; Threads management.
; int create_thread(int (*proc)(void *param), void *param, int stack_size)
; Creates a thread that executes the given function proc(param).
; Returns -1 on error, TID otherwise.
; If proc(param) returns, the returned value is passed to exit_thread().
; If stack_size is zero, uses the value from PE header of the executable.
proc create_thread stdcall uses ebx, thread_proc, param, stack_size
; 1. Determine stack size.
; Align stack_size up to page boundary;
mov ecx, [stack_size]
add ecx, 0xFFF
and ecx, not 0xFFF
jnz .stack_size_ok
; if this results in zero, read the value from the header of main module.
mov eax, [modules_list + MODULE.next]
mov eax, [eax + MODULE.base]
mov ecx, [eax+STRIPPED_PE_HEADER.SizeOfStackReserve]
cmp byte [eax], 'M'
jnz .stack_size_ok
mov ecx, [eax+3Ch]
mov ecx, [eax+ecx+IMAGE_NT_HEADERS.OptionalHeader.SizeOfStackReserve]
.stack_size_ok:
mov [stack_size], ecx
; 2. Allocate the stack.
mov eax, 68
mov ebx, 12
call FS_SYSCALL_PTR
test eax, eax
jz .fail
; 3. Copy parameters to the stack.
lea edx, [eax+ecx-16]
mov [edx], ecx
mov ebx, FS_SYSCALL_PTR
mov [edx+4], ebx
mov ebx, [thread_proc]
mov [edx+8], ebx
mov ebx, [param]
mov [edx+12], ebx
; 4. Call the kernel to create the thread.
mov eax, 51
mov ebx, 1
mov ecx, internal_thread_start
call FS_SYSCALL_PTR
cmp eax, -1
jz .fail_free
ret
.fail_free:
mov eax, 68
mov ebx, 13
lea ecx, [edx+12]
sub ecx, [stack_size]
call FS_SYSCALL_PTR
xor eax, eax
.fail:
dec eax
ret
endp
; void exit_thread(int exit_code)
; Terminates the current thread.
; exit_code is reserved; currently ignored
proc exit_thread stdcall, exit_code
; Use int 0x40 instead of call FS_SYSCALL_PTR, because we are freeing the stack.
mov eax, 68
mov ebx, 13
mov ecx, FS_STACK_MIN
int 0x40
or eax, -1
int 0x40
endp
; Real entry point of threads created by create_thread.
; Provides user-space initialization of the thread,
; calls user-provided thread routine,
; passes the returned value to exit_thread.
proc internal_thread_start
pop eax ; stack_size
lea ecx, [esp+12]
mov FS_STACK_MAX, ecx
sub ecx, eax
mov FS_STACK_MIN, ecx
pop FS_SYSCALL_PTR ; from caller's FS_SYSCALL_PTR
pop eax ; thread_proc
call eax ; param is still on the stack
push eax ; exit_code
push 0 ; no return address
jmp exit_thread
endp