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Restore stack pointer after FFI calls (and pray)

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Struma 2020-04-13 03:59:07 -04:00 • committed by Roza
parent 1605bfa6d6
commit d3a16e88a7
1 changed files with 23 additions and 2 deletions
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25
binding/miniffi-binding.cpp
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@ -273,13 +273,30 @@ RB_METHOD(MiniFFI_call) {
// apparently doesn't work anymore, so assembly is used instead.
// Technically also allows for an unlimited number of arguments,
// but the above code does not
// if esp isn't the same as it was before the stack
// setup and call, this'll try to reset it, which should let
// cdecl functions work as well as stdcall ones.
// ...On paper, anyway.
// Do not do not DO NOT try to run this from multiple
// threads at once, esp would need to be stored in a more
// dynamic location than this
#else
unsigned long ret = 0;
unsigned long sp = 0;
asm volatile(".intel_syntax noprefix\n"
".data\n"
"esp_store: .int 0\n"
".text\n"
"MiniFFI_call_asm:\n"
"lea ebx, esp_store\n"
"mov [ebx], esp\n"
"test ecx, ecx\n"
"jz call_void\n"
"sub ecx, 4\n"
"test ecx, ecx\n"
"mov esp_store, esp\n"
"jz loop_end\n"
"loop_start:\n"
"mov eax, [esi+ecx]\n"
@ -291,9 +308,13 @@ RB_METHOD(MiniFFI_call) {
"mov eax, [esi]\n"
"push eax\n"
"call_void:\n"
"call edi"
"call edi\n"
"lea ebx, esp_store\n"
"mov ebx, [ebx]\n"
"test esp, ebx\n"
"movnz esp, ebx"
: "+a"(ret)
: "c"(nimport * 4), "S"(&param), "D"(ApiFunction)
: "c"(nimport * 4), "b"(&sp), "S"(&param), "D"(ApiFunction)
: "memory");
#endif