diff options
Diffstat (limited to 'tools/testing/selftests/rseq/rseq.c')
| -rw-r--r-- | tools/testing/selftests/rseq/rseq.c | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c index 986b9458efb2..e20191fb40d4 100644 --- a/tools/testing/selftests/rseq/rseq.c +++ b/tools/testing/selftests/rseq/rseq.c @@ -29,12 +29,22 @@ #include <dlfcn.h> #include <stddef.h> +#include <linux/compiler.h> + #include "../kselftest.h" #include "rseq.h" -static const ptrdiff_t *libc_rseq_offset_p; -static const unsigned int *libc_rseq_size_p; -static const unsigned int *libc_rseq_flags_p; +/* + * Define weak versions to play nice with binaries that are statically linked + * against a libc that doesn't support registering its own rseq. + */ +__weak ptrdiff_t __rseq_offset; +__weak unsigned int __rseq_size; +__weak unsigned int __rseq_flags; + +static const ptrdiff_t *libc_rseq_offset_p = &__rseq_offset; +static const unsigned int *libc_rseq_size_p = &__rseq_size; +static const unsigned int *libc_rseq_flags_p = &__rseq_flags; /* Offset from the thread pointer to the rseq area. */ ptrdiff_t rseq_offset; @@ -108,10 +118,19 @@ int rseq_unregister_current_thread(void) static __attribute__((constructor)) void rseq_init(void) { - libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset"); - libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size"); - libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags"); - if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p) { + /* + * If the libc's registered rseq size isn't already valid, it may be + * because the binary is dynamically linked and not necessarily due to + * libc not having registered a restartable sequence. Try to find the + * symbols if that's the case. + */ + if (!*libc_rseq_size_p) { + libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset"); + libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size"); + libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags"); + } + if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p && + *libc_rseq_size_p != 0) { /* rseq registration owned by glibc */ rseq_offset = *libc_rseq_offset_p; rseq_size = *libc_rseq_size_p; |