diff options
| author | Tony Wu <tung7970@gmail.com> | 2013-05-12 19:04:29 +0400 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2013-05-17 22:59:28 +0400 |
| commit | e7438c4b893e87311d2fb0facb3e6a0df17abe01 (patch) | |
| tree | 042fe9b7e10dc9e00181bc41f99e900f8f2b5b99 /arch/mips | |
| parent | d552b233f692416d63bb93eb35bf24e5c95c7e0b (diff) | |
| download | linux-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.c | 6 |
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)) |