Messages in this thread | | | Subject | Re: [PATCH v5 16/19] tracing: probeevent: Add array type support | From | Ravi Bangoria <> | Date | Thu, 15 Mar 2018 11:18:19 +0530 |
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Hi Masami,
On 03/08/2018 02:20 PM, Masami Hiramatsu wrote: > Add array type support for probe events. > This allows user to get arraied types from memory address. > The array type syntax is > > TYPE[N] > > Where TYPE is one of types (u8/16/32/64,s8/16/32/64, > x8/16/32/64, symbol, string) and N is a fixed value less > than 64. > > The string array type is a bit different from other types. For > other base types, <base-type>[1] is equal to <base-type> > (e.g. +0(%di):x32[1] is same as +0(%di):x32.) But string[1] is not > equal to string. The string type itself represents "char array", > but string array type represents "char * array". So, for example, > +0(%di):string[1] is equal to +0(+0(%di)):string.
I was trying to test this patch. But I'm not getting proper data. Here is what I'm doing...
$ cat hello.c #include <stdio.h>
void foo1(int a[]) { printf("%d\n", a[2]); }
void foo(int a[]) { printf("%d\n", a[1]); foo1(a); }
void main() { int a[3] = {4, 5, 6}; printf("%d\n", a[0]); foo(a); }
$ gcc -g hello.c -o hello $ sudo ./perf probe -x ~/hello foo1 'a=a:x32[3]' $ sudo cat /sys/kernel/debug/tracing/uprobe_events p:probe_hello/foo1 /home/ravi/hello:0x00000000000005fc a=+96(%gpr31):x32[3]
$ sudo ./perf record -e probe_hello:foo1 ~/hello $ sudo ./perf script hello 6913 [038] 2857.704470: probe_hello:foo1: (100005fc) a={0xd69e4400,0x7fff,0x0}
I don't see proper values of the 'a'? Anything wrong with my perf commands :) ?
Thanks, Ravi
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