Re: [PATCH 1/2] arm64: Add support for function error injection
From: Leo Yan <hidden>
Date: 2019-07-25 01:42:15
Also in:
bpf, linux-arm-kernel, lkml
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 <redacted>Catalin, Will: Gentle ping ...
quoted hunk ↗ jump to hunk
--- 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.cdiff --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_EVENTSdiff --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 <linux/compiler.h> +#include <linux/linkage.h> +#include <asm/ptrace.h> +#include <asm-generic/error-injection.h> + +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 contextdiff --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.odiff --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 <linux/error-injection.h> +#include <linux/kprobes.h> + +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