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author | Florian Weimer <fweimer@redhat.com> | 2023-07-21 16:18:18 +0200 |
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committer | Arjun Shankar <arjun@redhat.com> | 2024-03-18 11:55:02 +0100 |
commit | c9ee9cc8b8e4f8671c1d487f83db333b6be6a925 (patch) | |
tree | 0a37ef6ebf7c4df0a7c98d1a4183cd832cf40118 | |
parent | 3cd02612e831500dacc8d731f23a52aae01cbc39 (diff) | |
download | glibc-c9ee9cc8b8e4f8671c1d487f83db333b6be6a925.tar.gz glibc-c9ee9cc8b8e4f8671c1d487f83db333b6be6a925.tar.xz glibc-c9ee9cc8b8e4f8671c1d487f83db333b6be6a925.zip |
nptl: Unconditionally use a 32-byte rseq area
If the kernel headers provide a larger struct rseq, we used that size as the argument to the rseq system call. As a result, rseq registration would fail on older kernels which only accept size 32. (cherry picked from commit 2c6b4b272e6b4d07303af25709051c3e96288f2d)
-rw-r--r-- | nptl/descr.h | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/nptl/descr.h b/nptl/descr.h index e2627bce05..c6ff376a36 100644 --- a/nptl/descr.h +++ b/nptl/descr.h @@ -34,7 +34,6 @@ #include <bits/types/res_state.h> #include <kernel-features.h> #include <tls-internal-struct.h> -#include <sys/rseq.h> #ifndef TCB_ALIGNMENT # define TCB_ALIGNMENT 32 @@ -408,14 +407,25 @@ struct pthread /* Used on strsignal. */ struct tls_internal_t tls_state; - /* rseq area registered with the kernel. */ - struct rseq rseq_area; + /* rseq area registered with the kernel. Use a custom definition + here to isolate from kernel struct rseq changes. The + implementation of sched_getcpu needs acccess to the cpu_id field; + the other fields are unused and not included here. */ + union + { + struct + { + uint32_t cpu_id_start; + uint32_t cpu_id; + }; + char pad[32]; /* Original rseq area size. */ + } rseq_area __attribute__ ((aligned (32))); /* Amount of end padding, if any, in this structure. This definition relies on rseq_area being last. */ #define PTHREAD_STRUCT_END_PADDING \ (sizeof (struct pthread) - offsetof (struct pthread, rseq_area) \ - + sizeof (struct rseq)) + + sizeof ((struct pthread) {}.rseq_area)) } __attribute ((aligned (TCB_ALIGNMENT))); static inline bool |