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Subject[RFC PATCH 3/6] perf: Generalize some arch callchain code
Date
- 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 (src, dst).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Borislav Petkov <bp@amd64.org>
---
arch/arm/kernel/perf_event.c | 43 +++---------------------------
arch/powerpc/kernel/perf_callchain.c | 49 +++++++++------------------------
arch/sh/kernel/perf_callchain.c | 37 +------------------------
arch/sparc/kernel/perf_event.c | 46 ++++++++++---------------------
arch/x86/kernel/cpu/perf_event.c | 45 +++++-------------------------
include/linux/perf_event.h | 10 ++++++-
kernel/perf_event.c | 40 ++++++++++++++++++++++++++-
7 files changed, 90 insertions(+), 180 deletions(-)
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index a07c3b1..0e3bbdb 100644
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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;
}


--
1.6.2.3


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