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([50.212.55.89]) by smtp.gmail.com with ESMTPSA id r20-20020a05620a299400b006b59ddb4bc5sm9288317qkp.84.2022.08.01.13.14.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Aug 2022 13:14:58 -0700 (PDT) From: Ben Wolsieffer X-Google-Original-From: Ben Wolsieffer Cc: Ben Wolsieffer , Russell King , Marc Zyngier , Arnd Bergmann , Ard Biesheuvel , Vladimir Murzin , "Russell King (Oracle)" , Nick Desaulniers , Catalin Marinas , Nicolas Pitre , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] ARM: v7m: handle faults Date: Mon, 1 Aug 2022 16:13:38 -0400 Message-Id: <20220801201347.1255392-2-Ben.Wolsieffer@hefring.com> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220801201347.1255392-1-Ben.Wolsieffer@hefring.com> References: <20220801201347.1255392-1-Ben.Wolsieffer@hefring.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Currently, any fault on an ARMv7M system will trigger the invalid entry exception handler, bringing down the entire system. This patch installs real handlers for the hard fault, memmanage, bus fault and usage fault exceptions. For kernel space faults, an oops is triggered, while user space faults kill the offending process with an appropriate signal. The fault status registers are parsed to construct an appropriate message and signal. This is based on a patch from Emcraft Systems' kernel tree [1], but I have significantly reworked it. [1] https://github.com/EmcraftSystems/linux-upstream/commit/2882de1d86bd536= c855feee582d44722434c2ac9 Signed-off-by: Ben Wolsieffer --- arch/arm/include/asm/v7m.h | 29 +++++++ arch/arm/kernel/Makefile | 2 +- arch/arm/kernel/entry-v7m.S | 68 +++++++++++++++- arch/arm/kernel/traps-v7m.c | 156 ++++++++++++++++++++++++++++++++++++ 4 files changed, 250 insertions(+), 5 deletions(-) create mode 100644 arch/arm/kernel/traps-v7m.c diff --git a/arch/arm/include/asm/v7m.h b/arch/arm/include/asm/v7m.h index 4512f7e1918f..b8c636a0578d 100644 --- a/arch/arm/include/asm/v7m.h +++ b/arch/arm/include/asm/v7m.h @@ -38,6 +38,35 @@ #define V7M_SCB_SHCSR_BUSFAULTENA (1 << 17) #define V7M_SCB_SHCSR_MEMFAULTENA (1 << 16) =20 +#define V7M_SCB_CFSR 0x28 + +#define V7M_SCB_CFSR_DIVBYZERO (1 << 25) +#define V7M_SCB_CFSR_UNALIGNED (1 << 24) +#define V7M_SCB_CFSR_NOCP (1 << 19) +#define V7M_SCB_CFSR_INVPC (1 << 18) +#define V7M_SCB_CFSR_INVSTATE (1 << 17) +#define V7M_SCB_CFSR_UNDEFINSTR (1 << 16) +#define V7M_SCB_CFSR_BFARVALID (1 << 15) +#define V7M_SCB_CFSR_LSPERR (1 << 13) +#define V7M_SCB_CFSR_STKERR (1 << 12) +#define V7M_SCB_CFSR_UNSTKERR (1 << 11) +#define V7M_SCB_CFSR_IMPRECISERR (1 << 10) +#define V7M_SCB_CFSR_PRECISERR (1 << 9) +#define V7M_SCB_CFSR_IBUSERR (1 << 8) +#define V7M_SCB_CFSR_MMARVALID (1 << 7) +#define V7M_SCB_CFSR_MLSPERR (1 << 5) +#define V7M_SCB_CFSR_MSTKERR (1 << 4) +#define V7M_SCB_CFSR_MUNSTKERR (1 << 3) +#define V7M_SCB_CFSR_DACCVIOL (1 << 1) +#define V7M_SCB_CFSR_IACCVIOL (1 << 0) + +#define V7M_SCB_HFSR 0x2c +#define V7M_SCB_HFSR_FORCED (1 << 30) +#define V7M_SCB_HFSR_VECTTBL (1 << 1) + +#define V7M_SCB_MMAR 0x34 +#define V7M_SCB_BFAR 0x38 + #define V7M_xPSR_FRAMEPTRALIGN 0x00000200 #define V7M_xPSR_EXCEPTIONNO V7M_SCB_ICSR_VECTACTIVE =20 diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 553866751e1a..5d3e66ebc77d 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -34,7 +34,7 @@ obj-$(CONFIG_ATAGS_PROC) +=3D atags_proc.o obj-$(CONFIG_DEPRECATED_PARAM_STRUCT) +=3D atags_compat.o =20 ifeq ($(CONFIG_CPU_V7M),y) -obj-y +=3D entry-v7m.o v7m.o +obj-y +=3D entry-v7m.o v7m.o traps-v7m.o else obj-y +=3D entry-armv.o endif diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S index de8a60363c85..62909731cd1f 100644 --- a/arch/arm/kernel/entry-v7m.S +++ b/arch/arm/kernel/entry-v7m.S @@ -84,6 +84,66 @@ __irq_entry: bx lr ENDPROC(__irq_entry) =20 +__hardfault_entry: + v7m_exception_entry + + @ + @ Invoke the Hard Fault handler + @ routine called with r0 =3D struct pt_regs * + mov r0, sp + bl do_hardfault + + @ execute the pending work, including reschedule + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq +ENDPROC(__hardfault_entry) + +__memmanage_entry: + v7m_exception_entry + + @ + @ Invoke the Mem Manage handler + @ routine called with r0 =3D struct pt_regs * + mov r0, sp + bl do_memmanage + + @ execute the pending work, including reschedule + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq +ENDPROC(__memmanage_entry) + +__busfault_entry: + v7m_exception_entry + + @ + @ Invoke the Bus Fault handler + @ routine called with r0 =3D struct pt_regs * + mov r0, sp + bl do_busfault + + @ execute the pending work, including reschedule + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq +ENDPROC(__busfault_entry) + +__usagefault_entry: + v7m_exception_entry + + @ + @ Invoke the Bus Fault handler + @ routine called with r0 =3D struct pt_regs * + mov r0, sp + bl do_usagefault + + @ execute the pending work, including reschedule + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq +ENDPROC(__usagefault_entry) + __pendsv_entry: v7m_exception_entry =20 @@ -138,10 +198,10 @@ ENTRY(vector_table) .long 0 @ 0 - Reset stack pointer .long __invalid_entry @ 1 - Reset .long __invalid_entry @ 2 - NMI - .long __invalid_entry @ 3 - HardFault - .long __invalid_entry @ 4 - MemManage - .long __invalid_entry @ 5 - BusFault - .long __invalid_entry @ 6 - UsageFault + .long __hardfault_entry @ 3 - HardFault + .long __memmanage_entry @ 4 - MemManage + .long __busfault_entry @ 5 - BusFault + .long __usagefault_entry @ 6 - UsageFault .long __invalid_entry @ 7 - Reserved .long __invalid_entry @ 8 - Reserved .long __invalid_entry @ 9 - Reserved diff --git a/arch/arm/kernel/traps-v7m.c b/arch/arm/kernel/traps-v7m.c new file mode 100644 index 000000000000..5fd9943448e9 --- /dev/null +++ b/arch/arm/kernel/traps-v7m.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2011 Dmitry Cherukhin, Emcraft Systems + * Copyright (C) 2022 Ben Wolsieffer, Hefring Engineering + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include + +#include +#include +#include +#include + +enum fault { + FAULT_HARDFALT =3D 3, + FAULT_MEMMANAGE =3D 4, + FAULT_BUSFAULT =3D 5, + FAULT_USAGEFAULT =3D 6 +}; + +struct exception { + const char *name; + int fault; + int test_bit; + int signo; + int si_code; + unsigned int user_debug; +}; + +static const struct exception unknown_exception =3D + {"unknown exception", 0, 0, SIGSEGV, SEGV_MAPERR, UDBG_SEGV}; + +static const struct exception exceptions[] =3D { + {"escalated to hard fault", FAULT_HARDFALT, V7M_SCB_HFSR_FORCED, SIGSE= GV, SEGV_MAPERR, UDBG_SEGV}, + {"vector read error", FAULT_HARDFALT, V7M_SCB_HFSR_VECTTBL, SIGSEGV, = SEGV_MAPERR, UDBG_SEGV}, + {"divide by 0", FAULT_USAGEFAULT, V7M_SCB_CFSR_DIVBYZERO, SIGSEGV, SE= GV_MAPERR, UDBG_SEGV}, + {"illegal unaligned access", FAULT_USAGEFAULT, V7M_SCB_CFSR_UNALIGNED, = SIGBUS, BUS_ADRALN, UDBG_BUS}, + {"no coprocessor", FAULT_USAGEFAULT, V7M_SCB_CFSR_NOCP, SIGILL, ILL_C= OPROC, UDBG_UNDEFINED}, + {"return to invalid PC", FAULT_USAGEFAULT, V7M_SCB_CFSR_INVPC, SIGSEGV,= SEGV_MAPERR, UDBG_SEGV}, + {"invalid ISA state", FAULT_USAGEFAULT, V7M_SCB_CFSR_INVSTATE, SIGSEGV= , SEGV_MAPERR, UDBG_SEGV}, + {"undefined instruction", FAULT_USAGEFAULT, V7M_SCB_CFSR_UNDEFINSTR, SIG= ILL, ILL_ILLOPC, UDBG_UNDEFINED}, + {"floating point state error", FAULT_BUSFAULT, V7M_SCB_CFSR_LSPERR, SI= GBUS, BUS_ADRERR, UDBG_BUS}, + {"exception stack push error", FAULT_BUSFAULT, V7M_SCB_CFSR_STKERR, SI= GBUS, BUS_ADRERR, UDBG_BUS}, + {"exception stack pop error", FAULT_BUSFAULT, V7M_SCB_CFSR_UNSTKERR, S= IGBUS, BUS_ADRERR, UDBG_BUS}, + {"imprecise data bus error", FAULT_BUSFAULT, V7M_SCB_CFSR_IMPRECISERR, = SIGBUS, BUS_ADRERR, UDBG_BUS}, + {"precise data bus error", FAULT_BUSFAULT, V7M_SCB_CFSR_PRECISERR, SIG= BUS, BUS_ADRERR, UDBG_BUS}, + {"pre-fetch error", FAULT_BUSFAULT, V7M_SCB_CFSR_IBUSERR, SIGBUS, BU= S_ADRERR, UDBG_BUS}, + {"floating point state error", FAULT_MEMMANAGE, V7M_SCB_CFSR_MLSPERR, S= IGSEGV, SEGV_MAPERR, UDBG_SEGV}, + {"exception stack push error", FAULT_MEMMANAGE, V7M_SCB_CFSR_MSTKERR, S= IGSEGV, SEGV_MAPERR, UDBG_SEGV}, + {"exception stack pop error", FAULT_MEMMANAGE, V7M_SCB_CFSR_MUNSTKERR, = SIGSEGV, SEGV_MAPERR, UDBG_SEGV}, + {"data access violation", FAULT_MEMMANAGE, V7M_SCB_CFSR_DACCVIOL, SIGSE= GV, SEGV_ACCERR, UDBG_SEGV}, + {"instruction access violation", FAULT_MEMMANAGE, V7M_SCB_CFSR_IACCVIOL, = SIGSEGV, SEGV_ACCERR, UDBG_SEGV}, + {NULL} +}; + +/* + * Common routine for high-level exception handlers. + * @param regs state of registers when the exception occurs + * @param fault IPSR, the fault number + */ +static void traps_v7m_common(struct pt_regs *regs, int fault) +{ + unsigned long status; + unsigned long hstatus; + unsigned long cstatus; + unsigned long addr; + size_t i; + const struct exception *exc =3D &unknown_exception; + + + hstatus =3D readl(BASEADDR_V7M_SCB + V7M_SCB_HFSR); + cstatus =3D readl(BASEADDR_V7M_SCB + V7M_SCB_CFSR); + + if (cstatus & V7M_SCB_CFSR_MMARVALID && (fault =3D=3D FAULT_MEMMANAGE || + (fault =3D=3D FAULT_HARDFALT && hstatus & V7M_SCB_HFSR_FORCED))) { + addr =3D readl(BASEADDR_V7M_SCB + V7M_SCB_MMAR); + } else if (cstatus & V7M_SCB_CFSR_BFARVALID && (fault =3D=3D FAULT_BUSFAU= LT || + (fault =3D=3D FAULT_HARDFALT && hstatus & V7M_SCB_HFSR_FORCED))) { + addr =3D readl(BASEADDR_V7M_SCB + V7M_SCB_BFAR); + } else { + addr =3D instruction_pointer(regs); + } + + writel(hstatus, BASEADDR_V7M_SCB + V7M_SCB_HFSR); + writel(cstatus, BASEADDR_V7M_SCB + V7M_SCB_CFSR); + + for (i =3D 0; exceptions[i].name !=3D NULL; ++i) { + if (fault !=3D exceptions[i].fault) + continue; + + status =3D fault =3D=3D FAULT_HARDFALT ? hstatus : cstatus; + if (!(status & exceptions[i].test_bit)) + continue; + + exc =3D &exceptions[i]; + break; + } + +#ifdef CONFIG_DEBUG_USER + if (user_mode(regs) && (user_debug & exc->user_debug)) { + pr_info("%s (%d): %s: addr=3D0x%px\n", + current->comm, task_pid_nr(current), exc->name, (void *)addr); + __show_regs(regs); + } +#endif + + arm_notify_die(exc->name, regs, exc->signo, exc->si_code, + (void __user *)addr, 0, fault); +} + +/* + * High-level exception handler for exception 3 (Hard Fault). + * @param regs state of registers when the exception occurred + */ +asmlinkage void do_hardfault(struct pt_regs *regs) +{ + traps_v7m_common(regs, FAULT_HARDFALT); +} + +/* + * High-level exception handler for exception 4 (Mem Manage). + * @param regs state of registers when the exception occurred + */ +asmlinkage void do_memmanage(struct pt_regs *regs) +{ + traps_v7m_common(regs, FAULT_MEMMANAGE); +} + +/* + * High-level exception handler for exception 5 (Bus Fault). + * @param regs state of registers when the exception occurred + */ +asmlinkage void do_busfault(struct pt_regs *regs) +{ + traps_v7m_common(regs, FAULT_BUSFAULT); +} + +/* + * High-level exception handler for exception 6 (Usage Fault). + * @param regs state of registers when the exception occurred + */ +asmlinkage void do_usagefault(struct pt_regs *regs) +{ + traps_v7m_common(regs, FAULT_USAGEFAULT); +} --=20 2.37.0 From nobody Sun Apr 12 04:21:24 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC7BEC00144 for ; Mon, 1 Aug 2022 20:16:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233364AbiHAUQP (ORCPT ); Mon, 1 Aug 2022 16:16:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234555AbiHAUPz (ORCPT ); Mon, 1 Aug 2022 16:15:55 -0400 Received: from mail-qv1-xf32.google.com (mail-qv1-xf32.google.com [IPv6:2607:f8b0:4864:20::f32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62314E4D for ; Mon, 1 Aug 2022 13:15:12 -0700 (PDT) Received: by mail-qv1-xf32.google.com with SMTP id mk9so6484065qvb.11 for ; Mon, 01 Aug 2022 13:15:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hefring-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YzbZWPC/awXZhFf2xsAbUtlwN59iYpbiuewriSD+EsE=; b=3+GZNArbYFpKf5Fywb/ATh5UrloxFjVRTkkdYUWQvEJsXJ+adhKxb/tGhlOyIyHOsH Zcd71UbGZR3g7+p2PVC8CmlZJNGhJegmPoAGVb2B1uH9mtRma5NvKV3qnnr9mKP8rHMG 3Yn8p/tUgs/6NYHR1cP0fKJQeiSWuljH3681EnVzrcSIPgwdgUry9e4qyzlLsSjEbWgl g4mXB7Tc8ccDhJuEdi4JMhRYSyVOYdkkwQGLnqJy0mvRMcRo0THxaS1XlBpSiAmsi3PM LUnPl3hStWKj/VJCMWwhD3y7M3xrS1qN640z0JYbn2dCXZOmgYFSRKA76DXHbhEsnlIu kNHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=YzbZWPC/awXZhFf2xsAbUtlwN59iYpbiuewriSD+EsE=; b=4cuOCnZsc16vlS8xAeWg2XFZLJpllmIEtkUHsRb77XA235Caxfwkm9ZXcKbktnF9f9 XZeHDOB8h7jfwappX52wHTnPsL6Zy7lxZ2yxoTMZHet2UVDf2cz7bviEHH9wnVfNNyJa VdNWPWYQI24gwIYaa1+9DHUY612Nlm6YwbDqrcAPPuxhlj9ReFO4apfz4nSDD37MQP3y bp//gEaURtcaUhC2FyK/UqYvFv0P1+t5p9eY7LoPnIbW8IA+vgFDQ9sUqvGLHHwXzOPO RCc8A1LseYhLXIRKfsUP6LOkxi2MjeGswhtNTcKsDh5fERhBN98pLFYL/rOT3RMUZZbl c3Vg== X-Gm-Message-State: ACgBeo19o6ZZCKCnzgr/JCGVpRXJQZZ/ucizx9c8ceuLj1bRu30GWKFD AgCNvc8NWKG+mxxYmqUNG6AouQ== X-Google-Smtp-Source: AA6agR7hDeg6lfiUq3q/202VwtcKoJvdC+JD6ptmlxHXn+2QC5RguPk64Lh2T0Inl/nSyYlVtYGvBw== X-Received: by 2002:a05:6214:2b0b:b0:476:cc01:93af with SMTP id jx11-20020a0562142b0b00b00476cc0193afmr2334899qvb.56.1659384911484; Mon, 01 Aug 2022 13:15:11 -0700 (PDT) Received: from hefring.. ([50.212.55.89]) by smtp.gmail.com with ESMTPSA id r20-20020a05620a299400b006b59ddb4bc5sm9288317qkp.84.2022.08.01.13.15.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Aug 2022 13:15:11 -0700 (PDT) From: Ben Wolsieffer X-Google-Original-From: Ben Wolsieffer Cc: Ben Wolsieffer , Russell King , Ard Biesheuvel , Arnd Bergmann , Mark Rutland , Marc Zyngier , Vladimir Murzin , "Russell King (Oracle)" , Nick Desaulniers , "Steven Rostedt (Google)" , Catalin Marinas , Nicolas Pitre , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] ARM: v7m: support undefined instruction hooks Date: Mon, 1 Aug 2022 16:13:39 -0400 Message-Id: <20220801201347.1255392-3-Ben.Wolsieffer@hefring.com> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220801201347.1255392-1-Ben.Wolsieffer@hefring.com> References: <20220801201347.1255392-1-Ben.Wolsieffer@hefring.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Call the common ARM undefined instruction handler, which handles running hooks to enable ptrace breakpoints and other features. Signed-off-by: Ben Wolsieffer --- arch/arm/include/asm/traps.h | 2 ++ arch/arm/kernel/traps-v7m.c | 8 +++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/traps.h b/arch/arm/include/asm/traps.h index 987fefb0a4db..e4253f4a86e1 100644 --- a/arch/arm/include/asm/traps.h +++ b/arch/arm/include/asm/traps.h @@ -19,6 +19,8 @@ struct undef_hook { void register_undef_hook(struct undef_hook *hook); void unregister_undef_hook(struct undef_hook *hook); =20 +void do_undefinstr(struct pt_regs *regs); + static inline int __in_irqentry_text(unsigned long ptr) { extern char __irqentry_text_start[]; diff --git a/arch/arm/kernel/traps-v7m.c b/arch/arm/kernel/traps-v7m.c index 5fd9943448e9..b324499e1010 100644 --- a/arch/arm/kernel/traps-v7m.c +++ b/arch/arm/kernel/traps-v7m.c @@ -20,6 +20,7 @@ #include #include #include +#include #include =20 enum fault { @@ -49,7 +50,6 @@ static const struct exception exceptions[] =3D { {"no coprocessor", FAULT_USAGEFAULT, V7M_SCB_CFSR_NOCP, SIGILL, ILL_C= OPROC, UDBG_UNDEFINED}, {"return to invalid PC", FAULT_USAGEFAULT, V7M_SCB_CFSR_INVPC, SIGSEGV,= SEGV_MAPERR, UDBG_SEGV}, {"invalid ISA state", FAULT_USAGEFAULT, V7M_SCB_CFSR_INVSTATE, SIGSEGV= , SEGV_MAPERR, UDBG_SEGV}, - {"undefined instruction", FAULT_USAGEFAULT, V7M_SCB_CFSR_UNDEFINSTR, SIG= ILL, ILL_ILLOPC, UDBG_UNDEFINED}, {"floating point state error", FAULT_BUSFAULT, V7M_SCB_CFSR_LSPERR, SI= GBUS, BUS_ADRERR, UDBG_BUS}, {"exception stack push error", FAULT_BUSFAULT, V7M_SCB_CFSR_STKERR, SI= GBUS, BUS_ADRERR, UDBG_BUS}, {"exception stack pop error", FAULT_BUSFAULT, V7M_SCB_CFSR_UNSTKERR, S= IGBUS, BUS_ADRERR, UDBG_BUS}, @@ -95,6 +95,12 @@ static void traps_v7m_common(struct pt_regs *regs, int f= ault) writel(hstatus, BASEADDR_V7M_SCB + V7M_SCB_HFSR); writel(cstatus, BASEADDR_V7M_SCB + V7M_SCB_CFSR); =20 + if (fault =3D=3D FAULT_USAGEFAULT && cstatus & V7M_SCB_CFSR_UNDEFINSTR) { + /* Handle undefined instruction hooks */ + do_undefinstr(regs); + return; + } + for (i =3D 0; exceptions[i].name !=3D NULL; ++i) { if (fault !=3D exceptions[i].fault) continue; --=20 2.37.0