From ccaf7caf2c73c6db920772bf08bf1d47b2170634 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 7 Nov 2016 15:07:02 +0000 Subject: [PATCH] MIPS: Clear ISA bit correctly in get_frame_info() 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 Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.") Cc: Leonid Yegoshin Cc: linux-mips@linux-mips.org Cc: # v3.10+ Patchwork: https://patchwork.linux-mips.org/patch/14528/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/process.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 48e30e0469ef..213278dbbc04 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -304,17 +304,14 @@ static inline int is_sp_move_ins(union mips_instruction *ip) 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; -- 2.30.2