Arm Backend: Expose PMU trace output from FVP run (#14401)

Exposes PMU trace output from an FVP. This lays part of the foundation
to enable us to use this output to as a data overlay in Model Explorer
visualisations.

The end goal here is to be able to visualise some profiling data in
Model Explorer using our Tosa Flatbuffer adapter. To enable this we need
to implement a few changes:

1. Expose PMU trace output from a FVP. This gives us performance data
from an FVP run. (This PR)
2. Expose Vela's debug database. This gives us generic information on
operators in a our model, and can be combined with the trace output to
provide more detailed profiling analysis
3. Write a script to combine the trace output and the debug database so
we can visualise it in Model Explorer in Executorch.


Here's a snippet of the PMU trace output: 
```
{
            "name": "axi_enabled_cycles",
            "ph": "X",
            "ts": "1029",
            "pid": "DMA",
            "tid": "axi_enabled_cycles",
            "dur": "1014"
        }
```
cc @digantdesai @freddan80 @per @zingo @oscarandersson8218

Author: jmahbs

backends/arm/scripts/run_fvp.sh

@@ -22,6 +22,7 @@ data_file=""
 target="ethos-u55-128"
 timeout="600"
 etrecord_file=""
+trace_file=""
 
 help() {
     echo "Usage: $(basename $0) [options]"
@@ -31,6 +32,7 @@ help() {
     echo "  --target=<TARGET>        Target to build and run for Default: ${target}"
     echo "  --timeout=<TIME_IN_SEC>  Maximum target runtime, used to detect hanging, might need to be higer on large models Default: ${timeout}"
     echo "  --etrecord=<FILE>        If ETDump is used you can supply a ETRecord file matching the PTE"
+    echo "  --trace_file=<FILE>      File to write PMU trace output to"
     exit 0
 }
 
@@ -42,6 +44,7 @@ for arg in "$@"; do
       --target=*) target="${arg#*=}";;
       --timeout=*) timeout="${arg#*=}";;
       --etrecord=*) etrecord_file="${arg#*=}";;
+      --trace_file=*) trace_file="${arg#*=}";;
       *)
       ;;
     esac
@@ -86,13 +89,22 @@ fi
 
 log_file=$(mktemp)
 
+extra_args_u55=()
+extra_args_u85=()
+
+if [[ -n "${trace_file}" ]]; then
+    extra_args_u55+=(-C "ethosu.extra_args=--pmu-trace ${trace_file}")
+    extra_args_u85+=(-C "mps4_board.subsystem.ethosu.extra_args=--pmu-trace ${trace_file}")
+fi
+
 if [[ ${target} == *"ethos-u55"*  ]]; then
     ${nobuf} ${fvp_model}                                   \
         -C ethosu.num_macs=${num_macs}                      \
         -C mps3_board.visualisation.disable-visualisation=1 \
         -C mps3_board.telnetterminal0.start_telnet=0        \
         -C mps3_board.uart0.out_file='-'                    \
         -C mps3_board.uart0.shutdown_on_eot=1               \
+        "${extra_args_u55[@]}"                              \
         -a "${elf_file}"                                    \
         ${data_file}                                        \
         --timelimit ${timeout} 2>&1 | sed 's/\r$//' | tee ${log_file} || true # seconds
@@ -105,6 +117,7 @@ elif [[ ${target} == *"ethos-u85"*  ]]; then
         -C mps4_board.telnetterminal0.start_telnet=0        \
         -C mps4_board.uart0.out_file='-'                    \
         -C mps4_board.uart0.shutdown_on_eot=1               \
+        "${extra_args_u85[@]}"                              \
         -a "${elf_file}"                                    \
         ${data_file}                                        \
         --timelimit ${timeout} 2>&1 | sed 's/\r$//' | tee ${log_file} || true # seconds