AP_Scripting: stash and restore FPU register context in LUAI_TRY

this fixes an issue where a lua library function triggers an exception
after it does a math operation which changes the floating point
registers on M7 MCUs (such as STM32H7). An example is math.random()
which calls math_random(), which pre-calculates a double value before
checking if the arguments to the call are valid. When it then checks
and finds invalid values the exception longjmp does not restore the
floating point registers.
This commit is contained in:
bugobliterator 2023-07-06 00:54:52 +10:00 committed by Andrew Tridgell
parent a564af680b
commit a121f665f1
2 changed files with 20 additions and 2 deletions

View File

@ -218,6 +218,15 @@ void AP_Scripting::repl_stop(void) {
// can't do any more cleanup here, closing the open FD's is the REPL's responsibility
}
/*
avoid optimisation of the thread function. This avoids nasty traps
where setjmp/longjmp does not properly handle save/restore of
floating point registers on exceptions. This is an extra protection
over the top of the fix in luaD_rawrunprotected() for the same issue
*/
#pragma GCC push_options
#pragma GCC optimize ("O0")
void AP_Scripting::thread(void) {
while (true) {
// reset flags
@ -275,6 +284,7 @@ void AP_Scripting::thread(void) {
}
}
}
#pragma GCC pop_options
void AP_Scripting::handle_mission_command(const AP_Mission::Mission_Command& cmd_in)
{

View File

@ -133,7 +133,9 @@ l_noret luaD_throw (lua_State *L, int errcode) {
}
}
// remove optimization
#pragma GCC push_options
#pragma GCC optimize ("O0")
int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
unsigned short oldnCcalls = L->nCcalls;
struct lua_longjmp lj;
@ -141,13 +143,19 @@ int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
lj.previous = L->errorJmp; /* chain new error handler */
L->errorJmp = &lj;
LUAI_TRY(L, &lj,
#ifdef ARM_MATH_CM7
__asm__("vpush {s16-s31}");
#endif
(*f)(L, ud);
);
#ifdef ARM_MATH_CM7
__asm__("vpop {s16-s31}");
#endif
L->errorJmp = lj.previous; /* restore old error handler */
L->nCcalls = oldnCcalls;
return lj.status;
}
#pragma GCC pop_options
/* }====================================================== */