From: "H. Peter Anvin" <hpa@linux.intel.com>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Kees Cook <keescook@chromium.org>, Linda Wang <lwang@redhat.com>,
Matt Fleming <matt.fleming@intel.com>,
"H. Peter Anvin" <hpa@linux.intel.com>
Subject: [PATCH 11/11] x86, smap: Reduce the SMAP overhead for signal handling
Date: Fri, 21 Sep 2012 12:43:15 -0700 [thread overview]
Message-ID: <1348256595-29119-12-git-send-email-hpa@linux.intel.com> (raw)
In-Reply-To: <1348256595-29119-1-git-send-email-hpa@linux.intel.com>
From: "H. Peter Anvin" <hpa@linux.intel.com>
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>
---
arch/x86/ia32/ia32_signal.c | 12 +++++++-----
arch/x86/include/asm/uaccess.h | 14 ++++++--------
arch/x86/kernel/signal.c | 24 ++++++++++++++----------
3 files changed, 27 insertions(+), 23 deletions(-)
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 673ac9b..05e62a3 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -250,11 +250,12 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
get_user_ex(tmp, &sc->fpstate);
buf = compat_ptr(tmp);
- err |= restore_i387_xstate_ia32(buf);
get_user_ex(*pax, &sc->ax);
} get_user_catch(err);
+ err |= restore_i387_xstate_ia32(buf);
+
return err;
}
@@ -502,7 +503,6 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
put_user_ex(sig, &frame->sig);
put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
- err |= copy_siginfo_to_user32(&frame->info, info);
/* Create the ucontext. */
if (cpu_has_xsave)
@@ -514,9 +514,6 @@ int ia32_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 |= ia32_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;
@@ -532,6 +529,11 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
put_user_ex(*((u64 *)&code), (u64 *)frame->retcode);
} put_user_catch(err);
+ err |= copy_siginfo_to_user32(&frame->info, info);
+ err |= ia32_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;
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index b92ece1..a91acfb 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -416,9 +416,8 @@ do { \
} while (0)
#define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
- asm volatile(ASM_STAC "\n" \
- "1: mov"itype" %1,%"rtype"0\n" \
- "2: " ASM_CLAC "\n" \
+ asm volatile("1: mov"itype" %1,%"rtype"0\n" \
+ "2:\n" \
_ASM_EXTABLE_EX(1b, 2b) \
: ltype(x) : "m" (__m(addr)))
@@ -460,9 +459,8 @@ struct __large_struct { unsigned long buf[100]; };
: ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
#define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
- asm volatile(ASM_STAC "\n" \
- "1: mov"itype" %"rtype"0,%1\n" \
- "2: " ASM_CLAC "\n" \
+ asm volatile("1: mov"itype" %"rtype"0,%1\n" \
+ "2:\n" \
_ASM_EXTABLE_EX(1b, 2b) \
: : ltype(x), "m" (__m(addr)))
@@ -470,13 +468,13 @@ struct __large_struct { unsigned long buf[100]; };
* uaccess_try and catch
*/
#define uaccess_try do { \
- int prev_err = current_thread_info()->uaccess_err; \
current_thread_info()->uaccess_err = 0; \
+ stac(); \
barrier();
#define uaccess_catch(err) \
+ clac(); \
(err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \
- current_thread_info()->uaccess_err = prev_err; \
} while (0)
/**
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b280908..9326128 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;
--
1.7.6.5
next prev parent reply other threads:[~2012-09-21 19:43 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 19:43 [PATCH 00/11] x86: Supervisor Mode Access Prevention H. Peter Anvin
2012-09-21 19:43 ` [PATCH 01/11] x86, cpufeature: Add feature bit for SMAP H. Peter Anvin
2012-09-21 19:43 ` [PATCH 02/11] x86-32, mm: The WP test should be done on a kernel page H. Peter Anvin
2012-09-21 19:58 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 03/11] x86, smap: Add CR4 bit for SMAP H. Peter Anvin
2012-09-21 19:59 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 04/11] x86, alternative: Use .pushsection/.popsection H. Peter Anvin
2012-09-21 20:00 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 05/11] x86, alternative: Add header guards to <asm/alternative-asm.h> H. Peter Anvin
2012-09-21 20:01 ` [tip:x86/smap] x86, alternative: Add header guards to <asm/ alternative-asm.h> tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 06/11] x86, smap: Add a header file with macros for STAC/CLAC H. Peter Anvin
2012-09-21 20:02 ` [tip:x86/smap] x86, smap: Add a header file with macros for STAC/ CLAC tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 07/11] x86, uaccess: Merge prototypes for clear_user/__clear_user H. Peter Anvin
2012-09-21 20:03 ` [tip:x86/smap] x86, uaccess: Merge prototypes for clear_user/ __clear_user tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 08/11] x86, smap: Add STAC and CLAC instructions to control user space access H. Peter Anvin
2012-09-21 20:04 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-22 0:16 ` [tip:x86/smap] x86-32, smap: Add STAC/ CLAC instructions to 32-bit kernel entry tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 09/11] x86, smap: Turn on Supervisor Mode Access Prevention H. Peter Anvin
2012-09-21 20:05 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 10/11] x86, smap: A page fault due to SMAP is an oops H. Peter Anvin
2012-09-21 20:06 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` H. Peter Anvin [this message]
2012-09-21 20:07 ` [tip:x86/smap] x86, smap: Reduce the SMAP overhead for signal handling tip-bot for H. Peter Anvin
2012-09-21 19:54 ` [PATCH 00/11] x86: Supervisor Mode Access Prevention Linus Torvalds
2012-09-21 19:57 ` H. Peter Anvin
2012-09-21 20:08 ` Ingo Molnar
2012-09-21 21:03 ` H. Peter Anvin
2012-09-21 21:09 ` Linus Torvalds
2012-09-21 21:12 ` H. Peter Anvin
2012-09-21 22:07 ` Eric W. Biederman
2012-09-21 22:12 ` H. Peter Anvin
2012-09-22 0:41 ` Eric W. Biederman
2012-09-24 23:27 ` [RFC PATCH] x86-32: Start out eflags and cr4 clean H. Peter Anvin
2012-09-25 13:27 ` Konrad Rzeszutek Wilk
2012-09-25 13:48 ` Ian Campbell
2012-09-26 11:29 ` Konrad Rzeszutek Wilk
2012-09-27 6:11 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-11-24 3:49 ` Yuhong Bao
2012-11-24 5:06 ` H. Peter Anvin
2012-09-27 6:11 ` [tip:x86/smap] x86, suspend: On wakeup always initialize cr4 and EFER tip-bot for H. Peter Anvin
2012-10-01 22:04 ` [tip:x86/urgent] x86, suspend: Correct the restore of CR4, EFER; skip computing EFLAGS.ID tip-bot for H. Peter Anvin
2012-10-02 6:52 ` tip-bot for H. Peter Anvin
2012-10-10 19:59 ` [RFC PATCH] x86-32: Start out eflags and cr4 clean Andres Salomon
2013-01-19 0:40 ` Andres Salomon
2013-01-19 0:42 ` H. Peter Anvin
2013-01-19 1:05 ` [Techteam] " Mitch Bradley
2013-01-19 2:35 ` H. Peter Anvin
2013-01-19 7:44 ` Mitch Bradley
2013-01-19 12:34 ` Daniel Drake
2013-01-19 19:15 ` [tip:x86/urgent] x86-32: Start out cr0 clean, disable paging before modifying cr3/4 tip-bot for H. Peter Anvin
2012-09-21 22:08 ` [PATCH 00/11] x86: Supervisor Mode Access Prevention Dave Jones
2012-09-21 22:10 ` H. Peter Anvin
2012-09-22 11:32 ` Ingo Molnar
2012-09-24 20:31 ` H. Peter Anvin
2012-09-24 20:43 ` Kees Cook
2012-09-24 20:51 ` H. Peter Anvin
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