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authorFlorian Weimer <fweimer@redhat.com>2024-07-08 21:14:00 +0200
committerFlorian Weimer <fweimer@redhat.com>2024-07-09 19:33:37 +0200
commit2e456ccf0c34a056e3ccafac4a0c7effef14d918 (patch)
treef8850016fc638b37f5edb32a729bb023d8084fa6 /manual
parentpo: incorporate translations (bg) (diff)
downloadglibc-2e456ccf0c34a056e3ccafac4a0c7effef14d918.tar.xz
glibc-2e456ccf0c34a056e3ccafac4a0c7effef14d918.zip
Linux: Make __rseq_size useful for feature detection (bug 31965)
The __rseq_size value is now the active area of struct rseq (so 20 initially), not the full struct size including padding at the end (32 initially). Update misc/tst-rseq to print some additional diagnostics. Reviewed-by: Michael Jeanson <mjeanson@efficios.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Diffstat (limited to 'manual')
-rw-r--r--manual/threads.texi8
1 files changed, 6 insertions, 2 deletions
diff --git a/manual/threads.texi b/manual/threads.texi
index e5544ff3da..25e99c9606 100644
--- a/manual/threads.texi
+++ b/manual/threads.texi
@@ -1007,8 +1007,12 @@ This variable is either zero (if restartable sequence registration
failed or has been disabled) or the size of the restartable sequence
registration. This can be different from the size of @code{struct rseq}
if the kernel has extended the size of the registration. If
-registration is successful, @code{__rseq_size} is at least 32 (the
-initial size of @code{struct rseq}).
+registration is successful, @code{__rseq_size} is at least 20 (the
+initially active size of @code{struct rseq}).
+
+Previous versions of @theglibc{} set this to 32 even if the kernel only
+supported the initial area of 20 bytes because the value included unused
+padding at the end of the restartable sequence area.
@end deftypevar
@deftypevar {unsigned int} __rseq_flags