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[PATCH 11/25] perf intel-pt: Fix last_ip usage

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From: Adrian Hunter <adrian.hunter@intel.com>

Intel PT uses IP compression based on the last IP. For decoding
purposes, 'last IP' is considered to be reset to zero whenever there is
a synchronization packet (PSB). The decoder wasn't doing that, and was
treating the zero value to mean that there was no last IP, whereas
compression can be done against the zero value. Fix by setting last_ip
to zero when a PSB is received and keep track of have_last_ip.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1495786658-18063-6-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index f9cd3aaef488..62e2c2ad3f1d 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -111,6 +111,7 @@ struct intel_pt_decoder {
 	bool have_tma;
 	bool have_cyc;
 	bool fixup_last_mtc;
+	bool have_last_ip;
 	uint64_t pos;
 	uint64_t last_ip;
 	uint64_t ip;
@@ -419,6 +420,7 @@ static uint64_t intel_pt_calc_ip(const struct intel_pt_pkt *packet,
 static inline void intel_pt_set_last_ip(struct intel_pt_decoder *decoder)
 {
 	decoder->last_ip = intel_pt_calc_ip(&decoder->packet, decoder->last_ip);
+	decoder->have_last_ip = true;
 }
 
 static inline void intel_pt_set_ip(struct intel_pt_decoder *decoder)
@@ -1672,6 +1674,8 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_PSB:
+			decoder->last_ip = 0;
+			decoder->have_last_ip = true;
 			intel_pt_clear_stack(&decoder->stack);
 			err = intel_pt_walk_psbend(decoder);
 			if (err == -EAGAIN)
@@ -1752,7 +1756,7 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
 
 static inline bool intel_pt_have_ip(struct intel_pt_decoder *decoder)
 {
-	return decoder->last_ip || decoder->packet.count == 0 ||
+	return decoder->have_last_ip || decoder->packet.count == 0 ||
 	       decoder->packet.count == 3 || decoder->packet.count == 6;
 }
 
@@ -1882,7 +1886,7 @@ static int intel_pt_walk_to_ip(struct intel_pt_decoder *decoder)
 				if (decoder->ip)
 					return 0;
 			}
-			if (decoder->packet.count)
+			if (decoder->packet.count && decoder->have_last_ip)
 				intel_pt_set_last_ip(decoder);
 			break;
 
@@ -1932,6 +1936,8 @@ static int intel_pt_walk_to_ip(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_PSB:
+			decoder->last_ip = 0;
+			decoder->have_last_ip = true;
 			intel_pt_clear_stack(&decoder->stack);
 			err = intel_pt_walk_psb(decoder);
 			if (err)
@@ -2066,6 +2072,7 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)
 
 	decoder->pge = false;
 	decoder->continuous_period = false;
+	decoder->have_last_ip = false;
 	decoder->last_ip = 0;
 	decoder->ip = 0;
 	intel_pt_clear_stack(&decoder->stack);
@@ -2074,6 +2081,7 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)
 	if (err)
 		return err;
 
+	decoder->have_last_ip = true;
 	decoder->pkt_state = INTEL_PT_STATE_NO_IP;
 
 	err = intel_pt_walk_psb(decoder);
@@ -2116,6 +2124,7 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
 			err = intel_pt_sync(decoder);
 			break;
 		case INTEL_PT_STATE_NO_IP:
+			decoder->have_last_ip = false;
 			decoder->last_ip = 0;
 			decoder->ip = 0;
 			/* Fall through */
-- 
2.9.4

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[GIT PULL 00/25] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 09/25] perf intel-pt: Fix missing stack clear Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 07/25] perf intel-pt: Move decoder error setting into one condition Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 23/25] perf intel-pt: Fix transactions_sample_type Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 04/25] tools lib api fs: Add sysfs__write_int function Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 05/25] perf stat: Add support to measure SMI cost Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 19/25] perf intel-pt: Add decoder support for ptwrite and power event packets Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 22/25] perf intel-pt: Remove redundant initial_skip checks Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 08/25] perf intel-pt: Improve sample timestamp Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 25/25] perf script: Fix message because field list option is -F not -f Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 20/25] perf intel-pt: Add reserved byte to CBR packet payload Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 11/25] perf intel-pt: Fix last_ip usage Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 14/25] perf intel-pt: Clear FUP flag on error Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  [PATCH 10/25] perf intel-pt: Ensure IP is zero when state is INTEL_PT_STATE_NO_IP Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-06-21 20:10 +0200
  Re: [GIT PULL 00/25] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2017-06-21 20:20 +0200

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