rseq/selftests: Fix riscv rseq_offset_deref_addv inline asm

commit 713e788c0e07e185fd44dd581f74855ef149722f upstream.

When working on OpenRISC support for restartable sequences I noticed
and fixed

rseq/selftests: Fix riscv rseq_offset_deref_addv inline asm

commit 713e788c0e07e185fd44dd581f74855ef149722f upstream.

When working on OpenRISC support for restartable sequences I noticed
and fixed these two issues with the riscv support bits.

1 The 'inc' argument to RSEQ_ASM_OP_R_DEREF_ADDV was being implicitly
passed to the macro. Fix this by adding 'inc' to the list of macro
arguments.
2 The inline asm input constraints for 'inc' and 'off' use "er", The
riscv gcc port does not have an "e" constraint, this looks to be
copied from the x86 port. Fix this by just using an "r" constraint.

I have compile tested this only for riscv. However, the same fixes I
use in the OpenRISC rseq selftests and everything passes with no issues.

Fixes: 171586a6ab66 ("selftests/rseq: riscv: Template memory ordering and percpu access mode")
Signed-off-by: Stafford Horne <shorne@gmail.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250114170721.3613280-1-shorne@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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selftests/rseq: Fix handling of glibc without rseq support

commit 336d02bc4c6bec5c3d933e5d470a94970f830957 upstream.

When porting librseq commit:

commit c7b45750fa85 ("Adapt to glibc __rseq_size f

selftests/rseq: Fix handling of glibc without rseq support

commit 336d02bc4c6bec5c3d933e5d470a94970f830957 upstream.

When porting librseq commit:

commit c7b45750fa85 ("Adapt to glibc __rseq_size feature detection")

from librseq to the kernel selftests, the following line was missed
at the end of rseq_init():

rseq_size = get_rseq_kernel_feature_size();

which effectively leaves rseq_size initialized to -1U when glibc does not
have rseq support. glibc supports rseq from version 2.35 onwards.

In a following librseq commit

commit c67d198627c2 ("Only set 'rseq_size' on first thread registration")

to mimic the libc behavior, a new approach is taken: don't set the
feature size in 'rseq_size' until at least one thread has successfully
registered. This allows using 'rseq_size' in fast-paths to test for both
registration status and available features. The caveat is that on libc
either all threads are registered or none are, while with bare librseq
it is the responsability of the user to register all threads using rseq.

This combines the changes from the following librseq git commits:

commit c7b45750fa85 ("Adapt to glibc __rseq_size feature detection")
commit c67d198627c2 ("Only set 'rseq_size' on first thread registration")

Fixes: a0cc649353bb ("selftests/rseq: Fix mm_cid test failure")
Reported-by: Raghavendra Rao Ananta <rananta@google.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Raghavendra Rao Ananta <rananta@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Carlos O'Donell <carlos@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Michael Jeanson <mjeanson@efficios.com>
Cc: linux-kselftest@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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selftests/rseq: Fix mm_cid test failure

commit a0cc649353bb726d4aa0db60dce467432197b746 upstream.

Adapt the rseq.c/rseq.h code to follow GNU C library changes introduced by:

glibc commit 2e456ccf0

selftests/rseq: Fix mm_cid test failure

commit a0cc649353bb726d4aa0db60dce467432197b746 upstream.

Adapt the rseq.c/rseq.h code to follow GNU C library changes introduced by:

glibc commit 2e456ccf0c34 ("Linux: Make __rseq_size useful for feature detection (bug 31965)")

Without this fix, rseq selftests for mm_cid fail:

./run_param_test.sh
Default parameters
Running test spinlock
Running compare-twice test spinlock
Running mm_cid test spinlock
Error: cpu id getter unavailable

Fixes: 18c2355838e7 ("selftests/rseq: Implement rseq mm_cid field support")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
CC: Carlos O'Donell <carlos@redhat.com>
CC: Florian Weimer <fweimer@redhat.com>
CC: linux-kselftest@vger.kernel.org
CC: stable@vger.kernel.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...