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3b1fff0803
We will use it to count how many addresses are in the entry->ip[] array,
excluding PERF_CONTEXT_{KERNEL,USER,etc} entries, so that we can really
return the number of entries specified by the user via the relevant
sysctl, kernel.perf_event_max_contexts, or via the per event
perf_event_attr.sample_max_stack knob.
This way we keep the perf_sample->ip_callchain->nr meaning, that is the
number of entries, be it real addresses or PERF_CONTEXT_ entries, while
honouring the max_stack knobs, i.e. the end result will be max_stack
entries if we have at least that many entries in a given stack trace.
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-s8teto51tdqvlfhefndtat9r@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
/*
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* Linux performance counter support for MIPS.
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*
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* Copyright (C) 2010 MIPS Technologies, Inc.
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* Author: Deng-Cheng Zhu
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*
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* This code is based on the implementation for ARM, which is in turn
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* based on the sparc64 perf event code and the x86 code. Performance
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* counter access is based on the MIPS Oprofile code. And the callchain
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* support references the code of MIPS stacktrace.c.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/perf_event.h>
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#include <asm/stacktrace.h>
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/* Callchain handling code. */
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/*
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* Leave userspace callchain empty for now. When we find a way to trace
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* the user stack callchains, we will add it here.
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*/
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static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
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unsigned long reg29)
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{
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unsigned long *sp = (unsigned long *)reg29;
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unsigned long addr;
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while (!kstack_end(sp)) {
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addr = *sp++;
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if (__kernel_text_address(addr)) {
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perf_callchain_store(entry, addr);
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if (entry->nr >= entry->max_stack)
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break;
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}
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}
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}
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void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
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struct pt_regs *regs)
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{
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unsigned long sp = regs->regs[29];
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#ifdef CONFIG_KALLSYMS
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unsigned long ra = regs->regs[31];
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unsigned long pc = regs->cp0_epc;
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if (raw_show_trace || !__kernel_text_address(pc)) {
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unsigned long stack_page =
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(unsigned long)task_stack_page(current);
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if (stack_page && sp >= stack_page &&
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sp <= stack_page + THREAD_SIZE - 32)
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save_raw_perf_callchain(entry, sp);
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return;
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}
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do {
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perf_callchain_store(entry, pc);
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if (entry->nr >= entry->max_stack)
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break;
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pc = unwind_stack(current, &sp, pc, &ra);
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} while (pc);
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#else
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save_raw_perf_callchain(entry, sp);
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#endif
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}
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