On Thu, Oct 26, 2023 at 01:06:27AM +0530, Swarup Laxman Kotiaklapudi wrote:
> Check ProtectionKey field in /proc/*/smaps output,
> if system supports page-based memory permissions.
> --- a/tools/testing/selftests/proc/proc-empty-vm.c
> +++ b/tools/testing/selftests/proc/proc-empty-vm.c
> @@ -37,6 +37,7 @@
> #include <sys/types.h>
> #include <sys/wait.h>
> #include <unistd.h>
> +#include "../kselftest.h"
I'd rather not include stuff. The reason is that this include makes
the test not (less) self-contained so it requires copying two files
to some machine where it is broken for debugging.
> @@ -83,10 +84,7 @@ static const char proc_pid_smaps_vsyscall_1[] =
> "SwapPss: 0 kB\n"
> "Locked: 0 kB\n"
> "THPeligible: 0\n"
> -/*
> - * "ProtectionKey:" field is conditional. It is possible to check it as well,
> - * but I don't have such machine.
> - */
> +"ProtectionKey: 0\n"
> ;
>
> static const char proc_pid_smaps_vsyscall_2[] =
> @@ -113,10 +111,7 @@ static const char proc_pid_smaps_vsyscall_2[] =
> "SwapPss: 0 kB\n"
> "Locked: 0 kB\n"
> "THPeligible: 0\n"
> -/*
> - * "ProtectionKey:" field is conditional. It is possible to check it as well,
> - * but I'm too tired.
> - */
> +"ProtectionKey: 0\n"
> ;
>
> static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
> @@ -241,13 +236,26 @@ static int test_proc_pid_smaps(pid_t pid)
> } else {
> ssize_t rv = read(fd, buf, sizeof(buf));
> close(fd);
> - if (g_vsyscall == 0) {
> - assert(rv == 0);
> - } else {
> - size_t len = strlen(g_proc_pid_maps_vsyscall);
> - /* TODO "ProtectionKey:" */
> - assert(rv > len);
> - assert(memcmp(buf, g_proc_pid_maps_vsyscall, len) == 0);
> + assert(rv >= 0);
> + assert(rv <= sizeof(buf));
> + if (g_vsyscall != 0) {
> + int pkey = pkey_alloc(0, 0);
I'd call syscall(). glibc might not have pkey_alloc(3) [[citation needed]]
And I'd move this pkey support testing to the very beginning (like vsyscall).
> + if (pkey < 0) {
> + size_t len = strlen(g_proc_pid_maps_vsyscall);
OK this test was broken, but it is not your fault. See my next patch.
> +
> + assert(rv > len);
> + assert(memcmp(buf, g_proc_pid_maps_vsyscall, len) == 0);
> + } else {
> + pkey_free(pkey);
> + static const char * const S[] = {
> + "ProtectionKey: 0\n"
> + };
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(S); i++)
> + assert(memmem(buf, rv, S[i], strlen(S[i])));
> + }
OK-ish.
