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nptl: Unconditionally use a 32-byte rseq area

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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.
This commit is contained in:
Florian Weimer 2023-07-21 16:18:18 +02:00
parent f7f181c12c
commit 2c6b4b272e
1 changed files with 14 additions and 4 deletions
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18
nptl/descr.h
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@ -34,7 +34,6 @@
#include <bits/types/res_state.h> #include <bits/types/res_state.h>
#include <kernel-features.h> #include <kernel-features.h>
#include <tls-internal-struct.h> #include <tls-internal-struct.h>
#include <sys/rseq.h>
#include <internal-sigset.h> #include <internal-sigset.h>
#ifndef TCB_ALIGNMENT #ifndef TCB_ALIGNMENT
@ -405,14 +404,25 @@ struct pthread
/* Used on strsignal. */ /* Used on strsignal. */
struct tls_internal_t tls_state; struct tls_internal_t tls_state;
/* rseq area registered with the kernel. */ /* rseq area registered with the kernel. Use a custom definition
struct rseq rseq_area; 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. /* Amount of end padding, if any, in this structure.
This definition relies on rseq_area being last. */ This definition relies on rseq_area being last. */
#define PTHREAD_STRUCT_END_PADDING \ #define PTHREAD_STRUCT_END_PADDING \
(sizeof (struct pthread) - offsetof (struct pthread, rseq_area) \ (sizeof (struct pthread) - offsetof (struct pthread, rseq_area) \
+ sizeof (struct rseq)) + sizeof ((struct pthread) {}.rseq_area))
} __attribute ((aligned (TCB_ALIGNMENT))); } __attribute ((aligned (TCB_ALIGNMENT)));
static inline bool static inline bool