move most of the _start operations to _start_c().
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
tools/include/nolibc/arch-x86_64.h | 28 +++++++---------------------
1 file changed, 7 insertions(+), 21 deletions(-)
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index e980ca5417d0..0048adf6b11f 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -8,6 +8,7 @@
#define _NOLIBC_ARCH_X86_64_H
#include "compiler.h"
+#include "crt.h"
/* Syscalls for x86_64 :
* - registers are 64-bit
@@ -153,9 +154,6 @@
_ret; \
})
-char **environ __attribute__((weak));
-const unsigned long *_auxv __attribute__((weak));
-
/* startup code */
/*
* x86-64 System V ABI mandates:
@@ -167,25 +165,13 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_pr
{
__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();
}
--
2.25.1
