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Commit 4f6dbe4a authored by David S. Miller's avatar David S. Miller
Browse files

sparc64: Add perf callchain support. 



Pretty straightforward, and it should be easy to add accurate
walk through of signal stack frames in userspace.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Tested-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 0299b137

arch/sparc/kernel/perf_event.c

+119 −1
Original line number Diff line number Diff line 
/* Performance event support for sparc64.

 *

 * Copyright (C) 2009 David S. Miller <davem@davemloft.net>

 * Copyright (C) 2009, 2010 David S. Miller <davem@davemloft.net>

 *

 * This code is based almost entirely upon the x86 perf event

 * code, which is:
@@ -18,11 +18,15 @@ 
#include <linux/kdebug.h>

#include <linux/mutex.h>



#include <asm/stacktrace.h>

#include <asm/cpudata.h>

#include <asm/uaccess.h>

#include <asm/atomic.h>

#include <asm/nmi.h>

#include <asm/pcr.h>



#include "kstack.h"



/* Sparc64 chips have two performance counters, 32-bits each, with

 * overflow interrupts generated on transition from 0xffffffff to 0.

 * The counters are accessed in one go using a 64-bit register.
@@ -1062,3 +1066,117 @@ void __init init_hw_perf_events(void) 


	register_die_notifier(&perf_event_nmi_notifier);

}



static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip)

{

	if (entry->nr < PERF_MAX_STACK_DEPTH)

		entry->ip[entry->nr++] = ip;

}



static void perf_callchain_kernel(struct pt_regs *regs,

				  struct perf_callchain_entry *entry)

{

	unsigned long ksp, fp;



	callchain_store(entry, PERF_CONTEXT_KERNEL);

	callchain_store(entry, regs->tpc);



	ksp = regs->u_regs[UREG_I6];

	fp = ksp + STACK_BIAS;

	do {

		struct sparc_stackf *sf;

		struct pt_regs *regs;

		unsigned long pc;



		if (!kstack_valid(current_thread_info(), fp))

			break;



		sf = (struct sparc_stackf *) fp;

		regs = (struct pt_regs *) (sf + 1);



		if (kstack_is_trap_frame(current_thread_info(), regs)) {

			if (user_mode(regs))

				break;

			pc = regs->tpc;

			fp = regs->u_regs[UREG_I6] + STACK_BIAS;

		} else {

			pc = sf->callers_pc;

			fp = (unsigned long)sf->fp + STACK_BIAS;

		}

		callchain_store(entry, pc);

	} while (entry->nr < PERF_MAX_STACK_DEPTH);

}



static void perf_callchain_user_64(struct pt_regs *regs,

				   struct perf_callchain_entry *entry)

{

	unsigned long ufp;



	callchain_store(entry, PERF_CONTEXT_USER);

	callchain_store(entry, regs->tpc);



	ufp = regs->u_regs[UREG_I6] + STACK_BIAS;

	do {

		struct sparc_stackf *usf, sf;

		unsigned long pc;



		usf = (struct sparc_stackf *) ufp;

		if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))

			break;



		pc = sf.callers_pc;

		ufp = (unsigned long)sf.fp + STACK_BIAS;

		callchain_store(entry, pc);

	} while (entry->nr < PERF_MAX_STACK_DEPTH);

}



static void perf_callchain_user_32(struct pt_regs *regs,

				   struct perf_callchain_entry *entry)

{

	unsigned long ufp;



	callchain_store(entry, PERF_CONTEXT_USER);

	callchain_store(entry, regs->tpc);



	ufp = regs->u_regs[UREG_I6];

	do {

		struct sparc_stackf32 *usf, sf;

		unsigned long pc;



		usf = (struct sparc_stackf32 *) ufp;

		if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))

			break;



		pc = sf.callers_pc;

		ufp = (unsigned long)sf.fp;

		callchain_store(entry, pc);

	} while (entry->nr < PERF_MAX_STACK_DEPTH);

}



/* Like powerpc we can't get PMU interrupts within the PMU handler,

 * so no need for seperate NMI and IRQ chains as on x86.

 */

static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);



struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)

{

	struct perf_callchain_entry *entry = &__get_cpu_var(callchain);



	entry->nr = 0;

	if (!user_mode(regs)) {

		stack_trace_flush();

		perf_callchain_kernel(regs, entry);

		if (current->mm)

			regs = task_pt_regs(current);

		else

			regs = NULL;

	}

	if (regs) {

		flushw_user();

		if (test_thread_flag(TIF_32BIT))

			perf_callchain_user_32(regs, entry);

		else

			perf_callchain_user_64(regs, entry);

	}

	return entry;

}