Hi Michael,
On 26/05/20 6:05 pm, Michael Ellerman wrote:
> [...]
>> +
>> +/* Override definitions as they might be inconsistent */
>> +#undef PKEY_DISABLE_ACCESS
>> +#define PKEY_DISABLE_ACCESS 0x3
>
> Why would they be inconsistent?
>
The definition in sys/mman.h still uses the value specific to
Intel's implementation i.e. 1, when this should have been 3
for powerpc. I have seen this on Ubuntu 18.04 and 20.04.
>
>> +/* 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
>
Thanks for reporting this.
>
> 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)
> {
>
>
Or can I use this from the pkey tests under selftests/vm?
static inline u32 *siginfo_get_pkey_ptr(siginfo_t *si)
{
#ifdef si_pkey
return &si->si_pkey;
#else
return (u32 *)(((u8 *)si) + si_pkey_offset);
#endif
}
Where si_pkey_offset is 0x20 for powerpc.
- Sandipan
