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 <[email protected]>
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
Links,
qemu-x86_64:
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230307/testrun/15303778/suite/kselftest-sigaltstack/test/sigaltstack_sas/details/
qemu-arm64:
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230307/testrun/15302557/suite/kselftest-sigaltstack/tests/
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230307/testrun/15302557/suite/kselftest-sigaltstack/test/sigaltstack_sas/log
kselftest: sigaltstack built with gcc-12 getting pass.
Test log:
---------
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
Links,
qemu-x86_64:
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230307/testrun/15303751/suite/kselftest-sigaltstack/tests/
qemu-arm64:
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230307/testrun/15302458/suite/kselftest-sigaltstack/tests/
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230307/testrun/15302458/suite/kselftest-sigaltstack/test/sigaltstack_sas/log
Steps to reproduce:
--------------
# To install tuxrun on your system globally:
# sudo pip3 install -U tuxrun==0.37.2
#
# See https://tuxrun.org/ for complete documentation.
tuxrun \
--runtime podman \
--device qemu-x86_64 \
--boot-args rw \
--kernel https://storage.tuxsuite.com/public/linaro/lkft/builds/2MfXLbLsvBufVn1MrsnXVZ133Bf/bzImage
\
--modules https://storage.tuxsuite.com/public/linaro/lkft/builds/2MfXLbLsvBufVn1MrsnXVZ133Bf/modules.tar.xz
\
--rootfs https://storage.tuxboot.com/debian/bookworm/amd64/rootfs.ext4.xz \
--parameters SKIPFILE=skipfile-lkft.yaml \
--parameters KSELFTEST=https://storage.tuxsuite.com/public/linaro/lkft/builds/2MfXLbLsvBufVn1MrsnXVZ133Bf/kselftest.tar.xz
\
--image docker.io/lavasoftware/lava-dispatcher:2023.01.0020.gc1598238f \
--tests kselftest-sigaltstack \
--timeouts boot=15
--
Linaro LKFT
https://lkft.linaro.org
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 <[email protected]>
>
> 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
+ LLVM
On Wed, 8 Mar 2023 at 00:58, Chang S. Bae <[email protected]> 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 <[email protected]>
> >
> > 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
On Tue, Mar 7, 2023 at 7:14 PM Naresh Kamboju <[email protected]> wrote:
>
> + LLVM
The offending code seems to be:
#if __s390x__
register unsigned long sp asm("%15");
#else
register unsigned long sp asm("sp");
#endif
if (sp < (unsigned long)sstack ||
sp >= (unsigned long)sstack + stack_size) {
ksft_exit_fail_msg("SP is not on sigaltstack\n");
}
Is that actually expected to work? asm("sp") is a horrible hack. I
would, maybe naively, expect a compiler to analyze this code, think
"sp is unconditionally uninitialized", and treat the comparison as
always-UB and thus generate whatever code seems convenient.
--Andy
>
> On Wed, 8 Mar 2023 at 00:58, Chang S. Bae <[email protected]> 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 <[email protected]>
> > >
> > > 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
On Wed, Mar 8, 2023 at 8:23 AM Andy Lutomirski <[email protected]> wrote:
>
> On Tue, Mar 7, 2023 at 7:14 PM Naresh Kamboju <[email protected]> wrote:
> >
> > + LLVM
>
> The offending code seems to be:
>
> #if __s390x__
> register unsigned long sp asm("%15");
> #else
> register unsigned long sp asm("sp");
> #endif
>
> if (sp < (unsigned long)sstack ||
> sp >= (unsigned long)sstack + stack_size) {
> ksft_exit_fail_msg("SP is not on sigaltstack\n");
> }
>
> Is that actually expected to work? asm("sp") is a horrible hack. I
> would, maybe naively, expect a compiler to analyze this code, think
> "sp is unconditionally uninitialized", and treat the comparison as
> always-UB and thus generate whatever code seems convenient.
Spot-on. -Wuninitialized should warn about that.
https://godbolt.org/z/do9Kqa3cG
Kees mentioned we should be using `current_stack_pointer`. I'll whip
up a patch using that.
>
> --Andy
>
> >
> > On Wed, 8 Mar 2023 at 00:58, Chang S. Bae <[email protected]> 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 <[email protected]>
> > > >
> > > > 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
>
--
Thanks,
~Nick Desaulniers