[Patch 04/11] Introduce user-space debug registers

[K.Prasad]

This patch introduces virtual debug registers to used by the per-thread
structure and wrapper routines to manage debug registers by process-related
functions.

Signed-off-by: K.Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/debugreg.h  |   23 +++++++++++++++++++++++
 arch/x86/include/asm/processor.h |   16 +++++++++-------
 2 files changed, 32 insertions(+), 7 deletions(-)

Index: linux-2.6-tip.hbkpt/arch/x86/include/asm/debugreg.h
===================================================================
--- linux-2.6-tip.hbkpt.orig/arch/x86/include/asm/debugreg.h
+++ linux-2.6-tip.hbkpt/arch/x86/include/asm/debugreg.h
@@ -49,6 +49,8 @@
 
 #define DR_LOCAL_ENABLE_SHIFT 0    /* Extra shift to the local enable bit */
 #define DR_GLOBAL_ENABLE_SHIFT 1   /* Extra shift to the global enable bit */
+#define DR_LOCAL_ENABLE (0x1)      /* Local enable for reg 0 */
+#define DR_GLOBAL_ENABLE (0x2)     /* Global enable for reg 0 */
 #define DR_ENABLE_SIZE 2           /* 2 enable bits per register */
 
 #define DR_LOCAL_ENABLE_MASK (0x55)  /* Set  local bits for all 4 regs */
@@ -67,4 +69,25 @@
 #define DR_LOCAL_SLOWDOWN (0x100)   /* Local slow the pipeline */
 #define DR_GLOBAL_SLOWDOWN (0x200)  /* Global slow the pipeline */
 
+/*
+ * HW breakpoint additions
+ */
+#ifdef __KERNEL__
+
+/* For process management */
+void flush_thread_hw_breakpoint(struct task_struct *tsk);
+int copy_thread_hw_breakpoint(struct task_struct *tsk,
+		struct task_struct *child, unsigned long clone_flags);
+void dump_thread_hw_breakpoint(struct task_struct *tsk, int u_debugreg[8]);
+void switch_to_thread_hw_breakpoint(struct task_struct *tsk);
+
+/* For CPU management */
+void load_debug_registers(void);
+static inline void hw_breakpoint_disable(void)
+{
+	set_debugreg(0UL, 7);
+}
+
+#endif	/* __KERNEL__ */
+
 #endif /* _ASM_X86_DEBUGREG_H */
Index: linux-2.6-tip.hbkpt/arch/x86/include/asm/processor.h
===================================================================
--- linux-2.6-tip.hbkpt.orig/arch/x86/include/asm/processor.h
+++ linux-2.6-tip.hbkpt/arch/x86/include/asm/processor.h
@@ -29,6 +29,7 @@ struct mm_struct;
 #include <linux/threads.h>
 #include <linux/init.h>
 
+#define HB_NUM 4
 /*
  * Default implementation of macro that returns current
  * instruction pointer ("program counter").
@@ -424,13 +425,14 @@ struct thread_struct {
 	unsigned long		ip;
 	unsigned long		fs;
 	unsigned long		gs;
-	/* Hardware debugging registers: */
-	unsigned long		debugreg0;
-	unsigned long		debugreg1;
-	unsigned long		debugreg2;
-	unsigned long		debugreg3;
-	unsigned long		debugreg6;
-	unsigned long		debugreg7;
+	/* Hardware breakpoint info */
+	struct hw_breakpoint	*hbkpt[HB_NUM];
+	unsigned int		hbkpt_num_installed;
+	/* Thread's view of debug reg 6 */
+	unsigned long		dr6;
+	/* Thread's view of debug reg 7 */
+	unsigned long		dr7;
+
 	/* Fault info: */
 	unsigned long		cr2;
 	unsigned long		trap_no;

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