From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 851ACC433DB for ; Sat, 27 Feb 2021 01:16:01 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EBF6964EDB for ; Sat, 27 Feb 2021 01:16:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EBF6964EDB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codefail.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4DnT9q57NYz3dn8 for ; Sat, 27 Feb 2021 12:15:59 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=codefail.de (client-ip=131.153.2.45; helo=h4.fbrelay.privateemail.com; envelope-from=cmr@codefail.de; receiver=) Received: from h4.fbrelay.privateemail.com (h4.fbrelay.privateemail.com [131.153.2.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4DnT6g6DDFz3cYt for ; Sat, 27 Feb 2021 12:13:15 +1100 (AEDT) Received: from MTA-14-4.privateemail.com (mta-14.privateemail.com [198.54.118.205]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by h3.fbrelay.privateemail.com (Postfix) with ESMTPS id 39BBB80D08 for ; Fri, 26 Feb 2021 20:13:11 -0500 (EST) Received: from mta-14.privateemail.com (localhost [127.0.0.1]) by mta-14.privateemail.com (Postfix) with ESMTP id A8C8480088 for ; Fri, 26 Feb 2021 20:13:08 -0500 (EST) Received: from oc8246131445.ibm.com (unknown [10.20.151.203]) by mta-14.privateemail.com (Postfix) with ESMTPA id 7AB9B80087 for ; Sat, 27 Feb 2021 01:13:08 +0000 (UTC) From: "Christopher M. Riedl" To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v7 07/10] powerpc/signal64: Replace restore_sigcontext() w/ unsafe_restore_sigcontext() Date: Fri, 26 Feb 2021 19:12:56 -0600 Message-Id: <20210227011259.11992-8-cmr@codefail.de> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20210227011259.11992-1-cmr@codefail.de> References: <20210227011259.11992-1-cmr@codefail.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Virus-Scanned: ClamAV using ClamSMTP X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 by replacing all uaccess functions with their 'unsafe' versions. Modify the callers to first open, call unsafe_restore_sigcontext(), and then close the uaccess window. Signed-off-by: Christopher M. Riedl --- v7: * Don't use unsafe_op_wrap() since Christophe indicates this macro may go away in the future. --- 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 78ae4bb4e590..23a44ec3ac01 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -327,14 +327,16 @@ 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, label) do { \ + if (__unsafe_restore_sigcontext(tsk, set, sig, sc)) \ + goto label; \ +} while (0) +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; @@ -349,27 +351,27 @@ 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. @@ -379,29 +381,27 @@ 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 @@ -410,14 +410,17 @@ 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 @@ -708,8 +711,14 @@ 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); @@ -812,8 +821,13 @@ 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->uc_mcontext, sizeof(uc->uc_mcontext))) + 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