#define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0)))

表示函數(shù)的參數(shù)傳遞是通過堆棧完成的。

3.7 描述3.3節(jié)中的ret_to_user 中斷返回過程，/arch/arm/kernel/entry-common.S

ENTRY(ret_to_user)

ret_slow_syscall:

disable_irq @ disable interrupts

ldr r1, [tsk, #TI_FLAGS]

tst r1, #_TIF_WORK_MASK

bne work_pending

no_work_pending:

/* perform. architecture specific actions before user return */

arch_ret_to_user r1, lr

@ slow_restore_user_regs

ldr r1, [sp, #S_PSR] @ get calling cpsr

ldr lr, [sp, #S_PC]! @ get pc

msr spsr_cxsf, r1 @ save in spsr_svc

ldmdb sp, {r0 - lr}^ @ get calling r0 - lr

mov r0, r0

add sp, sp, #S_FRAME_SIZE - S_PC

movs pc, lr @ return move spsr_svc into cpsr

第三章主要跟蹤了從中斷發(fā)生到調用到對應中斷號的desc->handle_irq(irq, desc)中斷函數(shù)的過程。后面的章節(jié)還會繼續(xù)講解后面的內容。