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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>
137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
/*
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* ARM callchain support
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*
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* Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
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* Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
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*
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* This code is based on the ARM OProfile backtrace code.
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*/
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#include <linux/perf_event.h>
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#include <linux/uaccess.h>
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#include <asm/stacktrace.h>
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/*
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* The registers we're interested in are at the end of the variable
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* length saved register structure. The fp points at the end of this
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* structure so the address of this struct is:
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* (struct frame_tail *)(xxx->fp)-1
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*
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* This code has been adapted from the ARM OProfile support.
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*/
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struct frame_tail {
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struct frame_tail __user *fp;
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unsigned long sp;
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unsigned long lr;
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} __attribute__((packed));
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/*
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* Get the return address for a single stackframe and return a pointer to the
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* next frame tail.
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*/
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static struct frame_tail __user *
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user_backtrace(struct frame_tail __user *tail,
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struct perf_callchain_entry_ctx *entry)
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{
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struct frame_tail buftail;
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unsigned long err;
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if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
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return NULL;
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pagefault_disable();
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err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
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pagefault_enable();
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if (err)
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return NULL;
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perf_callchain_store(entry, buftail.lr);
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/*
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* Frame pointers should strictly progress back up the stack
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* (towards higher addresses).
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*/
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if (tail + 1 >= buftail.fp)
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return NULL;
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return buftail.fp - 1;
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}
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void
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perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
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{
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struct frame_tail __user *tail;
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
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/* We don't support guest os callchain now */
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return;
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}
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perf_callchain_store(entry, regs->ARM_pc);
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if (!current->mm)
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return;
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tail = (struct frame_tail __user *)regs->ARM_fp - 1;
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while ((entry->nr < entry->max_stack) &&
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tail && !((unsigned long)tail & 0x3))
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tail = user_backtrace(tail, entry);
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}
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/*
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* Gets called by walk_stackframe() for every stackframe. This will be called
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* whist unwinding the stackframe and is like a subroutine return so we use
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* the PC.
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*/
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static int
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callchain_trace(struct stackframe *fr,
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void *data)
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{
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struct perf_callchain_entry_ctx *entry = data;
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perf_callchain_store(entry, fr->pc);
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return 0;
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}
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void
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perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
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{
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struct stackframe fr;
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
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/* We don't support guest os callchain now */
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return;
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}
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arm_get_current_stackframe(regs, &fr);
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walk_stackframe(&fr, callchain_trace, entry);
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}
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unsigned long perf_instruction_pointer(struct pt_regs *regs)
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{
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
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return perf_guest_cbs->get_guest_ip();
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return instruction_pointer(regs);
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}
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unsigned long perf_misc_flags(struct pt_regs *regs)
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{
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int misc = 0;
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if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
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if (perf_guest_cbs->is_user_mode())
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misc |= PERF_RECORD_MISC_GUEST_USER;
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else
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misc |= PERF_RECORD_MISC_GUEST_KERNEL;
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} else {
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if (user_mode(regs))
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misc |= PERF_RECORD_MISC_USER;
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else
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misc |= PERF_RECORD_MISC_KERNEL;
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}
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return misc;
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}
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