perf: Generalize some arch callchain code

- Most archs use one callchain buffer per cpu, except x86 that needs
  to deal with NMIs. Provide a default perf_callchain_buffer()
  implementation that x86 overrides.

- Centralize all the kernel/user regs handling and invoke new arch
  handlers from there: perf_callchain_user() / perf_callchain_kernel()
  That avoid all the user_mode(), current->mm checks and so...

- Invert some parameters in perf_callchain_*() helpers: entry to the
  left, regs to the right, following the traditional (dst, src).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Borislav Petkov <bp@amd64.org>

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index a07c3b1..0e3bbdb 100644 (file)
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -3044,17 +3044,13 @@ user_backtrace(struct frame_tail *tail,
        return buftail.fp - 1;
 }
 
-static void
-perf_callchain_user(struct pt_regs *regs,
-                   struct perf_callchain_entry *entry)
+void
+perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
        struct frame_tail *tail;
 
        perf_callchain_store(entry, PERF_CONTEXT_USER);
 
-       if (!user_mode(regs))
-               regs = task_pt_regs(current);
-
        tail = (struct frame_tail *)regs->ARM_fp - 1;
 
        while (tail && !((unsigned long)tail & 0x3))
@@ -3075,9 +3071,8 @@ callchain_trace(struct stackframe *fr,
        return 0;
 }
 
-static void
-perf_callchain_kernel(struct pt_regs *regs,
-                     struct perf_callchain_entry *entry)
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
        struct stackframe fr;
 
@@ -3088,33 +3083,3 @@ perf_callchain_kernel(struct pt_regs *regs,
        fr.pc = regs->ARM_pc;
        walk_stackframe(&fr, callchain_trace, 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 (!is_user)
-               perf_callchain_kernel(regs, entry);
-
-       if (current->mm)
-               perf_callchain_user(regs, entry);
-}
-
-static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);
-
-struct perf_callchain_entry *
-perf_callchain(struct pt_regs *regs)
-{
-       struct perf_callchain_entry *entry = &__get_cpu_var(pmc_irq_entry);
-
-       entry->nr = 0;
-       perf_do_callchain(regs, entry);
-       return entry;
-}

diff --git a/arch/powerpc/kernel/perf_callchain.c b/arch/powerpc/kernel/perf_callchain.c
index a286c2e..f7a85ed 100644 (file)
--- a/arch/powerpc/kernel/perf_callchain.c
+++ b/arch/powerpc/kernel/perf_callchain.c
@@ -46,8 +46,8 @@ static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
        return 0;
 }
 
-static void perf_callchain_kernel(struct pt_regs *regs,
-                                 struct perf_callchain_entry *entry)
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
        unsigned long sp, next_sp;
        unsigned long next_ip;
@@ -221,8 +221,8 @@ static int sane_signal_64_frame(unsigned long sp)
                puc == (unsigned long) &sf->uc;
 }
 
-static void perf_callchain_user_64(struct pt_regs *regs,
-                                  struct perf_callchain_entry *entry)
+static void perf_callchain_user_64(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
 {
        unsigned long sp, next_sp;
        unsigned long next_ip;
@@ -303,8 +303,8 @@ static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
        return __get_user_inatomic(*ret, ptr);
 }
 
-static inline void perf_callchain_user_64(struct pt_regs *regs,
-                                         struct perf_callchain_entry *entry)
+static inline void perf_callchain_user_64(struct perf_callchain_entry *entry,
+                                         struct pt_regs *regs)
 {
 }
 
@@ -423,8 +423,8 @@ static unsigned int __user *signal_frame_32_regs(unsigned int sp,
        return mctx->mc_gregs;
 }
 
-static void perf_callchain_user_32(struct pt_regs *regs,
-                                  struct perf_callchain_entry *entry)
+static void perf_callchain_user_32(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
 {
        unsigned int sp, next_sp;
        unsigned int next_ip;
@@ -471,32 +471,11 @@ static void perf_callchain_user_32(struct pt_regs *regs,
        }
 }
 
-/*
- * Since we can't get PMU interrupts inside a PMU interrupt handler,
- * we don't need separate irq and nmi entries here.
- */
-static DEFINE_PER_CPU(struct perf_callchain_entry, cpu_perf_callchain);
-
-struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+void
+perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
-       struct perf_callchain_entry *entry = &__get_cpu_var(cpu_perf_callchain);
-
-       entry->nr = 0;
-
-       if (!user_mode(regs)) {
-               perf_callchain_kernel(regs, entry);
-               if (current->mm)
-                       regs = task_pt_regs(current);
-               else
-                       regs = NULL;
-       }
-
-       if (regs) {
-               if (current_is_64bit())
-                       perf_callchain_user_64(regs, entry);
-               else
-                       perf_callchain_user_32(regs, entry);
-       }
-
-       return entry;
+       if (current_is_64bit())
+               perf_callchain_user_64(entry, regs);
+       else
+               perf_callchain_user_32(entry, regs);
 }

diff --git a/arch/sh/kernel/perf_callchain.c b/arch/sh/kernel/perf_callchain.c
index 00143f3..ef076a9 100644 (file)
--- a/arch/sh/kernel/perf_callchain.c
+++ b/arch/sh/kernel/perf_callchain.c
@@ -44,44 +44,11 @@ static const struct stacktrace_ops callchain_ops = {
        .address        = callchain_address,
 };
 
-static void
-perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
        perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
        perf_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);
-
-       /*
-        * 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;
-}

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 2a95a90..460162d 100644 (file)
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -1283,14 +1283,16 @@ void __init init_hw_perf_events(void)
        register_die_notifier(&perf_event_nmi_notifier);
 }
 
-static void perf_callchain_kernel(struct pt_regs *regs,
-                                 struct perf_callchain_entry *entry)
+void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                          struct pt_regs *regs)
 {
        unsigned long ksp, fp;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
        int graph = 0;
 #endif
 
+       stack_trace_flush();
+
        perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
        perf_callchain_store(entry, regs->tpc);
 
@@ -1330,8 +1332,8 @@ static void perf_callchain_kernel(struct pt_regs *regs,
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
 }
 
-static void perf_callchain_user_64(struct pt_regs *regs,
-                                  struct perf_callchain_entry *entry)
+static void perf_callchain_user_64(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
 {
        unsigned long ufp;
 
@@ -1353,8 +1355,8 @@ static void perf_callchain_user_64(struct pt_regs *regs,
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
 }
 
-static void perf_callchain_user_32(struct pt_regs *regs,
-                                  struct perf_callchain_entry *entry)
+static void perf_callchain_user_32(struct perf_callchain_entry *entry,
+                                  struct pt_regs *regs)
 {
        unsigned long ufp;
 
@@ -1376,30 +1378,12 @@ static void perf_callchain_user_32(struct pt_regs *regs,
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
 }
 
-/* Like powerpc we can't get PMU interrupts within the PMU handler,
- * so no need for separate 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)
+void
+perf_callchain_user(struct perf_callchain_entry *entry, 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;
+       flushw_user();
+       if (test_thread_flag(TIF_32BIT))
+               perf_callchain_user_32(entry, regs);
+       else
+               perf_callchain_user_64(entry, regs);
 }

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 8af28ca..39f8421 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1571,9 +1571,7 @@ const struct pmu *hw_perf_event_init(struct perf_event *event)
  * callchain support
  */
 
-
-static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);
-static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_nmi_entry);
+static DEFINE_PER_CPU(struct perf_callchain_entry, perf_callchain_entry_nmi);
 
 
 static void
@@ -1607,8 +1605,8 @@ static const struct stacktrace_ops backtrace_ops = {
        .walk_stack             = print_context_stack_bp,
 };
 
-static void
-perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
        perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
        perf_callchain_store(entry, regs->ip);
@@ -1653,14 +1651,12 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
 }
 #endif
 
-static void
-perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
+void
+perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
        struct stack_frame frame;
        const void __user *fp;
 
-       if (!user_mode(regs))
-               regs = task_pt_regs(current);
 
        fp = (void __user *)regs->bp;
 
@@ -1687,42 +1683,17 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *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 (!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 *perf_callchain_buffer(void)
 {
-       struct perf_callchain_entry *entry;
-
        if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
                /* TODO: We don't support guest os callchain now */
                return NULL;
        }
 
        if (in_nmi())
-               entry = &__get_cpu_var(pmc_nmi_entry);
-       else
-               entry = &__get_cpu_var(pmc_irq_entry);
-
-       entry->nr = 0;
-
-       perf_do_callchain(regs, entry);
+               return &__get_cpu_var(perf_callchain_entry_nmi);
 
-       return entry;
+       return &__get_cpu_var(perf_callchain_entry);
 }
 
 unsigned long perf_instruction_pointer(struct pt_regs *regs)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3588804..4db61dd 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -976,7 +976,15 @@ extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks
 extern void perf_event_comm(struct task_struct *tsk);
 extern void perf_event_fork(struct task_struct *tsk);
 
-extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);
+/* Callchains */
+DECLARE_PER_CPU(struct perf_callchain_entry, perf_callchain_entry);
+
+extern void perf_callchain_user(struct perf_callchain_entry *entry,
+                               struct pt_regs *regs);
+extern void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                                 struct pt_regs *regs);
+extern struct perf_callchain_entry *perf_callchain_buffer(void);
+
 
 static inline void
 perf_callchain_store(struct perf_callchain_entry *entry, u64 ip)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c772a3d..02efde6 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2937,13 +2937,49 @@ void perf_event_do_pending(void)
        __perf_pending_run();
 }
 
+DEFINE_PER_CPU(struct perf_callchain_entry, perf_callchain_entry);
+
 /*
  * Callchain support -- arch specific
  */
 
-__weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+__weak struct perf_callchain_entry *perf_callchain_buffer(void)
 {
-       return NULL;
+       return &__get_cpu_var(perf_callchain_entry);
+}
+
+__weak void perf_callchain_kernel(struct perf_callchain_entry *entry,
+                                 struct pt_regs *regs)
+{
+}
+
+__weak void perf_callchain_user(struct perf_callchain_entry *entry,
+                               struct pt_regs *regs)
+{
+}
+
+static struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
+{
+       struct perf_callchain_entry *entry;
+
+       entry = perf_callchain_buffer();
+       if (!entry)
+               return NULL;
+
+       entry->nr = 0;
+
+       if (!user_mode(regs)) {
+               perf_callchain_kernel(entry, regs);
+               if (current->mm)
+                       regs = task_pt_regs(current);
+               else
+                       regs = NULL;
+       }
+
+       if (regs)
+               perf_callchain_user(entry, regs);
+
+       return entry;
 }