From dc62d9e38d60752e65d0022ce984b471853ac6cd Mon Sep 17 00:00:00 2001
From: Tudor Brindus <tbrindus@janestreet.com>
Date: Sun, 13 Nov 2022 20:46:55 -0500
Subject: [PATCH] Recognize `int3` instructions in trace parser

Not quite sure why we'd be seeing this, but let's not crash when we do.
For now, treat a software interrupt as a jump.

Ref https://github.com/janestreet/magic-trace/issues/257
---
 core/event.ml       |  1 +
 core/event.mli      |  1 +
 src/perf_decode.ml  | 16 +++++++++++++++-
 src/trace_writer.ml | 14 +++++++++++---
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/core/event.ml b/core/event.ml
index b99177802..fcc9d44c2 100644
--- a/core/event.ml
+++ b/core/event.ml
@@ -7,6 +7,7 @@ module Kind = struct
     | Syscall
     | Sysret
     | Hardware_interrupt
+    | Interrupt
     | Iret
     | Jump
   [@@deriving sexp, compare, bin_io]
diff --git a/core/event.mli b/core/event.mli
index e9ab7f6d0..7d50acd49 100644
--- a/core/event.mli
+++ b/core/event.mli
@@ -7,6 +7,7 @@ module Kind : sig
     | Syscall
     | Sysret
     | Hardware_interrupt
+    | Interrupt
     | Iret
     | Jump
   [@@deriving sexp, compare]
diff --git a/src/perf_decode.ml b/src/perf_decode.ml
index 8e23f1641..de51e7c77 100644
--- a/src/perf_decode.ml
+++ b/src/perf_decode.ml
@@ -22,7 +22,7 @@ let perf_callstack_entry_re = Re.Perl.re "^\t *([0-9a-f]+) (.*)$" |> Re.compile
 
 let perf_branches_event_re =
   Re.Perl.re
-    {|^ *(call|return|tr strt|syscall|sysret|hw int|iret|tr end|tr strt tr end|tr end  (?:call|return|syscall|sysret|iret)|jmp|jcc) +([0-9a-f]+) (.*) => +([0-9a-f]+) (.*)$|}
+    {|^ *(call|return|tr strt|syscall|sysret|hw int|iret|int|tr end|tr strt tr end|tr end  (?:call|return|syscall|sysret|iret)|jmp|jcc) +([0-9a-f]+) (.*) => +([0-9a-f]+) (.*)$|}
   |> Re.compile
 ;;
 
@@ -243,6 +243,7 @@ let parse_perf_branches_event ?perf_maps (thread : Event.Thread.t) time line : E
       match String.strip kind with
       | "call" -> Some Call
       | "return" -> Some Return
+      | "int" -> Some Interrupt
       | "jmp" -> Some Jump
       | "jcc" -> Some Jump
       | "syscall" -> Some Syscall
@@ -495,6 +496,19 @@ let%test_module _ =
            (data (Trace (kind Call) (src 0x56234f77576b) (dst 0x56234f4bc7a0)))))) |}]
     ;;
 
+    let%expect_test "software interrupts" =
+      check
+        "1907478/1909463 457407.880965552:          1                                \
+         branches:uH:   int                      564aa58813d4 \
+         Builtins_RunMicrotasks+0x554 (/usr/local/bin/workload) =>     564aa584fa00 \
+         Builtins_Call_ReceiverIsNotNullOrUndefined+0x0 (/usr/local/bin/workload)";
+      [%expect
+        {|
+        ((Ok
+          ((thread ((pid (1907478)) (tid (1909463)))) (time 5d7h3m27.880965552s)
+           (data (Trace (kind Interrupt) (src 0x564aa58813d4) (dst 0x564aa584fa00)))))) |}]
+    ;;
+
     let%expect_test "decode error with a timestamp" =
       check
         " instruction trace error type 1 time 47170.086912826 cpu -1 pid 293415 tid \
diff --git a/src/trace_writer.ml b/src/trace_writer.ml
index 0905fad8e..2929f6d0f 100644
--- a/src/trace_writer.ml
+++ b/src/trace_writer.ml
@@ -1004,9 +1004,17 @@ let write_event (T t) ?events_writer event =
          ~time;
        (match kind, trace_state_change with
         | Some Call, (None | Some End) -> call t thread_info ~time ~location:dst
-        | ( Some (Call | Syscall | Return | Hardware_interrupt | Iret | Sysret | Jump)
+        | ( Some
+              ( Call
+              | Syscall
+              | Return
+              | Hardware_interrupt
+              | Iret
+              | Interrupt
+              | Sysret
+              | Jump )
           , Some Start )
-        | Some (Hardware_interrupt | Jump), Some End ->
+        | Some (Hardware_interrupt | Jump | Interrupt), Some End ->
           raise_s
             [%message
               "BUG: magic-trace devs thought this event was impossible, but you just \
@@ -1093,7 +1101,7 @@ let write_event (T t) ?events_writer event =
                ~addr:dst.instruction_pointer
                ~time;
              check_current_symbol t thread_info ~time dst)
-        | Some Jump, None ->
+        | Some (Jump | Interrupt), None ->
           Ocaml_hacks.check_current_symbol_track_entertraps t thread_info ~time dst
         (* (None, _) comes up when perf spews something magic-trace doesn't recognize.
        Instead of crashing, ignore it and keep going. *)