diff options
| author | Alexander Shishkin <alexander.shishkin@linux.intel.com> | 2019-12-05 17:28:52 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2019-12-17 13:32:46 +0100 |
| commit | ff61541cc6c1962957758ba433c574b76f588d23 (patch) | |
| tree | 0b2406edbbc8103f1b73a28e9eada88b496f71b1 /arch/x86/events | |
| parent | 1e69a0efc0bd0e02b8327e7186fbb4a81878ea0b (diff) | |
perf/x86/intel/bts: Fix the use of page_private()
Commit
8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver")
brought in a warning with the BTS buffer initialization
that is easily tripped with (assuming KPTI is disabled):
instantly throwing:
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 326 at arch/x86/events/intel/bts.c:86 bts_buffer_setup_aux+0x117/0x3d0
> Modules linked in:
> CPU: 2 PID: 326 Comm: perf Not tainted 5.4.0-rc8-00291-gceb9e77324fa #904
> RIP: 0010:bts_buffer_setup_aux+0x117/0x3d0
> Call Trace:
> rb_alloc_aux+0x339/0x550
> perf_mmap+0x607/0xc70
> mmap_region+0x76b/0xbd0
...
It appears to assume (for lost raisins) that PagePrivate() is set,
while later it actually tests for PagePrivate() before using
page_private().
Make it consistent and always check PagePrivate() before using
page_private().
Fixes: 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver")
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lkml.kernel.org/r/20191205142853.28894-2-alexander.shishkin@linux.intel.com
Diffstat (limited to 'arch/x86/events')
| -rw-r--r-- | arch/x86/events/intel/bts.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c index 38de4a7f6752..6a3b599ee0fe 100644 --- a/arch/x86/events/intel/bts.c +++ b/arch/x86/events/intel/bts.c @@ -63,9 +63,17 @@ struct bts_buffer { static struct pmu bts_pmu; +static int buf_nr_pages(struct page *page) +{ + if (!PagePrivate(page)) + return 1; + + return 1 << page_private(page); +} + static size_t buf_size(struct page *page) { - return 1 << (PAGE_SHIFT + page_private(page)); + return buf_nr_pages(page) * PAGE_SIZE; } static void * @@ -83,9 +91,7 @@ bts_buffer_setup_aux(struct perf_event *event, void **pages, /* count all the high order buffers */ for (pg = 0, nbuf = 0; pg < nr_pages;) { page = virt_to_page(pages[pg]); - if (WARN_ON_ONCE(!PagePrivate(page) && nr_pages > 1)) - return NULL; - pg += 1 << page_private(page); + pg += buf_nr_pages(page); nbuf++; } @@ -109,7 +115,7 @@ bts_buffer_setup_aux(struct perf_event *event, void **pages, unsigned int __nr_pages; page = virt_to_page(pages[pg]); - __nr_pages = PagePrivate(page) ? 1 << page_private(page) : 1; + __nr_pages = buf_nr_pages(page); buf->buf[nbuf].page = page; buf->buf[nbuf].offset = offset; buf->buf[nbuf].displacement = (pad ? BTS_RECORD_SIZE - pad : 0); |