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authorMark Rutland <mark.rutland@arm.com>2014-09-29 17:15:32 +0100
committerWill Deacon <will.deacon@arm.com>2014-10-30 12:16:58 +0000
commitd39976f0fd144d1cef4830d696e2a1e6d8058dc6 (patch)
tree55678594c84b9e3df6dd6c11eada7716733824c3 /arch/arm/kernel/perf_event.c
parent52a5566e7617ce2678c2a35c7982b808cb2b53f6 (diff)
arm: perf: factor out callchain code
The ARM callchain handling code is currently bundled with the ARM PMU management code, despite the two having no dependency on each other. This bundling has the unfortunate property of making callchain handling depend on CONFIG_HW_PERF_EVENTS, even though the callchain handling could be applied to software events in the absence of PMU hardware support. This patch separates the two, placing the callchain handling in perf_callchain.c and making it depend on CONFIG_PERF_EVENTS rather than CONFIG_HW_PERF_EVENTS, enabling callchain recording on kernels built without hardware perf event support. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm/kernel/perf_event.c')
-rw-r--r--arch/arm/kernel/perf_event.c132
1 files changed, 1 insertions, 131 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 266cba46db3..ae96b986d50 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -7,21 +7,18 @@
* Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
*
* This code is based on the sparc64 perf event code, which is in turn based
- * on the x86 code. Callchain code is based on the ARM OProfile backtrace
- * code.
+ * on the x86 code.
*/
#define pr_fmt(fmt) "hw perfevents: " fmt
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
-#include <linux/uaccess.h>
#include <linux/irq.h>
#include <linux/irqdesc.h>
#include <asm/irq_regs.h>
#include <asm/pmu.h>
-#include <asm/stacktrace.h>
static int
armpmu_map_cache_event(const unsigned (*cache_map)
@@ -533,130 +530,3 @@ int armpmu_register(struct arm_pmu *armpmu, int type)
return perf_pmu_register(&armpmu->pmu, armpmu->name, type);
}
-/*
- * Callchain handling code.
- */
-
-/*
- * The registers we're interested in are at the end of the variable
- * length saved register structure. The fp points at the end of this
- * structure so the address of this struct is:
- * (struct frame_tail *)(xxx->fp)-1
- *
- * This code has been adapted from the ARM OProfile support.
- */
-struct frame_tail {
- struct frame_tail __user *fp;
- unsigned long sp;
- unsigned long lr;
-} __attribute__((packed));
-
-/*
- * Get the return address for a single stackframe and return a pointer to the
- * next frame tail.
- */
-static struct frame_tail __user *
-user_backtrace(struct frame_tail __user *tail,
- struct perf_callchain_entry *entry)
-{
- struct frame_tail buftail;
- unsigned long err;
-
- if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
- return NULL;
-
- pagefault_disable();
- err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
- pagefault_enable();
-
- if (err)
- return NULL;
-
- perf_callchain_store(entry, buftail.lr);
-
- /*
- * Frame pointers should strictly progress back up the stack
- * (towards higher addresses).
- */
- if (tail + 1 >= buftail.fp)
- return NULL;
-
- return buftail.fp - 1;
-}
-
-void
-perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
-{
- struct frame_tail __user *tail;
-
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
- /* We don't support guest os callchain now */
- return;
- }
-
- perf_callchain_store(entry, regs->ARM_pc);
-
- if (!current->mm)
- return;
-
- tail = (struct frame_tail __user *)regs->ARM_fp - 1;
-
- while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
- tail && !((unsigned long)tail & 0x3))
- tail = user_backtrace(tail, entry);
-}
-
-/*
- * Gets called by walk_stackframe() for every stackframe. This will be called
- * whist unwinding the stackframe and is like a subroutine return so we use
- * the PC.
- */
-static int
-callchain_trace(struct stackframe *fr,
- void *data)
-{
- struct perf_callchain_entry *entry = data;
- perf_callchain_store(entry, fr->pc);
- return 0;
-}
-
-void
-perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
-{
- struct stackframe fr;
-
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
- /* We don't support guest os callchain now */
- return;
- }
-
- arm_get_current_stackframe(regs, &fr);
- walk_stackframe(&fr, callchain_trace, entry);
-}
-
-unsigned long perf_instruction_pointer(struct pt_regs *regs)
-{
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
- return perf_guest_cbs->get_guest_ip();
-
- return instruction_pointer(regs);
-}
-
-unsigned long perf_misc_flags(struct pt_regs *regs)
-{
- int misc = 0;
-
- if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
- if (perf_guest_cbs->is_user_mode())
- misc |= PERF_RECORD_MISC_GUEST_USER;
- else
- misc |= PERF_RECORD_MISC_GUEST_KERNEL;
- } else {
- if (user_mode(regs))
- misc |= PERF_RECORD_MISC_USER;
- else
- misc |= PERF_RECORD_MISC_KERNEL;
- }
-
- return misc;
-}