Re: [PATCH v4] Fix tst-pkey expectations on pkey_get [BZ #23202]

[Tulio Magno Quites Machado Filho <tuliom@ascii.art.br>]

"Lucas A. M. Magalhaes" <lamm@linux.ibm.com> writes:

> From the GNU C Library manual the pkey_set can receive a combination of
> PKEY_DISABLE_WRITE and PKEY_DISABLE_ACCESS.  However PKEY_DISABLE_ACCESS
> is more restrictive than PKEY_DISABLE_WRITE and includes its behavior.
>
> The test expects that after setting
> (PKEY_DISABLE_WRITE|PKEY_DISABLE_ACCESS) pkey_get should return the
> same.  This may not be true as PKEY_DISABLE_ACCESS will succeed in
> describe the state of the key in this case.
>
> The pkey behavior during signal handling is different between x86 and
> POWER.  This change make the test compatible with both architectures.

The patch LGTM.
This test is now passing on Linux >= 5.0, but it still fails on Linux <= 4.18
because of issues in the kernel.
I'm not sure if 4.19 should work.

Old kernels do return valid data:

[pid 56757] pkey_alloc(0, 0 <unfinished ...>
[pid 56758] set_robust_list(0x7fff8994f260, 24 <unfinished ...>
[pid 56757] <... pkey_alloc resumed> )  = 2
[pid 56758] <... set_robust_list resumed> ) = 0
[pid 56757] pkey_alloc(0, PKEY_DISABLE_ACCESS <unfinished ...>
[pid 56758] futex(0x100208a4, FUTEX_WAIT_PRIVATE, 0, NULL <unfinished ...>
[pid 56757] <... pkey_alloc resumed> )  = 3
[pid 56757] pkey_alloc(0, PKEY_DISABLE_WRITE) = 4
[pid 56757] mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fff89130000
[pid 56757] pkey_mprotect(0x7fff89130000, 65536, PROT_READ|PROT_WRITE, 2) = 0
[pid 56757] mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fff89120000
[pid 56757] pkey_mprotect(0x7fff89120000, 65536, PROT_READ|PROT_WRITE, 3) = 0
[pid 56757] mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fff89110000
[pid 56757] pkey_mprotect(0x7fff89110000, 65536, PROT_READ|PROT_WRITE, 4) = 0
[pid 56757] futex(0x100208a4, FUTEX_WAKE_PRIVATE, 2147483647) = 1
[pid 56758] <... futex resumed> )       = 0
[pid 56757] futex(0x7fff8994f250, FUTEX_WAIT, 56758, NULL <unfinished ...>
[pid 56758] mmap(NULL, 134217728, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7fff81110000
[pid 56758] munmap(0x7fff81110000, 49217536) = 0
[pid 56758] munmap(0x7fff88000000, 17891328) = 0
[pid 56758] mprotect(0x7fff84000000, 196608, PROT_READ|PROT_WRITE) = 0
[pid 56758] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 56758] rt_sigaction(SIGSEGV, {sa_handler=0x1001fca8, sa_mask=[], sa_flags=SA_RESETHAND|SA_SIGINFO}, NULL, 8) = 0
[pid 56758] rt_sigaction(SIGSEGV, {sa_handler=SIG_DFL, sa_mask=[SEGV], sa_flags=SA_RESTART}, {sa_handler=0x1001fca8, sa_mask=[], sa_flags=SA_RESETHAND|SA_SIGINFO}, 8) = 0
[pid 56758] write(1, "error: ../sysdeps/unix/sysv/linu"..., 90error: ../sysdeps/unix/sysv/linux/tst-pkey.c:161: not true: !check_page_access (i, false)
) = 90

Anyway, pushed as 8d42bf859a289944749d9f978c076cd318119867.

Thanks!

-- 
Tulio Magno