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Commit cf20d1ea authored by David Mosberger-Tang's avatar David Mosberger-Tang Committed by Tony Luck
Browse files

[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: default avatarDavid Mosberger-Tang <David.Mosberger@acm.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent f093182d

arch/ia64/kernel/signal.c

+5 −6
Original line number Diff line number Diff line
@@ -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);