perf intel-pt: Fix last_ip usage

BugLink: http://bugs.launchpad.net/bugs/1710646
commit ee14ac0ef6827cd6f9a572cc83dd0191ea17812c upstream.

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>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

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 40eb4e028fb5d7b2f21bdcc527210f7943e36905..cc33ec09ba539af65a60cfcc6e6c2efd1af523cb 100644 (file)
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -110,6 +110,7 @@ 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;
@@ -417,6 +418,7 @@ 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)
@@ -1640,6 +1642,8 @@ next:
                        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)
@@ -1720,7 +1724,7 @@ next:
 
 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;
 }
 
@@ -1850,7 +1854,7 @@ 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;
 
@@ -1900,6 +1904,8 @@ 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)
@@ -2036,6 +2042,7 @@ 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);
@@ -2044,6 +2051,7 @@ 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);
@@ -2086,6 +2094,7 @@ 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 */