nptl: Move the rseq area to the 'extra TLS' block

Move the rseq area to the newly added 'extra TLS' block, this is the
last step in adding support for the rseq extended ABI. The size of the
rseq area is now dynamic and depends on the rseq features reported by
the kernel through the elf auxiliary vector. This will allow
applications to use rseq features past the 32 bytes of the original rseq
ABI as they become available in future kernels.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>

1 files changed, 81 insertions, 16 deletions

diff --git a/sysdeps/unix/sysv/linux/tst-rseq.c b/sysdeps/unix/sysv/linux/tst-rseq.c
index b152280..00181cf 100644
--- a/sysdeps/unix/sysv/linux/tst-rseq.c
+++ b/sysdeps/unix/sysv/linux/tst-rseq.c
@@ -19,6 +19,8 @@
    not linked against libpthread.  */
 
 #include <support/check.h>
+#include <support/namespace.h>
+#include <support/xthread.h>
 #include <stdio.h>
 #include <sys/rseq.h>
 #include <unistd.h>
@@ -32,25 +34,82 @@
 # include <sys/auxv.h>
 # include <thread_pointer.h>
 # include <tls.h>
+# include <dl-tls.h>
+# include <sys/auxv.h>
 # include "tst-rseq.h"
 
+/* Used to check if the address of the rseq area comes before or after the tls
+   blocks depending on the TLS model.  */
+static __thread char tls_var __attribute__ ((tls_model ("initial-exec")));
+
 static void
 do_rseq_main_test (void)
 {
-  struct pthread *pd = THREAD_SELF;
-  size_t rseq_feature_size = MIN (MAX (getauxval (AT_RSEQ_FEATURE_SIZE),
-                                       RSEQ_AREA_SIZE_INITIAL_USED),
-                                  RSEQ_AREA_SIZE_MAX_USED);
+  size_t rseq_align = MAX (getauxval (AT_RSEQ_ALIGN), RSEQ_MIN_ALIGN);
+  size_t rseq_feature_size = MAX (getauxval (AT_RSEQ_FEATURE_SIZE),
+                                  RSEQ_AREA_SIZE_INITIAL_USED);
+  size_t rseq_alloc_size = roundup (MAX (rseq_feature_size,
+                                    RSEQ_AREA_SIZE_INITIAL_USED), rseq_align);
+  struct rseq *rseq_abi = __thread_pointer () + __rseq_offset;
 
   TEST_VERIFY_EXIT (rseq_thread_registered ());
+
+  /* __rseq_flags is unused and should always be '0'.  */
   TEST_COMPARE (__rseq_flags, 0);
-  TEST_VERIFY ((char *) __thread_pointer () + __rseq_offset
-               == (char *) &pd->rseq_area);
+
+  /* When rseq is registered, __rseq_size should report the feature size.  */
   TEST_COMPARE (__rseq_size, rseq_feature_size);
+
+  /* When rseq is registered, the 'cpu_id' field should be set to a valid cpu
+   * number.  */
+  TEST_VERIFY ((int32_t) rseq_abi->cpu_id >= 0);
+
+  /* The rseq area address must be aligned.  */
+  TEST_VERIFY (((unsigned long) rseq_abi % rseq_align) == 0);
+
+#if TLS_TCB_AT_TP
+  /* The rseq area block should come before the thread pointer and be at least
+     32 bytes. */
+  TEST_VERIFY (__rseq_offset <= -RSEQ_AREA_SIZE_INITIAL);
+
+  /* The rseq area block should come before TLS variables.  */
+  TEST_VERIFY ((intptr_t) rseq_abi < (intptr_t) &tls_var);
+#elif TLS_DTV_AT_TP
+  /* The rseq area block should come after the TCB, add the TLS block offset to
+     the rseq offset to get a value relative to the TCB and test that it's
+     non-negative.  */
+  TEST_VERIFY (__rseq_offset + TLS_TP_OFFSET >= 0);
+
+  /* The rseq area block should come after TLS variables.  */
+  TEST_VERIFY ((intptr_t) rseq_abi > (intptr_t) &tls_var);
+#else
+# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+#endif
+
+  /* Test a rseq registration with the same arguments as the internal
+     registration which should fail with errno == EBUSY.  */
+  TEST_VERIFY (((unsigned long) rseq_abi % rseq_align) == 0);
+  TEST_VERIFY (__rseq_size <= rseq_alloc_size);
+  int ret = syscall (__NR_rseq, rseq_abi, rseq_alloc_size, 0, RSEQ_SIG);
+  TEST_VERIFY (ret != 0);
+  TEST_COMPARE (errno, EBUSY);
+}
+
+static void *
+thread_func (void *ignored)
+{
+  do_rseq_main_test ();
+  return NULL;
 }
 
 static void
-do_rseq_test (void)
+proc_func (void *ignored)
+{
+  do_rseq_main_test ();
+}
+
+static int
+do_test (void)
 {
   if (!rseq_available ())
     {
@@ -62,21 +121,27 @@ do_rseq_test (void)
   printf ("info: getauxval (AT_RSEQ_FEATURE_SIZE): %ld\n",
           getauxval (AT_RSEQ_FEATURE_SIZE));
   printf ("info: getauxval (AT_RSEQ_ALIGN): %ld\n", getauxval (AT_RSEQ_ALIGN));
+
+  puts ("info: checking main thread");
+  do_rseq_main_test ();
+
+  puts ("info: checking main thread (2)");
   do_rseq_main_test ();
+
+  puts ("info: checking new thread");
+  xpthread_join (xpthread_create (NULL, thread_func, NULL));
+
+  puts ("info: checking subprocess");
+  support_isolate_in_subprocess (proc_func, NULL);
+
+  return 0;
 }
 #else /* RSEQ_SIG */
-static void
-do_rseq_test (void)
-{
-  FAIL_UNSUPPORTED ("glibc does not define RSEQ_SIG, skipping test");
-}
-#endif /* RSEQ_SIG */
-
 static int
 do_test (void)
 {
-  do_rseq_test ();
-  return 0;
+  FAIL_UNSUPPORTED ("glibc does not define RSEQ_SIG, skipping test");
 }
+#endif /* RSEQ_SIG */
 
 #include <support/test-driver.c>