrupts and exceptions handling is the setup of the `#PF` or [page fault](https://en.wikipedia.org/wiki/Page_fault) handler with the `early_trap_pf_init` function. Let's start from it.
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Early page fault handler
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--------------------------------------------------------------------------------
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@@ -20,7 +20,7 @@ void __init early_trap_pf_init(void)
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}
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```
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This macro defined in the [arch/x86/include/asm/desc.h](https://github.com/torvalds/linux/tree/master/arch/x86/include/asm/desc.h). We already saw macros like this in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html) - `set_system_intr_gate` and `set_intr_gate_ist`. This macro checks that given vector number is not greater than `255` (maximum vector number) and calls `_set_gate` function as `set_system_intr_gate` and `set_intr_gate_ist` did it:
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This macro defined in the [arch/x86/include/asm/desc.h](https://github.com/torvalds/linux/tree/master/arch/x86/include/asm/desc.h). We already saw macros like this in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html) - `set_system_intr_gate` and `set_intr_gate_ist`. This macro checks that given vector number is not greater than `255` (maximum vector number) and calls `_set_gate` function as `set_system_intr_gate` and `set_intr_gate_ist` did it:
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```C
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#define set_intr_gate(n, addr) \
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@@ -64,7 +64,7 @@ When the `early_trap_pf_init` will be called, the `set_intr_gate` will be expand
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trace_idtentry page_fault do_page_fault has_error_code=1
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```
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We saw in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html) how `#DB` and `#BP` handlers defined. They were defined with the `idtentry` macro, but here we can see `trace_idtentry`. This macro defined in the same source code file and depends on the `CONFIG_TRACING` kernel configuration option:
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We saw in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html) how `#DB` and `#BP` handlers defined. They were defined with the `idtentry` macro, but here we can see `trace_idtentry`. This macro defined in the same source code file and depends on the `CONFIG_TRACING` kernel configuration option:
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```assembly
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#ifdef CONFIG_TRACING
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@@ -79,7 +79,7 @@ idtentry \sym \do_sym has_error_code=\has_error_code
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#endif
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```
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We will not dive into exceptions [Tracing](https://en.wikipedia.org/wiki/Tracing_%28software%29) now. If `CONFIG_TRACING` is not set, we can see that `trace_idtentry` macro just expands to the normal `idtentry`. We already saw implementation of the `idtentry` macro in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html), so let's start from the `page_fault` exception handler.
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We will not dive into exceptions [Tracing](https://en.wikipedia.org/wiki/Tracing_%28software%29) now. If `CONFIG_TRACING` is not set, we can see that `trace_idtentry` macro just expands to the normal `idtentry`. We already saw implementation of the `idtentry` macro in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html), so let's start from the `page_fault` exception handler.
|
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|
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As we can see in the `idtentry` definition, the handler of the `page_fault` is `do_page_fault` function which defined in the [arch/x86/mm/fault.c](https://github.com/torvalds/linux/blob/master/arch/x86/mm/fault.c) and as all exceptions handlers it takes two arguments:
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|
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@@ -223,7 +223,7 @@ set_intr_gate(X86_TRAP_DE, divide_error);
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set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
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```
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We use `set_intr_gate` macro to set the interrupt gate for the `#DE` exception and `set_intr_gate_ist` for the `#NMI`. You can remember that we already used these macros when we have set the interrupts gates for the page fault handler, debug handler and etc, you can find explanation of it in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html). After this we setup exception gates for the following exceptions:
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We use `set_intr_gate` macro to set the interrupt gate for the `#DE` exception and `set_intr_gate_ist` for the `#NMI`. You can remember that we already used these macros when we have set the interrupts gates for the page fault handler, debug handler and etc, you can find explanation of it in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html). After this we setup exception gates for the following exceptions:
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```C
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set_system_intr_gate(X86_TRAP_OF, &overflow);
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@@ -421,7 +421,7 @@ set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
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#endif
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```
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Here we copy `idt_table` to the `nmi_dit_table` and setup exception handlers for the `#DB` or `Debug exception` and `#BR` or `Breakpoint exception`. You can remember that we already set these interrupt gates in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html), so why do we need to setup it again? We setup it again because when we initialized it before in the `early_trap_init` function, the `Task State Segment` was not ready yet, but now it is ready after the call of the `cpu_init` function.
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Here we copy `idt_table` to the `nmi_dit_table` and setup exception handlers for the `#DB` or `Debug exception` and `#BR` or `Breakpoint exception`. You can remember that we already set these interrupt gates in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html), so why do we need to setup it again? We setup it again because when we initialized it before in the `early_trap_init` function, the `Task State Segment` was not ready yet, but now it is ready after the call of the `cpu_init` function.
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That's all. Soon we will consider all handlers of these interrupts/exceptions.
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@@ -462,4 +462,4 @@ Links
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* [cpumasks and bitmaps](http://0xax.gitbooks.io/linux-insides/content/Concepts/cpumask.html)
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* [NX](https://en.wikipedia.org/wiki/NX_bit)
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* [Task State Segment](https://en.wikipedia.org/wiki/Task_state_segment)
|
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* [Previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html)
|
||||
@@ -62,7 +62,7 @@ native_irq_return_iret:
|
||||
iretq
|
||||
```
|
||||
|
||||
More about the `idtentry` macro you can read in the third part of the [http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html) chapter. Ok, now we saw the preparation before an exception handler will be executed and now time to look on the handlers. First of all let's look on the following handlers:
|
||||
More about the `idtentry` macro you can read in the third part of the [http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html) chapter. Ok, now we saw the preparation before an exception handler will be executed and now time to look on the handlers. First of all let's look on the following handlers:
|
||||
|
||||
* divide_error
|
||||
* overflow
|
||||
@@ -211,7 +211,7 @@ static inline void conditional_sti(struct pt_regs *regs)
|
||||
}
|
||||
```
|
||||
|
||||
more about `local_irq_enable` macro you can read in the second [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-2.html) of this chapter. The next and last call in the `do_error_trap` is the `do_trap` function. First of all the `do_trap` function defined the `tsk` variable which has `task_struct` type and represents the current interrupted process. After the definition of the `tsk`, we can see the call of the `do_trap_no_signal` function:
|
||||
more about `local_irq_enable` macro you can read in the second [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-2.html) of this chapter. The next and last call in the `do_error_trap` is the `do_trap` function. First of all the `do_trap` function defined the `tsk` variable which has `task_struct` type and represents the current interrupted process. After the definition of the `tsk`, we can see the call of the `do_trap_no_signal` function:
|
||||
|
||||
```C
|
||||
struct task_struct *tsk = current;
|
||||
@@ -463,7 +463,7 @@ That's all.
|
||||
Conclusion
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
It is the end of the fifth part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) chapter and we saw implementation of some interrupt handlers in this part. In the next part we will continue to dive into interrupt and exception handlers and will see handler for the [Non-Maskable Interrupts](https://en.wikipedia.org/wiki/Non-maskable_interrupt), handling of the math [coprocessor](https://en.wikipedia.org/wiki/Coprocessor) and [SIMD](https://en.wikipedia.org/wiki/SIMD) coprocessor exceptions and many many more.
|
||||
It is the end of the fifth part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) chapter and we saw implementation of some interrupt handlers in this part. In the next part we will continue to dive into interrupt and exception handlers and will see handler for the [Non-Maskable Interrupts](https://en.wikipedia.org/wiki/Non-maskable_interrupt), handling of the math [coprocessor](https://en.wikipedia.org/wiki/Coprocessor) and [SIMD](https://en.wikipedia.org/wiki/SIMD) coprocessor exceptions and many many more.
|
||||
|
||||
If you have any questions or suggestions write me a comment or ping me at [twitter](https://twitter.com/0xAX).
|
||||
|
||||
@@ -490,4 +490,4 @@ Links
|
||||
* [x87 FPU](https://en.wikipedia.org/wiki/X87)
|
||||
* [control register](https://en.wikipedia.org/wiki/Control_register)
|
||||
* [MMX](https://en.wikipedia.org/wiki/MMX_%28instruction_set%29)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-4.html)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-4.html)
|
||||
@@ -4,7 +4,7 @@ Interrupts and Interrupt Handling. Part 6.
|
||||
Non-maskable interrupt handler
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
It is sixth part of the [Interrupts and Interrupt Handling in the Linux kernel](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) chapter and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-5.html) we saw implementation of some exception handlers for the [General Protection Fault](https://en.wikipedia.org/wiki/General_protection_fault) exception, divide exception, invalid [opcode](https://en.wikipedia.org/wiki/Opcode) exceptions and etc. As I wrote in the previous part we will see implementations of the rest exceptions in this part. We will see implementation of the following handlers:
|
||||
It is sixth part of the [Interrupts and Interrupt Handling in the Linux kernel](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) chapter and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-5.html) we saw implementation of some exception handlers for the [General Protection Fault](https://en.wikipedia.org/wiki/General_protection_fault) exception, divide exception, invalid [opcode](https://en.wikipedia.org/wiki/Opcode) exceptions and etc. As I wrote in the previous part we will see implementations of the rest exceptions in this part. We will see implementation of the following handlers:
|
||||
|
||||
* [Non-Maskable](https://en.wikipedia.org/wiki/Non-maskable_interrupt) interrupt;
|
||||
* [BOUND](http://pdos.csail.mit.edu/6.828/2005/readings/i386/BOUND.htm) Range Exceeded Exception;
|
||||
@@ -21,13 +21,13 @@ A [Non-Maskable](https://en.wikipedia.org/wiki/Non-maskable_interrupt) interrupt
|
||||
* External hardware asserts the non-maskable interrupt [pin](https://en.wikipedia.org/wiki/CPU_socket) on the CPU.
|
||||
* The processor receives a message on the system bus or the APIC serial bus with a delivery mode `NMI`.
|
||||
|
||||
When the processor receives a `NMI` from one of these sources, the processor handles it immediately by calling the `NMI` handler pointed to by interrupt vector which has number `2` (see table in the first [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html)). We already filled the [Interrupt Descriptor Table](https://en.wikipedia.org/wiki/Interrupt_descriptor_table) with the [vector number](https://en.wikipedia.org/wiki/Interrupt_vector_table), address of the `nmi` interrupt handler and `NMI_STACK` [Interrupt Stack Table entry](https://github.com/torvalds/linux/blob/master/Documentation/x86/kernel-stacks):
|
||||
When the processor receives a `NMI` from one of these sources, the processor handles it immediately by calling the `NMI` handler pointed to by interrupt vector which has number `2` (see table in the first [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html)). We already filled the [Interrupt Descriptor Table](https://en.wikipedia.org/wiki/Interrupt_descriptor_table) with the [vector number](https://en.wikipedia.org/wiki/Interrupt_vector_table), address of the `nmi` interrupt handler and `NMI_STACK` [Interrupt Stack Table entry](https://github.com/torvalds/linux/blob/master/Documentation/x86/kernel-stacks):
|
||||
|
||||
```C
|
||||
set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
|
||||
```
|
||||
|
||||
in the `trap_init` function which defined in the [arch/x86/kernel/traps.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/traps.c) source code file. In the previous [parts](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) we saw that entry points of the all interrupt handlers are defined with the:
|
||||
in the `trap_init` function which defined in the [arch/x86/kernel/traps.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/traps.c) source code file. In the previous [parts](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) we saw that entry points of the all interrupt handlers are defined with the:
|
||||
|
||||
```assembly
|
||||
.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1
|
||||
@@ -169,7 +169,7 @@ pushq $-1
|
||||
ALLOC_PT_GPREGS_ON_STACK
|
||||
```
|
||||
|
||||
We already saw implementation of the `ALLOC_PT_GREGS_ON_STACK` macro in the third part of the interrupts [chapter](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-3.html). This macro defined in the [arch/x86/entry/calling.h](https://github.com/torvalds/linux/blob/master/arch/x86/entry/calling.h) and yet another allocates `120` bytes on stack for the general purpose registers, from the `rdi` to the `r15`:
|
||||
We already saw implementation of the `ALLOC_PT_GREGS_ON_STACK` macro in the third part of the interrupts [chapter](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-3.html). This macro defined in the [arch/x86/entry/calling.h](https://github.com/torvalds/linux/blob/master/arch/x86/entry/calling.h) and yet another allocates `120` bytes on stack for the general purpose registers, from the `rdi` to the `r15`:
|
||||
|
||||
```assembly
|
||||
.macro ALLOC_PT_GPREGS_ON_STACK addskip=0
|
||||
@@ -325,7 +325,7 @@ exception_exit(prev_state);
|
||||
return;
|
||||
```
|
||||
|
||||
After we have got the state of the previous context, we add the exception to the `notify_die` chain and if it will return `NOTIFY_STOP` we return from the exception. More about notify chains and the `context tracking` functions you can read in the [previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-5.html). In the next step we enable interrupts if they were disabled with the `contidional_sti` function that checks `IF` flag and call the `local_irq_enable` depends on its value:
|
||||
After we have got the state of the previous context, we add the exception to the `notify_die` chain and if it will return `NOTIFY_STOP` we return from the exception. More about notify chains and the `context tracking` functions you can read in the [previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-5.html). In the next step we enable interrupts if they were disabled with the `contidional_sti` function that checks `IF` flag and call the `local_irq_enable` depends on its value:
|
||||
|
||||
```C
|
||||
conditional_sti(regs);
|
||||
@@ -446,7 +446,7 @@ That's all.
|
||||
Conclusion
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
It is the end of the sixth part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) chapter and we saw implementation of some exception handlers in this part, like `non-maskable` interrupt, [SIMD](https://en.wikipedia.org/wiki/SIMD) and [x87 FPU](https://en.wikipedia.org/wiki/X87) floating point exception. Finally we have finsihed with the `trap_init` function in this part and will go ahead in the next part. The next our point is the external interrupts and the `early_irq_init` function from the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c).
|
||||
It is the end of the sixth part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) chapter and we saw implementation of some exception handlers in this part, like `non-maskable` interrupt, [SIMD](https://en.wikipedia.org/wiki/SIMD) and [x87 FPU](https://en.wikipedia.org/wiki/X87) floating point exception. Finally we have finsihed with the `trap_init` function in this part and will go ahead in the next part. The next our point is the external interrupts and the `early_irq_init` function from the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c).
|
||||
|
||||
If you have any questions or suggestions write me a comment or ping me at [twitter](https://twitter.com/0xAX).
|
||||
|
||||
@@ -477,4 +477,4 @@ Links
|
||||
* [RCU](https://en.wikipedia.org/wiki/Read-copy-update)
|
||||
* [MPX](https://en.wikipedia.org/wiki/Intel_MPX)
|
||||
* [x87 FPU](https://en.wikipedia.org/wiki/X87)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-5.html)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-5.html)
|
||||
@@ -4,7 +4,7 @@ Interrupts and Interrupt Handling. Part 7.
|
||||
Introduction to external interrupts
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
This is the seventh part of the Interrupts and Interrupt Handling in the Linux kernel [chapter](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-6.html) we have finished with the exceptions which are generated by the processor. In this part we will continue to dive to the interrupt handling and will start with the external hardware interrupt handling. As you can remember, in the previous part we have finished with the `trap_init` function from the [arch/x86/kernel/trap.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/traps.c) and the next step is the call of the `early_irq_init` function from the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c).
|
||||
This is the seventh part of the Interrupts and Interrupt Handling in the Linux kernel [chapter](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-6.html) we have finished with the exceptions which are generated by the processor. In this part we will continue to dive to the interrupt handling and will start with the external hardware interrupt handling. As you can remember, in the previous part we have finished with the `trap_init` function from the [arch/x86/kernel/trap.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/traps.c) and the next step is the call of the `early_irq_init` function from the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c).
|
||||
|
||||
Interrupts are signal that are sent across [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_%28PC_architecture%29) or `Interrupt Request Line` by a hardware or software. External hardware interrupts allow devices like keyboard, mouse and etc, to indicate that it needs attention of the processor. Once the processor receives the `Interrupt Request`, it will temporary stop execution of the running program and invoke special routine which depends on an interrupt. We already know that this routine is called interrupt handler (or how we will call it `ISR` or `Interrupt Service Routine` from this part). The `ISR` or `Interrupt Handler Routine` can be found in Interrupt Vector table that is located at fixed address in the memory. After the interrupt is handled processor resumes the interrupted process. At the boot/initialization time, the Linux kernel identifies all devices in the machine, and appropriate interrupt handlers are loaded into the interrupt table. As we saw in the previous parts, most exceptions are handled simply by the sending a [Unix signal](https://en.wikipedia.org/wiki/Unix_signal) to the interrupted process. That's why kernel is can handle an exception quickly. Unfortunately we can not use this approach for the external hardware interrupts, because often they arrive after (and sometimes long after) the process to which they are related has been suspended. So it would make no sense to send a Unix signal to the current process. External interrupt handling depends on the type of an interrupt:
|
||||
|
||||
@@ -434,7 +434,7 @@ That's all.
|
||||
Conclusion
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
It is the end of the seventh part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) chapter and we started to dive into external hardware interrupts in this part. We saw early initialization of the `irq_desc` structure which represents description of an external interrupt and contains information about it like list of irq actions, information about interrupt handler, interrupt's owner, count of the unhandled interrupt and etc. In the next part we will continue to research external interrupts.
|
||||
It is the end of the seventh part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) chapter and we started to dive into external hardware interrupts in this part. We saw early initialization of the `irq_desc` structure which represents description of an external interrupt and contains information about it like list of irq actions, information about interrupt handler, interrupt's owner, count of the unhandled interrupt and etc. In the next part we will continue to research external interrupts.
|
||||
|
||||
If you have any questions or suggestions write me a comment or ping me at [twitter](https://twitter.com/0xAX).
|
||||
|
||||
@@ -4,7 +4,7 @@ Interrupts and Interrupt Handling. Part 8.
|
||||
Non-early initialization of the IRQs
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
This is the eighth part of the Interrupts and Interrupt Handling in the Linux kernel [chapter](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-7.html) we started to dive into the external hardware [interrupts](https://en.wikipedia.org/wiki/Interrupt_request_%28PC_architecture%29). We looked on the implementation of the `early_irq_init` function from the [kernel/irq/irqdesc.c](https://github.com/torvalds/linux/blob/master/kernel/irq/irqdesc.c) source code file and saw the initialization of the `irq_desc` structure in this function. Remind that `irq_desc` structure (defined in the [include/linux/irqdesc.h](https://github.com/torvalds/linux/blob/master/include/linux/irqdesc.h#L46) is the foundation of interrupt management code in the Linux kernel and represents an interrupt descriptor. In this part we will continue to dive into the initialization stuff which is related to the external hardware interrupts.
|
||||
This is the eighth part of the Interrupts and Interrupt Handling in the Linux kernel [chapter](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) and in the previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-7.html) we started to dive into the external hardware [interrupts](https://en.wikipedia.org/wiki/Interrupt_request_%28PC_architecture%29). We looked on the implementation of the `early_irq_init` function from the [kernel/irq/irqdesc.c](https://github.com/torvalds/linux/blob/master/kernel/irq/irqdesc.c) source code file and saw the initialization of the `irq_desc` structure in this function. Remind that `irq_desc` structure (defined in the [include/linux/irqdesc.h](https://github.com/torvalds/linux/blob/master/include/linux/irqdesc.h#L46) is the foundation of interrupt management code in the Linux kernel and represents an interrupt descriptor. In this part we will continue to dive into the initialization stuff which is related to the external hardware interrupts.
|
||||
|
||||
Right after the call of the `early_irq_init` function in the [init/main.c](https://github.com/torvalds/linux/blob/master/init/main.c) we can see the call of the `init_IRQ` function. This function is architecture-specific and defined in the [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/kernel/irqinit.c). The `init_IRQ` function makes initialization of the `vector_irq` [percpu](http://0xax.gitbooks.io/linux-insides/content/Concepts/per-cpu.html) variable that defined in the same [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/kernel/irqinit.c) source code file:
|
||||
|
||||
@@ -22,7 +22,7 @@ and represents `percpu` array of the interrupt vector numbers. The `vector_irq_t
|
||||
typedef int vector_irq_t[NR_VECTORS];
|
||||
```
|
||||
|
||||
where `NR_VECTORS` is count of the vector number and as you can remember from the first [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html) of this chapter it is `256` for the [x86_64](https://en.wikipedia.org/wiki/X86-64):
|
||||
where `NR_VECTORS` is count of the vector number and as you can remember from the first [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html) of this chapter it is `256` for the [x86_64](https://en.wikipedia.org/wiki/X86-64):
|
||||
|
||||
```C
|
||||
#define NR_VECTORS 256
|
||||
@@ -105,7 +105,7 @@ In the loop we are accessing the `vecto_irq` per-cpu array with the `per_cpu` ma
|
||||
#define IRQ0_VECTOR ((FIRST_EXTERNAL_VECTOR + 16) & ~15)
|
||||
```
|
||||
|
||||
Why is `0x30` here? You can remember from the first [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-1.html) of this chapter that first 32 vector numbers from `0` to `31` are reserved by the processor and used for the processing of architecture-defined exceptions and interrupts. Vector numbers from `0x30` to `0x3f` are reserved for the [ISA](https://en.wikipedia.org/wiki/Industry_Standard_Architecture). So, it means that we fill the `vector_irq` from the `IRQ0_VECTOR` which is equal to the `32` to the `IRQ0_VECTOR + 16` (before the `0x30`).
|
||||
Why is `0x30` here? You can remember from the first [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-1.html) of this chapter that first 32 vector numbers from `0` to `31` are reserved by the processor and used for the processing of architecture-defined exceptions and interrupts. Vector numbers from `0x30` to `0x3f` are reserved for the [ISA](https://en.wikipedia.org/wiki/Industry_Standard_Architecture). So, it means that we fill the `vector_irq` from the `IRQ0_VECTOR` which is equal to the `32` to the `IRQ0_VECTOR + 16` (before the `0x30`).
|
||||
|
||||
In the end of the `init_IRQ` function we can see the call of the following function:
|
||||
|
||||
@@ -241,7 +241,7 @@ do { \
|
||||
} while (0)
|
||||
```
|
||||
|
||||
As we can see, first of all it expands to the call of the `alloc_system_vector` function that checks the given vector number in the `user_vectors` bitmap (read previous [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-7.html) about it) and if it is not set in the `user_vectors` bitmap we set it. After this we test that the `first_system_vector` is greater than given interrupt vector number and if it is greater we assign it:
|
||||
As we can see, first of all it expands to the call of the `alloc_system_vector` function that checks the given vector number in the `user_vectors` bitmap (read previous [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-7.html) about it) and if it is not set in the `user_vectors` bitmap we set it. After this we test that the `first_system_vector` is greater than given interrupt vector number and if it is greater we assign it:
|
||||
|
||||
```C
|
||||
if (!test_bit(vector, used_vectors)) {
|
||||
@@ -399,7 +399,7 @@ for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
|
||||
set_bit(i, used_vectors);
|
||||
```
|
||||
|
||||
You can remember how we did it in the sixth [part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-6.html) of this chapter.
|
||||
You can remember how we did it in the sixth [part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-6.html) of this chapter.
|
||||
|
||||
In the end of the `native_init_IRQ` function we can see the following check:
|
||||
|
||||
@@ -509,7 +509,7 @@ That's all.
|
||||
Conclusion
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
It is the end of the eighth part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/interrupts/index.html) chapter and we continued to dive into external hardware interrupts in this part. In the previous part we started to do it and saw early initialization of the `IRQs`. In this part we already saw non-early interrupts initialization in the `init_IRQ` function. We saw initialization of the `vector_irq` per-cpu array which is store vector numbers of the interrupts and will be used during interrupt handling and initialization of other stuff which is related to the external hardware interrupts.
|
||||
It is the end of the eighth part of the [Interrupts and Interrupt Handling](http://0xax.gitbooks.io/linux-insides/content/Interrupts/index.html) chapter and we continued to dive into external hardware interrupts in this part. In the previous part we started to do it and saw early initialization of the `IRQs`. In this part we already saw non-early interrupts initialization in the `init_IRQ` function. We saw initialization of the `vector_irq` per-cpu array which is store vector numbers of the interrupts and will be used during interrupt handling and initialization of other stuff which is related to the external hardware interrupts.
|
||||
|
||||
In the next part we will continue to learn interrupts handling related stuff and will see initialization of the `softirqs`.
|
||||
|
||||
@@ -539,4 +539,4 @@ Links
|
||||
* [Open Firmware](https://en.wikipedia.org/wiki/Open_Firmware)
|
||||
* [devicetree](https://en.wikipedia.org/wiki/Device_tree)
|
||||
* [RTC](https://en.wikipedia.org/wiki/Real-time_clock)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-7.html)
|
||||
* [Previous part](http://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-7.html)
|
||||
@@ -4,7 +4,7 @@
|
||||
延后中断(软中断，Tasklets 和工作队列)介绍
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
这是 Linux 内核[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html)的第九节，在[上一节](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-8.html)我们分析了源文件 [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/irqinit.c) 中的 `init_IRQ` 实现。接下来的这一节我们将继续深入学习外部硬件中断的初始化。
|
||||
这是 Linux 内核[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html)的第九节，在[上一节](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-8.html)我们分析了源文件 [arch/x86/kernel/irqinit.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/irqinit.c) 中的 `init_IRQ` 实现。接下来的这一节我们将继续深入学习外部硬件中断的初始化。
|
||||
|
||||
中断处理会有一些特点，其中最主要的两个是：
|
||||
|
||||
@@ -144,7 +144,7 @@ void raise_softirq(unsigned int nr)
|
||||
__raise_softirq_irqoff(nr);
|
||||
```
|
||||
|
||||
然后，通过 `in_interrupt` 函数获得 `irq_count` 值。我们在这一章的第一[小节](https://www.gitbook.com/book/xinqiu/linux-insides-cn/content/interrupts/interrupts-1.html)已经知道它是用来检测一个 cpu 是否处于中断环境。如果我们处于中断上下文中，我们就退出 `raise_softirq_irqoff` 函数，装回 `IF` 标志位并允许当前处理器的中断。如果不在中断上下文中，就会调用 `wakeup_softirqd` 函数：
|
||||
然后，通过 `in_interrupt` 函数获得 `irq_count` 值。我们在这一章的第一[小节](https://www.gitbook.com/book/xinqiu/linux-insides-cn/content/Interrupts/interrupts-1.html)已经知道它是用来检测一个 cpu 是否处于中断环境。如果我们处于中断上下文中，我们就退出 `raise_softirq_irqoff` 函数，装回 `IF` 标志位并允许当前处理器的中断。如果不在中断上下文中，就会调用 `wakeup_softirqd` 函数：
|
||||
|
||||
```C
|
||||
if (!in_interrupt())
|
||||
@@ -363,7 +363,7 @@ static void tasklet_action(struct softirq_action *a)
|
||||
}
|
||||
```
|
||||
|
||||
在 `tasklet_action` 开始时利用 `local_irq_disable` 宏禁用了当前处理器的中断(你可以阅读本书[第二部分](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-2.html)了解更多关于此宏的信息)。接下来获取到当前处理器对应的普通优先级 tasklet 列表并把它设置为 `NULL` ，这是因为所有的 tasklet 都将被执行。然后使能当前处理器的中断，循环遍历 tasklet 列表，每一次遍历都会对当前 tasklet 调用 `tasklet_trylock` 函数来更新它的状态为 `TASKLET_STATE_RUN`：
|
||||
在 `tasklet_action` 开始时利用 `local_irq_disable` 宏禁用了当前处理器的中断(你可以阅读本书[第二部分](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-2.html)了解更多关于此宏的信息)。接下来获取到当前处理器对应的普通优先级 tasklet 列表并把它设置为 `NULL` ，这是因为所有的 tasklet 都将被执行。然后使能当前处理器的中断，循环遍历 tasklet 列表，每一次遍历都会对当前 tasklet 调用 `tasklet_trylock` 函数来更新它的状态为 `TASKLET_STATE_RUN`：
|
||||
|
||||
```C
|
||||
static inline int tasklet_trylock(struct tasklet_struct *t)
|
||||
@@ -505,7 +505,7 @@ insert_work(pwq, work, worklist, work_flags);
|
||||
总结
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
现在结束了[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html)的第九节。这一节中我们继续讨论了外部硬件中断。在之前部分我们看到了 `IRQs` 的初始化和 `irq_desc` 数据结构，在这一节我们看到了用于延后函数的三个概念：`软中断`，`tasklet` 和`工作队列`。
|
||||
现在结束了[中断和中断处理](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html)的第九节。这一节中我们继续讨论了外部硬件中断。在之前部分我们看到了 `IRQs` 的初始化和 `irq_desc` 数据结构，在这一节我们看到了用于延后函数的三个概念：`软中断`，`tasklet` 和`工作队列`。
|
||||
|
||||
下一节将是 `中断和中断处理` 的最后一节。我们将会了解真正的硬件驱动，并试着学习它是怎样和中断子系统一起工作的。
|
||||
|
||||
@@ -523,4 +523,4 @@ insert_work(pwq, work, worklist, work_flags);
|
||||
* [CPU masks](http://xinqiu.gitbooks.io/linux-insides-cn/content/Concepts/cpumask.html)
|
||||
* [per-cpu](http://xinqiu.gitbooks.io/linux-insides-cn/content/Concepts/per-cpu.html)
|
||||
* [Workqueue](https://github.com/torvalds/linux/blob/master/Documentation/workqueue.txt)
|
||||
* [Previous part](http://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-8.html)
|
||||
* [Previous part](http://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-8.html)
|
||||
@@ -337,7 +337,7 @@ Last two steps of the `kmemcheck_fault` function is to call the `kmemcheck_acces
|
||||
static struct kmemcheck_error error_fifo[CONFIG_KMEMCHECK_QUEUE_SIZE];
|
||||
```
|
||||
|
||||
The `kmemcheck` mechanism declares special [tasklet](https://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-9.html):
|
||||
The `kmemcheck` mechanism declares special [tasklet](https://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-9.html):
|
||||
|
||||
```C
|
||||
static DECLARE_TASKLET(kmemcheck_tasklet, &do_wakeup, 0);
|
||||
@@ -429,6 +429,6 @@ Links
|
||||
* [translation lookaside buffer](https://en.wikipedia.org/wiki/Translation_lookaside_buffer)
|
||||
* [per-cpu variables](https://0xax.gitbooks.io/linux-insides/content/Concepts/per-cpu.html)
|
||||
* [flags register](https://en.wikipedia.org/wiki/FLAGS_register)
|
||||
* [tasklet](https://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-9.html)
|
||||
* [tasklet](https://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-9.html)
|
||||
* [Paging](http://0xax.gitbooks.io/linux-insides/content/Theory/Paging.html)
|
||||
* [Previous part](https://0xax.gitbooks.io/linux-insides/content/mm/linux-mm-2.html)
|
||||
|
||||
22
SUMMARY.md
22
SUMMARY.md
@@ -18,17 +18,17 @@
|
||||
* [Scheduler initialization](Initialization/linux-initialization-8.md)
|
||||
* [RCU initialization](Initialization/linux-initialization-9.md)
|
||||
* [End of initialization](Initialization/linux-initialization-10.md)
|
||||
* [Interrupts](interrupts/README.md)
|
||||
* [Introduction](interrupts/interrupts-1.md)
|
||||
* [Start to dive into interrupts](interrupts/interrupts-2.md)
|
||||
* [Interrupt handlers](interrupts/interrupts-3.md)
|
||||
* [Initialization of non-early interrupt gates](interrupts/interrupts-4.md)
|
||||
* [Implementation of some exception handlers](interrupts/interrupts-5.md)
|
||||
* [Handling Non-Maskable interrupts](interrupts/interrupts-6.md)
|
||||
* [Dive into external hardware interrupts](interrupts/interrupts-7.md)
|
||||
* [Initialization of external hardware interrupts structures](interrupts/interrupts-8.md)
|
||||
* [Softirq, Tasklets and Workqueues](interrupts/interrupts-9.md)
|
||||
* [Last part](interrupts/interrupts-10.md)
|
||||
* [Interrupts](Interrupts/README.md)
|
||||
* [Introduction](Interrupts/interrupts-1.md)
|
||||
* [Start to dive into interrupts](Interrupts/interrupts-2.md)
|
||||
* [Interrupt handlers](Interrupts/interrupts-3.md)
|
||||
* [Initialization of non-early interrupt gates](Interrupts/interrupts-4.md)
|
||||
* [Implementation of some exception handlers](Interrupts/interrupts-5.md)
|
||||
* [Handling Non-Maskable interrupts](Interrupts/interrupts-6.md)
|
||||
* [Dive into external hardware interrupts](Interrupts/interrupts-7.md)
|
||||
* [Initialization of external hardware interrupts structures](Interrupts/interrupts-8.md)
|
||||
* [Softirq, Tasklets and Workqueues](Interrupts/interrupts-9.md)
|
||||
* [Last part](Interrupts/interrupts-10.md)
|
||||
* [System calls](SysCall/README.md)
|
||||
* [Introduction to system calls](SysCall/syscall-1.md)
|
||||
* [How the Linux kernel handles a system call](SysCall/syscall-2.md)
|
||||
|
||||
@@ -303,7 +303,7 @@ static inline void raw_write_seqcount_end(seqcount_t *s)
|
||||
|
||||
and in the end we just call the `spin_unlock` macro to give access for other readers or writers.
|
||||
|
||||
That's all about `sequential lock` mechanism in the Linux kernel. Of course we did not consider full [API](https://en.wikipedia.org/wiki/Application_programming_interface) of this mechanism in this part. But all other functions are based on these which we described here. For example, Linux kernel also provides some safe macros/functions to use `sequential lock` mechanism in [interrupt handlers](https://en.wikipedia.org/wiki/Interrupt_handler) of [softirq](https://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-9.html): `write_seqclock_irq` and `write_sequnlock_irq`:
|
||||
That's all about `sequential lock` mechanism in the Linux kernel. Of course we did not consider full [API](https://en.wikipedia.org/wiki/Application_programming_interface) of this mechanism in this part. But all other functions are based on these which we described here. For example, Linux kernel also provides some safe macros/functions to use `sequential lock` mechanism in [interrupt handlers](https://en.wikipedia.org/wiki/Interrupt_handler) of [softirq](https://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-9.html): `write_seqclock_irq` and `write_sequnlock_irq`:
|
||||
|
||||
```C
|
||||
static inline void write_seqlock_irq(seqlock_t *sl)
|
||||
@@ -347,6 +347,6 @@ Links
|
||||
* [x86_64](https://en.wikipedia.org/wiki/X86-64)
|
||||
* [Timers and time management in the Linux kernel](https://0xax.gitbooks.io/linux-insides/content/Timers/)
|
||||
* [interrupt handlers](https://en.wikipedia.org/wiki/Interrupt_handler)
|
||||
* [softirq](https://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-9.html)
|
||||
* [softirq](https://0xax.gitbooks.io/linux-insides/content/Interrupts/interrupts-9.html)
|
||||
* [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_(PC_architecture))
|
||||
* [Previous part](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-5.html)
|
||||
|
||||
@@ -4,7 +4,7 @@ Linux 内核系统调用 第一节
|
||||
简介
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
这次提交为 [linux-insides](http://xinqiu.gitbooks.io/linux-insides-cn/content/) 添加一个新的章节，从标题就可以知道, 这一章节将介绍Linux 内核中 [System Call](https://en.wikipedia.org/wiki/System_call) 的概念。章节内容的选择并非偶然。在前一[章节](http://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html)我们了解了中断及中断处理。系统调用的概念与中断非常相似，这是因为软件中断是执行系统调用最常见的方式。我们将讨论系统调用概念的各个方面。例如，用户空间发起系统调用的细节，内核中一组系统调用处理器的执行过程, [VDSO](https://en.wikipedia.org/wiki/VDSO) 和 [vsyscall](https://lwn.net/Articles/446528/) 概念以及其他信息。
|
||||
这次提交为 [linux-insides](http://xinqiu.gitbooks.io/linux-insides-cn/content/) 添加一个新的章节，从标题就可以知道, 这一章节将介绍Linux 内核中 [System Call](https://en.wikipedia.org/wiki/System_call) 的概念。章节内容的选择并非偶然。在前一[章节](http://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html)我们了解了中断及中断处理。系统调用的概念与中断非常相似，这是因为软件中断是执行系统调用最常见的方式。我们将讨论系统调用概念的各个方面。例如，用户空间发起系统调用的细节，内核中一组系统调用处理器的执行过程, [VDSO](https://en.wikipedia.org/wiki/VDSO) 和 [vsyscall](https://lwn.net/Articles/446528/) 概念以及其他信息。
|
||||
|
||||
在了解 Linux 内核系统调用执行过程之前，了解一些系统调用的原理是有帮助的。我们从下面的段落开始。
|
||||
|
||||
@@ -403,4 +403,4 @@ fdput_pos(f);
|
||||
* [Virtual file system](https://en.wikipedia.org/wiki/Virtual_file_system)
|
||||
* [systemd](https://en.wikipedia.org/wiki/Systemd)
|
||||
* [epoll](https://en.wikipedia.org/wiki/Epoll)
|
||||
* [Previous chapter](http://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html)
|
||||
* [Previous chapter](http://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html)
|
||||
|
||||
@@ -114,7 +114,7 @@ asmlinkage const sys_call_ptr_t sys_call_table[__NR_syscall_max+1] = {
|
||||
|
||||
之后所有指向“ non-implemented ”系统调用元素的内容为 `sys_ni_syscall` 函数的地址，该函数仅返回 `-ENOSYS` 。 其他元素指向 `sys_syscall_name` 函数。
|
||||
|
||||
至此, 完成系统调用表的填充并且 Linux内核了解系统调用处理器的为值。但是 Linux 内核在处理用户空间程序的系统调用时并未立即调用 `sys_syscall_name` 函数。 记住关于中断及中断处理的 [章节](http://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/index.html)。当 Linux 内核获得处理中断的控制权, 在调用中断处理程序前，必须做一些准备如保存用户空间寄存器，切换至新的堆栈及其他很多工作。系统调用处理也是相同的情形。第一件事是处理系统调用的准备，但是在 Linux 内核开始这些准备之前, 系统调用的入口必须完成初始化，同时只有 Linux 内核知道如何执行这些准备。在下一章节我们将关注 Linux 内核中关于系统调用入口的初始化过程。
|
||||
至此, 完成系统调用表的填充并且 Linux内核了解系统调用处理器的为值。但是 Linux 内核在处理用户空间程序的系统调用时并未立即调用 `sys_syscall_name` 函数。 记住关于中断及中断处理的 [章节](http://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/index.html)。当 Linux 内核获得处理中断的控制权, 在调用中断处理程序前，必须做一些准备如保存用户空间寄存器，切换至新的堆栈及其他很多工作。系统调用处理也是相同的情形。第一件事是处理系统调用的准备，但是在 Linux 内核开始这些准备之前, 系统调用的入口必须完成初始化，同时只有 Linux 内核知道如何执行这些准备。在下一章节我们将关注 Linux 内核中关于系统调用入口的初始化过程。
|
||||
|
||||
系统调用入口初始化
|
||||
--------------------------------------------------------------------------------
|
||||
@@ -126,7 +126,7 @@ SYSCALL 引起操作系统系统调用处理器处于特权级0，通过加载IA
|
||||
|
||||
```
|
||||
|
||||
这就是说我们需要将系统调用入口放置到 `IA32_LSTAR` [model specific register](https://en.wikipedia.org/wiki/Model-specific_register) 。 这一操作在 Linux 内核初始过程时完成。若已阅读关于 Linux 内核中断及中断处理政界的 [第四节](http://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-4.html) , Linux 内核调用在初始化过程中调用 `trap_init` 函数。该函数在 [arch/x86/kernel/setup.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/setup.c) 源代码文件中定义，执行 `non-early` 异常处理（如除法错误，[协处理器](https://en.wikipedia.org/wiki/Coprocessor) 错误等 ）的初始化。除了 `non-early` 异常处理的初始化外, 函数调用 [arch/x86/kernel/cpu/common.c](https://github.com/torvalds/linux/blob/master/blob/arch/x86/kernel/cpu/common.c) 中 `cpu_init` 函数，调用相同源码文件中的 `syscall_init` 完成`per-cpu` 状态初始化。
|
||||
这就是说我们需要将系统调用入口放置到 `IA32_LSTAR` [model specific register](https://en.wikipedia.org/wiki/Model-specific_register) 。 这一操作在 Linux 内核初始过程时完成。若已阅读关于 Linux 内核中断及中断处理政界的 [第四节](http://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-4.html) , Linux 内核调用在初始化过程中调用 `trap_init` 函数。该函数在 [arch/x86/kernel/setup.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/setup.c) 源代码文件中定义，执行 `non-early` 异常处理（如除法错误，[协处理器](https://en.wikipedia.org/wiki/Coprocessor) 错误等 ）的初始化。除了 `non-early` 异常处理的初始化外, 函数调用 [arch/x86/kernel/cpu/common.c](https://github.com/torvalds/linux/blob/master/blob/arch/x86/kernel/cpu/common.c) 中 `cpu_init` 函数，调用相同源码文件中的 `syscall_init` 完成`per-cpu` 状态初始化。
|
||||
|
||||
该函数执行系统调用入口的初始化。查看函数的实现，函数没有参数且首先填充两个特殊模块寄存器：
|
||||
|
||||
|
||||
@@ -240,7 +240,7 @@ The last step in the `init_timers` function is the call of the:
|
||||
open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
|
||||
```
|
||||
|
||||
function. The `open_softirq` function may be already familar to you if you have read the ninth [part](https://xinqiu.gitbooks.io/linux-insides-cn/content/interrupts/interrupts-9.html) about the interrupts and interrupt handling in the Linux kernel. In short words, the `open_softirq` function defined in the [kernel/softirq.c](https://github.com/torvalds/linux/blob/master/kernel/softirq.c) source code file and executes initialization of the deferred interrupt handler.
|
||||
function. The `open_softirq` function may be already familar to you if you have read the ninth [part](https://xinqiu.gitbooks.io/linux-insides-cn/content/Interrupts/interrupts-9.html) about the interrupts and interrupt handling in the Linux kernel. In short words, the `open_softirq` function defined in the [kernel/softirq.c](https://github.com/torvalds/linux/blob/master/kernel/softirq.c) source code file and executes initialization of the deferred interrupt handler.
|
||||
|
||||
In our case the deferred function is the `run_timer_softirq` function that is will be called after a hardware interrupt in the `do_IRQ` function which defined in the [arch/x86/kernel/irq.c](https://github.com/torvalds/linux/blob/master/arch/x86/kernel/irq.c) source code file. The main point of this function is to handle a software dynamic timer. The Linux kernel does not do this thing during the hardware timer interrupt handling because this is time consuming operation.
|
||||
|
||||
|
||||
Reference in New Issue
Block a user