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[95.114.116.215]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-496b4d8d6efsm201357975e9.0.2026.07.26.17.10.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Jul 2026 17:10:52 -0700 (PDT) Date: Mon, 27 Jul 2026 02:10:19 +0200 From: Karl Mehltretter To: Kees Cook Cc: "Russell King (Oracle)" , Linus Walleij , Nathan Chancellor , Sami Tolvanen , Zhen Lei , Arnd Bergmann , =?utf-8?Q?Micha=C5=82?= Pecio , Sebastian Andrzej Siewior , linux-arm-kernel@lists.infradead.org, Russell King , Will Deacon , Mark Rutland , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-hardening@vger.kernel.org Subject: Re: [PATCH v3] ARM: traps: Implement KCFI trap handler for ARM32 Message-ID: References: <20260715175223.make.153-kees@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260715175223.make.153-kees@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260726_171055_865476_A593B223 X-CRM114-Status: GOOD ( 11.65 ) 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 On Wed, Jul 15, 2026 at 10:52:27AM +0100, Kees Cook wrote: > +bool arm_cfi_handle_failure(struct pt_regs *regs, enum bug_trap_type type) > +{ > + switch (type) { > + case BUG_TRAP_TYPE_BUG: > + die("Oops - CFI", regs, 0); > + break; > + case BUG_TRAP_TYPE_WARN: > + /* Permissive mode: skip the trapping instruction and continue. */ > + instruction_pointer(regs) += 4; > + break; On Thumb-2, Clang emits a 16-bit BKPT for CFI checks. This skips the following Thumb instruction. Thanks, Karl