selftests/powerpc: Add a routine for retrieving an AUXV entry

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/tools/testing/selftests/powerpc/pmu/lib.c b/tools/testing/selftests/powerpc/pmu/lib.c
index 11e26e8cf33a5381bd5c01e0fb7d387cd38d0b82..9768dea37bf3157f17d1329be5501d1d9f0a6204 100644 (file)
--- a/tools/testing/selftests/powerpc/pmu/lib.c
+++ b/tools/testing/selftests/powerpc/pmu/lib.c
@@ -5,10 +5,15 @@
 
 #define _GNU_SOURCE    /* For CPU_ZERO etc. */
 
+#include <elf.h>
 #include <errno.h>
+#include <fcntl.h>
+#include <link.h>
 #include <sched.h>
 #include <setjmp.h>
 #include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 #include <sys/wait.h>
 
 #include "utils.h"
@@ -250,3 +255,46 @@ out_close:
 out:
        return rc;
 }
+
+static char auxv[4096];
+
+void *get_auxv_entry(int type)
+{
+       ElfW(auxv_t) *p;
+       void *result;
+       ssize_t num;
+       int fd;
+
+       fd = open("/proc/self/auxv", O_RDONLY);
+       if (fd == -1) {
+               perror("open");
+               return NULL;
+       }
+
+       result = NULL;
+
+       num = read(fd, auxv, sizeof(auxv));
+       if (num < 0) {
+               perror("read");
+               goto out;
+       }
+
+       if (num > sizeof(auxv)) {
+               printf("Overflowed auxv buffer\n");
+               goto out;
+       }
+
+       p = (ElfW(auxv_t) *)auxv;
+
+       while (p->a_type != AT_NULL) {
+               if (p->a_type == type) {
+                       result = (void *)p->a_un.a_val;
+                       break;
+               }
+
+               p++;
+       }
+out:
+       close(fd);
+       return result;
+}

diff --git a/tools/testing/selftests/powerpc/pmu/lib.h b/tools/testing/selftests/powerpc/pmu/lib.h
index ca5d72ae3be6b0cc8aed1e1caabb2f7b0d062317..0f0339c8a6f6fbbf518b198cd56b175efcb7975c 100644 (file)
--- a/tools/testing/selftests/powerpc/pmu/lib.h
+++ b/tools/testing/selftests/powerpc/pmu/lib.h
@@ -29,6 +29,7 @@ extern int notify_parent(union pipe write_pipe);
 extern int notify_parent_of_error(union pipe write_pipe);
 extern pid_t eat_cpu(int (test_function)(void));
 extern bool require_paranoia_below(int level);
+extern void *get_auxv_entry(int type);
 
 struct addr_range {
        uint64_t first, last;