Commit 2ab44633 authored by Zhangjin Wu's avatar Zhangjin Wu Committed by Willy Tarreau
Browse files

tools/nolibc: i386: shrink _start with _start_c 



move most of the _start operations to _start_c(), include the
stackprotector initialization.

Signed-off-by: default avatarZhangjin Wu <falcon@tinylab.org>
Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
parent ded8af47

tools/include/nolibc/arch-i386.h

+7 −27
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#define _NOLIBC_ARCH_I386_H



#include "compiler.h"

#include "crt.h"



/* Syscalls for i386 :

 *   - mostly similar to x86_64
@@ -154,9 +155,6 @@ 
	_eax;							\

})



char **environ __attribute__((weak));

const unsigned long *_auxv __attribute__((weak));



/* startup code */

/*

 * i386 System V ABI mandates:
@@ -167,30 +165,12 @@ const unsigned long *_auxv __attribute__((weak)); 
void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)

{

	__asm__ volatile (

#ifdef _NOLIBC_STACKPROTECTOR

		"call __stack_chk_init\n"   /* initialize stack protector                    */

#endif

		"pop %eax\n"                /* argc   (first arg, %eax)                      */

		"mov %esp, %ebx\n"          /* argv[] (second arg, %ebx)                     */

		"lea 4(%ebx,%eax,4),%ecx\n" /* then a NULL then envp (third arg, %ecx)       */

		"mov %ecx, environ\n"       /* save environ                                  */

		"xor  %ebp, %ebp\n"       /* zero the stack frame                                */

		"mov %ecx, %edx\n"          /* search for auxv (follows NULL after last env) */

		"0:\n"

		"add $4, %edx\n"            /* search for auxv using edx, it follows the     */

		"cmp -4(%edx), %ebp\n"      /* ... NULL after last env (ebp is zero here)    */

		"jnz 0b\n"

		"mov %edx, _auxv\n"         /* save it into _auxv                            */

		"and $-16, %esp\n"          /* x86 ABI : esp must be 16-byte aligned before  */

		"sub $4, %esp\n"            /* the call instruction (args are aligned)       */

		"push %ecx\n"               /* push all registers on the stack so that we    */

		"push %ebx\n"               /* support both regparm and plain stack modes    */

		"push %eax\n"

		"call main\n"               /* main() returns the status code in %eax        */

		"mov %eax, %ebx\n"          /* retrieve exit code (32-bit int)               */

		"movl $1, %eax\n"           /* NR_exit == 1                                  */

		"int $0x80\n"               /* exit now                                      */

		"hlt\n"                     /* ensure it does not                            */

		"mov  %esp, %eax\n"       /* save stack pointer to %eax, as arg1 of _start_c     */

		"and  $-16, %esp\n"       /* last pushed argument must be 16-byte aligned        */

		"push %eax\n"             /* push arg1 on stack to support plain stack modes too */

		"call _start_c\n"         /* transfer to c runtime                               */

		"hlt\n"                   /* ensure it does not return                           */

	);

	__builtin_unreachable();

}