|
因?yàn)橄敫櫹略谛陆ㄟM(jìn)程時(shí)，如何處理新建進(jìn)程的vruntime，所以跟蹤了下fork。
以glic-2.17中ARM為例（unicore架構(gòu)的沒找到）,實(shí)際上通過寄存器向系統(tǒng)調(diào)用傳遞的參數(shù)為： r7: __NR_clone 120 r0: CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD r1: NULL r2: NULL r3: NULL r4: &THREAD_SELF->tid  fork()---->__fork()---->__libc_fork()
__libc_fork()---->INLINE_SYSCALL (clone, 5, CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD, NULL, NULL, NULL, &THREAD_SELF->tid)
#define INLINE_SYSCALL(name, nr, args...) ({ unsigned int _sys_result = \
#define INTERNAL_SYSCALL(name, err, nr, args...) \ INTERNAL_SYSCALL_RAW(SYS_ify(name), err, nr, args) //#define __NR_clone 120 #define SYS_ify(syscall_name) (__NR_##syscall_name)
//err沒用使用，也沒有傳遞宏參，第一次見到 關(guān)于宏INTERAL_SYSCALL_RAW還是滿有意思的，寫了個(gè)函數(shù)測試下，真實(shí)的看下庫如何向系統(tǒng)調(diào)用傳參： #define LOAD_ARGS_0() #define ASM_ARGS_0 #define LOAD_ARGS_1(a1) int _a1tmp = (int)(a1); LOAD_ARGS_0 () _a1 = _a1tmp; #define ASM_ARGS_1 ASM_ARGS_0, "r" (_a1) #define LOAD_ARGS_2(a1, a2) int _a2tmp = (int)(a2); LOAD_ARGS_1(a1) register int _a2 asm ("a2") = _a2tmp; #define ASM_ARGS_2 ASM_ARGS_1, "r" (_a2) #define LOAD_ARGS_3(a1, a2, a3) int _a3tmp = (int)(a3); LOAD_ARGS_2 (a1, a2) register int _a3 asm ("a3") = _a3tmp; #define ASM_ARGS_3 ASM_ARGS_2, "r" (_a3) #define LOAD_ARGS_4(a1, a2, a3, a4) int _a4tmp = (int) (a4); LOAD_ARGS_3 (a1, a2, a3) register int _a4 asm ("a4") = _a4tmp; #define ASM_ARGS_4 ASM_ARGS_3, "r" (_a4) #define LOAD_ARGS_5(a1, a2, a3, a4, a5) int _v1tmp = (int)(a5); LOAD_ARGS_4 (a1, a2, a3, a4) register int _v1 asm ("v1") = _v1tmp; #define ASM_ARGS_5 ASM_ARGS_4, "r" (_v1) #define INTERNAL_SYSCALL_RAW(name, err, nr, args...) ({ register int _a1 asm("r0"), _nr asm("r7"); LOAD_ARGS_5 (args) _nr = name; asm volatile ("swi 0x0" : "=r" (_a1) : "r" (_nr) ASM_ARGS_##nr : "memory" ); _a1; }) void test(void) { INTERNAL_SYSCALL_RAW(120, , 5, 6, 7, 8, 9, 0); }
預(yù)處理后即為： void test(void) { ({ register int _a1 asm("r0"), _nr asm("r7"); int _v1tmp = (int)(0); int _a4tmp = (int) (9); int _a3tmp = (int)(8); int _a2tmp = (int)(7); int _a1tmp = (int)(6); _a1 = _a1tmp; register int _a2 asm ("a2") = _a2tmp; register int _a3 asm ("a3") = _a3tmp; register int _a4 asm ("a4") = _a4tmp; register int _v1 asm ("v1") = _v1tmp; _nr = 120; asm volatile ( "swi 0x0" : "=r" (_a1) : "r" (_nr) , "r" (_a1), "r" (_a2), 相應(yīng)的匯編代碼：  test:
stmfd sp!, {r4, r7, fp}
add fp, sp, #8
sub sp, sp, #28
mov r3, #0
str r3, [fp, #-32]
mov r3, #9
str r3, [fp, #-28]
mov r3, #8
str r3, [fp, #-24]
mov r3, #7
str r3, [fp, #-20]
mov r3, #6
str r3, [fp, #-16]
ldr r0, [fp, #-16]
ldr r1, [fp, #-20]
ldr r2, [fp, #-24]
ldr r3, [fp, #-28]
ldr r4, [fp, #-32]
mov r7, #120
#APP
@ 16 "go.c" 1
swi 0x0
@ 0 "" 2
sub sp, fp, #8
ldmfd sp!, {r4, r7, fp}
bx lr
|
|
|
