tools/nolibc: add auxiliary vector retrieval for s390

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>

diff --git a/tools/include/nolibc/arch-s390.h b/tools/include/nolibc/arch-s390.h
index 039b454e79f0a46c69d27e3b70823fd1c7bb621a..6b0e54ed543dd89716f8b4338f800b91c44fe6c3 100644 (file)
--- a/tools/include/nolibc/arch-s390.h
+++ b/tools/include/nolibc/arch-s390.h
@@ -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 */