ARM: 6357/1: hw-breakpoint: add new ptrace requests for hw-breakpoint interaction

For debuggers to take advantage of the hw-breakpoint framework in the kernel,
it is necessary to expose the API calls via a ptrace interface.

This patch exposes the hardware breakpoints framework as a collection of
virtual registers, accesible using PTRACE_SETHBPREGS and PTRACE_GETHBPREGS
requests. The breakpoints are stored in the debug_info struct of the running
thread.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: S. Karthikeyan <informkarthik@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 17 insertions, 1 deletions

diff --git a/arch/arm/include/asm/hw_breakpoint.h b/arch/arm/include/asm/hw_breakpoint.h
index 33048c700caa..4d8ae9d67abe 100644
--- a/arch/arm/include/asm/hw_breakpoint.h
+++ b/arch/arm/include/asm/hw_breakpoint.h
@@ -2,6 +2,11 @@
 #define _ARM_HW_BREAKPOINT_H
 
 #ifdef __KERNEL__
+
+struct task_struct;
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+
 struct arch_hw_breakpoint_ctrl {
                 u32 __reserved  : 9,
                 mismatch        : 1,
@@ -102,7 +107,6 @@ static inline void decode_ctrl_reg(u32 reg,
 struct notifier_block;
 struct perf_event;
 struct pmu;
-struct task_struct;
 
 extern struct pmu perf_ops_bp;
 extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
@@ -111,13 +115,19 @@ extern int arch_check_bp_in_kernelspace(struct perf_event *bp);
 extern int arch_validate_hwbkpt_settings(struct perf_event *bp);
 extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
                                            unsigned long val, void *data);
+
 extern u8 arch_get_debug_arch(void);
 extern u8 arch_get_max_wp_len(void);
+extern void clear_ptrace_hw_breakpoint(struct task_struct *tsk);
 
 int arch_install_hw_breakpoint(struct perf_event *bp);
 void arch_uninstall_hw_breakpoint(struct perf_event *bp);
 void hw_breakpoint_pmu_read(struct perf_event *bp);
 int hw_breakpoint_slots(int type);
 
+#else
+static inline void clear_ptrace_hw_breakpoint(struct task_struct *tsk) {}
+
+#endif  /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif  /* __KERNEL__ */
 #endif  /* _ARM_HW_BREAKPOINT_H */
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index 7bed3daf83b8..67357baaeeeb 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -19,6 +19,7 @@
 
 #ifdef __KERNEL__
 
+#include <asm/hw_breakpoint.h>
 #include <asm/ptrace.h>
 #include <asm/types.h>
 
@@ -41,6 +42,9 @@ struct debug_entry {
 struct debug_info {
         int                     nsaved;
         struct debug_entry      bp[2];
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+        struct perf_event       *hbp[ARM_MAX_HBP_SLOTS];
+#endif
 };
 
 struct thread_struct {
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 7ce15eb15f72..783d50f32618 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -29,6 +29,8 @@
 #define PTRACE_SETCRUNCHREGS    26
 #define PTRACE_GETVFPREGS       27
 #define PTRACE_SETVFPREGS       28
+#define PTRACE_GETHBPREGS       29
+#define PTRACE_SETHBPREGS       30
 
 /*
  * PSR bits