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Subject[RFT v2 4/4] coresight: Document for CoreSight trace disassembler
Date
This commit documents CoreSight trace disassembler usage and gives
example for it.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
Documentation/trace/coresight.txt | 52 +++++++++++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)

diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
index 6f0120c..b8f2359 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -381,3 +381,55 @@ sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tuto
$ taskset -c 2 ./sort_autofdo
Bubble sorting array of 30000 elements
5806 ms
+
+
+Tracing data disassembler
+-------------------------
+
+'perf script' supports to use script to parse tracing packet and rely on
+'objdump' for disassembled lines, this can convert tracing data to readable
+program execution flow for easily reviewing tracing data.
+
+The CoreSight trace disassembler is located in the folder:
+tools/perf/scripts/python/arm-cs-trace-disasm.py. This script support below
+options:
+
+ -d, --objdump: Set path to objdump executable, this option is
+ mandatory.
+ -k, --vmlinux: Set path to vmlinux file.
+ -v, --verbose: Enable debugging log, after enable this option the
+ script dumps every event data.
+
+Below is one example for using python script to dump CoreSight trace
+disassembler:
+
+ $ perf script -s arm-cs-trace-disasm.py -i perf.data \
+ -F cpu,event,ip,addr,sym -- -d objdump -k ./vmlinux > cs-disasm.log
+
+Below is one example for the disassembler log:
+
+ARM CoreSight Trace Data Assembler Dump
+ ffff000008a5f2dc <etm4_enable_hw+0x344>:
+ ffff000008a5f2dc: 340000a0 cbz w0, ffff000008a5f2f0 <etm4_enable_hw+0x358>
+ ffff000008a5f2f0 <etm4_enable_hw+0x358>:
+ ffff000008a5f2f0: f9400260 ldr x0, [x19]
+ ffff000008a5f2f4: d5033f9f dsb sy
+ ffff000008a5f2f8: 913ec000 add x0, x0, #0xfb0
+ ffff000008a5f2fc: b900001f str wzr, [x0]
+ ffff000008a5f300: f9400bf3 ldr x19, [sp, #16]
+ ffff000008a5f304: a8c27bfd ldp x29, x30, [sp], #32
+ ffff000008a5f308: d65f03c0 ret
+ ffff000008a5fa18 <etm4_enable+0x1b0>:
+ ffff000008a5fa18: 14000025 b ffff000008a5faac <etm4_enable+0x244>
+ ffff000008a5faac <etm4_enable+0x244>:
+ ffff000008a5faac: b9406261 ldr w1, [x19, #96]
+ ffff000008a5fab0: 52800015 mov w21, #0x0 // #0
+ ffff000008a5fab4: f901ca61 str x1, [x19, #912]
+ ffff000008a5fab8: 2a1503e0 mov w0, w21
+ ffff000008a5fabc: 3940e261 ldrb w1, [x19, #56]
+ ffff000008a5fac0: f901ce61 str x1, [x19, #920]
+ ffff000008a5fac4: a94153f3 ldp x19, x20, [sp, #16]
+ ffff000008a5fac8: a9425bf5 ldp x21, x22, [sp, #32]
+ ffff000008a5facc: a94363f7 ldp x23, x24, [sp, #48]
+ ffff000008a5fad0: a8c47bfd ldp x29, x30, [sp], #64
+ ffff000008a5fad4: d65f03c0 ret
--
2.7.4
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