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
