From: David Mosberger-Tang <davidm@mostang.com>
Date: Thu, 3 Nov 2005 06:40:19 +0000 (-0800)
Subject: [IA64] align signal-frame even when not using alternate signal-stack
X-Git-Tag: v2.6.15-rc1~42^2~7^2
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf20d1eafb648bf395b153cbcd0cde40f88c220a;p=linux-2.6

[IA64] align signal-frame even when not using alternate signal-stack

At the moment, attempting to invoke a signal-handler on the normal
stack is guaranteed to fail if the stack-pointer happens not to be
16-byte aligned.  This is because the signal-trampoline will attempt
to store fp-regs with stf.spill instructions, which will trap for
misaligned addresses.  This isn't terribly useful behavior.  It's
better to just always align the signal frame to the next lower 16-byte
boundary.

Signed-off-by: David Mosberger-Tang <David.Mosberger@acm.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---

diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c
index 774f34b675..58ce07efc5 100644
--- a/arch/ia64/kernel/signal.c
+++ b/arch/ia64/kernel/signal.c
@@ -387,15 +387,14 @@ setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
 	     struct sigscratch *scr)
 {
 	extern char __kernel_sigtramp[];
-	unsigned long tramp_addr, new_rbs = 0;
+	unsigned long tramp_addr, new_rbs = 0, new_sp;
 	struct sigframe __user *frame;
 	long err;
 
-	frame = (void __user *) scr->pt.r12;
+	new_sp = scr->pt.r12;
 	tramp_addr = (unsigned long) __kernel_sigtramp;
-	if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags((unsigned long) frame) == 0) {
-		frame = (void __user *) ((current->sas_ss_sp + current->sas_ss_size)
-					 & ~(STACK_ALIGN - 1));
+	if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(new_sp) == 0) {
+		new_sp = current->sas_ss_sp + current->sas_ss_size;
 		/*
 		 * We need to check for the register stack being on the signal stack
 		 * separately, because it's switched separately (memory stack is switched
@@ -404,7 +403,7 @@ setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
 		if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
 			new_rbs = (current->sas_ss_sp + sizeof(long) - 1) & ~(sizeof(long) - 1);
 	}
-	frame = (void __user *) frame - ((sizeof(*frame) + STACK_ALIGN - 1) & ~(STACK_ALIGN - 1));
+	frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 
 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		return force_sigsegv_info(sig, frame);