hw-breakpoints: prepare the code for Hardware Breakpoint interfaces

The generic hardware breakpoint interface provides an abstraction of
hardware breakpoints in front of specific arch implementations for both kernel
and user side breakpoints.
This includes execution breakpoints and read/write breakpoints, also known as
"watchpoints".

This patch introduces header files containing constants, structure definitions
and declaration of functions used by the hardware breakpoint core and x86
specific code.
It also introduces an array based storage for the debug-register values in
'struct thread_struct', while modifying all users of debugreg<n> member in the
structure.

[ Impact: add headers for new hardware breakpoint interface ]

Original-patch-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 0b2fab0051e..448b34a8e39 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -29,6 +29,7 @@ struct mm_struct;
 #include <linux/threads.h>
 #include <linux/init.h>
 
+#define HBP_NUM 4
 /*
  * Default implementation of macro that returns current
  * instruction pointer ("program counter").
@@ -431,12 +432,11 @@ struct thread_struct {
         unsigned long           fs;
         unsigned long           gs;
         /* Hardware debugging registers: */
-        unsigned long           debugreg0;
-        unsigned long           debugreg1;
-        unsigned long           debugreg2;
-        unsigned long           debugreg3;
+        unsigned long           debugreg[HBP_NUM];
         unsigned long           debugreg6;
         unsigned long           debugreg7;
+        /* Hardware breakpoint info */
+        struct hw_breakpoint    *hbp[HBP_NUM];
         /* Fault info: */
         unsigned long           cr2;
         unsigned long           trap_no;