linux异常处理流程 ===================== linux异常处理与裸流程基本是一样的 1. 设置好异常向量表(把异常向量表放在异常向量的位置) 2. 写异常处理函数 3. 执行异常处理 - 异常向量表在启动过程中的流程所在的位置 :: start_kernel() ... local_irq_disable() ... setup_arch(&command_line) paging_init devicemaps_init early_trap_init(vectors) //设置异常向量表 ... trap_init() ... early_irq_init() init_IRQ() ... local_irq_enabled() 异常向量表的建立 ----------------- :: void __init early_trap_init(void *vectors_base) { #ifndef CONFIG_CPU_V7M unsigned long vectors = (unsigned long)vectors_base; //异常向量表vectors的基址 extern char __stubs_start[], __stubs_end[]; //汇编和链接脚本定义的各异常处理的核心代码 extern char __vectors_start[], __vectors_end[]; //汇编中定义的异常向量表的标号 unsigned i; vectors_page = vectors_base; /* * Poison the vectors page with an undefined instruction. This * instruction is chosen to be undefined for both ARM and Thumb * ISAs. The Thumb version is an undefined instruction with a * branch back to the undefined instruction. */ for (i = 0; i < PAGE_SIZE / sizeof(u32); i++) ((u32 *)vectors_base)[i] = 0xe7fddef1; /* * Copy the vectors, stubs and kuser helpers (in entry-armv.S) * into the vector page, mapped at 0xffff0000, and ensure these * are visible to the instruction stream. */ //拷贝异常向量表到vectors起始地址 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start); //拷贝异常处理核心代码到异常向量表base+0x1000位置 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start); //从用户空间可以访问的内核段提供的用户代码拷贝到固定位置 kuser_init(vectors_base); //刷异常向量这两页，如果icache中有相关代码的话 flush_icache_range(vectors, vectors + PAGE_SIZE * 2); #else /* ifndef CONFIG_CPU_V7M */ /* * on V7-M there is no need to copy the vector table to a dedicated * memory area. The address is configurable and so a table in the kernel * image can be used. */ #endif } 异常向量表内容 --------------- 以下内容在 arch/arm/kernel/entry-armv.S中定义 :: .L__vectors_start: W(b) vector_rst //复位异常 W(b) vector_und //未定义指令异常 W(ldr) pc, .L__vectors_start + 0x1000 //软中断swi异常 W(b) vector_pabt //预取指异常 W(b) vector_dabt //数据异常(如访问没有权限的地址) W(b) vector_addrexcptn //保留，没使用 W(b) vector_irq //中断 W(b) vector_fiq //快速中断 .data .align 2 .globl cr_alignment cr_alignment: .space 4 以下内容在 arch/arm/kernel/vmlinux.lds.h中定义 :: #define ARM_VECTORS \ __vectors_start = .; \ .vectors 0xffff0000 : AT(__vectors_start) { \ *(.vectors) \ } \ . = __vectors_start + SIZEOF(.vectors); \ __vectors_end = .; \ \ __stubs_start = .; \ .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) { \ *(.stubs) \ } \ . = __stubs_start + SIZEOF(.stubs); \ __stubs_end = .; \ \ PROVIDE(vector_fiq_offset = vector_fiq - ADDR(.vectors)); vectors_start开始位置为0xffff0000 异常的初步跳转分析 ------------------ :: vector_rst: ARM( swi SYS_ERROR0 ) //复位异常，这里执行软中断异常 THUMB( svc #0 ) THUMB( nop ) b vector_und /* * Interrupt dispatcher //irq中断处理 */ vector_stub irq, IRQ_MODE, 4 .long __irq_usr @ 0 (USR_26 / USR_32) .long __irq_invalid @ 1 (FIQ_26 / FIQ_32) .long __irq_invalid @ 2 (IRQ_26 / IRQ_32) .long __irq_svc @ 3 (SVC_26 / SVC_32) .long __irq_invalid @ 4 .long __irq_invalid @ 5 .long __irq_invalid @ 6 .long __irq_invalid @ 7 .long __irq_invalid @ 8 .long __irq_invalid @ 9 .long __irq_invalid @ a .long __irq_invalid @ b .long __irq_invalid @ c .long __irq_invalid @ d .long __irq_invalid @ e .long __irq_invalid @ f /* * Data abort dispatcher * Enter in ABT mode, spsr = USR CPSR, lr = USR PC */ //数据异常 vector_stub dabt, ABT_MODE, 8 .long __dabt_usr @ 0 (USR_26 / USR_32) .long __dabt_invalid @ 1 (FIQ_26 / FIQ_32) .long __dabt_invalid @ 2 (IRQ_26 / IRQ_32) .long __dabt_svc @ 3 (SVC_26 / SVC_32) .long __dabt_invalid @ 4 .long __dabt_invalid @ 5 .long __dabt_invalid @ 6 .long __dabt_invalid @ 7 .long __dabt_invalid @ 8 .long __dabt_invalid @ 9 .long __dabt_invalid @ a .long __dabt_invalid @ b .long __dabt_invalid @ c .long __dabt_invalid @ d .long __dabt_invalid @ e .long __dabt_invalid @ f /* * Prefetch abort dispatcher * Enter in ABT mode, spsr = USR CPSR, lr = USR PC */ //预取指异常 vector_stub pabt, ABT_MODE, 4 .long __pabt_usr @ 0 (USR_26 / USR_32) .long __pabt_invalid @ 1 (FIQ_26 / FIQ_32) .long __pabt_invalid @ 2 (IRQ_26 / IRQ_32) .long __pabt_svc @ 3 (SVC_26 / SVC_32) .long __pabt_invalid @ 4 .long __pabt_invalid @ 5 .long __pabt_invalid @ 6 .long __pabt_invalid @ 7 .long __pabt_invalid @ 8 .long __pabt_invalid @ 9 .long __pabt_invalid @ a .long __pabt_invalid @ b .long __pabt_invalid @ c .long __pabt_invalid @ d .long __pabt_invalid @ e .long __pabt_invalid @ f /* * Undef instr entry dispatcher * Enter in UND mode, spsr = SVC/USR CPSR, lr = SVC/USR PC */ //未定义异常 vector_stub und, UND_MODE .long __und_usr @ 0 (USR_26 / USR_32) .long __und_invalid @ 1 (FIQ_26 / FIQ_32) .long __und_invalid @ 2 (IRQ_26 / IRQ_32) .long __und_svc @ 3 (SVC_26 / SVC_32) .long __und_invalid @ 4 .long __und_invalid @ 5 .long __und_invalid @ 6 .long __und_invalid @ 7 .long __und_invalid @ 8 .long __und_invalid @ 9 .long __und_invalid @ a .long __und_invalid @ b .long __und_invalid @ c .long __und_invalid @ d .long __und_invalid @ e .long __und_invalid @ f .align 5 :: /* * Vector stubs. * * This code is copied to 0xffff1000 so we can use branches in the * vectors, rather than ldr's. Note that this code must not exceed * a page size. * * Common stub entry macro: * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC * * SP points to a minimal amount of processor-private memory, the address * of which is copied into r0 for the mode specific abort handler. */ //这是一个宏定义,上面代码中会用到此宏 .macro vector_stub, name, mode, correction=0 .align 5 vector_\name: .if \correction sub lr, lr, #\correction .endif @ @ Save r0, lr_ (parent PC) and spsr_ @ (parent CPSR) @ stmia sp, {r0, lr} @ save r0, lr mrs lr, spsr str lr, [sp, #8] @ save spsr @ @ Prepare for SVC32 mode. IRQs remain disabled. @ mrs r0, cpsr eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE) msr spsr_cxsf, r0 @ @ the branch table must immediately follow this code @ and lr, lr, #0x0f THUMB( adr r0, 1f ) THUMB( ldr lr, [r0, lr, lsl #2] ) mov r0, sp ARM( ldr lr, [pc, lr, lsl #2] ) movs pc, lr @ branch to handler in SVC mode ENDPROC(vector_\name) **irq中断** :: __irq_usr: usr_entry kuser_cmpxchg_check irq_handler get_thread_info tsk mov why, #0 b ret_to_user_from_irq UNWIND(.fnend ) ENDPROC(__irq_usr) user_entry ret_ro_user_from_irq等都在此文件中定义，此处不再列出 :: .macro irq_handler #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER ldr r1, =handle_arch_irq mov r0, sp badr lr, 9997f ldr pc, [r1] #else arch_irq_handler_default #endif 9997: .endm