selftests: vDSO: vdso_standalone_test_x86: Use vdso_init_form_sysinfo_ehdr

vdso_standalone_test_x86 is the only user of vdso_init_from_auxv().
Instead of combining the parsing the aux vector with the parsing of the
vDSO, split them apart into getauxval() and the regular
vdso_init_from_sysinfo_ehdr().

The implementation of getauxval() is taken from
tools/include/nolibc/stdlib.h.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-10-28e14e031ed8@linutronix.de

diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
index 644915862af8883131e5defd336f1bd80736fc0f..500608f89c66b5747e3d845ebc54e4c3a35b6ccd 100644 (file)
--- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
+++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
@@ -15,6 +15,7 @@
 #include <sys/time.h>
 #include <unistd.h>
 #include <stdint.h>
+#include <linux/auxvec.h>
 
 #include "parse_vdso.h"
 
@@ -84,6 +85,30 @@ void to_base10(char *lastdig, time_t n)
        }
 }
 
+unsigned long getauxval(const unsigned long *auxv, unsigned long type)
+{
+       unsigned long ret;
+
+       if (!auxv)
+               return 0;
+
+       while (1) {
+               if (!auxv[0] && !auxv[1]) {
+                       ret = 0;
+                       break;
+               }
+
+               if (auxv[0] == type) {
+                       ret = auxv[1];
+                       break;
+               }
+
+               auxv += 2;
+       }
+
+       return ret;
+}
+
 void c_main(void **stack)
 {
        /* Parse the stack */
@@ -96,7 +121,7 @@ void c_main(void **stack)
        stack++;
 
        /* Now we're pointing at auxv.  Initialize the vDSO parser. */
-       vdso_init_from_auxv((void *)stack);
+       vdso_init_from_sysinfo_ehdr(getauxval((unsigned long *)stack, AT_SYSINFO_EHDR));
 
        /* Find gettimeofday. */
        typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);