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[45.79.223.146]) by smtp.gmail.com with ESMTPSA id h12sm18316685ywm.91.2019.08.06.03.01.12 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 06 Aug 2019 03:01:21 -0700 (PDT) From: Leo Yan To: Russell King , Oleg Nesterov , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , "Naveen N. Rao" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, clang-built-linux@googlegroups.com, Masami Hiramatsu Cc: Leo Yan Subject: [PATCH v2 3/3] arm: Add support for function error injection Date: Tue, 6 Aug 2019 18:00:15 +0800 Message-Id: <20190806100015.11256-4-leo.yan@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190806100015.11256-1-leo.yan@linaro.org> References: <20190806100015.11256-1-leo.yan@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch implements arm specific functions regs_set_return_value() and override_function_with_return() to support function error injection. In the exception flow, it updates pt_regs::ARM_pc with pt_regs::ARM_lr so can override the probed function return. Signed-off-by: Leo Yan --- arch/arm/Kconfig | 1 + arch/arm/include/asm/ptrace.h | 5 +++++ arch/arm/lib/Makefile | 2 ++ arch/arm/lib/error-inject.c | 19 +++++++++++++++++++ 4 files changed, 27 insertions(+) create mode 100644 arch/arm/lib/error-inject.c -- 2.17.1 diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 33b00579beff..2d3d44a037f6 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -77,6 +77,7 @@ config ARM select HAVE_EXIT_THREAD select HAVE_FAST_GUP if ARM_LPAE 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/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 b25c54585048..8f56484a7156 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -42,3 +42,5 @@ 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..2d696dc94893 --- /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, when kprobe returns back from exception it will override + * the end of probed function and directly return to the predefined + * function's caller. + */ + instruction_pointer_set(regs, regs->ARM_lr); +} +NOKPROBE_SYMBOL(override_function_with_return);