Patch "selftests/rseq: check if libc rseq support is registered" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests/rseq: check if libc rseq support is registered

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-rseq-check-if-libc-rseq-support-is-registe.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d55fefacc40d90d53e23d05b56b1b879b8eabdbd
Author: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
Date:   Tue Jun 14 11:48:30 2022 -0400

    selftests/rseq: check if libc rseq support is registered
    
    [ Upstream commit d1a997ba4c1bf65497d956aea90de42a6398f73a ]
    
    When checking for libc rseq support in the library constructor, don't
    only depend on the symbols presence, check that the registration was
    completed.
    
    This targets a scenario where the libc has rseq support but it is not
    wired for the current architecture in 'bits/rseq.h', we want to fallback
    to our internal registration mechanism.
    
    Signed-off-by: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
    Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220614154830.1367382-4-mjeanson@xxxxxxxxxxxx
    Stable-dep-of: 3bcbc20942db ("selftests/rseq: Play nice with binaries statically linked against glibc 2.35+")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 986b9458efb26..4177f9507bbee 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -111,7 +111,8 @@ void rseq_init(void)
 	libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset");
 	libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size");
 	libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags");
-	if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p) {
+	if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p &&
+			*libc_rseq_size_p != 0) {
 		/* rseq registration owned by glibc */
 		rseq_offset = *libc_rseq_offset_p;
 		rseq_size = *libc_rseq_size_p;