Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a7e30b8d91d3291de4543d97849193ebc3ec4c1c
Commit: a7e30b8d91d3291de4543d97849193ebc3ec4c1c
Parent: bb7aa6d47fcd4f9ab18b4ade2ba078f7719f74ca
Author: Philippe Rétornaz <[EMAIL PROTECTED]>
AuthorDate: Wed Oct 10 18:52:24 2007 -0400
Committer: Haavard Skinnemoen <[EMAIL PROTECTED]>
CommitDate: Thu Oct 11 13:32:56 2007 +0200
[AVR32] Fix random segfault with preemption
As explained on:
http://www.avrfreaks.net/index.php?nameÿphpBB2&fileÿewtopic&tS307
If the current process is preempted before it can copy RAR_SUP and
RSR_SUP both register are lost and the process will segfault as soon
as it return from the syscall since the return adress will be
corrupted.
This patch disable IRQ as soon as we enter the syscall path and
reenable them when the copy is done.
In the interrupt handlers, check if we are interrupting the srrf
instruction, if so disable interrupts and return. The interrupt
handler will be re-called immediatly when the interrupts are
reenabled.
After some stressing workload:
- find / > /dev/null in loop
- top (in ssh)
- ping -f avr32
The segfaults are not seen anymore.
Signed-off-by: Philippe Rétornaz <[EMAIL PROTECTED]>
Signed-off-by: Haavard Skinnemoen <[EMAIL PROTECTED]>
---
arch/avr32/kernel/entry-avr32b.S | 26 +++++++++++++++++++++++++-
1 files changed, 25 insertions(+), 1 deletions(-)
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 42657f1..ccadfd9 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -159,11 +159,18 @@ handle_vmalloc_miss:
.section .scall.text,"ax",@progbits
system_call:
+#ifdef CONFIG_PREEMPT
+ mask_interrupts
+#endif
pushm r12 /* r12_orig */
stmts --sp, r0-lr
- zero_fp
+
mfsr r0, SYSREG_RAR_SUP
mfsr r1, SYSREG_RSR_SUP
+#ifdef CONFIG_PREEMPT
+ unmask_interrupts
+#endif
+ zero_fp
stm --sp, r0-r1
/* check for syscall tracing */
@@ -638,6 +645,13 @@ irq_level\level:
stmts --sp,r0-lr
mfsr r8, rar_int\level
mfsr r9, rsr_int\level
+
+#ifdef CONFIG_PREEMPT
+ sub r11, pc, (. - system_call)
+ cp.w r11, r8
+ breq 4f
+#endif
+
pushm r8-r9
mov r11, sp
@@ -668,6 +682,16 @@ irq_level\level:
sub sp, -4 /* ignore r12_orig */
rete
+#ifdef CONFIG_PREEMPT
+4: mask_interrupts
+ mfsr r8, rsr_int\level
+ sbr r8, 16
+ mtsr rsr_int\level, r8
+ ldmts sp++, r0-lr
+ sub sp, -4 /* ignore r12_orig */
+ rete
+#endif
+
2: get_thread_info r0
ld.w r1, r0[TI_flags]
bld r1, TIF_CPU_GOING_TO_SLEEP
-
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