From 08d89227bfe2a81fccaa8273e4d5402eba0cca6c Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 13 May 2024 20:41:01 +1000
Subject: [PATCH 1/2] AP_Scripting: added example script that causes a hard
 fault

this exercises rapid fault handling
---
 .../AP_Scripting/examples/fault_handling.lua  | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 libraries/AP_Scripting/examples/fault_handling.lua

diff --git a/libraries/AP_Scripting/examples/fault_handling.lua b/libraries/AP_Scripting/examples/fault_handling.lua
new file mode 100644
index 0000000000000..0a95e84f7b7ac
--- /dev/null
+++ b/libraries/AP_Scripting/examples/fault_handling.lua
@@ -0,0 +1,56 @@
+--[[
+   example script to test fault handling with pcall
+--]]
+
+local MAV_SEVERITY = {EMERGENCY=0, ALERT=1, CRITICAL=2, ERROR=3, WARNING=4, NOTICE=5, INFO=6, DEBUG=7}
+
+gcs:send_text(MAV_SEVERITY.INFO, "Loading fault test")
+
+local test_count = 0
+local fault_count = 0
+
+--[[
+   evaluate a lua function and return nil on fault or the functions return value
+--]]
+local function evaluate(f)
+   local ok, s = pcall(f)
+   eval_func = nil
+   if ok then
+      return s
+   end
+   fault_count = fault_count + 1
+   return nil
+end
+
+local function nil_deref()
+   local loc = nil
+   return loc:lat()
+end
+
+local function bad_random()
+   return math.random(1,0)
+end
+
+local function run_test()
+   local script_variant = test_count % 2
+   if script_variant == 0 then
+      evaluate(nil_deref)
+   elseif script_variant == 1 then
+      evaluate(bad_random)
+   end
+end
+
+local function update()
+   if test_count % 100 == 0 then
+      gcs:send_text(MAV_SEVERITY.INFO,string.format("Test %u fault_count %u", test_count, fault_count))
+   end
+   test_count = test_count + 1
+   run_test()
+   assert(fault_count == test_count, "fault and test counts should match")
+   return update,1
+end
+
+gcs:send_text(MAV_SEVERITY.INFO, "Starting fault test in 2 seconds")
+
+-- wait a while for GCS to connect
+return update,2000

From ea5418ecca5d87d78d70f1112b71e32025fff447 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 13 May 2024 20:55:55 +1000
Subject: [PATCH 2/2] AP_Scripting: fixed float register save/restore in
 setjmp/longjmp

the register save must happen before the setjmp() call, which means
outside of the LUAI_TRY() macro. We also should be saving all 32
floating point registers
---
 libraries/AP_Scripting/lua/src/ldo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libraries/AP_Scripting/lua/src/ldo.c b/libraries/AP_Scripting/lua/src/ldo.c
index c07f4fdb32854..6c627dc3a9fe1 100644
--- a/libraries/AP_Scripting/lua/src/ldo.c
+++ b/libraries/AP_Scripting/lua/src/ldo.c
@@ -142,10 +142,10 @@ int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
   lj.status = LUA_OK;
   lj.previous = L->errorJmp;  /* chain new error handler */
   L->errorJmp = &lj;
-  LUAI_TRY(L, &lj,
 #ifdef ARM_MATH_CM7
     __asm__("vpush {s16-s31}");
 #endif
+  LUAI_TRY(L, &lj,
     (*f)(L, ud);
   );
 #ifdef ARM_MATH_CM7