diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/rseq-internal.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/rseq-internal.h | 33 |
1 files changed, 31 insertions, 2 deletions
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h index 48eebc1e16..37a8f630b6 100644 --- a/sysdeps/unix/sysv/linux/rseq-internal.h +++ b/sysdeps/unix/sysv/linux/rseq-internal.h @@ -25,18 +25,47 @@ #include <stdio.h> #include <sys/rseq.h> +/* 32 is the initially required value for the area size. The + actually used rseq size may be less (20 bytes initially). */ +#define RSEQ_AREA_SIZE_INITIAL 32 +#define RSEQ_AREA_SIZE_INITIAL_USED 20 + +/* The variables are in .data.relro but are not yet write-protected. */ +extern unsigned int _rseq_size attribute_hidden; +extern ptrdiff_t _rseq_offset attribute_hidden; + #ifdef RSEQ_SIG static inline bool rseq_register_current_thread (struct pthread *self, bool do_rseq) { if (do_rseq) { + unsigned int size; +#if IS_IN (rtld) + /* Use the hidden symbol in ld.so. */ + size = _rseq_size; +#else + size = __rseq_size; +#endif + if (size < RSEQ_AREA_SIZE_INITIAL) + /* 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, - sizeof (self->rseq_area), - 0, RSEQ_SIG); + 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; } |