On 29/01/14 21:14, Arnaldo Carvalho de Melo wrote:
> Em Wed, Jan 29, 2014 at 04:14:44PM +0200, Adrian Hunter escreveu:
>> perf buildid-cache does not make another
>> copy of kcore if the buildid and modules
>> match an existing copy. That does not
>
> Humm, what is the problem? Having the ref reloc symbol we can fix things
> up, no? I.e. just using map->reloc the old kcore copy should be ok to
> use, no need to replace the kcore copy in the cache. Or am I missing
> something?
The current implementation works on the basis that kcore
matches the perf data recorded. This is just a fix for that.
I am afraid it is that way because it meets my needs.
I did not think of allowing for relocation because I
need to be able to walk the code. Relocation was one
of the things I was trying to avoid.
For me making a copy of kcore is far superior because
it can be made to have the jump labels mostly the
right way around too. e.g. run a dummy perf record
while making the copy.
>
> - Arnaldo
>
>> take into account the possibility that
>> the kernel has been relocated. Extend
>> the check to check if the reference
>> relocation symbol matches too, otherwise
>> do make a copy.
>>
>> Signed-off-by: Adrian Hunter <adrian.hun...@intel.com>
>> ---
>> tools/perf/builtin-buildid-cache.c | 33 +++++++++++++++++++++++++++++----
>> 1 file changed, 29 insertions(+), 4 deletions(-)
>>
>> diff --git a/tools/perf/builtin-buildid-cache.c
>> b/tools/perf/builtin-buildid-cache.c
>> index cfede86..b22dbb1 100644
>> --- a/tools/perf/builtin-buildid-cache.c
>> +++ b/tools/perf/builtin-buildid-cache.c
>> @@ -63,11 +63,35 @@ static int build_id_cache__kcore_dir(char *dir, size_t
>> sz)
>> return 0;
>> }
>>
>> +static bool same_kallsyms_reloc(const char *from_dir, char *to_dir)
>> +{
>> + char from[PATH_MAX];
>> + char to[PATH_MAX];
>> + const char *name;
>> + u64 addr1 = 0, addr2 = 0;
>> + int i;
>> +
>> + scnprintf(from, sizeof(from), "%s/kallsyms", from_dir);
>> + scnprintf(to, sizeof(to), "%s/kallsyms", to_dir);
>> +
>> + for (i = 0; (name = ref_reloc_sym_names[i]) != NULL; i++) {
>> + addr1 = kallsyms__get_function_start(from, name);
>> + if (addr1)
>> + break;
>> + }
>> +
>> + if (name)
>> + addr2 = kallsyms__get_function_start(to, name);
>> +
>> + return addr1 == addr2;
>> +}
>> +
>> static int build_id_cache__kcore_existing(const char *from_dir, char
>> *to_dir,
>> size_t to_dir_sz)
>> {
>> char from[PATH_MAX];
>> char to[PATH_MAX];
>> + char to_subdir[PATH_MAX];
>> struct dirent *dent;
>> int ret = -1;
>> DIR *d;
>> @@ -86,10 +110,11 @@ static int build_id_cache__kcore_existing(const char
>> *from_dir, char *to_dir,
>> continue;
>> scnprintf(to, sizeof(to), "%s/%s/modules", to_dir,
>> dent->d_name);
>> - if (!compare_proc_modules(from, to)) {
>> - scnprintf(to, sizeof(to), "%s/%s", to_dir,
>> - dent->d_name);
>> - strlcpy(to_dir, to, to_dir_sz);
>> + scnprintf(to_subdir, sizeof(to_subdir), "%s/%s",
>> + to_dir, dent->d_name);
>> + if (!compare_proc_modules(from, to) &&
>> + same_kallsyms_reloc(from_dir, to_subdir)) {
>> + strlcpy(to_dir, to_subdir, to_dir_sz);
>> ret = 0;
>> break;
>> }
>> --
>> 1.7.11.7
>
>
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