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authorPaul Mundt <lethal@linux-sh.org>2009-11-05 08:20:09 +0100
committerPaul Mundt <lethal@linux-sh.org>2009-11-05 08:20:09 +0100
commit830fafecc211bef5bc6e253ab7e39c9e7560f758 (patch)
tree561181cfabc36698cc392b752b7bdc241ac8123b
parentsh: Default-enable SPU clock for SH7724. (diff)
downloadlinux-830fafecc211bef5bc6e253ab7e39c9e7560f758.tar.xz
linux-830fafecc211bef5bc6e253ab7e39c9e7560f758.zip
sh: perf events: Preliminary callchain support.
This implements preliminary support for perf callchains (at the moment only the kernel side is implemented). The actual implementation itself is just a simple wrapper around the unwinder API, which allows for callchain generation with or without the dwarf unwinder. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
-rw-r--r--arch/sh/kernel/Makefile2
-rw-r--r--arch/sh/kernel/perf_callchain.c98
2 files changed, 99 insertions, 1 deletions
diff --git a/arch/sh/kernel/Makefile b/arch/sh/kernel/Makefile
index 0a67bafce425..8edb927a1f30 100644
--- a/arch/sh/kernel/Makefile
+++ b/arch/sh/kernel/Makefile
@@ -39,7 +39,7 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_DUMP_CODE) += disassemble.o
obj-$(CONFIG_HIBERNATION) += swsusp.o
obj-$(CONFIG_DWARF_UNWINDER) += dwarf.o
-obj-$(CONFIG_PERF_EVENTS) += perf_event.o
+obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_callchain.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) += localtimer.o
diff --git a/arch/sh/kernel/perf_callchain.c b/arch/sh/kernel/perf_callchain.c
new file mode 100644
index 000000000000..24ea837eac5b
--- /dev/null
+++ b/arch/sh/kernel/perf_callchain.c
@@ -0,0 +1,98 @@
+/*
+ * Performance event callchain support - SuperH architecture code
+ *
+ * Copyright (C) 2009 Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_event.h>
+#include <linux/percpu.h>
+#include <asm/unwinder.h>
+#include <asm/ptrace.h>
+
+static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip)
+{
+ if (entry->nr < PERF_MAX_STACK_DEPTH)
+ entry->ip[entry->nr++] = ip;
+}
+
+static void callchain_warning(void *data, char *msg)
+{
+}
+
+static void
+callchain_warning_symbol(void *data, char *msg, unsigned long symbol)
+{
+}
+
+static int callchain_stack(void *data, char *name)
+{
+ return 0;
+}
+
+static void callchain_address(void *data, unsigned long addr, int reliable)
+{
+ struct perf_callchain_entry *entry = data;
+
+ if (reliable)
+ callchain_store(entry, addr);
+}
+
+static const struct stacktrace_ops callchain_ops = {
+ .warning = callchain_warning,
+ .warning_symbol = callchain_warning_symbol,
+ .stack = callchain_stack,
+ .address = callchain_address,
+};
+
+static void
+perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
+{
+ callchain_store(entry, PERF_CONTEXT_KERNEL);
+ callchain_store(entry, regs->pc);
+
+ unwind_stack(NULL, regs, NULL, &callchain_ops, entry);
+}
+
+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 == 0)
+ return;
+
+ if (is_user && current->state != TASK_RUNNING)
+ return;
+
+ /*
+ * Only the kernel side is implemented for now.
+ */
+ if (!is_user)
+ perf_callchain_kernel(regs, entry);
+}
+
+/*
+ * No need for separate IRQ and NMI entries.
+ */
+static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);
+
+struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+ struct perf_callchain_entry *entry = &__get_cpu_var(callchain);
+
+ entry->nr = 0;
+
+ perf_do_callchain(regs, entry);
+
+ return entry;
+}