Messages in this thread | | | Subject | Re: [PATCH] tools lib traceevent: add checks for returned EVENT_ERROR type | From | Dean Nelson <> | Date | Fri, 7 Aug 2015 08:01:02 -0500 |
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On 08/07/2015 05:59 AM, Jiri Olsa wrote: > On Mon, Aug 03, 2015 at 01:08:05PM -0400, Dean Nelson wrote: >> Running the following perf-stat command on an arm64 system produces the >> following result... >> >> [root@aarch64 ~]# perf stat -e kmem:mm_page_alloc -a sleep 1 >> Warning: [kmem:mm_page_alloc] function sizeof not defined >> Warning: Error: expected type 4 but read 0 >> Segmentation fault >> [root@aarch64 ~]# > > hum, what kernel are you running on? I dont see that warning
The system is based on v4.2-rc3 and my .config has...
CONFIG_SPARSEMEM_VMEMMAP=y
which matters, as the sizeof operator is introduced through...
#define pfn_to_page __pfn_to_page
when __pfn_to_page is defined as...
#define __pfn_to_page(pfn) (vmemmap + (pfn))
which only happens when '#elif defined(CONFIG_SPARSEMEM_VMEMMAP)' is true.
Now vmemmap was redefined about a year ago by commit 08375198b01001c0e43b to be...
#define VMEMMAP_SIZE ALIGN((1UL << (VA_BITS - PAGE_SHIFT)) * sizeof(struct page), PUD_SIZE) #define VMALLOC_END (PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K) #define vmemmap ((struct page *)(VMALLOC_END + SZ_64K))
And VMEMMAP_SIZE has the sizeof operator. The ALIGN() macro introduces a typeof operator which also would be an issue if the parser had gotten that far.
This vmemmap stuff can be found in arch/arm64/include/asm/pgtable.h.
Now backing up a step or two, the pfn_to_page() macro is referenced in include/trace/events/kmem.h as the first of the 'args' passed to TP_prink()...
TRACE_EVENT(mm_page_alloc, : TP_printk("page=%p pfn=%lu order=%d migratetype=%d gfp_flags=%s", __entry->pfn != -1UL ? pfn_to_page(__entry->pfn) : NULL, __entry->pfn != -1UL ? __entry->pfn : 0, __entry->order, __entry->migratetype, show_gfp_flags(__entry->gfp_flags)) );
Hope that helps.
> on my system: > > [jolsa@krava perf]$ sudo ./perf stat -e kmem:mm_page_alloc -a sleep 1 > > Performance counter stats for 'system wide': > > 227 kmem:mm_page_alloc > > 1.000762466 seconds time elapsed > > Cc-ing Namhyung > > > jirka > >> >> The second warning message and SIGSEGV stem from the issue expressed in the >> first warning message, and are the result of ignoring the EVENT_ERROR type >> returned back through the call chain. >> >> Dealing with the first warning message is beyond the scope of this patch. But >> the second warning is addressed by this patch's first hunk. And the SIGSEGV is >> eliminated by its second hunk. >> >> Signed-off-by: Dean Nelson <dnelson@redhat.com> >> --- >> tools/lib/traceevent/event-parse.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c >> index cc25f05..72e2933 100644 >> --- a/tools/lib/traceevent/event-parse.c >> +++ b/tools/lib/traceevent/event-parse.c >> @@ -1680,6 +1680,9 @@ process_cond(struct event_format *event, struct print_arg *top, char **tok) >> type = process_arg(event, left, &token); >> >> again: >> + if (type == EVENT_ERROR) >> + goto out_free; >> + >> /* Handle other operations in the arguments */ >> if (type == EVENT_OP && strcmp(token, ":") != 0) { >> type = process_op(event, left, &token); >> @@ -1940,7 +1943,7 @@ process_op(struct event_format *event, struct print_arg *arg, char **tok) >> >> type = process_arg_token(event, right, tok, type); >> >> - if (right->type == PRINT_OP && >> + if (type != EVENT_ERROR && right->type == PRINT_OP && >> get_op_prio(arg->op.op) < get_op_prio(right->op.op)) { >> struct print_arg tmp; >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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