Unverified Commit ee55ff80 authored by Guo Ren's avatar Guo Ren Committed by Palmer Dabbelt
Browse files

riscv: Add support for function error injection 



Inspired by the commit 42d038c4 ("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

Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 74784081

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ config RISCV 
	select HAVE_DEBUG_KMEMLEAK

	select HAVE_DMA_CONTIGUOUS if MMU

	select HAVE_EBPF_JIT if MMU

	select HAVE_FUNCTION_ERROR_INJECTION

	select HAVE_FUTEX_CMPXCHG if FUTEX

	select HAVE_GCC_PLUGINS

	select HAVE_GENERIC_VDSO if MMU && 64BIT

arch/riscv/include/asm/ptrace.h

+6 −0
Original line number Diff line number Diff line
@@ -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);

arch/riscv/lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -5,3 +5,5 @@ lib-y += memset.o 
lib-y			+= memmove.o

lib-$(CONFIG_MMU)	+= uaccess.o

lib-$(CONFIG_64BIT)	+= tishift.o



obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

arch/riscv/lib/error-inject.c

0 → 100644
+10 −0
Original line number Diff line number Diff line 
// 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);