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Commit 5aae8a53 authored by K.Prasad's avatar K.Prasad Committed by Paul Mackerras
Browse files

powerpc, hw_breakpoints: Implement hw_breakpoints for 64-bit server processors 



Implement perf-events based hw-breakpoint interfaces for PowerPC
64-bit server (Book III S) processors.  This allows access to a
given location to be used as an event that can be counted or
profiled by the perf_events subsystem.

This is done using the DABR (data breakpoint register), which can
also be used for process debugging via ptrace.  When perf_event
hw_breakpoint support is configured in, the perf_event subsystem
manages the DABR and arbitrates access to it, and ptrace then
creates a perf_event when it is requested to set a data breakpoint.

[Adopted suggestions from Paul Mackerras <paulus@samba.org> to
- emulate_step() all system-wide breakpoints and single-step only the
  per-task breakpoints
- perform arch-specific cleanup before unregistration through
  arch_unregister_hw_breakpoint()
]

Signed-off-by: default avatarK.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent f7136c51

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ config PPC 
	select GENERIC_ATOMIC64 if PPC32

	select HAVE_PERF_EVENTS

	select HAVE_REGS_AND_STACK_ACCESS_API

	select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64



config EARLY_PRINTK

	bool

arch/powerpc/include/asm/cputable.h

+4 −0
Original line number Diff line number Diff line
@@ -517,6 +517,10 @@ static inline int cpu_has_feature(unsigned long feature) 
		& feature);

}



#ifdef CONFIG_HAVE_HW_BREAKPOINT

#define HBP_NUM 1

#endif /* CONFIG_HAVE_HW_BREAKPOINT */



#endif /* !__ASSEMBLY__ */



#endif /* __KERNEL__ */

arch/powerpc/include/asm/hw_breakpoint.h

0 → 100644
+73 −0
Original line number Diff line number Diff line 
/*

 * PowerPC BookIII S hardware breakpoint definitions

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

 *

 * Copyright 2010, IBM Corporation.

 * Author: K.Prasad <prasad@linux.vnet.ibm.com>

 *

 */



#ifndef _PPC_BOOK3S_64_HW_BREAKPOINT_H

#define _PPC_BOOK3S_64_HW_BREAKPOINT_H



#ifdef	__KERNEL__

#ifdef CONFIG_HAVE_HW_BREAKPOINT



struct arch_hw_breakpoint {

	u8		len; /* length of the target data symbol */

	int		type;

	unsigned long	address;

};



#include <linux/kdebug.h>

#include <asm/reg.h>

#include <asm/system.h>



static inline int hw_breakpoint_slots(int type)

{

	return HBP_NUM;

}

struct perf_event;

struct pmu;

struct perf_sample_data;



#define HW_BREAKPOINT_ALIGN 0x7

/* Maximum permissible length of any HW Breakpoint */

#define HW_BREAKPOINT_LEN 0x8



extern int arch_bp_generic_fields(int type, int *gen_bp_type);

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);

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);

extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);



extern struct pmu perf_ops_bp;

extern void ptrace_triggered(struct perf_event *bp, int nmi,

			struct perf_sample_data *data, struct pt_regs *regs);

static inline void hw_breakpoint_disable(void)

{

	set_dabr(0);

}



#else	/* CONFIG_HAVE_HW_BREAKPOINT */

static inline void hw_breakpoint_disable(void) { }

#endif	/* CONFIG_HAVE_HW_BREAKPOINT */

#endif	/* __KERNEL__ */

#endif	/* _PPC_BOOK3S_64_HW_BREAKPOINT_H */

arch/powerpc/include/asm/processor.h

+8 −0
Original line number Diff line number Diff line
@@ -209,6 +209,14 @@ struct thread_struct { 
#ifdef CONFIG_PPC64

	unsigned long	start_tb;	/* Start purr when proc switched in */

	unsigned long	accum_tb;	/* Total accumilated purr for process */

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	struct perf_event *ptrace_bps[HBP_NUM];

	/*

	 * Helps identify source of single-step exception and subsequent

	 * hw-breakpoint enablement

	 */

	struct perf_event *last_hit_ubp;

#endif /* CONFIG_HAVE_HW_BREAKPOINT */

#endif

	unsigned long	dabr;		/* Data address breakpoint register */

#ifdef CONFIG_ALTIVEC

arch/powerpc/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ obj-y += vdso32/ 
obj-$(CONFIG_PPC64)		+= setup_64.o sys_ppc32.o \

				   signal_64.o ptrace32.o \

				   paca.o nvram_64.o firmware.o

obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o

obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_ppc970.o cpu_setup_pa6t.o

obj64-$(CONFIG_RELOCATABLE)	+= reloc_64.o

obj-$(CONFIG_PPC_BOOK3E_64)	+= exceptions-64e.o