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[45.33.106.81]) by smtp.gmail.com with ESMTPSA id 21sm19324907pjh.25.2019.07.16.04.13.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Jul 2019 04:13:31 -0700 (PDT) From: Leo Yan To: Russell King , Oleg Nesterov , Catalin Marinas , Will Deacon , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Masami Hiramatsu , Justin He Subject: [PATCH 2/2] arm: Add support for function error injection Date: Tue, 16 Jul 2019 19:13:01 +0800 Message-Id: <20190716111301.1855-3-leo.yan@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190716111301.1855-1-leo.yan@linaro.org> References: <20190716111301.1855-1-leo.yan@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190716_041332_923992_691A26AD X-CRM114-Status: GOOD ( 16.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Leo Yan MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP This patch implement regs_set_return_value() and override_function_with_return() to support function error injection for arm. In the exception flow, we can update pt_regs::ARM_pc with pt_regs::ARM_lr so that can override the probed function return. Signed-off-by: Leo Yan --- arch/arm/Kconfig | 1 + arch/arm/include/asm/error-injection.h | 13 +++++++++++++ arch/arm/include/asm/ptrace.h | 5 +++++ arch/arm/lib/Makefile | 2 ++ arch/arm/lib/error-inject.c | 19 +++++++++++++++++++ 5 files changed, 40 insertions(+) create mode 100644 arch/arm/include/asm/error-injection.h create mode 100644 arch/arm/lib/error-inject.c diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8869742a85df..f7932a5e29ea 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -74,6 +74,7 @@ config ARM select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU select HAVE_EXIT_THREAD select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL + select HAVE_FUNCTION_ERROR_INJECTION if !THUMB2_KERNEL select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG select HAVE_FUNCTION_TRACER if !XIP_KERNEL select HAVE_GCC_PLUGINS diff --git a/arch/arm/include/asm/error-injection.h b/arch/arm/include/asm/error-injection.h new file mode 100644 index 000000000000..da057e8ed224 --- /dev/null +++ b/arch/arm/include/asm/error-injection.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ + +#ifndef __ASM_ERROR_INJECTION_H_ +#define __ASM_ERROR_INJECTION_H_ + +#include +#include +#include +#include + +void override_function_with_return(struct pt_regs *regs); + +#endif /* __ASM_ERROR_INJECTION_H_ */ diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 91d6b7856be4..3b41f37b361a 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -89,6 +89,11 @@ static inline long regs_return_value(struct pt_regs *regs) return regs->ARM_r0; } +static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc) +{ + regs->ARM_r0 = rc; +} + #define instruction_pointer(regs) (regs)->ARM_pc #ifdef CONFIG_THUMB2_KERNEL diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile index 0bff0176db2c..d3d7430ecd76 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -43,3 +43,5 @@ ifeq ($(CONFIG_KERNEL_MODE_NEON),y) CFLAGS_xor-neon.o += $(NEON_FLAGS) obj-$(CONFIG_XOR_BLOCKS) += xor-neon.o endif + +obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o diff --git a/arch/arm/lib/error-inject.c b/arch/arm/lib/error-inject.c new file mode 100644 index 000000000000..96319d017114 --- /dev/null +++ b/arch/arm/lib/error-inject.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include + +void override_function_with_return(struct pt_regs *regs) +{ + /* + * 'regs' represents the state on entry of a predefined function in + * the kernel/module and which is captured on a kprobe. + * + * 'regs->ARM_lr' contains the the link register for the probed + * function and assign it to 'regs->ARM_pc', so when kprobe returns + * back from exception it will override the end of probed function + * and drirectly return to the predefined function's caller. + */ + regs->ARM_pc = regs->ARM_lr; +} +NOKPROBE_SYMBOL(override_function_with_return);