From patchwork Thu Jun 15 10:16:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 13281023 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8C2ECEB64DB for ; Thu, 15 Jun 2023 10:17:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=LZMGw9XBFondlJkvHQbB7mmV/Nn4xMPX4XhRKrqgztY=; b=pzeZ3G5RH3Y7MI t0oKNztMrFQrj7oSl26+JLJ8N3O+vnLLN/tdsMq7U10FNgX0pYszwL0K/AfXCkJgXmL4s9lEvXuw9 lO8k2+dEtWE2ZSSjNkSD5RZu8s+lEm4fZOUwHx1j8JemywK+s0Mgiv3LPjYLY7dAhsOziv5NOoK1l D/LpZeKfvCrLAFdw+RrUJ4Q2Bh3UEoM1qUfXu8Y3+bDtXmWN9a0AcBbCpXNkWDftlD/kmimBItSPl Is9dzuo7YSBdK5+j2BZq7fMyLHwfjpwwC98hYW/PGVNDiuht7LazQZR01RbzqTohmsoCMiVxsgzXB 7JW28cXyfdisa/6IaFcQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q9k2u-00EQZt-04; Thu, 15 Jun 2023 10:17:40 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q9k2m-00EQYB-2E for linux-arm-kernel@lists.infradead.org; Thu, 15 Jun 2023 10:17:34 +0000 From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1686824251; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u0qXv0B7KfGpR37XgJ0r3BNRqqkIsJyhJ++FYc4Lnb8=; b=rsjlbE5x+fuHTEemgMLYfAV6xDt8NLjlFgpaIFx5ULchPiAI0OEmiGGYbNGv8EHld8Nrgx 6Q2dB70o9eu/DKrjQIoZLPIyQZg3QaM2VMGjGeVB0yvWqRNYZZ0f80yUicAPpOwi1xWUPm VQxAuxwVEuzXVflwEKlJEFtMC9j/EcZ+TP7h3IXxKL9SR3thITUlIEPPRFDuaWD6Mvr4ni DAn0YJuA9G28HmVGEJhS4hPMPJ1MeTz5/uDGy6wW7ar2QtfYW8gaShNKd+fkC8u0vqyYC0 3Ayo1v91GnBjF8fpdAapkYRS9wuKIox2Cr+w+z4W1ptTZWs2hfAwYFDR5FkEHA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1686824251; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u0qXv0B7KfGpR37XgJ0r3BNRqqkIsJyhJ++FYc4Lnb8=; b=LmZF/LI6DN6wwOmOBDA0Vdk4KUKVbkTDTCF02b1DbJJx8BwZdR78V0Jvo6kjUxuRFlHfrq y175kDVBkApj/CDA== To: linux-arm-kernel@lists.infradead.org Cc: Russell King , Ard Biesheuvel , Thomas Gleixner , Sebastian Andrzej Siewior Subject: [PATCH 3/3] ARM: vfp: Use vfp_lock() in vfp_entry(). Date: Thu, 15 Jun 2023 12:16:56 +0200 Message-Id: <20230615101656.1308942-4-bigeasy@linutronix.de> In-Reply-To: <20230615101656.1308942-1-bigeasy@linutronix.de> References: <20230615101656.1308942-1-bigeasy@linutronix.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230615_031733_012596_6976122C X-CRM114-Status: GOOD ( 14.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org vfp_entry() is invoked from exception handler and is fully preemptible. It uses local_bh_disable() to remain uninterrupted while checking the VFP state. This is not working on PREEMPT_RT because local_bh_disable() synchronizes the relevant section but the context remains fully preemptible. Use vfp_lock() for uninterrupted access. VFP_bounce() is invoked from within vfp_entry() and may send a signal. Sending a signal uses spinlock_t which becomes a sleeping lock on PREEMPT_RT and must not be acquired within a preempt-disabled section. Move the vfp_raise_sigfpe() block outside of the preempt-disabled section. Signed-off-by: Sebastian Andrzej Siewior --- arch/arm/vfp/vfpmodule.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 524aec81134ba..67d7042bc3d5c 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -267,7 +267,7 @@ static void vfp_panic(char *reason, u32 inst) /* * Process bitmask of exception conditions. */ -static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs) +static int vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr) { int si_code = 0; @@ -275,8 +275,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_ if (exceptions == VFP_EXCEPTION_ERROR) { vfp_panic("unhandled bounce", inst); - vfp_raise_sigfpe(FPE_FLTINV, regs); - return; + return FPE_FLTINV; } /* @@ -304,8 +303,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_ RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF); RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV); - if (si_code) - vfp_raise_sigfpe(si_code, regs); + return si_code; } /* @@ -351,6 +349,8 @@ static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs) static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) { u32 fpscr, orig_fpscr, fpsid, exceptions; + int si_code2 = 0; + int si_code = 0; pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc); @@ -396,8 +396,8 @@ static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) * unallocated VFP instruction but with FPSCR.IXE set and not * on VFP subarch 1. */ - vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs); - return; + si_code = vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr); + goto exit; } /* @@ -421,14 +421,14 @@ static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) */ exceptions = vfp_emulate_instruction(trigger, fpscr, regs); if (exceptions) - vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); + si_code2 = vfp_raise_exceptions(exceptions, trigger, orig_fpscr); /* * If there isn't a second FP instruction, exit now. Note that * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1. */ if ((fpexc & (FPEXC_EX | FPEXC_FP2V)) != (FPEXC_EX | FPEXC_FP2V)) - return; + goto exit; /* * The barrier() here prevents fpinst2 being read @@ -440,7 +440,13 @@ static void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) emulate: exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs); if (exceptions) - vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); + si_code = vfp_raise_exceptions(exceptions, trigger, orig_fpscr); +exit: + vfp_unlock(); + if (si_code2) + vfp_raise_sigfpe(si_code2, regs); + if (si_code) + vfp_raise_sigfpe(si_code, regs); } static void vfp_enable(void *unused) @@ -707,7 +713,7 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger) if (!user_mode(regs)) return vfp_kmode_exception(regs, trigger); - local_bh_disable(); + vfp_lock(); fpexc = fmrx(FPEXC); /* @@ -772,6 +778,7 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger) * replay the instruction that trapped. */ fmxr(FPEXC, fpexc); + vfp_unlock(); } else { /* Check for synchronous or asynchronous exceptions */ if (!(fpexc & (FPEXC_EX | FPEXC_DEX))) { @@ -786,17 +793,17 @@ static int vfp_support_entry(struct pt_regs *regs, u32 trigger) if (!(fpscr & FPSCR_IXE)) { if (!(fpscr & FPSCR_LENGTH_MASK)) { pr_debug("not VFP\n"); - local_bh_enable(); + vfp_unlock(); return -ENOEXEC; } fpexc |= FPEXC_DEX; } } bounce: regs->ARM_pc += 4; + /* VFP_bounce() will invoke vfp_unlock() */ VFP_bounce(trigger, fpexc, regs); } - local_bh_enable(); return 0; }