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
This commit is contained in:
H. Peter Anvin
parent
40d3cd6695
commit
5e88353d8b
3 changed files with 27 additions and 23 deletions
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@ -250,11 +250,12 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
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get_user_ex(tmp, &sc->fpstate);
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buf = compat_ptr(tmp);
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err |= restore_i387_xstate_ia32(buf);
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get_user_ex(*pax, &sc->ax);
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} get_user_catch(err);
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err |= restore_i387_xstate_ia32(buf);
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return err;
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}
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@ -502,7 +503,6 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(sig, &frame->sig);
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put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
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put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
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err |= copy_siginfo_to_user32(&frame->info, info);
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/* Create the ucontext. */
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if (cpu_has_xsave)
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@ -514,9 +514,6 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(sas_ss_flags(regs->sp),
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&frame->uc.uc_stack.ss_flags);
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put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
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err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (ka->sa.sa_flags & SA_RESTORER)
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restorer = ka->sa.sa_restorer;
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@ -532,6 +529,11 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(*((u64 *)&code), (u64 *)frame->retcode);
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} put_user_catch(err);
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err |= copy_siginfo_to_user32(&frame->info, info);
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err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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return -EFAULT;
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@ -416,9 +416,8 @@ do { \
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} while (0)
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#define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
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asm volatile(ASM_STAC "\n" \
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"1: mov"itype" %1,%"rtype"0\n" \
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"2: " ASM_CLAC "\n" \
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asm volatile("1: mov"itype" %1,%"rtype"0\n" \
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"2:\n" \
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_ASM_EXTABLE_EX(1b, 2b) \
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: ltype(x) : "m" (__m(addr)))
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@ -460,9 +459,8 @@ struct __large_struct { unsigned long buf[100]; };
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: ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
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#define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
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asm volatile(ASM_STAC "\n" \
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"1: mov"itype" %"rtype"0,%1\n" \
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"2: " ASM_CLAC "\n" \
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asm volatile("1: mov"itype" %"rtype"0,%1\n" \
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"2:\n" \
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_ASM_EXTABLE_EX(1b, 2b) \
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: : ltype(x), "m" (__m(addr)))
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@ -470,13 +468,13 @@ struct __large_struct { unsigned long buf[100]; };
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* uaccess_try and catch
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*/
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#define uaccess_try do { \
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int prev_err = current_thread_info()->uaccess_err; \
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current_thread_info()->uaccess_err = 0; \
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stac(); \
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barrier();
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#define uaccess_catch(err) \
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clac(); \
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(err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \
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current_thread_info()->uaccess_err = prev_err; \
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} while (0)
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/**
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@ -114,11 +114,12 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
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regs->orig_ax = -1; /* disable syscall checks */
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get_user_ex(buf, &sc->fpstate);
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err |= restore_i387_xstate(buf);
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get_user_ex(*pax, &sc->ax);
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} get_user_catch(err);
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err |= restore_i387_xstate(buf);
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return err;
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}
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@ -357,7 +358,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(sig, &frame->sig);
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put_user_ex(&frame->info, &frame->pinfo);
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put_user_ex(&frame->uc, &frame->puc);
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err |= copy_siginfo_to_user(&frame->info, info);
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/* Create the ucontext. */
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if (cpu_has_xsave)
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@ -369,9 +369,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(sas_ss_flags(regs->sp),
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&frame->uc.uc_stack.ss_flags);
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put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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/* Set up to return from userspace. */
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restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
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@ -389,6 +386,11 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
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} put_user_catch(err);
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err |= copy_siginfo_to_user(&frame->info, info);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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return -EFAULT;
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@ -436,8 +438,6 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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put_user_ex(sas_ss_flags(regs->sp),
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&frame->uc.uc_stack.ss_flags);
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put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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/* Set up to return from userspace. If provided, use a stub
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already in userspace. */
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@ -450,6 +450,9 @@ static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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}
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} put_user_catch(err);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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return -EFAULT;
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@ -855,9 +858,6 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
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&frame->uc.uc_stack.ss_flags);
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put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
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put_user_ex(0, &frame->uc.uc__pad0);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (ka->sa.sa_flags & SA_RESTORER) {
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restorer = ka->sa.sa_restorer;
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@ -869,6 +869,10 @@ static int x32_setup_rt_frame(int sig, struct k_sigaction *ka,
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put_user_ex(restorer, &frame->pretcode);
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} put_user_catch(err);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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return -EFAULT;
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