2021-01-12 13:07:27

by Jinyang He

[permalink] [raw]
Subject: [PATCH 3/4] MIPS: Fix get_frame_info() handing of function size

[1]: Commit b6c7a324df37b ("MIPS: Fix get_frame_info() handling of
microMIPS function size")
[2]: Commit 2b424cfc69728 ("MIPS: Remove function size check in
get_frame_info()")

First patch added a constant to check the number of iterations against.
Second patch fixed the situation that info->func_size is zero.

However, func_size member became useless after the second commit. Without
ip_end, the get frame_size operation may be out of range although KALLSYMS
enabled. Thus, check func_size first. Then make ip_end be the sum of ip
and a constant (512) if func_size is equal to 0. Otherwise make ip_end be
the sum of ip and func_size.

Signed-off-by: Jinyang He <[email protected]>
---
arch/mips/kernel/process.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 94dfdf4..bef8f8d 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -390,10 +390,8 @@ static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)
static int get_frame_info(struct mips_frame_info *info)
{
bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
- union mips_instruction insn, *ip;
- const unsigned int max_insns = 128;
+ union mips_instruction insn, *ip, *ip_end;
unsigned int last_insn_size = 0;
- unsigned int i;
bool saw_jump = false;

info->pc_offset = -1;
@@ -403,7 +401,9 @@ static int get_frame_info(struct mips_frame_info *info)
if (!ip)
goto err;

- for (i = 0; i < max_insns; i++) {
+ ip_end = (void *)ip + (info->func_size ? info->func_size : 512);
+
+ while(ip < ip_end) {
ip = (void *)ip + last_insn_size;

if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
--
2.1.0