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Commit 67968b8c authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Greg Kroah-Hartman
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perf/x86/intel/pt: Use pointer arithmetics instead in ToPA entry calculation 



[ Upstream commit 539f7c26b41d4ed7d88dd9756de3966ae7ca07b4 ]

Currently, pt_buffer_reset_offsets() calculates the current ToPA entry by
casting pointers to addresses and performing ungainly subtractions and
divisions instead of a simpler pointer arithmetic, which would be perfectly
applicable in that case. Fix that.

Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20190821124727.73310-4-alexander.shishkin@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Stable-dep-of: ad97196379d0 ("perf/x86/intel/pt: Fix a topa_entry base address calculation")
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent e3fb71f7

arch/x86/events/intel/pt.c

+1 −2
Original line number Diff line number Diff line
@@ -1031,8 +1031,7 @@ static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head) 
	pg = pt_topa_next_entry(buf, pg);



	buf->cur = (struct topa *)((unsigned long)buf->topa_index[pg] & PAGE_MASK);

	buf->cur_idx = ((unsigned long)buf->topa_index[pg] -

			(unsigned long)buf->cur) / sizeof(struct topa_entry);

	buf->cur_idx = buf->topa_index[pg] - TOPA_ENTRY(buf->cur, 0);

	buf->output_off = head & (pt_buffer_region_size(buf) - 1);



	local64_set(&buf->head, head);