perf_counter: x86: callchain support

[linux-block.git] / arch / x86 / kernel / cpu / perf_counter.c

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index b8885ccd8049e3220c6ee3be8695b21d2ebf28fb..e16dfafc6d72e0340f6a48c7b466cfa0fb23f7dd 100644 (file)
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -16,8 +16,10 @@
 #include <linux/module.h>
 #include <linux/kdebug.h>
 #include <linux/sched.h>
+#include <linux/uaccess.h>
 
 #include <asm/apic.h>
+#include <asm/stacktrace.h>
 
 static bool perf_counters_initialized __read_mostly;
 
@@ -958,3 +960,155 @@ hw_perf_counter_init(struct perf_counter *counter)
 
        return &x86_perf_counter_ops;
 }
+
+/*
+ * callchain support
+ */
+
+static inline
+void callchain_store(struct perf_callchain_entry *entry, unsigned long ip)
+{
+       if (entry->nr < MAX_STACK_DEPTH)
+               entry->ip[entry->nr++] = ip;
+}
+
+static DEFINE_PER_CPU(struct perf_callchain_entry, irq_entry);
+static DEFINE_PER_CPU(struct perf_callchain_entry, nmi_entry);
+
+
+static void
+backtrace_warning_symbol(void *data, char *msg, unsigned long symbol)
+{
+       /* Ignore warnings */
+}
+
+static void backtrace_warning(void *data, char *msg)
+{
+       /* Ignore warnings */
+}
+
+static int backtrace_stack(void *data, char *name)
+{
+       /* Don't bother with IRQ stacks for now */
+       return -1;
+}
+
+static void backtrace_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 backtrace_ops = {
+       .warning                = backtrace_warning,
+       .warning_symbol         = backtrace_warning_symbol,
+       .stack                  = backtrace_stack,
+       .address                = backtrace_address,
+};
+
+static void
+perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
+{
+       unsigned long bp;
+       char *stack;
+
+       callchain_store(entry, instruction_pointer(regs));
+
+       stack = ((char *)regs + sizeof(struct pt_regs));
+#ifdef CONFIG_FRAME_POINTER
+       bp = frame_pointer(regs);
+#else
+       bp = 0;
+#endif
+
+       dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, entry);
+}
+
+
+struct stack_frame {
+       const void __user       *next_fp;
+       unsigned long           return_address;
+};
+
+static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
+{
+       int ret;
+
+       if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
+               return 0;
+
+       ret = 1;
+       pagefault_disable();
+       if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
+               ret = 0;
+       pagefault_enable();
+
+       return ret;
+}
+
+static void
+perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
+{
+       struct stack_frame frame;
+       const void __user *fp;
+
+       regs = (struct pt_regs *)current->thread.sp0 - 1;
+       fp   = (void __user *)regs->bp;
+
+       callchain_store(entry, regs->ip);
+
+       while (entry->nr < MAX_STACK_DEPTH) {
+               frame.next_fp        = NULL;
+               frame.return_address = 0;
+
+               if (!copy_stack_frame(fp, &frame))
+                       break;
+
+               if ((unsigned long)fp < user_stack_pointer(regs))
+                       break;
+
+               callchain_store(entry, frame.return_address);
+               fp = frame.next_fp;
+       }
+}
+
+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;
+
+       if (!is_user)
+               perf_callchain_kernel(regs, entry);
+
+       if (current->mm)
+               perf_callchain_user(regs, entry);
+}
+
+struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+       struct perf_callchain_entry *entry;
+
+       if (in_nmi())
+               entry = &__get_cpu_var(nmi_entry);
+       else
+               entry = &__get_cpu_var(irq_entry);
+
+       entry->nr = 0;
+
+       perf_do_callchain(regs, entry);
+
+       return entry;
+}