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-rw-r--r--libc/sysdeps/linux/arm/sigaction.c12
-rw-r--r--libc/sysdeps/linux/arm/sigrestorer.S33
2 files changed, 34 insertions, 11 deletions
diff --git a/libc/sysdeps/linux/arm/sigaction.c b/libc/sysdeps/linux/arm/sigaction.c
index 1066d33dd..8ab2be797 100644
--- a/libc/sysdeps/linux/arm/sigaction.c
+++ b/libc/sysdeps/linux/arm/sigaction.c
@@ -57,14 +57,7 @@ int __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oa
memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
kact.sa_flags = act->sa_flags;
# ifdef HAVE_SA_RESTORER
- /* If the user specified SA_ONSTACK this means she is trying to
- use the old-style stack switching. Unfortunately this
- requires the sa_restorer field so we cannot install our own
- handler. (In fact the user is likely to be out of luck anyway
- since the kernel currently only supports stack switching via
- the X/Open sigaltstack interface, but we allow for the
- possibility that this might change in the future.) */
- if (kact.sa_flags & (SA_RESTORER | SA_ONSTACK)) {
+ if (kact.sa_flags & SA_RESTORER) {
kact.sa_restorer = act->sa_restorer;
} else {
kact.sa_restorer = choose_restorer (kact.sa_flags);
@@ -103,8 +96,7 @@ int __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oa
kact.sa_mask = act->sa_mask.__val[0];
kact.sa_flags = act->sa_flags;
# ifdef HAVE_SA_RESTORER
- /* See the comments above for why we test SA_ONSTACK. */
- if (kact.sa_flags & (SA_RESTORER | SA_ONSTACK)) {
+ if (kact.sa_flags & SA_RESTORER) {
kact.sa_restorer = act->sa_restorer;
} else {
kact.sa_restorer = choose_restorer (kact.sa_flags);
diff --git a/libc/sysdeps/linux/arm/sigrestorer.S b/libc/sysdeps/linux/arm/sigrestorer.S
index bc175de6a..5b996ea83 100644
--- a/libc/sysdeps/linux/arm/sigrestorer.S
+++ b/libc/sysdeps/linux/arm/sigrestorer.S
@@ -20,13 +20,33 @@
/* If no SA_RESTORER function was specified by the application we use
one of these. This avoids the need for the kernel to synthesise a return
- instruction on the stack, which would involve expensive cache flushes. */
+ instruction on the stack, which would involve expensive cache flushes.
+
+ Nowadays (2.6 series, and somewhat earlier) the kernel uses a high page
+ for signal trampolines, so the cache flushes are not an issue. But since
+ we do not have a vDSO, continue to use these so that we can provide
+ unwind information.
+
+ Start the unwind tables at least one instruction before the signal
+ trampoline, because the unwinder will assume we are returning after
+ a call site. */
.global __default_sa_restorer
.type __default_sa_restorer,%function
.align 2
+#ifdef __ARM_EABI__
+ .fnstart
+ .save {r0-r15}
+ .pad #12
+ nop
+__default_sa_restorer:
+ mov r7, $SYS_ify(sigreturn)
+ swi 0x0
+ .fnend
+#else
__default_sa_restorer:
DO_CALL (sigreturn)
+#endif
#ifdef __NR_rt_sigreturn
@@ -34,7 +54,18 @@ __default_sa_restorer:
.global __default_rt_sa_restorer
.type __default_rt_sa_restorer,%function
.align 2
+#ifdef __ARM_EABI__
+ .fnstart
+ .save {r0-r15}
+ .pad #168
+ nop
+__default_rt_sa_restorer:
+ mov r7, $SYS_ify(rt_sigreturn)
+ swi 0x0
+ .fnend
+#else
__default_rt_sa_restorer:
DO_CALL (rt_sigreturn)
+#endif
#endif