diff options
| -rw-r--r-- | tools/testing/selftests/rseq/rseq.c | 32 | ||||
| -rw-r--r-- | tools/testing/selftests/rseq/rseq.h | 9 |
2 files changed, 33 insertions, 8 deletions
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c index 5b9772cdf265..f6156790c3b4 100644 --- a/tools/testing/selftests/rseq/rseq.c +++ b/tools/testing/selftests/rseq/rseq.c @@ -61,7 +61,6 @@ unsigned int rseq_size = -1U; unsigned int rseq_flags; static int rseq_ownership; -static int rseq_reg_success; /* At least one rseq registration has succeded. */ /* Allocate a large area for the TLS. */ #define RSEQ_THREAD_AREA_ALLOC_SIZE 1024 @@ -152,14 +151,27 @@ int rseq_register_current_thread(void) } rc = sys_rseq(&__rseq_abi, get_rseq_min_alloc_size(), 0, RSEQ_SIG); if (rc) { - if (RSEQ_READ_ONCE(rseq_reg_success)) { + /* + * After at least one thread has registered successfully + * (rseq_size > 0), the registration of other threads should + * never fail. + */ + if (RSEQ_READ_ONCE(rseq_size) > 0) { /* Incoherent success/failure within process. */ abort(); } return -1; } assert(rseq_current_cpu_raw() >= 0); - RSEQ_WRITE_ONCE(rseq_reg_success, 1); + + /* + * The first thread to register sets the rseq_size to mimic the libc + * behavior. + */ + if (RSEQ_READ_ONCE(rseq_size) == 0) { + RSEQ_WRITE_ONCE(rseq_size, get_rseq_kernel_feature_size()); + } + return 0; } @@ -235,12 +247,18 @@ void rseq_init(void) return; } rseq_ownership = 1; - if (!rseq_available()) { - rseq_size = 0; - return; - } + + /* Calculate the offset of the rseq area from the thread pointer. */ rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer(); + + /* rseq flags are deprecated, always set to 0. */ rseq_flags = 0; + + /* + * Set the size to 0 until at least one thread registers to mimic the + * libc behavior. + */ + rseq_size = 0; } static __attribute__((destructor)) diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h index 4e217b620e0c..062d10925a10 100644 --- a/tools/testing/selftests/rseq/rseq.h +++ b/tools/testing/selftests/rseq/rseq.h @@ -60,7 +60,14 @@ extern ptrdiff_t rseq_offset; /* - * Size of the registered rseq area. 0 if the registration was + * The rseq ABI is composed of extensible feature fields. The extensions + * are done by appending additional fields at the end of the structure. + * The rseq_size defines the size of the active feature set which can be + * used by the application for the current rseq registration. Features + * starting at offset >= rseq_size are inactive and should not be used. + * + * The rseq_size is the intersection between the available allocation + * size for the rseq area and the feature size supported by the kernel. * unsuccessful. */ extern unsigned int rseq_size; |