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perf core: Add a 'nr' field to perf_event_callchain_context
We will use it to count how many addresses are in the entry->ip[] array, excluding PERF_CONTEXT_{KERNEL,USER,etc} entries, so that we can really return the number of entries specified by the user via the relevant sysctl, kernel.perf_event_max_contexts, or via the per event perf_event_attr.sample_max_stack knob. This way we keep the perf_sample->ip_callchain->nr meaning, that is the number of entries, be it real addresses or PERF_CONTEXT_ entries, while honouring the max_stack knobs, i.e. the end result will be max_stack entries if we have at least that many entries in a given stack trace. Cc: David Ahern <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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9 files changed

+18
-17
lines changed

9 files changed

+18
-17
lines changed

‎arch/arm/kernel/perf_callchain.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -75,7 +75,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
7575

7676
tail = (struct frame_tail __user *)regs->ARM_fp - 1;
7777

78-
while ((entry->entry->nr < entry->max_stack) &&
78+
while ((entry->nr < entry->max_stack) &&
7979
tail && !((unsigned long)tail & 0x3))
8080
tail = user_backtrace(tail, entry);
8181
}

‎arch/arm64/kernel/perf_callchain.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -122,7 +122,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
122122

123123
tail = (struct frame_tail __user *)regs->regs[29];
124124

125-
while (entry->entry->nr < entry->max_stack &&
125+
while (entry->nr < entry->max_stack &&
126126
tail && !((unsigned long)tail & 0xf))
127127
tail = user_backtrace(tail, entry);
128128
} else {
@@ -132,7 +132,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
132132

133133
tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;
134134

135-
while ((entry->entry->nr < entry->max_stack) &&
135+
while ((entry->nr < entry->max_stack) &&
136136
tail && !((unsigned long)tail & 0x3))
137137
tail = compat_user_backtrace(tail, entry);
138138
#endif

‎arch/metag/kernel/perf_callchain.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -65,7 +65,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
6565

6666
--frame;
6767

68-
while ((entry->entry->nr < entry->max_stack) && frame)
68+
while ((entry->nr < entry->max_stack) && frame)
6969
frame = user_backtrace(frame, entry);
7070
}
7171

‎arch/mips/kernel/perf_event.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -35,7 +35,7 @@ static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
3535
addr = *sp++;
3636
if (__kernel_text_address(addr)) {
3737
perf_callchain_store(entry, addr);
38-
if (entry->entry->nr >= entry->max_stack)
38+
if (entry->nr >= entry->max_stack)
3939
break;
4040
}
4141
}
@@ -59,7 +59,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
5959
}
6060
do {
6161
perf_callchain_store(entry, pc);
62-
if (entry->entry->nr >= entry->max_stack)
62+
if (entry->nr >= entry->max_stack)
6363
break;
6464
pc = unwind_stack(current, &sp, pc, &ra);
6565
} while (pc);

‎arch/powerpc/perf/callchain.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -247,7 +247,7 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
247247
sp = regs->gpr[1];
248248
perf_callchain_store(entry, next_ip);
249249

250-
while (entry->entry->nr < entry->max_stack) {
250+
while (entry->nr < entry->max_stack) {
251251
fp = (unsigned long __user *) sp;
252252
if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
253253
return;
@@ -453,7 +453,7 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
453453
sp = regs->gpr[1];
454454
perf_callchain_store(entry, next_ip);
455455

456-
while (entry->entry->nr < entry->max_stack) {
456+
while (entry->nr < entry->max_stack) {
457457
fp = (unsigned int __user *) (unsigned long) sp;
458458
if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
459459
return;

‎arch/sparc/kernel/perf_event.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1756,7 +1756,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
17561756
}
17571757
}
17581758
#endif
1759-
} while (entry->entry->nr < entry->max_stack);
1759+
} while (entry->nr < entry->max_stack);
17601760
}
17611761

17621762
static inline int
@@ -1790,7 +1790,7 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
17901790
pc = sf.callers_pc;
17911791
ufp = (unsigned long)sf.fp + STACK_BIAS;
17921792
perf_callchain_store(entry, pc);
1793-
} while (entry->entry->nr < entry->max_stack);
1793+
} while (entry->nr < entry->max_stack);
17941794
}
17951795

17961796
static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
@@ -1822,7 +1822,7 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
18221822
ufp = (unsigned long)sf.fp;
18231823
}
18241824
perf_callchain_store(entry, pc);
1825-
} while (entry->entry->nr < entry->max_stack);
1825+
} while (entry->nr < entry->max_stack);
18261826
}
18271827

18281828
void

‎arch/x86/events/core.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2283,7 +2283,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
22832283

22842284
fp = compat_ptr(ss_base + regs->bp);
22852285
pagefault_disable();
2286-
while (entry->entry->nr < entry->max_stack) {
2286+
while (entry->nr < entry->max_stack) {
22872287
unsigned long bytes;
22882288
frame.next_frame = 0;
22892289
frame.return_address = 0;
@@ -2343,7 +2343,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
23432343
return;
23442344

23452345
pagefault_disable();
2346-
while (entry->entry->nr < entry->max_stack) {
2346+
while (entry->nr < entry->max_stack) {
23472347
unsigned long bytes;
23482348
frame.next_frame = NULL;
23492349
frame.return_address = 0;

‎include/linux/perf_event.h

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -64,6 +64,7 @@ struct perf_callchain_entry {
6464
struct perf_callchain_entry_ctx {
6565
struct perf_callchain_entry *entry;
6666
u32 max_stack;
67+
u32 nr;
6768
};
6869

6970
struct perf_raw_record {
@@ -1080,9 +1081,10 @@ extern int sysctl_perf_event_max_stack;
10801081

10811082
static inline int perf_callchain_store(struct perf_callchain_entry_ctx *ctx, u64 ip)
10821083
{
1083-
struct perf_callchain_entry *entry = ctx->entry;
1084-
if (entry->nr < ctx->max_stack) {
1084+
if (ctx->nr < ctx->max_stack) {
1085+
struct perf_callchain_entry *entry = ctx->entry;
10851086
entry->ip[entry->nr++] = ip;
1087+
++ctx->nr;
10861088
return 0;
10871089
} else {
10881090
return -1; /* no more room, stop walking the stack */

‎kernel/events/callchain.c

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -196,8 +196,7 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
196196

197197
ctx.entry = entry;
198198
ctx.max_stack = max_stack;
199-
200-
entry->nr = init_nr;
199+
ctx.nr = entry->nr = init_nr;
201200

202201
if (kernel && !user_mode(regs)) {
203202
if (add_mark)

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