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tools/nolibc: mips: shrink _start with _start_c

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

Also clean up the instructions in delayed slots.

Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
This commit is contained in:
Zhangjin Wu 2023-07-16 02:28:55 +08:00 committed by Willy Tarreau
parent 539287d751
commit 431b806b9b
1 changed files with 8 additions and 38 deletions
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46
tools/include/nolibc/arch-mips.h
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@ -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"
".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 */
"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. */
"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"*/
"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 _start_c\n" /* transfer to c runtime */
" nop\n" /* delayed slot */
".set pop\n"
);
__builtin_unreachable();