diff options
| author | Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> | 2014-07-14 16:23:29 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-07-18 12:30:14 +0100 |
| commit | 8cf2389bc4456057a4d9663d22429fb677f1b13e (patch) | |
| tree | f4c25ee98fed26110709e4ddb330e30c3d87bd07 /arch/arm/kernel/iwmmxt.S | |
| parent | 6b076991dca9817e75c37e2f0db6d52611ea42fa (diff) | |
ARM: 8100/1: Fix preemption disable in iwmmxt_task_enable()
commit 431a84b1a4f7d1a0085d5b91330c5053cc8e8b12
("ARM: 8034/1: Disable preemption in iwmmxt_task_enable()")
introduced macros {inc,dec}_preempt_count to iwmmxt_task_enable
to make it run with preemption disabled.
Unfortunately, other functions in iwmmxt.S also use concan_{save,dump,load}
sections located in iwmmxt_task_enable() to deal with iWMMXt coprocessor.
This causes an unbalanced preempt_count due to excessive dec_preempt_count
and destroyed return addresses in callers of concan_ labels due to a register
collision:
Linux version 3.16.0-rc3-00062-gd92a333-dirty (jef@armhf) (gcc version 4.8.3 (Debian 4.8.3-4) ) #5 PREEMPT Thu Jul 3 19:46:39 CEST 2014
CPU: ARMv7 Processor [560f5815] revision 5 (ARMv7), cr=10c5387d
CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache
Machine model: SolidRun CuBox
...
PJ4 iWMMXt v2 coprocessor enabled.
...
Unable to handle kernel paging request at virtual address fffffffe
pgd = bb25c000
[fffffffe] *pgd=3bfde821, *pte=00000000, *ppte=00000000
Internal error: Oops: 80000007 [#1] PREEMPT ARM
Modules linked in:
CPU: 0 PID: 62 Comm: startpar Not tainted 3.16.0-rc3-00062-gd92a333-dirty #5
task: bb230b80 ti: bb256000 task.ti: bb256000
PC is at 0xfffffffe
LR is at iwmmxt_task_copy+0x44/0x4c
pc : [<fffffffe>] lr : [<800130ac>] psr: 40000033
sp : bb257de8 ip : 00000013 fp : bb257ea4
r10: bb256000 r9 : fffffdfe r8 : 76e898e6
r7 : bb257ec8 r6 : bb256000 r5 : 7ea12760 r4 : 000000a0
r3 : ffffffff r2 : 00000003 r1 : bb257df8 r0 : 00000000
Flags: nZcv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment user
Control: 10c5387d Table: 3b25c019 DAC: 00000015
Process startpar (pid: 62, stack limit = 0xbb256248)
This patch fixes the issue by moving concan_{save,dump,load} into separate
code sections and make iwmmxt_task_enable() call them in the same way the
other functions use concan_ symbols. The test for valid ownership is moved
to concan_save and is safe for the other user of it, iwmmxt_task_disable().
The register collision is also resolved by moving concan_ symbols as
{inc,dec}_preempt_count are now local to iwmmxt_task_enable().
Fixes: 431a84b1a4f7 ("ARM: 8034/1: Disable preemption in iwmmxt_task_enable()")
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/iwmmxt.S')
| -rw-r--r-- | arch/arm/kernel/iwmmxt.S | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/arch/arm/kernel/iwmmxt.S b/arch/arm/kernel/iwmmxt.S index a5599cfc43cb..2b32978ae905 100644 --- a/arch/arm/kernel/iwmmxt.S +++ b/arch/arm/kernel/iwmmxt.S @@ -94,13 +94,19 @@ ENTRY(iwmmxt_task_enable) mrc p15, 0, r2, c2, c0, 0 mov r2, r2 @ cpwait + bl concan_save - teq r1, #0 @ test for last ownership - mov lr, r9 @ normal exit from exception - beq concan_load @ no owner, skip save +#ifdef CONFIG_PREEMPT_COUNT + get_thread_info r10 +#endif +4: dec_preempt_count r10, r3 + mov pc, r9 @ normal exit from exception concan_save: + teq r1, #0 @ test for last ownership + beq concan_load @ no owner, skip save + tmrc r2, wCon @ CUP? wCx @@ -138,7 +144,7 @@ concan_dump: wstrd wR15, [r1, #MMX_WR15] 2: teq r0, #0 @ anything to load? - beq 3f + moveq pc, lr @ if not, return concan_load: @@ -171,14 +177,9 @@ concan_load: @ clear CUP/MUP (only if r1 != 0) teq r1, #0 mov r2, #0 - beq 3f - tmcr wCon, r2 + moveq pc, lr -3: -#ifdef CONFIG_PREEMPT_COUNT - get_thread_info r10 -#endif -4: dec_preempt_count r10, r3 + tmcr wCon, r2 mov pc, lr /* |