diff options
| author | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 12:43:15 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 12:45:27 -0700 |
| commit | 5e88353d8b5f483bc1c873ad24ac2b59a6b66c73 (patch) | |
| tree | f5651873e535e4feabea0da5d253d0326b4bd029 /arch/x86/kernel/signal.c | |
| parent | 40d3cd6695014bf3c44e2ca66b610b18acaf923d (diff) | |
x86, smap: Reduce the SMAP overhead for signal handling
Signal handling contains a bunch of accesses to individual user space
items, which causes an excessive number of STAC and CLAC
instructions. Instead, let get/put_user_try ... get/put_user_catch()
contain the STAC and CLAC instructions.
This means that get/put_user_try no longer nests, and furthermore that
it is no longer legal to use user space access functions other than
__get/put_user_ex() inside those blocks. However, these macros are
x86-specific anyway and are only used in the signal-handling paths; a
simple reordering of moving the larger subroutine calls out of the
try...catch blocks resolves that problem.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-12-git-send-email-hpa@linux.intel.com
Diffstat (limited to 'arch/x86/kernel/signal.c')
| -rw-r--r-- | arch/x86/kernel/signal.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index b280908a376e..932612887e92 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -114,11 +114,12 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, regs->orig_ax = -1; /* disable syscall checks */ get_user_ex(buf, &sc->fpstate); - err |= restore_i387_xstate(buf); get_user_ex(*pax, &sc->ax); } get_user_catch(err); + err |= restore_i387_xstate(buf); + return err; } @@ -357,7 +358,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, put_user_ex(sig, &frame->sig); put_user_ex(&frame->info, &frame->pinfo); put_user_ex(&frame->uc, &frame->puc); - err |= copy_siginfo_to_user(&frame->info, info); /* Create the ucontext. */ if (cpu_has_xsave) @@ -369,9 +369,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, put_user_ex(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size); - err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, - regs, set->sig[0]); - err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); /* Set up to return from userspace. */ restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn); @@ -389,6 +386,11 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode); } put_user_catch(err); + err |= copy_siginfo_to_user(&frame->info, info); + err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, + regs, set->sig[0]); + err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); + if (err) return -EFAULT; @@ -436,8 +438,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, put_user_ex(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size); - err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); - err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); /* Set up to return from userspace. If provided, use a stub already in userspace. */ @@ -450,6 +450,9 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, } } put_user_catch(err); + err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); + err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); + if (err) return -EFAULT; @@ -855,9 +858,6 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka, &frame->uc.uc_stack.ss_flags); put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size); put_user_ex(0, &frame->uc.uc__pad0); - err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, - regs, set->sig[0]); - err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (ka->sa.sa_flags & SA_RESTORER) { restorer = ka->sa.sa_restorer; @@ -869,6 +869,10 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka, put_user_ex(restorer, &frame->pretcode); } put_user_catch(err); + err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, + regs, set->sig[0]); + err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); + if (err) return -EFAULT; |