1/*
2 * Linux performance counter support for MIPS.
3 *
4 * Copyright (C) 2010 MIPS Technologies, Inc.
5 * Author: Deng-Cheng Zhu
6 *
7 * This code is based on the implementation for ARM, which is in turn
8 * based on the sparc64 perf event code and the x86 code. Performance
9 * counter access is based on the MIPS Oprofile code. And the callchain
10 * support references the code of MIPS stacktrace.c.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 */
16
17#include <linux/perf_event.h>
18
19#include <asm/stacktrace.h>
20
21/* Callchain handling code. */
22
23/*
24 * Leave userspace callchain empty for now. When we find a way to trace
25 * the user stack callchains, we will add it here.
26 */
27
28static void save_raw_perf_callchain(struct perf_callchain_entry *entry,
29	unsigned long reg29)
30{
31	unsigned long *sp = (unsigned long *)reg29;
32	unsigned long addr;
33
34	while (!kstack_end(sp)) {
35		addr = *sp++;
36		if (__kernel_text_address(addr)) {
37			perf_callchain_store(entry, addr);
38			if (entry->nr >= PERF_MAX_STACK_DEPTH)
39				break;
40		}
41	}
42}
43
44void perf_callchain_kernel(struct perf_callchain_entry *entry,
45		      struct pt_regs *regs)
46{
47	unsigned long sp = regs->regs[29];
48#ifdef CONFIG_KALLSYMS
49	unsigned long ra = regs->regs[31];
50	unsigned long pc = regs->cp0_epc;
51
52	if (raw_show_trace || !__kernel_text_address(pc)) {
53		unsigned long stack_page =
54			(unsigned long)task_stack_page(current);
55		if (stack_page && sp >= stack_page &&
56		    sp <= stack_page + THREAD_SIZE - 32)
57			save_raw_perf_callchain(entry, sp);
58		return;
59	}
60	do {
61		perf_callchain_store(entry, pc);
62		if (entry->nr >= PERF_MAX_STACK_DEPTH)
63			break;
64		pc = unwind_stack(current, &sp, pc, &ra);
65	} while (pc);
66#else
67	save_raw_perf_callchain(entry, sp);
68#endif
69}
70