This is a note to let you know that I've just added the patch titled
MIPS: Clear ISA bit correctly in get_frame_info()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-clear-isa-bit-correctly-in-get_frame_info.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ccaf7caf2c73c6db920772bf08bf1d47b2170634 Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@xxxxxxxxxx>
Date: Mon, 7 Nov 2016 15:07:02 +0000
Subject: MIPS: Clear ISA bit correctly in get_frame_info()
From: Paul Burton <paul.burton@xxxxxxxxxx>
commit ccaf7caf2c73c6db920772bf08bf1d47b2170634 upstream.
get_frame_info() can be called in microMIPS kernels with the ISA bit
already clear. For example this happens when unwind_stack_by_address()
is called because we begin with a PC that has the ISA bit set & subtract
the (odd) offset from the preceding symbol (which does not have the ISA
bit set). Since get_frame_info() unconditionally subtracts 1 from the PC
in microMIPS kernels it incorrectly misaligns the address it then
attempts to access code at, leading to an address error exception.
Fix this by using msk_isa16_mode() to clear the ISA bit, which allows
get_frame_info() to function regardless of whether it is provided with a
PC that has the ISA bit set or not.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.")
Cc: Leonid Yegoshin <leonid.yegoshin@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/14528/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/mips/kernel/process.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -299,17 +299,14 @@ static inline int is_sp_move_ins(union m
static int get_frame_info(struct mips_frame_info *info)
{
-#ifdef CONFIG_CPU_MICROMIPS
- union mips_instruction *ip = (void *) (((char *) info->func) - 1);
-#else
- union mips_instruction *ip = info->func;
-#endif
+ union mips_instruction *ip;
unsigned max_insns = info->func_size / sizeof(union mips_instruction);
unsigned i;
info->pc_offset = -1;
info->frame_size = 0;
+ ip = (void *)msk_isa16_mode((ulong)info->func);
if (!ip)
goto err;
Patches currently in stable-queue which might be from paul.burton@xxxxxxxxxx are
queue-4.4/mips-calculate-micromips-ra-properly-when-unwinding-the-stack.patch
queue-4.4/mips-fix-get_frame_info-handling-of-micromips-function-size.patch
queue-4.4/mips-handle-micromips-jumps-in-the-same-way-as-mips32-mips64-jumps.patch
queue-4.4/mips-fix-is_jump_ins-handling-of-16b-micromips-instructions.patch
queue-4.4/mips-clear-isa-bit-correctly-in-get_frame_info.patch
queue-4.4/mips-prevent-unaligned-accesses-during-stack-unwinding.patch