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tools/nolibc: s390: shrink _start with _start_c

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

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 02:32:19 +08:00 committed by Willy Tarreau
parent eea70cdac6
commit c48d8af2fa
1 changed files with 5 additions and 31 deletions
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36
tools/include/nolibc/arch-s390.h
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@ -9,6 +9,7 @@
#include <asm/unistd.h>
#include "compiler.h"
#include "crt.h"
/* Syscalls for s390:
* - registers are 64-bit
@ -137,41 +138,14 @@
_arg1; \
})
char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
"lg %r2,0(%r15)\n" /* argument count */
"la %r3,8(%r15)\n" /* argument pointers */
"xgr %r0,%r0\n" /* r0 will be our NULL value */
/* search for envp */
"lgr %r4,%r3\n" /* start at argv */
"0:\n"
"clg %r0,0(%r4)\n" /* entry zero? */
"la %r4,8(%r4)\n" /* advance pointer */
"jnz 0b\n" /* no -> test next pointer */
/* yes -> r4 now contains start of envp */
"larl %r1,environ\n"
"stg %r4,0(%r1)\n"
/* search for auxv */
"lgr %r5,%r4\n" /* start at envp */
"1:\n"
"clg %r0,0(%r5)\n" /* entry zero? */
"la %r5,8(%r5)\n" /* advance pointer */
"jnz 1b\n" /* no -> test next pointer */
"larl %r1,_auxv\n" /* yes -> store value in _auxv */
"stg %r5,0(%r1)\n"
"aghi %r15,-160\n" /* allocate new stackframe */
"xc 0(8,%r15),0(%r15)\n" /* clear backchain */
"brasl %r14,main\n" /* ret value of main is arg to exit */
"lghi %r1,1\n" /* __NR_exit */
"svc 0\n"
"lgr %r2, %r15\n" /* save stack pointer to %r2, as arg1 of _start_c */
"aghi %r15, -160\n" /* allocate new stackframe */
"xc 0(8,%r15), 0(%r15)\n" /* clear backchain */
"brasl %r14, _start_c\n" /* transfer to c runtime */
);
__builtin_unreachable();
}