Hi Guo,
On Mon, 13 Jul 2020 23:39:22 +0000
guoren@xxxxxxxxxx wrote:
> From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
>
> Inspired by the commit 42d038c4fb00 ("arm64: Add support for function
> error injection"), this patch supports function error injection for
> riscv.
>
> This patch mainly support two functions: one is regs_set_return_value()
> which is used to overwrite the return value; the another function is
> override_function_with_return() which is to override the probed
> function returning and jump to its caller.
>
> Test log:
> cd /sys/kernel/debug/fail_function
> echo sys_clone > inject
> echo 100 > probability
> echo 1 > interval
> ls /
> [ 313.176875] FAULT_INJECTION: forcing a failure.
> [ 313.176875] name fail_function, interval 1, probability 100, space 0, times 1
> [ 313.184357] CPU: 0 PID: 87 Comm: sh Not tainted 5.8.0-rc5-00007-g6a758cc #117
> [ 313.187616] Call Trace:
> [ 313.189100] [<ffffffe0002036b6>] walk_stackframe+0x0/0xc2
> [ 313.191626] [<ffffffe00020395c>] show_stack+0x40/0x4c
> [ 313.193927] [<ffffffe000556c60>] dump_stack+0x7c/0x96
> [ 313.194795] [<ffffffe0005522e8>] should_fail+0x140/0x142
> [ 313.195923] [<ffffffe000299ffc>] fei_kprobe_handler+0x2c/0x5a
> [ 313.197687] [<ffffffe0009e2ec4>] kprobe_breakpoint_handler+0xb4/0x18a
> [ 313.200054] [<ffffffe00020357e>] do_trap_break+0x36/0xca
> [ 313.202147] [<ffffffe000201bca>] ret_from_exception+0x0/0xc
> [ 313.204556] [<ffffffe000201bbc>] ret_from_syscall+0x0/0x2
> -sh: can't fork: Invalid argument
OK, this looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Thank you,
>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/include/asm/ptrace.h | 6 ++++++
> arch/riscv/lib/Makefile | 2 ++
> arch/riscv/lib/error-inject.c | 10 ++++++++++
> 4 files changed, 19 insertions(+)
> create mode 100644 arch/riscv/lib/error-inject.c
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 0e9f5eb..ad73174 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -58,6 +58,7 @@ config RISCV
> select HAVE_DMA_CONTIGUOUS if MMU
> select HAVE_EBPF_JIT if MMU
> select HAVE_FUTEX_CMPXCHG if FUTEX
> + select HAVE_FUNCTION_ERROR_INJECTION
> select HAVE_GENERIC_VDSO if MMU && 64BIT
> select HAVE_KPROBES
> select HAVE_KPROBES_ON_FTRACE
> diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
> index 23372bb..cb4abb6 100644
> --- a/arch/riscv/include/asm/ptrace.h
> +++ b/arch/riscv/include/asm/ptrace.h
> @@ -109,6 +109,12 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
> return regs->a0;
> }
>
> +static inline void regs_set_return_value(struct pt_regs *regs,
> + unsigned long val)
> +{
> + regs->a0 = val;
> +}
> +
> extern int regs_query_register_offset(const char *name);
> extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
> unsigned int n);
> diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
> index 0d0db80..04baa93 100644
> --- a/arch/riscv/lib/Makefile
> +++ b/arch/riscv/lib/Makefile
> @@ -4,3 +4,5 @@ lib-y += memcpy.o
> lib-y += memset.o
> lib-y += uaccess.o
> lib-$(CONFIG_64BIT) += tishift.o
> +
> +obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
> diff --git a/arch/riscv/lib/error-inject.c b/arch/riscv/lib/error-inject.c
> new file mode 100644
> index 00000000..d667ade
> --- /dev/null
> +++ b/arch/riscv/lib/error-inject.c
> @@ -0,0 +1,10 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/error-injection.h>
> +#include <linux/kprobes.h>
> +
> +void override_function_with_return(struct pt_regs *regs)
> +{
> + instruction_pointer_set(regs, regs->ra);
> +}
> +NOKPROBE_SYMBOL(override_function_with_return);
> --
> 2.7.4
>
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
