On Mon, Feb 06, 2006 at 09:30:27PM +0300, Sergei Organov wrote:
> The patch below disables FIQ in IRQ handler to fix race condition
> that may result in recursive entry into IRQ handler through FIQ
> handler.
Applied, with updated comment.
Andrew
Index: hal/arm/arch/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/arm/arch/current/ChangeLog,v
retrieving revision 1.105
diff -u -r1.105 ChangeLog
--- hal/arm/arch/current/ChangeLog 8 Feb 2006 12:06:38 -0000 1.105
+++ hal/arm/arch/current/ChangeLog 9 Feb 2006 16:46:29 -0000
@@ -1,3 +1,9 @@
+2006-02-06 Sergei Organov <[EMAIL PROTECTED]>
+
+ * src/vectors.S: disable FIQ in IRQ handler to fix race condition
+ of recursively entering IRQ handler through FIQ handler. Remove
+ unreferenced handle_IRQ_or_FIQ label.
+
2006-01-18 Jay Foster <[EMAIL PROTECTED]>
* src/context.S (hal_thread_switch_context): Close race condition
Index: hal/arm/arch/current/src/vectors.S
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/arm/arch/current/src/vectors.S,v
retrieving revision 1.55
diff -u -r1.55 vectors.S
--- hal/arm/arch/current/src/vectors.S 23 Nov 2004 14:11:19 -0000 1.55
+++ hal/arm/arch/current/src/vectors.S 9 Feb 2006 16:46:31 -0000
@@ -787,11 +787,16 @@
mov r2,#CYGNUM_HAL_VECTOR_IRQ
mov r3,sp
-handle_IRQ_or_FIQ:
-
mrs r4,cpsr // switch to Supervisor Mode
bic r4,r4,#CPSR_MODE_BITS
- orr r4,r4,#CPSR_SUPERVISOR_MODE
+ // When handling an IRQ we must disable FIQ unless the current
+ // mode in CPSR is IRQ. If we were to get a FIQ while in another
+ // mode, the FIQ handling code would transform the FIQ into an
+ // IRQ and call the non-reentrant IRQ handler again. As a result,
+ // for example, the stack pointer would be set to the beginning
+ // of the exception_stack clobbering the registers we have just
+ // saved.
+ orr r4,r4,#CPSR_SUPERVISOR_MODE|CPSR_FIQ_DISABLE
msr cpsr,r4
mov r5,sp // save original svc sp
