On Sun, Oct 9, 2016 at 10:15 AM, Joel Fernandes <joe...@google.com> wrote:
> On Fri, Oct 7, 2016 at 10:28 PM, Joel Fernandes <joe...@google.com> wrote:
>> If FTRACE_PER_CPU flag is passed to ramoops pdata, split the space into
>> multiple zones depending on the number of CPUs.
>>
>> This speeds up the performance of function tracing by about 280% in my tests
>> as
>> we avoid the locking. The trade off being lesser space available per CPU.
>> Let
>> the ramoops user decide which option they want based on pdata flag.
>>
>> Signed-off-by: Joel Fernandes <joe...@google.com>
>> ---
>> fs/pstore/ram.c | 70
>> +++++++++++++++++++++++++++++++++++-----------
>> include/linux/pstore_ram.h | 3 ++
>> 2 files changed, 56 insertions(+), 17 deletions(-)
>>
>> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> [..]
>> @@ -391,14 +418,21 @@ static void ramoops_free_przs(struct ramoops_context
>> *cxt)
>> {
>> int i;
>>
>> - if (!cxt->przs)
>> - return;
>> + /* Free dump PRZs */
>> + if (cxt->przs) {
>> + for (i = 0; i < cxt->max_dump_cnt; i++)
>> + persistent_ram_free(cxt->przs[i]);
>>
>> - for (i = 0; i < cxt->max_dump_cnt; i++)
>> - persistent_ram_free(cxt->przs[i]);
>> + kfree(cxt->przs);
>> + cxt->max_dump_cnt = 0;
>> + }
>>
>> - kfree(cxt->przs);
>> - cxt->max_dump_cnt = 0;
>> + /* Free ftrace PRZs */
>> + if (cxt->fprzs) {
>> + for (i = 0; i < nr_cpu_ids; i++)
>> + persistent_ram_free(cxt->przs[i]);
>
> I am supposed to free fprzs[i] here, instead of przs[i]. Also need to
> check flag and free correct number of zones. Will fix for v2, sorry
> about that.
I think the cpu id needs to be bounds-checked against the size of the
allocation. In theory, CPU hot-plug could grow the number of CPUs
after pstore is initialized.
-Kees
--
Kees Cook
Nexus Security
