kallsyms_lookup_name is not returning per_cpu symbols when called.
The symbols show up when you run something with the kallsyms_iter
struct but not through the regular interface. I have looked through
the code and I am not able to determine with certainty if its designed
this way or just busted. Any help with this would be appreciated.
The following code does display the per_cpu symbols, they just don't
seem to show up when called from kallsyms_lookup_name.
struct kallsym_iter mdb_iter;
int mdb_kallsyms(char *str, int (*print)(char *s, ...))
{
register loff_t pos = 0;
register struct kallsym_iter *iter = &mdb_iter;
if (!print)
return 0;
// set to beginning of the kallsyms list
reset_iter(iter, 0);
while (1)
{
// search the kallsyms list
if (!update_iter(iter, pos++))
break;
if (!iter->name[0])
continue;
// if an exclusion search was specified, skip non-matching entries
if (str && *str && !strstr(iter->name, str))
continue;
if (iter->module_name[0])
{
if (print("%0*lx %c %s [%s]\n", (int)(2*sizeof(void*)),
iter->value, iter->type, iter->name,
iter->module_name))
return 1;
}
else
{
if (print("%0*lx %c %s\n", (int)(2*sizeof(void*)),
iter->value, iter->type, iter->name))
return 1;
}
}
return 0;
}
EXPORT_SYMBOL_GPL(mdb_kallsyms);
I tracked this down and it turns out to be a page mapping problem with
one of the sound drivers on the system trashing memory. It's a bug,
but a bug in a vendor supplied driver.
Jeff
On 11/18/15, Jeffrey Merkey <[email protected]> wrote:
> kallsyms_lookup_name is not returning per_cpu symbols when called.
> The symbols show up when you run something with the kallsyms_iter
> struct but not through the regular interface. I have looked through
> the code and I am not able to determine with certainty if its designed
> this way or just busted. Any help with this would be appreciated.
>
> The following code does display the per_cpu symbols, they just don't
> seem to show up when called from kallsyms_lookup_name.
>
>
> struct kallsym_iter mdb_iter;
> int mdb_kallsyms(char *str, int (*print)(char *s, ...))
> {
> register loff_t pos = 0;
> register struct kallsym_iter *iter = &mdb_iter;
>
> if (!print)
> return 0;
>
> // set to beginning of the kallsyms list
> reset_iter(iter, 0);
> while (1)
> {
> // search the kallsyms list
> if (!update_iter(iter, pos++))
> break;
>
> if (!iter->name[0])
> continue;
>
> // if an exclusion search was specified, skip non-matching entries
> if (str && *str && !strstr(iter->name, str))
> continue;
>
> if (iter->module_name[0])
> {
> if (print("%0*lx %c %s [%s]\n", (int)(2*sizeof(void*)),
> iter->value, iter->type, iter->name,
> iter->module_name))
> return 1;
> }
> else
> {
> if (print("%0*lx %c %s\n", (int)(2*sizeof(void*)),
> iter->value, iter->type, iter->name))
> return 1;
> }
> }
> return 0;
> }
> EXPORT_SYMBOL_GPL(mdb_kallsyms);
>
Take that back, I just reproduced it again. Seems to affect random
symbols not just per cpu. I'll research some more.
On 11/18/15, Jeffrey Merkey <[email protected]> wrote:
> I tracked this down and it turns out to be a page mapping problem with
> one of the sound drivers on the system trashing memory. It's a bug,
> but a bug in a vendor supplied driver.
>
> Jeff
>
> On 11/18/15, Jeffrey Merkey <[email protected]> wrote:
>> kallsyms_lookup_name is not returning per_cpu symbols when called.
>> The symbols show up when you run something with the kallsyms_iter
>> struct but not through the regular interface. I have looked through
>> the code and I am not able to determine with certainty if its designed
>> this way or just busted. Any help with this would be appreciated.
>>
>> The following code does display the per_cpu symbols, they just don't
>> seem to show up when called from kallsyms_lookup_name.
>>
>>
>> struct kallsym_iter mdb_iter;
>> int mdb_kallsyms(char *str, int (*print)(char *s, ...))
>> {
>> register loff_t pos = 0;
>> register struct kallsym_iter *iter = &mdb_iter;
>>
>> if (!print)
>> return 0;
>>
>> // set to beginning of the kallsyms list
>> reset_iter(iter, 0);
>> while (1)
>> {
>> // search the kallsyms list
>> if (!update_iter(iter, pos++))
>> break;
>>
>> if (!iter->name[0])
>> continue;
>>
>> // if an exclusion search was specified, skip non-matching entries
>> if (str && *str && !strstr(iter->name, str))
>> continue;
>>
>> if (iter->module_name[0])
>> {
>> if (print("%0*lx %c %s [%s]\n", (int)(2*sizeof(void*)),
>> iter->value, iter->type, iter->name,
>> iter->module_name))
>> return 1;
>> }
>> else
>> {
>> if (print("%0*lx %c %s\n", (int)(2*sizeof(void*)),
>> iter->value, iter->type, iter->name))
>> return 1;
>> }
>> }
>> return 0;
>> }
>> EXPORT_SYMBOL_GPL(mdb_kallsyms);
>>
>
Got to the bottom of this one. bug closed.
Jeff
On 11/18/15, Jeffrey Merkey <[email protected]> wrote:
> kallsyms_lookup_name is not returning per_cpu symbols when called.
> The symbols show up when you run something with the kallsyms_iter
> struct but not through the regular interface. I have looked through
> the code and I am not able to determine with certainty if its designed
> this way or just busted. Any help with this would be appreciated.
>
> The following code does display the per_cpu symbols, they just don't
> seem to show up when called from kallsyms_lookup_name.
>
>
> struct kallsym_iter mdb_iter;
> int mdb_kallsyms(char *str, int (*print)(char *s, ...))
> {
> register loff_t pos = 0;
> register struct kallsym_iter *iter = &mdb_iter;
>
> if (!print)
> return 0;
>
> // set to beginning of the kallsyms list
> reset_iter(iter, 0);
> while (1)
> {
> // search the kallsyms list
> if (!update_iter(iter, pos++))
> break;
>
> if (!iter->name[0])
> continue;
>
> // if an exclusion search was specified, skip non-matching entries
> if (str && *str && !strstr(iter->name, str))
> continue;
>
> if (iter->module_name[0])
> {
> if (print("%0*lx %c %s [%s]\n", (int)(2*sizeof(void*)),
> iter->value, iter->type, iter->name,
> iter->module_name))
> return 1;
> }
> else
> {
> if (print("%0*lx %c %s\n", (int)(2*sizeof(void*)),
> iter->value, iter->type, iter->name))
> return 1;
> }
> }
> return 0;
> }
> EXPORT_SYMBOL_GPL(mdb_kallsyms);
>