perf: Drop the skip argument from perf_arch_fetch_regs_caller

Drop this argument now that we always want to rewind only to the
state of the first caller.
It means frame pointers are not necessary anymore to reliably get
the source of an event. But this also means we need this helper
to be a macro now, as an inline function is not an option since
we need to know when to provide a default implentation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/arch/powerpc/include/asm/perf_event.h b/arch/powerpc/include/asm/perf_event.h
index e6d4ce69b126eef07a463fc144ef2020ed53ad05..5c16b891d501f8f3943a10311d1020da608843d1 100644 (file)
--- a/arch/powerpc/include/asm/perf_event.h
+++ b/arch/powerpc/include/asm/perf_event.h
@@ -21,3 +21,15 @@
 #ifdef CONFIG_FSL_EMB_PERF_EVENT
 #include <asm/perf_event_fsl_emb.h>
 #endif
+
+#ifdef CONFIG_PERF_EVENTS
+#include <asm/ptrace.h>
+#include <asm/reg.h>
+
+#define perf_arch_fetch_caller_regs(regs, __ip)                        \
+       do {                                                    \
+               (regs)->nip = __ip;                             \
+               (regs)->gpr[1] = *(unsigned long *)__get_SP();  \
+               asm volatile("mfmsr %0" : "=r" ((regs)->msr));  \
+       } while (0)
+#endif

diff --git a/arch/powerpc/kernel/misc.S b/arch/powerpc/kernel/misc.S
index 22e507c8a5566d1f4dfcfe9db67482e3c0e83e35..2d29752cbe169ea9398fbd1381cd9eff64ec28c8 100644 (file)
--- a/arch/powerpc/kernel/misc.S
+++ b/arch/powerpc/kernel/misc.S
@@ -127,29 +127,3 @@ _GLOBAL(__setup_cpu_power7)
 _GLOBAL(__restore_cpu_power7)
        /* place holder */
        blr
-
-/*
- * Get a minimal set of registers for our caller's nth caller.
- * r3 = regs pointer, r5 = n.
- *
- * We only get R1 (stack pointer), NIP (next instruction pointer)
- * and LR (link register).  These are all we can get in the
- * general case without doing complicated stack unwinding, but
- * fortunately they are enough to do a stack backtrace, which
- * is all we need them for.
- */
-_GLOBAL(perf_arch_fetch_caller_regs)
-       mr      r6,r1
-       cmpwi   r5,0
-       mflr    r4
-       ble     2f
-       mtctr   r5
-1:     PPC_LL  r6,0(r6)
-       bdnz    1b
-       PPC_LL  r4,PPC_LR_STKOFF(r6)
-2:     PPC_LL  r7,0(r6)
-       PPC_LL  r7,PPC_LR_STKOFF(r7)
-       PPC_STL r6,GPR1-STACK_FRAME_OVERHEAD(r3)
-       PPC_STL r4,_NIP-STACK_FRAME_OVERHEAD(r3)
-       PPC_STL r7,_LINK-STACK_FRAME_OVERHEAD(r3)
-       blr

diff --git a/arch/sparc/include/asm/perf_event.h b/arch/sparc/include/asm/perf_event.h
index 7e2669894ce8346152ba1910e4122f954dd7a1a2..74c4e0cd889c700a0a901937bd716366fb882c10 100644 (file)
--- a/arch/sparc/include/asm/perf_event.h
+++ b/arch/sparc/include/asm/perf_event.h
@@ -6,7 +6,15 @@ extern void set_perf_event_pending(void);
 #define        PERF_EVENT_INDEX_OFFSET 0
 
 #ifdef CONFIG_PERF_EVENTS
+#include <asm/ptrace.h>
+
 extern void init_hw_perf_events(void);
+
+extern void
+__perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip);
+
+#define perf_arch_fetch_caller_regs(pt_regs, ip)       \
+       __perf_arch_fetch_caller_regs(pt_regs, ip, 1);
 #else
 static inline void init_hw_perf_events(void)   { }
 #endif

diff --git a/arch/sparc/kernel/helpers.S b/arch/sparc/kernel/helpers.S
index 92090cc9e82937a2daf6730dca89668ce9e04869..682fee06a16b044e28275935f45fba73accee3a5 100644 (file)
--- a/arch/sparc/kernel/helpers.S
+++ b/arch/sparc/kernel/helpers.S
@@ -47,9 +47,9 @@ stack_trace_flush:
        .size           stack_trace_flush,.-stack_trace_flush
 
 #ifdef CONFIG_PERF_EVENTS
-       .globl          perf_arch_fetch_caller_regs
-       .type           perf_arch_fetch_caller_regs,#function
-perf_arch_fetch_caller_regs:
+       .globl          __perf_arch_fetch_caller_regs
+       .type           __perf_arch_fetch_caller_regs,#function
+__perf_arch_fetch_caller_regs:
        /* We always read the %pstate into %o5 since we will use
         * that to construct a fake %tstate to store into the regs.
         */

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 254883d0c7e088424ed983154613b4ad889435e1..02de29830ffef4db9b93f3c3b709f14f1ecacd95 100644 (file)
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -140,6 +140,19 @@ extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
 extern unsigned long perf_misc_flags(struct pt_regs *regs);
 #define perf_misc_flags(regs)  perf_misc_flags(regs)
 
+#include <asm/stacktrace.h>
+
+/*
+ * We abuse bit 3 from flags to pass exact information, see perf_misc_flags
+ * and the comment with PERF_EFLAGS_EXACT.
+ */
+#define perf_arch_fetch_caller_regs(regs, __ip)                {       \
+       (regs)->ip = (__ip);                                    \
+       (regs)->bp = caller_frame_pointer();                    \
+       (regs)->cs = __KERNEL_CS;                               \
+       regs->flags = 0;                                        \
+}
+
 #else
 static inline void init_hw_perf_events(void)           { }
 static inline void perf_events_lapic_init(void)        { }

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index a957463d3c7ac126709f0b53366ad3def2ee588b..2b16a2ad23dc6b9647028c0808f8f45b094e74ac 100644 (file)
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -78,17 +78,14 @@ struct stack_frame_ia32 {
     u32 return_address;
 };
 
-static inline unsigned long rewind_frame_pointer(int n)
+static inline unsigned long caller_frame_pointer(void)
 {
        struct stack_frame *frame;
 
        get_bp(frame);
 
 #ifdef CONFIG_FRAME_POINTER
-       while (n--) {
-               if (probe_kernel_address(&frame->next_frame, frame))
-                       break;
-       }
+       frame = frame->next_frame;
 #endif
 
        return (unsigned long)frame;

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 9632fb61e8f9d80c20e0ec94ddb89d511b5a0275..2c075fe573d0f9605e51a93bf5f58dff9542dbda 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1706,22 +1706,6 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
        return entry;
 }
 
-void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip)
-{
-       regs->ip = ip;
-       /*
-        * perf_arch_fetch_caller_regs adds another call, we need to increment
-        * the skip level
-        */
-       regs->bp = rewind_frame_pointer(skip + 1);
-       regs->cs = __KERNEL_CS;
-       /*
-        * We abuse bit 3 to pass exact information, see perf_misc_flags
-        * and the comment with PERF_EFLAGS_EXACT.
-        */
-       regs->flags = 0;
-}
-
 unsigned long perf_instruction_pointer(struct pt_regs *regs)
 {
        unsigned long ip;

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index fb6c91eac7e3eb7cef23b2be992a0ed6eece85a0..bea785cef493a51808260157e7db243d1b73ae64 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -905,8 +905,10 @@ extern atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
 
 extern void __perf_sw_event(u32, u64, int, struct pt_regs *, u64);
 
-extern void
-perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip);
+#ifndef perf_arch_fetch_caller_regs
+static inline void
+perf_arch_fetch_caller_regs(struct regs *regs, unsigned long ip) { }
+#endif
 
 /*
  * Take a snapshot of the regs. Skip ip and frame pointer to
@@ -916,31 +918,11 @@ perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip);
  * - bp for callchains
  * - eflags, for future purposes, just in case
  */
-static inline void perf_fetch_caller_regs(struct pt_regs *regs, int skip)
+static inline void perf_fetch_caller_regs(struct pt_regs *regs)
 {
-       unsigned long ip;
-
        memset(regs, 0, sizeof(*regs));
 
-       switch (skip) {
-       case 1 :
-               ip = CALLER_ADDR0;
-               break;
-       case 2 :
-               ip = CALLER_ADDR1;
-               break;
-       case 3 :
-               ip = CALLER_ADDR2;
-               break;
-       case 4:
-               ip = CALLER_ADDR3;
-               break;
-       /* No need to support further for now */
-       default:
-               ip = 0;
-       }
-
-       return perf_arch_fetch_caller_regs(regs, ip, skip);
+       perf_arch_fetch_caller_regs(regs, CALLER_ADDR0);
 }
 
 static inline void
@@ -950,7 +932,7 @@ perf_sw_event(u32 event_id, u64 nr, int nmi, struct pt_regs *regs, u64 addr)
                struct pt_regs hot_regs;
 
                if (!regs) {
-                       perf_fetch_caller_regs(&hot_regs, 1);
+                       perf_fetch_caller_regs(&hot_regs);
                        regs = &hot_regs;
                }
                __perf_sw_event(event_id, nr, nmi, regs, addr);

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 3d685d1f2a03f0099f159ac96eb648eed107a0a7..8ee8b6e6b25ed7a91791b694dab3fae73d8fa1da 100644 (file)
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -705,7 +705,7 @@ perf_trace_##call(void *__data, proto)                                      \
        int __data_size;                                                \
        int rctx;                                                       \
                                                                        \
-       perf_fetch_caller_regs(&__regs, 1);                             \
+       perf_fetch_caller_regs(&__regs);                                \
                                                                        \
        __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
        __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index e099650cd249a7fb728e00f409b9557d598ceb8f..9ae4dbcdf4699b6f71167b4070aeb00ef13cf98a 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2851,11 +2851,6 @@ __weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
        return NULL;
 }
 
-__weak
-void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int skip)
-{
-}
-
 
 /*
  * We assume there is only KVM supporting the callbacks.

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index cb6f365016e48f0c7f7848cbaebb39d45fb80c45..21db1d3a48d072ed7978a216689f0fee6f5cc6d6 100644 (file)
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -9,8 +9,6 @@
 #include <linux/kprobes.h>
 #include "trace.h"
 
-EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
-
 static char *perf_trace_buf[4];
 
 /*