Commit 431b806b authored by Zhangjin Wu's avatar Zhangjin Wu Committed by Willy Tarreau
Browse files

tools/nolibc: mips: shrink _start with _start_c 



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

Also clean up the instructions in delayed slots.

Signed-off-by: default avatarZhangjin Wu <falcon@tinylab.org>
Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
parent 539287d7

tools/include/nolibc/arch-mips.h

+8 −38
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#define _NOLIBC_ARCH_MIPS_H



#include "compiler.h"

#include "crt.h"



/* Syscalls for MIPS ABI O32 :

 *   - WARNING! there's always a delayed slot!
@@ -173,50 +174,19 @@ 
	_arg4 ? -_num : _num;                                                 \

})



char **environ __attribute__((weak));

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



/* startup code, note that it's called __start on MIPS */

void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector __start(void)

{

	__asm__ volatile (

		/*".set nomips16\n"*/

		".set push\n"

		".set noreorder\n"

		".option pic0\n"

#ifdef _NOLIBC_STACKPROTECTOR

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

		"nop\n"                  /* delayed slot                                       */

#endif

		/*".ent __start\n"*/

		/*"__start:\n"*/

		"lw $a0,($sp)\n"        /* argc was in the stack                               */

		"addiu  $a1, $sp, 4\n"  /* argv = sp + 4                                       */

		"sll $a2, $a0, 2\n"     /* a2 = argc * 4                                       */

		"add   $a2, $a2, $a1\n" /* envp = argv + 4*argc ...                            */

		"addiu $a2, $a2, 4\n"   /*        ... + 4                                      */

		"lui $a3, %hi(environ)\n"     /* load environ into a3 (hi)                     */

		"addiu $a3, %lo(environ)\n"   /* load environ into a3 (lo)                     */

		"sw $a2,($a3)\n"              /* store envp(a2) into environ                   */



		"move $t0, $a2\n"             /* iterate t0 over envp, look for NULL           */

		"0:"                          /* do {                                          */

		"lw $a3, ($t0)\n"             /*   a3=*(t0);                                   */

		"bne $a3, $0, 0b\n"           /* } while (a3);                                 */

		"addiu $t0, $t0, 4\n"         /* delayed slot: t0+=4;                          */

		"lui $a3, %hi(_auxv)\n"       /* load _auxv into a3 (hi)                       */

		"addiu $a3, %lo(_auxv)\n"     /* load _auxv into a3 (lo)                       */

		"sw $t0, ($a3)\n"             /* store t0 into _auxv                           */



		"move  $a0, $sp\n"       /* save stack pointer to $a0, as arg1 of _start_c */

		"li    $t0, -8\n"

		"and $sp, $sp, $t0\n"   /* sp must be 8-byte aligned                           */

		"addiu $sp,$sp,-16\n"   /* the callee expects to save a0..a3 there!            */

		"jal main\n"            /* main() returns the status code, we'll exit with it. */

		"and   $sp, $sp, $t0\n"  /* $sp must be 8-byte aligned                     */

		"addiu $sp, $sp, -16\n"  /* the callee expects to save a0..a3 there        */

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

		" nop\n"                 /* delayed slot                                   */

		"move $a0, $v0\n"       /* retrieve 32-bit exit code from v0                   */

		"li $v0, 4001\n"        /* NR_exit == 4001                                     */

		"syscall\n"

		/*".end __start\n"*/

		".set pop\n"

	);

	__builtin_unreachable();