From 93dd23b65dd8819c850055ab8941308d41e52628 Mon Sep 17 00:00:00 2001 From: wuyuxin Date: Mon, 16 Nov 2020 20:31:05 +0800 Subject: [PATCH] Update linux-initialization-2.md --- Initialization/linux-initialization-2.md | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/Initialization/linux-initialization-2.md b/Initialization/linux-initialization-2.md index 55c1b17..4046604 100644 --- a/Initialization/linux-initialization-2.md +++ b/Initialization/linux-initialization-2.md @@ -115,7 +115,11 @@ Where: * `Offset` - is offset to entry point of an interrupt handler; * `DPL` - Descriptor Privilege Level; * `P` - Segment Present flag; -* `Segment selector` - a code segment selector in GDT or LDT +* `Segment selector` - a code segment selector in GDT or LDT (actually it always point to GDT in linux) +```C +#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) // 0000 0000 0001 0000 +#define GDT_ENTRY_KERNEL_CS 2 +``` * `IST` - provides ability to switch to a new stack for interrupts handling. And the last `Type` field describes type of the `IDT` entry. There are three different kinds of gates for interrupts: @@ -164,7 +168,7 @@ where `NUM_EXCEPTION_VECTORS` expands to `32`. As we can see, We're filling only and inserts an interrupt gate to the `IDT` table which is represented by the `&idt_descr` array. -The `early_idt_handler_array` array is declaredd in the [arch/x86/include/asm/segment.h](https://github.com/torvalds/linux/blob/master/arch/x86/include/asm/segment.h) header file and contains addresses of the first `32` exception handlers: +The `early_idt_handler_array` array is declared in the [arch/x86/include/asm/segment.h](https://github.com/torvalds/linux/blob/master/arch/x86/include/asm/segment.h) header file and contains addresses of the first `32` exception handlers: ```C #define EARLY_IDT_HANDLER_SIZE 9