Let's move most of the _start operations to _start_c().
Signed-off-by: Zhangjin Wu falcon@tinylab.org --- tools/include/nolibc/arch-x86_64.h | 27 ++++++--------------------- 1 file changed, 6 insertions(+), 21 deletions(-)
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h index 4c0192815a59..116dcd8e1413 100644 --- a/tools/include/nolibc/arch-x86_64.h +++ b/tools/include/nolibc/arch-x86_64.h @@ -153,9 +153,6 @@ _ret; \ })
-char **environ __attribute__((weak)); -const unsigned long *_auxv __attribute__((weak)); - /* startup code */ /* * x86-64 System V ABI mandates: @@ -167,25 +164,13 @@ 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(); }