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Wed, 24 Jul 2019 18:42:12 -0700 (PDT) Date: Thu, 25 Jul 2019 09:42:04 +0800 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: Re: [PATCH 1/2] arm64: Add support for function error injection Message-ID: <20190725014125.GB6764@leoy-ThinkPad-X240s> References: <20190716111301.1855-1-leo.yan@linaro.org> <20190716111301.1855-2-leo.yan@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190716111301.1855-2-leo.yan@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jul 16, 2019 at 07:13:00PM +0800, Leo Yan wrote: > This patch implement regs_set_return_value() and > override_function_with_return() to support function error injection > for arm64. > > In the exception flow, arm64's general register x30 contains the value > for the link register; so we can just update pt_regs::pc with it rather > than redirecting execution to a dummy function that returns. > > This patch is heavily inspired by the commit 7cd01b08d35f ("powerpc: > Add support for function error injection"). > > Signed-off-by: Leo Yan Catalin, Will: Gentle ping ... > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/error-injection.h | 13 +++++++++++++ > arch/arm64/include/asm/ptrace.h | 5 +++++ > arch/arm64/lib/Makefile | 2 ++ > arch/arm64/lib/error-inject.c | 19 +++++++++++++++++++ > 5 files changed, 40 insertions(+) > create mode 100644 arch/arm64/include/asm/error-injection.h > create mode 100644 arch/arm64/lib/error-inject.c > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 697ea0510729..a6d9e622977d 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -142,6 +142,7 @@ config ARM64 > select HAVE_EFFICIENT_UNALIGNED_ACCESS > select HAVE_FTRACE_MCOUNT_RECORD > select HAVE_FUNCTION_TRACER > + select HAVE_FUNCTION_ERROR_INJECTION > select HAVE_FUNCTION_GRAPH_TRACER > select HAVE_GCC_PLUGINS > select HAVE_HW_BREAKPOINT if PERF_EVENTS > diff --git a/arch/arm64/include/asm/error-injection.h b/arch/arm64/include/asm/error-injection.h > new file mode 100644 > index 000000000000..da057e8ed224 > --- /dev/null > +++ b/arch/arm64/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/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h > index dad858b6adc6..3aafbbe218a2 100644 > --- a/arch/arm64/include/asm/ptrace.h > +++ b/arch/arm64/include/asm/ptrace.h > @@ -294,6 +294,11 @@ static inline unsigned long regs_return_value(struct pt_regs *regs) > return regs->regs[0]; > } > > +static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc) > +{ > + regs->regs[0] = rc; > +} > + > /** > * regs_get_kernel_argument() - get Nth function argument in kernel > * @regs: pt_regs of that context > diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile > index 33c2a4abda04..f182ccb0438e 100644 > --- a/arch/arm64/lib/Makefile > +++ b/arch/arm64/lib/Makefile > @@ -33,3 +33,5 @@ UBSAN_SANITIZE_atomic_ll_sc.o := n > lib-$(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) += uaccess_flushcache.o > > obj-$(CONFIG_CRC32) += crc32.o > + > +obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o > diff --git a/arch/arm64/lib/error-inject.c b/arch/arm64/lib/error-inject.c > new file mode 100644 > index 000000000000..35661c2de4b0 > --- /dev/null > +++ b/arch/arm64/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->regs[30]' contains the the link register for the probed > + * function and assign it to 'regs->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->pc = regs->regs[30]; > +} > +NOKPROBE_SYMBOL(override_function_with_return); > -- > 2.17.1 >