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[45.33.106.81]) by smtp.gmail.com with ESMTPSA id i124sm128217887pfe.61.2019.07.31.09.58.30 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 31 Jul 2019 09:58:34 -0700 (PDT) Date: Thu, 1 Aug 2019 00:58:26 +0800 From: Leo Yan To: Will Deacon Cc: Russell King , Oleg Nesterov , Catalin Marinas , 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: <20190731165826.GG16088@leoy-ThinkPad-X240s> References: <20190716111301.1855-1-leo.yan@linaro.org> <20190716111301.1855-2-leo.yan@linaro.org> <20190731160836.qmzlk3ndbahwhfmu@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190731160836.qmzlk3ndbahwhfmu@willie-the-truck> 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 Hi Will, Thanks for reviewing. On Wed, Jul 31, 2019 at 05:08:37PM +0100, Will Deacon wrote: > 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 > > --- > > 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_ */ > > Why isn't this prototype in the asm-generic header? Seems weird to have to > duplicate it for each architecture. Yeah. When I spin for new version patches, will try to refactor in the asm-generic header. > > 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 > > extra "the" Will fix. > > + * 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. > > directly Will fix. > > + */ > > + regs->pc = regs->regs[30]; > > I suppose we could be all fancy and do: > > instruction_pointer_set(regs, procedure_link_pointer(regs)); > > How about that? Ah, good point. Will change to use the common APIs. Thanks, Leo Yan