sparc64: Add perf callchain support.

Pretty straightforward, and it should be easy to add accurate
walk through of signal stack frames in userspace.

Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 119 insertions, 1 deletions

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 198fb4e79ba2..2386ac6ec956 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -1,6 +1,6 @@
 /* Performance event support for sparc64.
  *
- * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
+ * Copyright (C) 2009, 2010 David S. Miller <davem@davemloft.net>
  *
  * This code is based almost entirely upon the x86 perf event
  * code, which is:
@@ -18,11 +18,15 @@
 #include <linux/kdebug.h>
 #include <linux/mutex.h>
 
+#include <asm/stacktrace.h>
 #include <asm/cpudata.h>
+#include <asm/uaccess.h>
 #include <asm/atomic.h>
 #include <asm/nmi.h>
 #include <asm/pcr.h>
 
+#include "kstack.h"
+
 /* Sparc64 chips have two performance counters, 32-bits each, with
  * overflow interrupts generated on transition from 0xffffffff to 0.
  * The counters are accessed in one go using a 64-bit register.
@@ -1062,3 +1066,117 @@ void __init init_hw_perf_events(void)
 
         register_die_notifier(&perf_event_nmi_notifier);
 }
+
+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 perf_callchain_kernel(struct pt_regs *regs,
+                                  struct perf_callchain_entry *entry)
+{
+        unsigned long ksp, fp;
+
+        callchain_store(entry, PERF_CONTEXT_KERNEL);
+        callchain_store(entry, regs->tpc);
+
+        ksp = regs->u_regs[UREG_I6];
+        fp = ksp + STACK_BIAS;
+        do {
+                struct sparc_stackf *sf;
+                struct pt_regs *regs;
+                unsigned long pc;
+
+                if (!kstack_valid(current_thread_info(), fp))
+                        break;
+
+                sf = (struct sparc_stackf *) fp;
+                regs = (struct pt_regs *) (sf + 1);
+
+                if (kstack_is_trap_frame(current_thread_info(), regs)) {
+                        if (user_mode(regs))
+                                break;
+                        pc = regs->tpc;
+                        fp = regs->u_regs[UREG_I6] + STACK_BIAS;
+                } else {
+                        pc = sf->callers_pc;
+                        fp = (unsigned long)sf->fp + STACK_BIAS;
+                }
+                callchain_store(entry, pc);
+        } while (entry->nr < PERF_MAX_STACK_DEPTH);
+}
+
+static void perf_callchain_user_64(struct pt_regs *regs,
+                                   struct perf_callchain_entry *entry)
+{
+        unsigned long ufp;
+
+        callchain_store(entry, PERF_CONTEXT_USER);
+        callchain_store(entry, regs->tpc);
+
+        ufp = regs->u_regs[UREG_I6] + STACK_BIAS;
+        do {
+                struct sparc_stackf *usf, sf;
+                unsigned long pc;
+
+                usf = (struct sparc_stackf *) ufp;
+                if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
+                        break;
+
+                pc = sf.callers_pc;
+                ufp = (unsigned long)sf.fp + STACK_BIAS;
+                callchain_store(entry, pc);
+        } while (entry->nr < PERF_MAX_STACK_DEPTH);
+}
+
+static void perf_callchain_user_32(struct pt_regs *regs,
+                                   struct perf_callchain_entry *entry)
+{
+        unsigned long ufp;
+
+        callchain_store(entry, PERF_CONTEXT_USER);
+        callchain_store(entry, regs->tpc);
+
+        ufp = regs->u_regs[UREG_I6];
+        do {
+                struct sparc_stackf32 *usf, sf;
+                unsigned long pc;
+
+                usf = (struct sparc_stackf32 *) ufp;
+                if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
+                        break;
+
+                pc = sf.callers_pc;
+                ufp = (unsigned long)sf.fp;
+                callchain_store(entry, pc);
+        } while (entry->nr < PERF_MAX_STACK_DEPTH);
+}
+
+/* Like powerpc we can't get PMU interrupts within the PMU handler,
+ * so no need for seperate NMI and IRQ chains as on x86.
+ */
+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;
+        if (!user_mode(regs)) {
+                stack_trace_flush();
+                perf_callchain_kernel(regs, entry);
+                if (current->mm)
+                        regs = task_pt_regs(current);
+                else
+                        regs = NULL;
+        }
+        if (regs) {
+                flushw_user();
+                if (test_thread_flag(TIF_32BIT))
+                        perf_callchain_user_32(regs, entry);
+                else
+                        perf_callchain_user_64(regs, entry);
+        }
+        return entry;
+}