| Message ID | 20210203184323.20792-8-cmr@codefail.de (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | Improve signal performance on PPC64 with KUAP | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (44158b256b30415079588d0fcb1bccbdc2ccd009) |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 141 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
Hi Chris, > Previously restore_sigcontext() performed a costly KUAP switch on every > uaccess operation. These repeated uaccess switches cause a significant > drop in signal handling performance. > > Rewrite restore_sigcontext() to assume that a userspace read access > window is open. Replace all uaccess functions with their 'unsafe' > versions which avoid the repeated uaccess switches. > Much of the same comments apply here as to the last patch: - the commit message might be improved by adding that you are also changing the calling functions to open the uaccess window before calling into the new unsafe functions - I have checked that the safe to unsafe conversions look right. - I think you're opening too wide a window in user_read_access_begin, it seems to me that it could be reduced to just the uc_mcontext. (Again, not that it makes a difference with the current HW.) Kind regards, Daniel > Signed-off-by: Christopher M. Riedl <cmr@codefail.de> > --- > arch/powerpc/kernel/signal_64.c | 68 ++++++++++++++++++++------------- > 1 file changed, 41 insertions(+), 27 deletions(-) > > diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c > index 4248e4489ff1..d668f8af18fe 100644 > --- a/arch/powerpc/kernel/signal_64.c > +++ b/arch/powerpc/kernel/signal_64.c > @@ -326,14 +326,14 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc, > /* > * Restore the sigcontext from the signal frame. > */ > - > -static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > - struct sigcontext __user *sc) > +#define unsafe_restore_sigcontext(tsk, set, sig, sc, e) \ > + unsafe_op_wrap(__unsafe_restore_sigcontext(tsk, set, sig, sc), e) > +static long notrace __unsafe_restore_sigcontext(struct task_struct *tsk, sigset_t *set, > + int sig, struct sigcontext __user *sc) > { > #ifdef CONFIG_ALTIVEC > elf_vrreg_t __user *v_regs; > #endif > - unsigned long err = 0; > unsigned long save_r13 = 0; > unsigned long msr; > struct pt_regs *regs = tsk->thread.regs; > @@ -348,27 +348,28 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > save_r13 = regs->gpr[13]; > > /* copy the GPRs */ > - err |= __copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr)); > - err |= __get_user(regs->nip, &sc->gp_regs[PT_NIP]); > + unsafe_copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr), > + efault_out); > + unsafe_get_user(regs->nip, &sc->gp_regs[PT_NIP], efault_out); > /* get MSR separately, transfer the LE bit if doing signal return */ > - err |= __get_user(msr, &sc->gp_regs[PT_MSR]); > + unsafe_get_user(msr, &sc->gp_regs[PT_MSR], efault_out); > if (sig) > regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); > - err |= __get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3]); > - err |= __get_user(regs->ctr, &sc->gp_regs[PT_CTR]); > - err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]); > - err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]); > - err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]); > + unsafe_get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3], efault_out); > + unsafe_get_user(regs->ctr, &sc->gp_regs[PT_CTR], efault_out); > + unsafe_get_user(regs->link, &sc->gp_regs[PT_LNK], efault_out); > + unsafe_get_user(regs->xer, &sc->gp_regs[PT_XER], efault_out); > + unsafe_get_user(regs->ccr, &sc->gp_regs[PT_CCR], efault_out); > /* Don't allow userspace to set SOFTE */ > set_trap_norestart(regs); > - err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]); > - err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]); > - err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]); > + unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out); > + unsafe_get_user(regs->dsisr, &sc->gp_regs[PT_DSISR], efault_out); > + unsafe_get_user(regs->result, &sc->gp_regs[PT_RESULT], efault_out); > > if (!sig) > regs->gpr[13] = save_r13; > if (set != NULL) > - err |= __get_user(set->sig[0], &sc->oldmask); > + unsafe_get_user(set->sig[0], &sc->oldmask, efault_out); > > /* > * Force reload of FP/VEC. > @@ -378,29 +379,28 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX); > > #ifdef CONFIG_ALTIVEC > - err |= __get_user(v_regs, &sc->v_regs); > - if (err) > - return err; > + unsafe_get_user(v_regs, &sc->v_regs, efault_out); > if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128))) > return -EFAULT; > /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ > if (v_regs != NULL && (msr & MSR_VEC) != 0) { > - err |= __copy_from_user(&tsk->thread.vr_state, v_regs, > - 33 * sizeof(vector128)); > + unsafe_copy_from_user(&tsk->thread.vr_state, v_regs, > + 33 * sizeof(vector128), efault_out); > tsk->thread.used_vr = true; > } else if (tsk->thread.used_vr) { > memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128)); > } > /* Always get VRSAVE back */ > if (v_regs != NULL) > - err |= __get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]); > + unsafe_get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], > + efault_out); > else > tsk->thread.vrsave = 0; > if (cpu_has_feature(CPU_FTR_ALTIVEC)) > mtspr(SPRN_VRSAVE, tsk->thread.vrsave); > #endif /* CONFIG_ALTIVEC */ > /* restore floating point */ > - err |= copy_fpr_from_user(tsk, &sc->fp_regs); > + unsafe_copy_fpr_from_user(tsk, &sc->fp_regs, efault_out); > #ifdef CONFIG_VSX > /* > * Get additional VSX data. Update v_regs to point after the > @@ -409,14 +409,17 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > */ > v_regs += ELF_NVRREG; > if ((msr & MSR_VSX) != 0) { > - err |= copy_vsx_from_user(tsk, v_regs); > + unsafe_copy_vsx_from_user(tsk, v_regs, efault_out); > tsk->thread.used_vsr = true; > } else { > for (i = 0; i < 32 ; i++) > tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0; > } > #endif > - return err; > + return 0; > + > +efault_out: > + return -EFAULT; > } > > #ifdef CONFIG_PPC_TRANSACTIONAL_MEM > @@ -701,8 +704,14 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, > if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) > do_exit(SIGSEGV); > set_current_blocked(&set); > - if (restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) > + > + if (!user_read_access_begin(new_ctx, ctx_size)) > + return -EFAULT; > + if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) { > + user_read_access_end(); > do_exit(SIGSEGV); > + } > + user_read_access_end(); > > /* This returns like rt_sigreturn */ > set_thread_flag(TIF_RESTOREALL); > @@ -807,8 +816,13 @@ SYSCALL_DEFINE0(rt_sigreturn) > * causing a TM bad thing. > */ > current->thread.regs->msr &= ~MSR_TS_MASK; > - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) > + if (!user_read_access_begin(uc, sizeof(*uc))) > + return -EFAULT; > + if (__unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) { > + user_read_access_end(); > goto badframe; > + } > + user_read_access_end(); > } > > if (restore_altstack(&uc->uc_stack)) > -- > 2.26.1
On Fri Feb 12, 2021 at 3:17 PM CST, Daniel Axtens wrote: > Hi Chris, > > > Previously restore_sigcontext() performed a costly KUAP switch on every > > uaccess operation. These repeated uaccess switches cause a significant > > drop in signal handling performance. > > > > Rewrite restore_sigcontext() to assume that a userspace read access > > window is open. Replace all uaccess functions with their 'unsafe' > > versions which avoid the repeated uaccess switches. > > > > Much of the same comments apply here as to the last patch: > - the commit message might be improved by adding that you are also > changing the calling functions to open the uaccess window before > calling into the new unsafe functions > > - I have checked that the safe to unsafe conversions look right. > > - I think you're opening too wide a window in user_read_access_begin, > it seems to me that it could be reduced to just the > uc_mcontext. (Again, not that it makes a difference with the current > HW.) Ok, I'll fix these in the next version as well. > > Kind regards, > Daniel > > > Signed-off-by: Christopher M. Riedl <cmr@codefail.de> > > --- > > arch/powerpc/kernel/signal_64.c | 68 ++++++++++++++++++++------------- > > 1 file changed, 41 insertions(+), 27 deletions(-) > > > > diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c > > index 4248e4489ff1..d668f8af18fe 100644 > > --- a/arch/powerpc/kernel/signal_64.c > > +++ b/arch/powerpc/kernel/signal_64.c > > @@ -326,14 +326,14 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc, > > /* > > * Restore the sigcontext from the signal frame. > > */ > > - > > -static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > > - struct sigcontext __user *sc) > > +#define unsafe_restore_sigcontext(tsk, set, sig, sc, e) \ > > + unsafe_op_wrap(__unsafe_restore_sigcontext(tsk, set, sig, sc), e) > > +static long notrace __unsafe_restore_sigcontext(struct task_struct *tsk, sigset_t *set, > > + int sig, struct sigcontext __user *sc) > > { > > #ifdef CONFIG_ALTIVEC > > elf_vrreg_t __user *v_regs; > > #endif > > - unsigned long err = 0; > > unsigned long save_r13 = 0; > > unsigned long msr; > > struct pt_regs *regs = tsk->thread.regs; > > @@ -348,27 +348,28 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > > save_r13 = regs->gpr[13]; > > > > /* copy the GPRs */ > > - err |= __copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr)); > > - err |= __get_user(regs->nip, &sc->gp_regs[PT_NIP]); > > + unsafe_copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr), > > + efault_out); > > + unsafe_get_user(regs->nip, &sc->gp_regs[PT_NIP], efault_out); > > /* get MSR separately, transfer the LE bit if doing signal return */ > > - err |= __get_user(msr, &sc->gp_regs[PT_MSR]); > > + unsafe_get_user(msr, &sc->gp_regs[PT_MSR], efault_out); > > if (sig) > > regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); > > - err |= __get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3]); > > - err |= __get_user(regs->ctr, &sc->gp_regs[PT_CTR]); > > - err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]); > > - err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]); > > - err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]); > > + unsafe_get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3], efault_out); > > + unsafe_get_user(regs->ctr, &sc->gp_regs[PT_CTR], efault_out); > > + unsafe_get_user(regs->link, &sc->gp_regs[PT_LNK], efault_out); > > + unsafe_get_user(regs->xer, &sc->gp_regs[PT_XER], efault_out); > > + unsafe_get_user(regs->ccr, &sc->gp_regs[PT_CCR], efault_out); > > /* Don't allow userspace to set SOFTE */ > > set_trap_norestart(regs); > > - err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]); > > - err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]); > > - err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]); > > + unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out); > > + unsafe_get_user(regs->dsisr, &sc->gp_regs[PT_DSISR], efault_out); > > + unsafe_get_user(regs->result, &sc->gp_regs[PT_RESULT], efault_out); > > > > if (!sig) > > regs->gpr[13] = save_r13; > > if (set != NULL) > > - err |= __get_user(set->sig[0], &sc->oldmask); > > + unsafe_get_user(set->sig[0], &sc->oldmask, efault_out); > > > > /* > > * Force reload of FP/VEC. > > @@ -378,29 +379,28 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > > regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX); > > > > #ifdef CONFIG_ALTIVEC > > - err |= __get_user(v_regs, &sc->v_regs); > > - if (err) > > - return err; > > + unsafe_get_user(v_regs, &sc->v_regs, efault_out); > > if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128))) > > return -EFAULT; > > /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ > > if (v_regs != NULL && (msr & MSR_VEC) != 0) { > > - err |= __copy_from_user(&tsk->thread.vr_state, v_regs, > > - 33 * sizeof(vector128)); > > + unsafe_copy_from_user(&tsk->thread.vr_state, v_regs, > > + 33 * sizeof(vector128), efault_out); > > tsk->thread.used_vr = true; > > } else if (tsk->thread.used_vr) { > > memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128)); > > } > > /* Always get VRSAVE back */ > > if (v_regs != NULL) > > - err |= __get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]); > > + unsafe_get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], > > + efault_out); > > else > > tsk->thread.vrsave = 0; > > if (cpu_has_feature(CPU_FTR_ALTIVEC)) > > mtspr(SPRN_VRSAVE, tsk->thread.vrsave); > > #endif /* CONFIG_ALTIVEC */ > > /* restore floating point */ > > - err |= copy_fpr_from_user(tsk, &sc->fp_regs); > > + unsafe_copy_fpr_from_user(tsk, &sc->fp_regs, efault_out); > > #ifdef CONFIG_VSX > > /* > > * Get additional VSX data. Update v_regs to point after the > > @@ -409,14 +409,17 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, > > */ > > v_regs += ELF_NVRREG; > > if ((msr & MSR_VSX) != 0) { > > - err |= copy_vsx_from_user(tsk, v_regs); > > + unsafe_copy_vsx_from_user(tsk, v_regs, efault_out); > > tsk->thread.used_vsr = true; > > } else { > > for (i = 0; i < 32 ; i++) > > tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0; > > } > > #endif > > - return err; > > + return 0; > > + > > +efault_out: > > + return -EFAULT; > > } > > > > #ifdef CONFIG_PPC_TRANSACTIONAL_MEM > > @@ -701,8 +704,14 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, > > if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) > > do_exit(SIGSEGV); > > set_current_blocked(&set); > > - if (restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) > > + > > + if (!user_read_access_begin(new_ctx, ctx_size)) > > + return -EFAULT; > > + if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) { > > + user_read_access_end(); > > do_exit(SIGSEGV); > > + } > > + user_read_access_end(); > > > > /* This returns like rt_sigreturn */ > > set_thread_flag(TIF_RESTOREALL); > > @@ -807,8 +816,13 @@ SYSCALL_DEFINE0(rt_sigreturn) > > * causing a TM bad thing. > > */ > > current->thread.regs->msr &= ~MSR_TS_MASK; > > - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) > > + if (!user_read_access_begin(uc, sizeof(*uc))) > > + return -EFAULT; > > + if (__unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) { > > + user_read_access_end(); > > goto badframe; > > + } > > + user_read_access_end(); > > } > > > > if (restore_altstack(&uc->uc_stack)) > > -- > > 2.26.1
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index 4248e4489ff1..d668f8af18fe 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -326,14 +326,14 @@ static long setup_tm_sigcontexts(struct sigcontext __user *sc, /* * Restore the sigcontext from the signal frame. */ - -static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, - struct sigcontext __user *sc) +#define unsafe_restore_sigcontext(tsk, set, sig, sc, e) \ + unsafe_op_wrap(__unsafe_restore_sigcontext(tsk, set, sig, sc), e) +static long notrace __unsafe_restore_sigcontext(struct task_struct *tsk, sigset_t *set, + int sig, struct sigcontext __user *sc) { #ifdef CONFIG_ALTIVEC elf_vrreg_t __user *v_regs; #endif - unsigned long err = 0; unsigned long save_r13 = 0; unsigned long msr; struct pt_regs *regs = tsk->thread.regs; @@ -348,27 +348,28 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, save_r13 = regs->gpr[13]; /* copy the GPRs */ - err |= __copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr)); - err |= __get_user(regs->nip, &sc->gp_regs[PT_NIP]); + unsafe_copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr), + efault_out); + unsafe_get_user(regs->nip, &sc->gp_regs[PT_NIP], efault_out); /* get MSR separately, transfer the LE bit if doing signal return */ - err |= __get_user(msr, &sc->gp_regs[PT_MSR]); + unsafe_get_user(msr, &sc->gp_regs[PT_MSR], efault_out); if (sig) regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); - err |= __get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3]); - err |= __get_user(regs->ctr, &sc->gp_regs[PT_CTR]); - err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]); - err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]); - err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]); + unsafe_get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3], efault_out); + unsafe_get_user(regs->ctr, &sc->gp_regs[PT_CTR], efault_out); + unsafe_get_user(regs->link, &sc->gp_regs[PT_LNK], efault_out); + unsafe_get_user(regs->xer, &sc->gp_regs[PT_XER], efault_out); + unsafe_get_user(regs->ccr, &sc->gp_regs[PT_CCR], efault_out); /* Don't allow userspace to set SOFTE */ set_trap_norestart(regs); - err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]); - err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]); - err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]); + unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out); + unsafe_get_user(regs->dsisr, &sc->gp_regs[PT_DSISR], efault_out); + unsafe_get_user(regs->result, &sc->gp_regs[PT_RESULT], efault_out); if (!sig) regs->gpr[13] = save_r13; if (set != NULL) - err |= __get_user(set->sig[0], &sc->oldmask); + unsafe_get_user(set->sig[0], &sc->oldmask, efault_out); /* * Force reload of FP/VEC. @@ -378,29 +379,28 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX); #ifdef CONFIG_ALTIVEC - err |= __get_user(v_regs, &sc->v_regs); - if (err) - return err; + unsafe_get_user(v_regs, &sc->v_regs, efault_out); if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128))) return -EFAULT; /* Copy 33 vec registers (vr0..31 and vscr) from the stack */ if (v_regs != NULL && (msr & MSR_VEC) != 0) { - err |= __copy_from_user(&tsk->thread.vr_state, v_regs, - 33 * sizeof(vector128)); + unsafe_copy_from_user(&tsk->thread.vr_state, v_regs, + 33 * sizeof(vector128), efault_out); tsk->thread.used_vr = true; } else if (tsk->thread.used_vr) { memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128)); } /* Always get VRSAVE back */ if (v_regs != NULL) - err |= __get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]); + unsafe_get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], + efault_out); else tsk->thread.vrsave = 0; if (cpu_has_feature(CPU_FTR_ALTIVEC)) mtspr(SPRN_VRSAVE, tsk->thread.vrsave); #endif /* CONFIG_ALTIVEC */ /* restore floating point */ - err |= copy_fpr_from_user(tsk, &sc->fp_regs); + unsafe_copy_fpr_from_user(tsk, &sc->fp_regs, efault_out); #ifdef CONFIG_VSX /* * Get additional VSX data. Update v_regs to point after the @@ -409,14 +409,17 @@ static long restore_sigcontext(struct task_struct *tsk, sigset_t *set, int sig, */ v_regs += ELF_NVRREG; if ((msr & MSR_VSX) != 0) { - err |= copy_vsx_from_user(tsk, v_regs); + unsafe_copy_vsx_from_user(tsk, v_regs, efault_out); tsk->thread.used_vsr = true; } else { for (i = 0; i < 32 ; i++) tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0; } #endif - return err; + return 0; + +efault_out: + return -EFAULT; } #ifdef CONFIG_PPC_TRANSACTIONAL_MEM @@ -701,8 +704,14 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set))) do_exit(SIGSEGV); set_current_blocked(&set); - if (restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) + + if (!user_read_access_begin(new_ctx, ctx_size)) + return -EFAULT; + if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) { + user_read_access_end(); do_exit(SIGSEGV); + } + user_read_access_end(); /* This returns like rt_sigreturn */ set_thread_flag(TIF_RESTOREALL); @@ -807,8 +816,13 @@ SYSCALL_DEFINE0(rt_sigreturn) * causing a TM bad thing. */ current->thread.regs->msr &= ~MSR_TS_MASK; - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) + if (!user_read_access_begin(uc, sizeof(*uc))) + return -EFAULT; + if (__unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) { + user_read_access_end(); goto badframe; + } + user_read_access_end(); } if (restore_altstack(&uc->uc_stack))
Previously restore_sigcontext() performed a costly KUAP switch on every uaccess operation. These repeated uaccess switches cause a significant drop in signal handling performance. Rewrite restore_sigcontext() to assume that a userspace read access window is open. Replace all uaccess functions with their 'unsafe' versions which avoid the repeated uaccess switches. Signed-off-by: Christopher M. Riedl <cmr@codefail.de> --- arch/powerpc/kernel/signal_64.c | 68 ++++++++++++++++++++------------- 1 file changed, 41 insertions(+), 27 deletions(-)