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Subject[RFC Patch 5/9] Use wrapper routines around debug registers in processor related functions
This patch enables the use of wrapper routines to access the debug/breakpoint
registers.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
---
arch/x86/kernel/smpboot.c | 3 +++
arch/x86/power/cpu_32.c | 16 +++-------------
arch/x86/power/cpu_64.c | 15 +++------------
include/asm-x86/debugreg.h | 29 +++++++++++++++++++++++++++++
include/asm-x86/processor.h | 10 +++-------
5 files changed, 41 insertions(+), 32 deletions(-)

Index: linux-bkpt-lkml-27-rc9/arch/x86/power/cpu_32.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/power/cpu_32.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/power/cpu_32.c
@@ -11,6 +11,7 @@
#include <linux/suspend.h>
#include <asm/mtrr.h>
#include <asm/mce.h>
+#include <asm/debugreg.h>

static struct saved_context saved_context;

@@ -46,6 +47,7 @@ static void __save_processor_state(struc
ctxt->cr2 = read_cr2();
ctxt->cr3 = read_cr3();
ctxt->cr4 = read_cr4_safe();
+ disable_debug_registers();
}

/* Needed by apm.c */
@@ -78,19 +80,7 @@ static void fix_processor_context(void)
load_TR_desc(); /* This does ltr */
load_LDT(&current->active_mm->context); /* This does lldt */

- /*
- * Now maybe reload the debug registers
- */
- if (current->thread.debugreg7) {
- set_debugreg(current->thread.debugreg0, 0);
- set_debugreg(current->thread.debugreg1, 1);
- set_debugreg(current->thread.debugreg2, 2);
- set_debugreg(current->thread.debugreg3, 3);
- /* no 4 and 5 */
- set_debugreg(current->thread.debugreg6, 6);
- set_debugreg(current->thread.debugreg7, 7);
- }
-
+ load_debug_registers();
}

static void __restore_processor_state(struct saved_context *ctxt)
Index: linux-bkpt-lkml-27-rc9/arch/x86/power/cpu_64.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/power/cpu_64.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/power/cpu_64.c
@@ -14,6 +14,7 @@
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mtrr.h>
+#include <asm/debugreg.h>

static void fix_processor_context(void);

@@ -69,6 +70,7 @@ static void __save_processor_state(struc
ctxt->cr3 = read_cr3();
ctxt->cr4 = read_cr4();
ctxt->cr8 = read_cr8();
+ disable_debug_registers();
}

void save_processor_state(void)
@@ -151,16 +153,5 @@ static void fix_processor_context(void)
load_TR_desc(); /* This does ltr */
load_LDT(&current->active_mm->context); /* This does lldt */

- /*
- * Now maybe reload the debug registers
- */
- if (current->thread.debugreg7){
- loaddebug(&current->thread, 0);
- loaddebug(&current->thread, 1);
- loaddebug(&current->thread, 2);
- loaddebug(&current->thread, 3);
- /* no 4 and 5 */
- loaddebug(&current->thread, 6);
- loaddebug(&current->thread, 7);
- }
+ load_debug_registers();
}
Index: linux-bkpt-lkml-27-rc9/arch/x86/kernel/smpboot.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/kernel/smpboot.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/kernel/smpboot.c
@@ -61,6 +61,7 @@
#include <asm/mtrr.h>
#include <asm/vmi.h>
#include <asm/genapic.h>
+#include <asm/debugreg.h>
#include <linux/mc146818rtc.h>

#include <mach_apic.h>
@@ -342,6 +343,7 @@ static void __cpuinit start_secondary(vo
setup_secondary_clock();

wmb();
+ load_debug_registers();
cpu_idle();
}

@@ -1382,6 +1384,7 @@ int __cpu_disable(void)
remove_cpu_from_maps(cpu);
unlock_vector_lock();
fixup_irqs(cpu_online_map);
+ disable_debug_registers();
return 0;
}

Index: linux-bkpt-lkml-27-rc9/include/asm-x86/debugreg.h
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/include/asm-x86/debugreg.h
+++ linux-bkpt-lkml-27-rc9/include/asm-x86/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 +69,31 @@
#define DR_LOCAL_SLOWDOWN (0x100) /* Local slow the pipeline */
#define DR_GLOBAL_SLOWDOWN (0x200) /* Global slow the pipeline */

+/*
+ * HW breakpoint additions
+ */
+#ifdef __KERNEL__
+
+#define HB_NUM 4 /* Number of hardware breakpoints */
+
+/* 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 disable_debug_registers(void)
+{
+ set_debugreg(0UL, 7);
+}
+
+/* For use by ptrace */
+unsigned long thread_get_debugreg(struct task_struct *tsk, int n);
+int thread_set_debugreg(struct task_struct *tsk, int n, unsigned long val);
+
+#endif /* __KERNEL__ */
+
#endif
Index: linux-bkpt-lkml-27-rc9/include/asm-x86/processor.h
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/include/asm-x86/processor.h
+++ linux-bkpt-lkml-27-rc9/include/asm-x86/processor.h
@@ -381,13 +381,9 @@ 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 */
+ unsigned long vdr6;
+ struct thread_hw_breakpoint *hw_breakpoint_info;
/* Fault info: */
unsigned long cr2;
unsigned long trap_no;

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