OpenWrt – Rev 1
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From: Felix Fietkau <nbd@nbd.name>
Date: Wed, 18 Apr 2018 10:50:05 +0200
Subject: [PATCH] MIPS: only process negative stack offsets on stack traces
Fixes endless back traces in cases where the compiler emits a stack
pointer increase in a branch delay slot (probably for some form of
function return).
[ 3.475442] BUG: MAX_STACK_TRACE_ENTRIES too low!
[ 3.480070] turning off the locking correctness validator.
[ 3.485521] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.34 #0
[ 3.491475] Stack : 00000000 00000000 00000000 00000000 80e0fce2 00000034 00000000 00000000
[ 3.499764] 87c3838c 80696377 8061047c 00000000 00000001 00000001 87c2d850 6534689f
[ 3.508059] 00000000 00000000 80e10000 00000000 00000000 000000cf 0000000f 00000000
[ 3.516353] 00000000 806a0000 00076891 00000000 00000000 00000000 ffffffff 00000000
[ 3.524648] 806c0000 00000004 80e10000 806a0000 00000003 80690000 00000000 80700000
[ 3.532942] ...
[ 3.535362] Call Trace:
[ 3.537818] [<80010a48>] show_stack+0x58/0x100
[ 3.542207] [<804c2f78>] dump_stack+0xe8/0x170
[ 3.546613] [<80079f90>] save_trace+0xf0/0x110
[ 3.551010] [<8007b1ec>] mark_lock+0x33c/0x78c
[ 3.555413] [<8007bf48>] __lock_acquire+0x2ac/0x1a08
[ 3.560337] [<8007de60>] lock_acquire+0x64/0x8c
[ 3.564846] [<804e1570>] _raw_spin_lock_irqsave+0x54/0x78
[ 3.570186] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.574770] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.579257] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.583839] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.588329] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.592911] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.597401] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.601983] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.606473] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.611055] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.615545] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.620125] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.624619] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.629197] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.633691] [<801b618c>] kernfs_notify+0x94/0xac
[ 3.638269] [<801b7b10>] sysfs_notify+0x74/0xa0
[ 3.642763] [<801b618c>] kernfs_notify+0x94/0xac
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -360,6 +360,8 @@ static inline int is_sp_move_ins(union m
if (ip->i_format.opcode == addiu_op ||
ip->i_format.opcode == daddiu_op) {
+ if (ip->i_format.simmediate > 0)
+ return 0;
*frame_size = -ip->i_format.simmediate;
return 1;
}