From patchwork Sun Feb 21 01:23:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Christopher M. Riedl" X-Patchwork-Id: 1442747 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4Djnjw41Thz9sBJ for ; Sun, 21 Feb 2021 12:27:32 +1100 (AEDT) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Djnjw1l4Lz3dmD for ; Sun, 21 Feb 2021 12:27:32 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=codefail.de (client-ip=68.65.122.27; helo=mta-07-4.privateemail.com; envelope-from=cmr@codefail.de; receiver=) Received: from MTA-07-4.privateemail.com (mta-07-4.privateemail.com [68.65.122.27]) (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 4Djnf40rcLz30Q6 for ; Sun, 21 Feb 2021 12:24:09 +1100 (AEDT) Received: from MTA-07.privateemail.com (localhost [127.0.0.1]) by MTA-07.privateemail.com (Postfix) with ESMTP id E8F1F6004F for ; Sat, 20 Feb 2021 20:24:07 -0500 (EST) Received: from oc8246131445.ibm.com (unknown [10.20.151.213]) by MTA-07.privateemail.com (Postfix) with ESMTPA id C3D8460049 for ; Sun, 21 Feb 2021 01:24:07 +0000 (UTC) From: "Christopher M. Riedl" To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v6 06/10] powerpc/signal64: Replace setup_sigcontext() w/ unsafe_setup_sigcontext() Date: Sat, 20 Feb 2021 19:23:57 -0600 Message-Id: <20210221012401.22328-7-cmr@codefail.de> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20210221012401.22328-1-cmr@codefail.de> References: <20210221012401.22328-1-cmr@codefail.de> MIME-Version: 1.0 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+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Previously setup_sigcontext() performed a costly KUAP switch on every uaccess operation. These repeated uaccess switches cause a significant drop in signal handling performance. Rewrite setup_sigcontext() to assume that a userspace write access window is open by replacing all uaccess functions with their 'unsafe' versions. Modify the callers to first open, call unsafe_setup_sigcontext() and then close the uaccess window. Signed-off-by: Christopher M. Riedl --- arch/powerpc/kernel/signal_64.c | 71 ++++++++++++++++++++------------- 1 file changed, 44 insertions(+), 27 deletions(-) diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index bd8d210c9115..3faaa736ed62 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -101,9 +101,13 @@ static void prepare_setup_sigcontext(struct task_struct *tsk) * Set up the sigcontext for the signal frame. */ -static long setup_sigcontext(struct sigcontext __user *sc, - struct task_struct *tsk, int signr, sigset_t *set, - unsigned long handler, int ctx_has_vsx_region) +#define unsafe_setup_sigcontext(sc, tsk, signr, set, handler, \ + ctx_has_vsx_region, e) \ + unsafe_op_wrap(__unsafe_setup_sigcontext(sc, tsk, signr, set, \ + handler, ctx_has_vsx_region), e) +static long notrace __unsafe_setup_sigcontext(struct sigcontext __user *sc, + struct task_struct *tsk, int signr, sigset_t *set, + unsigned long handler, int ctx_has_vsx_region) { /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the * process never used altivec yet (MSR_VEC is zero in pt_regs of @@ -118,20 +122,19 @@ static long setup_sigcontext(struct sigcontext __user *sc, #endif struct pt_regs *regs = tsk->thread.regs; unsigned long msr = regs->msr; - long err = 0; /* Force usr to alway see softe as 1 (interrupts enabled) */ unsigned long softe = 0x1; BUG_ON(tsk != current); #ifdef CONFIG_ALTIVEC - err |= __put_user(v_regs, &sc->v_regs); + unsafe_put_user(v_regs, &sc->v_regs, efault_out); /* save altivec registers */ if (tsk->thread.used_vr) { /* Copy 33 vec registers (vr0..31 and vscr) to the stack */ - err |= __copy_to_user(v_regs, &tsk->thread.vr_state, - 33 * sizeof(vector128)); + unsafe_copy_to_user(v_regs, &tsk->thread.vr_state, + 33 * sizeof(vector128), efault_out); /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg) * contains valid data. */ @@ -140,12 +143,12 @@ static long setup_sigcontext(struct sigcontext __user *sc, /* We always copy to/from vrsave, it's 0 if we don't have or don't * use altivec. */ - err |= __put_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33]); + unsafe_put_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out); #else /* CONFIG_ALTIVEC */ - err |= __put_user(0, &sc->v_regs); + unsafe_put_user(0, &sc->v_regs, efault_out); #endif /* CONFIG_ALTIVEC */ /* copy fpr regs and fpscr */ - err |= copy_fpr_to_user(&sc->fp_regs, tsk); + unsafe_copy_fpr_to_user(&sc->fp_regs, tsk, efault_out); /* * Clear the MSR VSX bit to indicate there is no valid state attached @@ -160,24 +163,27 @@ static long setup_sigcontext(struct sigcontext __user *sc, */ if (tsk->thread.used_vsr && ctx_has_vsx_region) { v_regs += ELF_NVRREG; - err |= copy_vsx_to_user(v_regs, tsk); + unsafe_copy_vsx_to_user(v_regs, tsk, efault_out); /* set MSR_VSX in the MSR value in the frame to * indicate that sc->vs_reg) contains valid data. */ msr |= MSR_VSX; } #endif /* CONFIG_VSX */ - err |= __put_user(&sc->gp_regs, &sc->regs); + unsafe_put_user(&sc->gp_regs, &sc->regs, efault_out); WARN_ON(!FULL_REGS(regs)); - err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE); - err |= __put_user(msr, &sc->gp_regs[PT_MSR]); - err |= __put_user(softe, &sc->gp_regs[PT_SOFTE]); - err |= __put_user(signr, &sc->signal); - err |= __put_user(handler, &sc->handler); + unsafe_copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE, efault_out); + unsafe_put_user(msr, &sc->gp_regs[PT_MSR], efault_out); + unsafe_put_user(softe, &sc->gp_regs[PT_SOFTE], efault_out); + unsafe_put_user(signr, &sc->signal, efault_out); + unsafe_put_user(handler, &sc->handler, efault_out); if (set != NULL) - err |= __put_user(set->sig[0], &sc->oldmask); + unsafe_put_user(set->sig[0], &sc->oldmask, efault_out); - return err; + return 0; + +efault_out: + return -EFAULT; } #ifdef CONFIG_PPC_TRANSACTIONAL_MEM @@ -670,12 +676,15 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, if (old_ctx != NULL) { prepare_setup_sigcontext(current); - if (!access_ok(old_ctx, ctx_size) - || setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL, 0, - ctx_has_vsx_region) - || __copy_to_user(&old_ctx->uc_sigmask, - ¤t->blocked, sizeof(sigset_t))) + if (!user_write_access_begin(old_ctx, ctx_size)) return -EFAULT; + + unsafe_setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL, + 0, ctx_has_vsx_region, efault_out); + unsafe_copy_to_user(&old_ctx->uc_sigmask, ¤t->blocked, + sizeof(sigset_t), efault_out); + + user_write_access_end(); } if (new_ctx == NULL) return 0; @@ -704,6 +713,10 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, /* This returns like rt_sigreturn */ set_thread_flag(TIF_RESTOREALL); return 0; + +efault_out: + user_write_access_end(); + return -EFAULT; } @@ -854,9 +867,13 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set, } else { err |= __put_user(0, &frame->uc.uc_link); prepare_setup_sigcontext(tsk); - err |= setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig, - NULL, (unsigned long)ksig->ka.sa.sa_handler, - 1); + if (!user_write_access_begin(&frame->uc.uc_mcontext, + sizeof(frame->uc.uc_mcontext))) + return -EFAULT; + err |= __unsafe_setup_sigcontext(&frame->uc.uc_mcontext, tsk, + ksig->sig, NULL, + (unsigned long)ksig->ka.sa.sa_handler, 1); + user_write_access_end(); } err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (err)