diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/rseq-internal.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/rseq-internal.h | 49 |
1 files changed, 38 insertions, 11 deletions
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h index 00be15c..f89e784 100644 --- a/sysdeps/unix/sysv/linux/rseq-internal.h +++ b/sysdeps/unix/sysv/linux/rseq-internal.h @@ -26,6 +26,30 @@ #include <sys/rseq.h> #include <ldsodefs.h> #include <thread_pointer.h> +#include <rseq-access.h> + +/* rseq area registered with the kernel. Use a custom definition here to + isolate from the system provided header which could lack some fields of the + Extended ABI. + + This is only used to get the field offsets and sizes, it should never be + used for direct object allocations. + + Access to fields of the Extended ABI beyond the 20 bytes of the original ABI + (after 'flags') must be gated by a check of the feature size. */ +struct rseq_area +{ + /* Original ABI. */ + uint32_t cpu_id_start; + uint32_t cpu_id; + uint64_t rseq_cs; + uint32_t flags; + /* Extended ABI. */ + uint32_t node_id; + uint32_t mm_cid; + /* Flexible array member to discourage direct object allocations. */ + char end[]; +}; /* Minimum size of the rseq area allocation required by the syscall. The actually used rseq feature size may be less (20 bytes initially). */ @@ -47,10 +71,12 @@ extern size_t _rseq_align attribute_hidden; /* Size of the active features in the rseq area. Populated from the auxiliary vector with a minimum of '20'. + Set to '0' on registration failure of the main thread. In .data.relro but not yet write-protected. */ extern unsigned int _rseq_size attribute_hidden; -/* Offset from the thread pointer to the rseq area. +/* Offset from the thread pointer to the rseq area, always set to allow + checking the registration status by reading the 'cpu_id' field. In .data.relro but not yet write-protected. */ extern ptrdiff_t _rseq_offset attribute_hidden; @@ -75,34 +101,35 @@ rseq_register_current_thread (struct pthread *self, bool do_rseq) { unsigned int size = __rseq_size; + /* The feature size can be smaller than the minimum rseq area size of 32 + bytes accepted by the syscall, if this is the case, bump the size of + the registration to the minimum. The 'extra TLS' block is always at + least 32 bytes. */ 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.cpu_id_start, 0); - THREAD_SETMEM (self, rseq_area.rseq_cs, 0); - THREAD_SETMEM (self, rseq_area.flags, 0); + RSEQ_SETMEM (cpu_id, RSEQ_CPU_ID_UNINITIALIZED); + RSEQ_SETMEM (cpu_id_start, 0); + RSEQ_SETMEM (rseq_cs, 0); + RSEQ_SETMEM (flags, 0); - int ret = INTERNAL_SYSCALL_CALL (rseq, &self->rseq_area, - size, 0, RSEQ_SIG); + int ret = INTERNAL_SYSCALL_CALL (rseq, RSEQ_SELF (), 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); + RSEQ_SETMEM (cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED); return false; } #else /* RSEQ_SIG */ static inline bool rseq_register_current_thread (struct pthread *self, bool do_rseq) { - THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED); + RSEQ_SETMEM (cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED); return false; } #endif /* RSEQ_SIG */ |