We faced segmentation fault on perf top -G at very high sampling rate due to a corrupted callchain. While the root cause was not revealed (I failed to figure it out), this patch tries to protect us from the segfault on such cases.
Unified · Split
| @@ -555,6 +555,8 @@ enum perf_event_type { · 554 unmodified lines | |||
| 555 | PERF_RECORD_MAX, /* non-ABI */ | 555 | PERF_RECORD_MAX, /* non-ABI */ |
| 556 | }; | 556 | }; |
| 557 | 557 | ||
| 558 | #define PERF_MAX_STACK_DEPTH 255 | ||
| 559 | |||
| 558 | enum perf_callchain_context { | 560 | enum perf_callchain_context { |
| 559 | PERF_CONTEXT_HV = (__u64)-32, | 561 | PERF_CONTEXT_HV = (__u64)-32, |
| 560 | PERF_CONTEXT_KERNEL = (__u64)-128, | 562 | PERF_CONTEXT_KERNEL = (__u64)-128, |
| @@ -609,8 +611,6 @@ struct perf_guest_info_callbacks { · 48 unmodified lines | |||
| 609 | #include <linux/sysfs.h> | 611 | #include <linux/sysfs.h> |
| 610 | #include <asm/local.h> | 612 | #include <asm/local.h> |
| 611 | 613 | ||
| 612 | #define PERF_MAX_STACK_DEPTH 255 | ||
| 613 | |||
| 614 | struct perf_callchain_entry { | 614 | struct perf_callchain_entry { |
| 615 | __u64 nr; | 615 | __u64 nr; |
| 616 | __u64 ip[PERF_MAX_STACK_DEPTH]; | 616 | __u64 ip[PERF_MAX_STACK_DEPTH]; |
| @@ -300,6 +300,11 @@ int machine__resolve_callchain(struct machine *self, · 299 unmodified lines | |||
| 300 | 300 | ||
| 301 | callchain_cursor_reset(&callchain_cursor); | 301 | callchain_cursor_reset(&callchain_cursor); |
| 302 | 302 | ||
| 303 | if (chain->nr > PERF_MAX_STACK_DEPTH) { | ||
| 304 | pr_warning("corrupted callchain. skipping...\n"); | ||
| 305 | return 0; | ||
| 306 | } | ||
| 307 | |||
| 303 | for (i = 0; i < chain->nr; i++) { | 308 | for (i = 0; i < chain->nr; i++) { |
| 304 | u64 ip; | 309 | u64 ip; |
| 305 | struct addr_location al; | 310 | struct addr_location al; |
| @@ -318,7 +323,14 @@ int machine__resolve_callchain(struct machine *self, · 12 unmodified lines | |||
| 318 | case PERF_CONTEXT_USER: | 323 | case PERF_CONTEXT_USER: |
| 319 | cpumode = PERF_RECORD_MISC_USER; break; | 324 | cpumode = PERF_RECORD_MISC_USER; break; |
| 320 | default: | 325 | default: |
| 321 | break; | 326 | pr_debug("invalid callchain context: " |
| 327 | "%"PRId64"\n", (s64) ip); | ||
| 328 | /* | ||
| 329 | * It seems the callchain is corrupted. | ||
| 330 | * Discard all. | ||
| 331 | */ | ||
| 332 | callchain_cursor_reset(&callchain_cursor); | ||
| 333 | return 0; | ||
| 322 | } | 334 | } |
| 323 | continue; | 335 | continue; |
| 324 | } | 336 | } |