Hi Sandipan,
Sandipan Das <sandipan@xxxxxxxxxxxxx> writes:
> diff --git a/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c b/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c
> new file mode 100644
> index 000000000000..b346ad205e68
> --- /dev/null
> +++ b/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c
> @@ -0,0 +1,326 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +/*
> + * Copyright 2020, Sandipan Das, IBM Corp.
> + *
> + * Test if applying execute protection on pages using memory
> + * protection keys works as expected.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <signal.h>
> +
> +#include <time.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +
> +#include "utils.h"
> +
> +/* Override definitions as they might be inconsistent */
> +#undef PKEY_DISABLE_ACCESS
> +#define PKEY_DISABLE_ACCESS 0x3
Why would they be inconsistent?
> +/* Older distros might not define this */
> +#ifndef SEGV_PKUERR
> +#define SEGV_PKUERR 4
> +#endif
...
> +
> + /* Restore permissions in order to continue */
> + switch (fcode) {
> + case SEGV_ACCERR:
> + if (mprotect(insns, pgsize, PROT_READ | PROT_WRITE)) {
> + perror("mprotect");
> + goto fail;
> + }
> + break;
> + case SEGV_PKUERR:
> + if (sinfo->si_pkey != fpkey)
> + goto fail;
This doesn't compile on older distros, eg Ubuntu 16.04:
pkey_exec_prot.c: In function 'segv_handler':
pkey_exec_prot.c:121:12: error: 'siginfo_t {aka struct <anonymous>}' has no member named 'si_pkey'
if (sinfo->si_pkey != fpkey)
^
pkey_exec_prot.c:151:24: error: 'siginfo_t {aka struct <anonymous>}' has no member named 'si_pkey'
pkey_set_rights(sinfo->si_pkey, 0);
^
../../lib.mk:142: recipe for target '/output/kselftest/powerpc/mm/pkey_exec_prot' failed
I think a reasonable solution is to use the absence of SEGV_PKUERR to
basically turn the whole test into a nop at build time, eg:
diff --git a/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c b/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c
index b346ad205e68..218257b89fbb 100644
--- a/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c
+++ b/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c
@@ -30,9 +30,7 @@
#define PKEY_DISABLE_EXECUTE 0x4
/* Older distros might not define this */
-#ifndef SEGV_PKUERR
-#define SEGV_PKUERR 4
-#endif
+#ifdef SEGV_PKUERR
#define SYS_pkey_mprotect 386
#define SYS_pkey_alloc 384
@@ -319,6 +317,13 @@ static int test(void)
return 0;
}
+#else
+static int test(void)
+{
+ printf("Test built with old libc lacking pkey support.\n");
+ SKIP_IF(true);
+}
+#endif /* SEGV_PKUERR */
int main(void)
{
cheers
