[PATCH v2 8/8] nptl: rseq failure after registration on main thread is fatal

[Florian Weimer <fweimer@redhat.com>]

This simplifies the application programming model.

Browser sandboxes have already been fixed:

  Sandbox is incompatible with rseq registration
  <https://bugzilla.mozilla.org/show_bug.cgi?id=1651701>

  Allow rseq in the Linux sandboxes. r=gcp
  <https://hg.mozilla.org/mozilla-central/rev/042425712eb1>

  Sandbox needs to support rseq system call
  <https://bugs.chromium.org/p/chromium/issues/detail?id=1104160>

  Linux sandbox: Allow rseq(2)
  <https://chromium.googlesource.com/chromium/src.git/+/230675d9ac8f1>
---
v2: New patch.  Tested with Firefox 94.0 on Fedora 35.

 nptl/pthread_create.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 4608fd9068..c097fc54e6 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -370,7 +370,8 @@ start_thread (void *arg)
   /* Register rseq TLS to the kernel.  */
   {
     bool do_rseq = THREAD_GETMEM (pd, flags) & ATTR_FLAG_DO_RSEQ;
-    rseq_register_current_thread (pd, do_rseq);
+    if (!rseq_register_current_thread (pd, do_rseq) && do_rseq)
+      __libc_fatal ("Fatal glibc error: rseq registration failed\n");
   }
 
 #ifndef __ASSUME_SET_ROBUST_LIST
-- 
2.33.1