The patch below disables FIQ in IRQ handler to fix race condition
that may result in recursive entry into IRQ handler through FIQ
handler.
-- Sergei.
Index: packages/hal/arm/arch/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/arm/arch/current/ChangeLog,v
retrieving revision 1.104
diff -a -u -r1.104 ChangeLog
--- packages/hal/arm/arch/current/ChangeLog 21 Apr 2005 18:17:54 -0000
1.104
+++ packages/hal/arm/arch/current/ChangeLog 6 Feb 2006 18:27:06 -0000
@@ -1,3 +1,9 @@
+2006-02-06 Sergei Organov <[EMAIL PROTECTED]>
+
+ * src/vectors.S: disable FIQ in IRQ handler to fix race condition
+ recursively entering IRQ handler through FIQ handler. Remove
+ unreferenced handle_IRQ_or_FIQ label.
+
2005-04-21 Ian Campbell <[EMAIL PROTECTED]>
* src/redboot_linux_exec.c: Added -t option which takes the
Index: packages/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 -a -u -r1.55 vectors.S
--- packages/hal/arm/arch/current/src/vectors.S 23 Nov 2004 14:11:19 -0000
1.55
+++ packages/hal/arm/arch/current/src/vectors.S 6 Feb 2006 18:27:09 -0000
@@ -787,11 +787,14 @@
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
+ // We must disable FIQ here (IRQ is already disabled) as switching
+ // from IRQ to SVC mode will cheat FIQ handler and it will pass
through
+ // the control back to us (should FIQ happen after the statement
below)
+ // resulting in recursion that we aren't ready to handle, e.g., what
+ // we have saved on the exception stack will be clobbered.
+ orr r4,r4,#CPSR_SUPERVISOR_MODE|CPSR_FIQ_DISABLE
msr cpsr,r4
mov r5,sp // save original svc sp
