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tools/nolibc: add auxiliary vector retrieval for s390

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In the _start block we now iterate over envp to find the auxiliary
vector after the NULL. The pointer is saved into an _auxv variable
that is marked as weak so that it's accessible from multiple units.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Sven Schnelle 2023-01-10 08:24:31 +01:00 committed by Paul E. McKenney
parent d01869cf1e
commit 241c4b4e02
1 changed files with 10 additions and 0 deletions
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10
tools/include/nolibc/arch-s390.h
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@ -160,6 +160,7 @@ struct sys_stat_struct {
})
char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
@ -179,6 +180,15 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
"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 */