Project import generated by Copybara.
GitOrigin-RevId: 0acb173e07e155358594d3ce7b5f19e91bb9fec3
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index 986b945..7159eb7 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -26,114 +26,104 @@
#include <assert.h>
#include <signal.h>
#include <limits.h>
-#include <dlfcn.h>
-#include <stddef.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 ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
-/* Offset from the thread pointer to the rseq area. */
-ptrdiff_t rseq_offset;
-
-/* Size of the registered rseq area. 0 if the registration was
- unsuccessful. */
-unsigned int rseq_size = -1U;
-
-/* Flags used during rseq registration. */
-unsigned int rseq_flags;
-
-static int rseq_ownership;
-
-static
-__thread struct rseq_abi __rseq_abi __attribute__((tls_model("initial-exec"))) = {
- .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED,
+__thread volatile struct rseq __rseq_abi = {
+ .cpu_id = RSEQ_CPU_ID_UNINITIALIZED,
};
-static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len,
+/*
+ * Shared with other libraries. This library may take rseq ownership if it is
+ * still 0 when executing the library constructor. Set to 1 by library
+ * constructor when handling rseq. Set to 0 in destructor if handling rseq.
+ */
+int __rseq_handled;
+
+/* Whether this library have ownership of rseq registration. */
+static int rseq_ownership;
+
+static __thread volatile uint32_t __rseq_refcount;
+
+static void signal_off_save(sigset_t *oldset)
+{
+ sigset_t set;
+ int ret;
+
+ sigfillset(&set);
+ ret = pthread_sigmask(SIG_BLOCK, &set, oldset);
+ if (ret)
+ abort();
+}
+
+static void signal_restore(sigset_t oldset)
+{
+ int ret;
+
+ ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+ if (ret)
+ abort();
+}
+
+static int sys_rseq(volatile struct rseq *rseq_abi, uint32_t rseq_len,
int flags, uint32_t sig)
{
return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
}
-int rseq_available(void)
-{
- int rc;
-
- rc = sys_rseq(NULL, 0, 0, 0);
- if (rc != -1)
- abort();
- switch (errno) {
- case ENOSYS:
- return 0;
- case EINVAL:
- return 1;
- default:
- abort();
- }
-}
-
int rseq_register_current_thread(void)
{
- int rc;
+ int rc, ret = 0;
+ sigset_t oldset;
- if (!rseq_ownership) {
- /* Treat libc's ownership as a successful registration. */
+ if (!rseq_ownership)
return 0;
+ signal_off_save(&oldset);
+ if (__rseq_refcount == UINT_MAX) {
+ ret = -1;
+ goto end;
}
- rc = sys_rseq(&__rseq_abi, sizeof(struct rseq_abi), 0, RSEQ_SIG);
- if (rc)
- return -1;
- assert(rseq_current_cpu_raw() >= 0);
- return 0;
+ if (__rseq_refcount++)
+ goto end;
+ rc = sys_rseq(&__rseq_abi, sizeof(struct rseq), 0, RSEQ_SIG);
+ if (!rc) {
+ assert(rseq_current_cpu_raw() >= 0);
+ goto end;
+ }
+ if (errno != EBUSY)
+ __rseq_abi.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED;
+ ret = -1;
+ __rseq_refcount--;
+end:
+ signal_restore(oldset);
+ return ret;
}
int rseq_unregister_current_thread(void)
{
- int rc;
+ int rc, ret = 0;
+ sigset_t oldset;
- if (!rseq_ownership) {
- /* Treat libc's ownership as a successful unregistration. */
- return 0;
- }
- rc = sys_rseq(&__rseq_abi, sizeof(struct rseq_abi), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
- if (rc)
- return -1;
- return 0;
-}
-
-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) {
- /* rseq registration owned by glibc */
- rseq_offset = *libc_rseq_offset_p;
- rseq_size = *libc_rseq_size_p;
- rseq_flags = *libc_rseq_flags_p;
- return;
- }
- if (!rseq_available())
- return;
- rseq_ownership = 1;
- rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer();
- rseq_size = sizeof(struct rseq_abi);
- rseq_flags = 0;
-}
-
-static __attribute__((destructor))
-void rseq_exit(void)
-{
if (!rseq_ownership)
- return;
- rseq_offset = 0;
- rseq_size = -1U;
- rseq_ownership = 0;
+ return 0;
+ signal_off_save(&oldset);
+ if (!__rseq_refcount) {
+ ret = -1;
+ goto end;
+ }
+ if (--__rseq_refcount)
+ goto end;
+ rc = sys_rseq(&__rseq_abi, sizeof(struct rseq),
+ RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
+ if (!rc)
+ goto end;
+ __rseq_refcount = 1;
+ ret = -1;
+end:
+ signal_restore(oldset);
+ return ret;
}
int32_t rseq_fallback_current_cpu(void)
@@ -147,3 +137,20 @@ int32_t rseq_fallback_current_cpu(void)
}
return cpu;
}
+
+void __attribute__((constructor)) rseq_init(void)
+{
+ /* Check whether rseq is handled by another library. */
+ if (__rseq_handled)
+ return;
+ __rseq_handled = 1;
+ rseq_ownership = 1;
+}
+
+void __attribute__((destructor)) rseq_fini(void)
+{
+ if (!rseq_ownership)
+ return;
+ __rseq_handled = 0;
+ rseq_ownership = 0;
+}
