[PATCH 1/2] selftests/powerpc: Refactor the AUXV routines

[Michael Ellerman]

Refactor the AUXV routines so they are more composable. In a future test
we want to look for many AUXV entries and we don't want to have to read
/proc/self/auxv each time.

Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
 tools/testing/selftests/powerpc/include/utils.h |  6 ++-
 tools/testing/selftests/powerpc/utils.c         | 53 +++++++++++++++++--------
 2 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/powerpc/include/utils.h 
b/tools/testing/selftests/powerpc/include/utils.h
index 53405e8a52ab..735815b3ad7f 100644
--- a/tools/testing/selftests/powerpc/include/utils.h
+++ b/tools/testing/selftests/powerpc/include/utils.h
@@ -24,7 +24,11 @@ typedef uint8_t u8;
 
 void test_harness_set_timeout(uint64_t time);
 int test_harness(int (test_function)(void), char *name);
-extern void *get_auxv_entry(int type);
+
+int read_auxv(char *buf, ssize_t buf_size);
+void *find_auxv_entry(int type, char *auxv);
+void *get_auxv_entry(int type);
+
 int pick_online_cpu(void);
 
 static inline bool have_hwcap(unsigned long ftr)
diff --git a/tools/testing/selftests/powerpc/utils.c 
b/tools/testing/selftests/powerpc/utils.c
index dcf74184bfd0..d46916867a6f 100644
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -19,45 +19,64 @@
 
 static char auxv[4096];
 
-void *get_auxv_entry(int type)
+int read_auxv(char *buf, ssize_t buf_size)
 {
-       ElfW(auxv_t) *p;
-       void *result;
        ssize_t num;
-       int fd;
+       int rc, fd;
 
        fd = open("/proc/self/auxv", O_RDONLY);
        if (fd == -1) {
                perror("open");
-               return NULL;
+               return -errno;
        }
 
-       result = NULL;
-
-       num = read(fd, auxv, sizeof(auxv));
+       num = read(fd, buf, buf_size);
        if (num < 0) {
                perror("read");
+               rc = -EIO;
                goto out;
        }
 
-       if (num > sizeof(auxv)) {
-               printf("Overflowed auxv buffer\n");
+       if (num > buf_size) {
+               printf("overflowed auxv buffer\n");
+               rc = -EOVERFLOW;
                goto out;
        }
 
+       rc = 0;
+out:
+       close(fd);
+       return rc;
+}
+
+void *find_auxv_entry(int type, char *auxv)
+{
+       ElfW(auxv_t) *p;
+
        p = (ElfW(auxv_t) *)auxv;
 
        while (p->a_type != AT_NULL) {
-               if (p->a_type == type) {
-                       result = (void *)p->a_un.a_val;
-                       break;
-               }
+               if (p->a_type == type)
+                       return p;
 
                p++;
        }
-out:
-       close(fd);
-       return result;
+
+       return NULL;
+}
+
+void *get_auxv_entry(int type)
+{
+       ElfW(auxv_t) *p;
+
+       if (read_auxv(auxv, sizeof(auxv)))
+               return NULL;
+
+       p = find_auxv_entry(type, auxv);
+       if (p)
+               return (void *)p->a_un.a_val;
+
+       return NULL;
 }
 
 int pick_online_cpu(void)
-- 
2.7.4