Lightemerald/windows-user-space-emulator
2
0
Fork 0
mirror of https://github.com/momo5502/emulator.git synced 2026-01-19 19:53:56 +00:00
Code Issues Packages Projects Releases Wiki Activity

Fix FS and GS handling

Browse Source
This commit is contained in:
ssvine
2025-12-30 15:19:05 +03:00
parent 57ad277158
commit f25ee26c36
7 changed files with 93 additions and 53 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
src/windows-emulator/emulator_thread.cpp
View File

@@ -19,7 +19,7 @@ namespace
descriptor |= ((base & 0xFF0000) << 16); // Base[23:16]
descriptor |= (0xF3ULL << 40); // P=1, DPL=3, S=1, Type=3 (Data RW Accessed)
descriptor |= (static_cast<uint64_t>((limit & 0xF0000) >> 16) << 48); // Limit[19:16]
descriptor |= (0x40ULL << 52); // G=0 (byte), D=1 (32-bit), L=0, AVL=0
descriptor |= (0x40ULL << 48); // G=0 (byte), D=1 (32-bit), L=0, AVL=0
descriptor |= ((base & 0xFF000000) << 32); // Base[31:24]
// Write the updated descriptor to GDT index 10 (selector 0x53)
@@ -283,14 +283,10 @@ emulator_thread::emulator_thread(memory_manager& memory, const process_context&
// Note: CurrentLocale and other fields will be initialized by WOW64 runtime
});
// CRITICAL: Setup FS segment (0x53) to point to 32-bit TEB for accurate WOW64 emulation
// This mimics what Windows kernel does during NtCreateUserProcess for WOW64 processes
// Without this, FS:0 won't correctly access the 32-bit TEB
//
// NOTE: We cannot use set_segment_base() here because that sets the FS_BASE MSR
// which is for 64-bit flat addressing. 32-bit code uses actual GDT-based segmentation
// with selector 0x53, so we must modify the GDT entry directly.
setup_wow64_fs_segment(memory, teb32_addr);
this->teb64->access([&](TEB64& teb_obj) {
// teb64.ExceptionList initially points to teb32
teb_obj.NtTib.ExceptionList = teb32_addr;
});
// Use the allocator to reserve memory for CONTEXT64
this->wow64_cpu_reserved = emulator_object<WOW64_CPURESERVED>{memory, wow64_cpureserved_base};
@@ -489,3 +485,14 @@ void emulator_thread::setup_registers(x86_64_emulator& emu, const process_contex
emu.reg(x86_register::rdx, context.ntdll_image_base);
emu.reg(x86_register::rip, context.ldr_initialize_thunk);
}
void emulator_thread::refresh_execution_context(x86_64_emulator& emu) const
{
(void)emu;
if (this->teb32.has_value())
{
// Refresh GDT entry for FS selector on context switch
setup_wow64_fs_segment(*this->memory_ptr, this->teb32->value());
}
}