powerpc, hw_breakpoint: Discard extraneous interrupt due to accesses outside symbol length

Many a times, the requested breakpoint length can be less than the
fixed breakpoint length i.e. 8 bytes supported by PowerPC 64-bit
server (Book III S) processors.  This could lead to extraneous
interrupts resulting in false breakpoint notifications.  This
detects and discards such interrupts for non-ptrace requests.
We don't change ptrace behaviour to avoid breaking compatability.

[Suggestion from Paul Mackerras <paulus@samba.org> to add a new flag in
'struct arch_hw_breakpoint' to identify extraneous interrupts]

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 6576bad1069c..ea87f8ae7bdb 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -27,6 +27,7 @@
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 
 struct arch_hw_breakpoint {
+        bool            extraneous_interrupt;
         u8              len; /* length of the target data symbol */
         int             type;
         unsigned long   address;