void sigsegv_handler(int signal, siginfo_t *info, void *raw_context)
{
#ifndef _M_GENERIC
if (signal != SIGSEGV)
{
// We are not interested in other signals - handle it as usual.
return;
}
ucontext_t *context = (ucontext_t *)raw_context;
int sicode = info->si_code;
if (sicode != SEGV_MAPERR && sicode != SEGV_ACCERR)
{
// Huh? Return.
return;
}
void *fault_memory_ptr = (void *)info->si_addr;
// Get all the information we can out of the context.
mcontext_t *ctx = &context->uc_mcontext;
#ifdef _M_X64
u8 *fault_instruction_ptr = (u8 *)CREG_RIP(ctx);
#else
u8 *fault_instruction_ptr = (u8 *)CREG_EIP(ctx);
#endif
if (!JitInterface::IsInCodeSpace(fault_instruction_ptr)) {
// Let's not prevent debugging.
return;
}
u64 bad_address = (u64)fault_memory_ptr;
u64 memspace_bottom = (u64)Memory::base;
if (bad_address < memspace_bottom) {
PanicAlertT("Exception handler - access below memory space. %08llx%08llx",
bad_address >> 32, bad_address);
}
if (bad_address < memspace_bottom) {
PanicAlertT("Exception handler - access below memory space. %08llx%08llx",
bad_address >> 32, bad_address);
}
u32 em_address = (u32)(bad_address - memspace_bottom);
// Backpatch time.
// Seems we'll need to disassemble to get access_type - that work is probably
// best done and debugged on the Windows side.
int access_type = 0;
CONTEXT fake_ctx;
#ifdef _M_X64
fake_ctx.Rax = CREG_RAX(ctx);
fake_ctx.Rip = CREG_RIP(ctx);
#else
fake_ctx.Eax = CREG_EAX(ctx);
fake_ctx.Eip = CREG_EIP(ctx);
#endif
const u8 *new_rip = jit->BackPatch(fault_instruction_ptr, access_type, em_address, &fake_ctx);
if (new_rip)
{
#ifdef _M_X64
CREG_RAX(ctx) = fake_ctx.Rax;
CREG_RIP(ctx) = fake_ctx.Rip;
#else
CREG_EAX(ctx) = fake_ctx.Eax;
CREG_EIP(ctx) = fake_ctx.Eip;
#endif
}
