From mboxrd@z Thu Jan 1 00:00:00 1970 From: davidm@mostang.com (David Mosberger-Tang) Date: Thu, 03 Nov 2005 06:40:19 +0000 Subject: [patch] align signal-frame even when not using alternate signal-stack Message-Id: <20051103064019.5B552B3421@localhost.localdomain> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org [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. (Lightly) tested patch attached below. Signed-off-by: David Mosberger-Tang diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c --- a/arch/ia64/kernel/signal.c +++ b/arch/ia64/kernel/signal.c @@ -387,15 +387,14 @@ setup_frame (int sig, struct k_sigaction 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 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);