[PATCH 5.4 035/152] arm/ftrace: Fix BE text poking

Greg Kroah-Hartman
2020-03-03T17:53:34Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit be993e44badc448add6a18d6f12b20615692c4c3 ]

The __patch_text() function already applies __opcode_to_mem_*(), so
when __opcode_to_mem_*() is not the identity (BE*), it is applied
twice, wrecking the instruction.

Fixes: 42e51f187f86 ("arm/ftrace: Use __patch_text()")
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/kernel/ftrace.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index bda949fd84e8b..93caf757f1d5d 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -81,13 +81,10 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
{
unsigned long replaced;

- if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
+ if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
old = __opcode_to_mem_thumb32(old);
- new = __opcode_to_mem_thumb32(new);
- } else {
+ else
old = __opcode_to_mem_arm(old);
- new = __opcode_to_mem_arm(new);
- }

if (validate) {
if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
--
2.20.1