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| author | Michael Jeanson <mjeanson@efficios.com> | 2024-11-07 22:23:49 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2024-11-07 22:23:49 +0100 |
| commit | 97f60abd25628425971f07e9b0e7f8eec0741235 (patch) | |
| tree | 20b20195d5bd7beec6bb49ae2086081157e79003 | |
| parent | c18de3b76ab679acb5a98e27a60fcb7626729f52 (diff) | |
| download | glibc-97f60abd25628425971f07e9b0e7f8eec0741235.zip glibc-97f60abd25628425971f07e9b0e7f8eec0741235.tar.gz glibc-97f60abd25628425971f07e9b0e7f8eec0741235.tar.bz2 | |
nptl: initialize rseq area prior to registration
Per the rseq syscall documentation, 3 fields are required to be
initialized by userspace prior to registration, they are 'cpu_id',
'rseq_cs' and 'flags'. Since we have no guarantee that 'struct pthread'
is cleared on all architectures, explicitly set those 3 fields prior to
registration.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
| -rw-r--r-- | nptl/descr.h | 2 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/rseq-internal.h | 10 |
2 files changed, 12 insertions, 0 deletions
diff --git a/nptl/descr.h b/nptl/descr.h index 65d3baa..66e4be1 100644 --- a/nptl/descr.h +++ b/nptl/descr.h @@ -414,6 +414,8 @@ struct pthread { uint32_t cpu_id_start; uint32_t cpu_id; + uint64_t rseq_cs; + uint32_t flags; }; char pad[32]; /* Original rseq area size. */ } rseq_area __attribute__ ((aligned (32))); diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h index 7ea935b..37a8f63 100644 --- a/sysdeps/unix/sysv/linux/rseq-internal.h +++ b/sysdeps/unix/sysv/linux/rseq-internal.h @@ -51,11 +51,21 @@ rseq_register_current_thread (struct pthread *self, bool do_rseq) /* The initial implementation used only 20 bytes out of 32, but still expected size 32. */ size = RSEQ_AREA_SIZE_INITIAL; + + /* Initialize the rseq fields that are read by the kernel on + registration, there is no guarantee that struct pthread is + cleared on all architectures. */ + THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_UNINITIALIZED); + THREAD_SETMEM (self, rseq_area.rseq_cs, 0); + THREAD_SETMEM (self, rseq_area.flags, 0); + int ret = INTERNAL_SYSCALL_CALL (rseq, &self->rseq_area, size, 0, RSEQ_SIG); if (!INTERNAL_SYSCALL_ERROR_P (ret)) return true; } + /* When rseq is disabled by tunables or the registration fails, inform + userspace by setting 'cpu_id' to RSEQ_CPU_ID_REGISTRATION_FAILED. */ THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED); return false; } |