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Commit 7e788d96 authored by Deng-Cheng Zhu's avatar Deng-Cheng Zhu Committed by Ralf Baechle
Browse files

MIPS: Perf-events: Add callchain support 



Adds callchain support for MIPS Perf-events. For more info on this feature,
please refer to tools/perf/Documentation/perf-report.txt and
tools/perf/design.txt.

Currently userspace callchain data is not recorded, because we do not have
a safe way to do this.

Signed-off-by: default avatarDeng-Cheng Zhu <dengcheng.zhu@gmail.com>
Acked-by: default avatarDavid Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Cc: a.p.zijlstra@chello.nl
Cc: paulus@samba.org
Cc: mingo@elte.hu
Cc: acme@redhat.com
Cc: jamie.iles@picochip.com
Cc: matt@console-pimps.org
Patchwork: https://patchwork.linux-mips.org/patch/1690/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 14f70012

arch/mips/kernel/perf_event.c

+107 −1
Original line number Diff line number Diff line
@@ -6,7 +6,8 @@ 
 *

 * This code is based on the implementation for ARM, which is in turn

 * based on the sparc64 perf event code and the x86 code. Performance

 * counter access is based on the MIPS Oprofile code.

 * counter access is based on the MIPS Oprofile code. And the callchain

 * support references the code of MIPS stacktrace.c.

 *

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

 * it under the terms of the GNU General Public License version 2 as
@@ -486,3 +487,108 @@ handle_associated_event(struct cpu_hw_events *cpuc, 
	if (perf_event_overflow(event, 0, data, regs))

		mipspmu->disable_event(idx);

}



/* Callchain handling code. */

static inline void

callchain_store(struct perf_callchain_entry *entry,

		u64 ip)

{

	if (entry->nr < PERF_MAX_STACK_DEPTH)

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

}



/*

 * Leave userspace callchain empty for now. When we find a way to trace

 * the user stack callchains, we add here.

 */

static void

perf_callchain_user(struct pt_regs *regs,

		    struct perf_callchain_entry *entry)

{

}



static void save_raw_perf_callchain(struct perf_callchain_entry *entry,

	unsigned long reg29)

{

	unsigned long *sp = (unsigned long *)reg29;

	unsigned long addr;



	while (!kstack_end(sp)) {

		addr = *sp++;

		if (__kernel_text_address(addr)) {

			callchain_store(entry, addr);

			if (entry->nr >= PERF_MAX_STACK_DEPTH)

				break;

		}

	}

}



static void

perf_callchain_kernel(struct pt_regs *regs,

		      struct perf_callchain_entry *entry)

{

	unsigned long sp = regs->regs[29];

#ifdef CONFIG_KALLSYMS

	unsigned long ra = regs->regs[31];

	unsigned long pc = regs->cp0_epc;



	callchain_store(entry, PERF_CONTEXT_KERNEL);

	if (raw_show_trace || !__kernel_text_address(pc)) {

		unsigned long stack_page =

			(unsigned long)task_stack_page(current);

		if (stack_page && sp >= stack_page &&

		    sp <= stack_page + THREAD_SIZE - 32)

			save_raw_perf_callchain(entry, sp);

		return;

	}

	do {

		callchain_store(entry, pc);

		if (entry->nr >= PERF_MAX_STACK_DEPTH)

			break;

		pc = unwind_stack(current, &sp, pc, &ra);

	} while (pc);

#else

	callchain_store(entry, PERF_CONTEXT_KERNEL);

	save_raw_perf_callchain(entry, sp);

#endif

}



static void

perf_do_callchain(struct pt_regs *regs,

		  struct perf_callchain_entry *entry)

{

	int is_user;



	if (!regs)

		return;



	is_user = user_mode(regs);



	if (!current || !current->pid)

		return;



	if (is_user && current->state != TASK_RUNNING)

		return;



	if (!is_user) {

		perf_callchain_kernel(regs, entry);

		if (current->mm)

			regs = task_pt_regs(current);

		else

			regs = NULL;

	}

	if (regs)

		perf_callchain_user(regs, entry);

}



static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);



struct perf_callchain_entry *

perf_callchain(struct pt_regs *regs)

{

	struct perf_callchain_entry *entry = &__get_cpu_var(pmc_irq_entry);



	entry->nr = 0;

	perf_do_callchain(regs, entry);

	return entry;

}