Commit 8b5ee2c6 authored by Tiezhu Yang's avatar Tiezhu Yang Committed by Huacai Chen
Browse files

LoongArch: Add support for function error injection 



Inspired by the commit 42d038c4 ("arm64: Add support for function
error injection") and the commit ee55ff80 ("riscv: Add support for
function error injection"), this patch supports function error injection
for LoongArch.

Mainly implement two functions:
(1) regs_set_return_value() which is used to overwrite the return value,
(2) override_function_with_return() which is used to override the probed
function returning and jump to its caller.

Here is a simple test under CONFIG_FUNCTION_ERROR_INJECTION and
CONFIG_FAIL_FUNCTION:

  # echo sys_clone > /sys/kernel/debug/fail_function/inject
  # echo 100 > /sys/kernel/debug/fail_function/probability
  # dmesg
  bash: fork: Invalid argument
  # dmesg
  ...
  FAULT_INJECTION: forcing a failure.
  name fail_function, interval 1, probability 100, space 0, times 1
  ...
  Call Trace:
  [<90000000002238f4>] show_stack+0x5c/0x180
  [<90000000012e384c>] dump_stack_lvl+0x60/0x88
  [<9000000000b1879c>] should_fail_ex+0x1b0/0x1f4
  [<900000000032ead4>] fei_kprobe_handler+0x28/0x6c
  [<9000000000230970>] kprobe_breakpoint_handler+0xf0/0x118
  [<90000000012e3e60>] do_bp+0x2c4/0x358
  [<9000000002241924>] exception_handlers+0x1924/0x10000
  [<900000000023b7d0>] sys_clone+0x0/0x4
  [<90000000012e4744>] do_syscall+0x7c/0x94
  [<9000000000221e44>] handle_syscall+0xc4/0x160

Tested-by: default avatarHengqi Chen <hengqi.chen@gmail.com>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarTiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent d4c937c2

arch/loongarch/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -100,6 +100,7 @@ config LOONGARCH 
	select HAVE_FAST_GUP

	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_FUNCTION_ARG_ACCESS_API

	select HAVE_FUNCTION_ERROR_INJECTION

	select HAVE_FUNCTION_GRAPH_TRACER

	select HAVE_FUNCTION_TRACER

	select HAVE_GENERIC_VDSO

arch/loongarch/include/asm/ptrace.h

+5 −0
Original line number Diff line number Diff line
@@ -154,6 +154,11 @@ static inline long regs_return_value(struct pt_regs *regs) 
	return regs->regs[4];

}



static inline void regs_set_return_value(struct pt_regs *regs, unsigned long val)

{

	regs->regs[4] = val;

}



#define instruction_pointer(regs) ((regs)->csr_era)

#define profile_pc(regs) instruction_pointer(regs)

arch/loongarch/lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -5,3 +5,5 @@ 


lib-y	+= delay.o memset.o memcpy.o memmove.o \

	   clear_user.o copy_user.o csum.o dump_tlb.o unaligned.o



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

arch/loongarch/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->regs[1]);

}

NOKPROBE_SYMBOL(override_function_with_return);