Subject: [Patch 1/2] PPC64-HWBKPT: Disable interrupts for data breakpoint exceptions

From: "K.Prasad" <[email-masked]>
Date: Wed, 14 Apr 2010 09:18:09 +0530

Data address breakpoint exceptions are currently handled along with page-faults
which require interrupts to remain in enabled state. Since exception handling
for data breakpoints aren't pre-empt safe, we handle them separately.

Signed-off-by: K.Prasad <[email-masked]>
---
 arch/powerpc/kernel/exceptions-64s.S |   13 ++++++++++++-
 arch/powerpc/mm/fault.c              |    5 +++--
 2 files changed, 15 insertions(+), 3 deletions(-)

Index: linux-2.6.ppc64_test/arch/powerpc/kernel/exceptions-64s.S
===================================================================
--- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/exceptions-64s.S
+++ linux-2.6.ppc64_test/arch/powerpc/kernel/exceptions-64s.S
@@ -735,8 +735,11 @@ _STATIC(do_hash_page)
 	std	r3,_DAR(r1)
 	std	r4,_DSISR(r1)
 
-	andis.	r0,r4,0xa450		/* weird error? */
+	andis.	r0,r4,0xa410		/* weird error? */
 	bne-	handle_page_fault	/* if not, try to insert a HPTE */
+	andis.  r0,r4,DSISR_DABRMATCH@h
+	bne-    handle_dabr_fault
+
 BEGIN_FTR_SECTION
 	andis.	r0,r4,0x0020		/* Is it a segment table fault? */
 	bne-	do_ste_alloc		/* If so handle it */
@@ -823,6 +826,14 @@ END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISER
 	bl	.raw_local_irq_restore
 	b	11f
 
+/* We have a data breakpoint exception - handle it */
+handle_dabr_fault:
+	ld      r4,_DAR(r1)
+	ld      r5,_DSISR(r1)
+	addi    r3,r1,STACK_FRAME_OVERHEAD
+	bl      .do_dabr
+	b       .ret_from_except_lite
+
 /* Here we have a page fault that hash_page can't handle. */
 handle_page_fault:
 	ENABLE_INTS
Index: linux-2.6.ppc64_test/arch/powerpc/mm/fault.c
===================================================================
--- linux-2.6.ppc64_test.orig/arch/powerpc/mm/fault.c
+++ linux-2.6.ppc64_test/arch/powerpc/mm/fault.c
@@ -151,13 +151,14 @@ int __kprobes do_page_fault(struct pt_re
 	if (!user_mode(regs) && (address >= TASK_SIZE))
 		return SIGSEGV;
 
-#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
+#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || \
+			     defined(CONFIG_PPC_BOOK3S_64))
   	if (error_code & DSISR_DABRMATCH) {
 		/* DABR match */
 		do_dabr(regs, address, error_code);
 		return 0;
 	}
-#endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/
+#endif
 
 	if (in_atomic() || mm == NULL) {
 		if (!user_mode(regs))