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authorTony Wu <tung7970@gmail.com>2013-05-12 19:04:29 +0400
committerRalf Baechle <ralf@linux-mips.org>2013-05-17 22:59:28 +0400
commite7438c4b893e87311d2fb0facb3e6a0df17abe01 (patch)
tree042fe9b7e10dc9e00181bc41f99e900f8f2b5b99 /arch/mips
parentd552b233f692416d63bb93eb35bf24e5c95c7e0b (diff)
downloadlinux-e7438c4b893e87311d2fb0facb3e6a0df17abe01.tar.xz
MIPS: Fix sibling call handling in get_frame_info
Given a function, get_frame_info() analyzes its instructions to figure out frame size and return address. get_frame_info() works as follows: 1. analyze up to 128 instructions if the function size is unknown 2. search for 'addiu/daddiu sp,sp,-immed' for frame size 3. search for 'sw ra,offset(sp)' for return address 4. end search when it sees jr/jal/jalr This leads to an issue when the given function is a sibling call, example shown as follows. 801ca110 <schedule>: 801ca110: 8f820000 lw v0,0(gp) 801ca114: 8c420000 lw v0,0(v0) 801ca118: 080726f0 j 801c9bc0 <__schedule> 801ca11c: 00000000 nop 801ca120 <io_schedule>: 801ca120: 27bdffe8 addiu sp,sp,-24 801ca124: 3c028022 lui v0,0x8022 801ca128: afbf0014 sw ra,20(sp) In this case, get_frame_info() cannot properly detect schedule's frame info, and eventually returns io_schedule's instead. This patch adds 'j' to the end search condition to workaround sibling call cases. Signed-off-by: Tony Wu <tung7970@gmail.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/5236/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips')
-rw-r--r--arch/mips/kernel/process.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index eb902c1f0cad..785bf2a4129a 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -264,7 +264,7 @@ static inline int is_ra_save_ins(union mips_instruction *ip)
#endif
}
-static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
+static inline int is_jump_ins(union mips_instruction *ip)
{
#ifdef CONFIG_CPU_MICROMIPS
/*
@@ -288,6 +288,8 @@ static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
return 0;
return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
#else
+ if (ip->j_format.opcode == j_op)
+ return 1;
if (ip->j_format.opcode == jal_op)
return 1;
if (ip->r_format.opcode != spec_op)
@@ -350,7 +352,7 @@ static int get_frame_info(struct mips_frame_info *info)
for (i = 0; i < max_insns; i++, ip++) {
- if (is_jal_jalr_jr_ins(ip))
+ if (is_jump_ins(ip))
break;
if (!info->frame_size) {
if (is_sp_move_ins(ip))