+ LLVM
On Wed, 8 Mar 2023 at 00:58, Chang S. Bae <chang.seok.bae@xxxxxxxxx> wrote:
>
> On 3/6/2023 10:57 PM, Naresh Kamboju wrote:
> > kselftest: sigaltstack built with clang-16 getting failed but passed with
> > gcc-12 build. Please find more details about test logs on clang-16 and
> > gcc-12 and steps to reproduce locally on your machine by using tuxrun.
> >
> > Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> >
> > Test log:
> > ----------
> >
> > Linux version 6.3.0-rc1-next-20230307 (tuxmake@tuxmake) (Debian clang
> > version 16.0.0 (++20230228093516+60692a66ced6-1~exp1~20230228093525.41),
> > Debian LLD 16.0.0) #1 SMP PREEMPT @1678159722
> > ...
> > kselftest: Running tests in sigaltstack
> > TAP version 13
> > 1..1
> > # selftests: sigaltstack: sas
> > # # [NOTE] the stack size is 21104
> > # TAP version 13
> > # 1..3
> > # ok 1 Initial sigaltstack state was SS_DISABLE
> > # Bail out! SP is not on sigaltstack
> > # # Planned tests != run tests (3 != 1)
> > # # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> > not ok 1 selftests: sigaltstack: sas # exit=1
> <snip>
>
> > Linux version 6.3.0-rc1-next-20230307 (tuxmake@tuxmake)
> > (aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils
> > for Debian) 2.40) #1 SMP PREEMPT @1678159736
> > ...
> > kselftest: Running tests in sigaltstack
> > TAP version 13
> > 1..1
> > # selftests: sigaltstack: sas
> > # # [NOTE] the stack size is 50080
> > # TAP version 13
> > # 1..3
> > # ok 1 Initial sigaltstack state was SS_DISABLE
> > # # [RUN] signal USR1
> > # ok 2 sigaltstack is disabled in sighandler
> > # # [RUN] switched to user ctx
> > # # [RUN] signal USR2
> > # # [OK] Stack preserved
> > # ok 3 sigaltstack is still SS_AUTODISARM after signal
> > # # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0
> > ok 1 selftests: sigaltstack: sas
>
> At glance, the log shows the altstack size difference between LLVM and GCC.
>
> But, when I tried with the LLVM that I have,
>
> $ clang --version
> clang version 13.0.0 ...
>
> it failed only with this compiler:
>
> $ rm sas;clang -o sas sas.c;./sas
> # [NOTE] the stack size is 8192
> TAP version 13
> 1..3
> ok 1 Initial sigaltstack state was SS_DISABLE
> Bail out! SP is not on sigaltstack
> # Planned tests != run tests (3 != 1)
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> $ rm sas;gcc -o sas sas.c;./sas
> # [NOTE] the stack size is 8192
> TAP version 13
> 1..3
> ok 1 Initial sigaltstack state was SS_DISABLE
> # [RUN] signal USR1
> ok 2 sigaltstack is disabled in sighandler
> # [RUN] switched to user ctx
> # [RUN] signal USR2
> # [OK] Stack preserved
> ok 3 sigaltstack is still SS_AUTODISARM after signal
> # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> The same is true with some old versions -- e.g. the one that came with
> commit 0c49ad415512 ("tools/testing/selftests/sigaltstack/sas.c: improve
> output of sigaltstack testcase"):
>
> $ rm sas;clang -o sas sas.c;./sas
> [OK] Initial sigaltstack state was SS_DISABLE
> [FAIL] SP is not on sigaltstack
>
> $ rm sas;gcc -o sas sas.c;./sas
> [OK] Initial sigaltstack state was SS_DISABLE
> [RUN] signal USR1
> [OK] sigaltstack is disabled in sighandler
> [RUN] switched to user ctx
> [RUN] signal USR2
> [OK] Stack preserved
> [OK] sigaltstack is still SS_AUTODISARM after signal
> [OK] Test passed
>
> So, this test failure appears to have been there for a while. I think
> the LLVM folks need to take a look at it.
>
> Thanks,
> Chang
