move most of the _start operations to _start_c().
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
tools/include/nolibc/x86_64/crt.h | 25 +++++++------------------
1 file changed, 7 insertions(+), 18 deletions(-)
diff --git a/tools/include/nolibc/x86_64/crt.h b/tools/include/nolibc/x86_64/crt.h
index 6fede1235efc..03899042854e 100644
--- a/tools/include/nolibc/x86_64/crt.h
+++ b/tools/include/nolibc/x86_64/crt.h
@@ -18,27 +18,16 @@ void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
- "call __stack_chk_init\n" /* initialize stack protector */
+ "call __stack_chk_init\n" /* initialize stack protector */
#endif
- "pop %rdi\n" /* argc (first arg, %rdi) */
- "mov %rsp, %rsi\n" /* argv[] (second arg, %rsi) */
- "lea 8(%rsi,%rdi,8),%rdx\n" /* then a NULL then envp (third arg, %rdx) */
- "mov %rdx, environ\n" /* save environ */
- "xor %ebp, %ebp\n" /* zero the stack frame */
- "mov %rdx, %rax\n" /* search for auxv (follows NULL after last env) */
- "0:\n"
- "add $8, %rax\n" /* search for auxv using rax, it follows the */
- "cmp -8(%rax), %rbp\n" /* ... NULL after last env (rbp is zero here) */
- "jnz 0b\n"
- "mov %rax, _auxv\n" /* save it into _auxv */
- "and $-16, %rsp\n" /* x86 ABI : esp must be 16-byte aligned before call */
- "call main\n" /* main() returns the status code, we'll exit with it. */
- "mov %eax, %edi\n" /* retrieve exit code (32 bit) */
- "mov $60, %eax\n" /* NR_exit == 60 */
- "syscall\n" /* really exit */
- "hlt\n" /* ensure it does not return */
+ "xor %ebp, %ebp\n" /* zero the stack frame */
+ "mov %rsp, %rdi\n" /* save stack pointer to %rdi, as arg1 of _start_c */
+ "and $-16, %rsp\n" /* %rsp must be 16-byte aligned before call */
+ "call _start_c\n" /* transfer to c runtime */
+ "hlt\n" /* ensure it does not return */
);
__builtin_unreachable();
+
}
#endif /* _NOLIBC_X86_64_CRT_H */
--
2.25.1
