add real syscall64 src

2019-11-10 16:16:08 +01:00
parent 4c0419d6ca
commit 116c03eb24
1 changed files with 76 additions and 0 deletions
--- a/content/projects/syscall64.md
+++ b/content/projects/syscall64.md
@@ -8,3 +8,79 @@ A slightly hacky way (C macros) to do direct syscalls on either x86 or x64 windo
 without any code change.

 http://vcs.wacked.codes/wacked/syscall64
+
+Use with this:
+```
+;http://blogs.msdn.com/b/oldnewthing/archive/2004/01/14/58579.aspx
+format ms coff
+
+include 'u:\fasm\INCLUDE\win32wx.inc'
+public _syscall64
+section '.text' code readable executable
+
+; Converts the arguments and then executes SYSCALL
+; 1. Param: Count of args to pass to syscall
+; 2. Param: Syscall id
+; 3. - X. Param: Params for syscall
+_syscall64:
+        ; Those registers are pushed here so that the LEAVE instr cleans up the converted params without me needing to
+        ; calc how much space those needed. Seriously what's 4*3 again?
+        push edi
+        push ebx
+        push edx ; used by the x64 code
+        
+        push ebp
+        mov ebp, esp
+        
+        ; Alloc space for params
+        mov ecx, [ebp + 4*3 + 0x08] ; cnt
+        cmp ecx, 4 ; Reserve shadow space
+        jge @f
+        mov ecx, 4
+@@:
+        shl ecx, 3
+        sub esp, ecx
+        
+        and esp, 0xFFFFFFF0 ; Align stack
+        
+        ; Convert params to x64
+        mov edi, esp ; Destination
+        mov ecx, [ebp + 4*3 + 0x08] ; Count
+        lea ebx, [ebp + 4*3 + 0x10] ; Source for params
+CONVERT_PARAMS_LOOP:    
+        test ecx, ecx
+        je @f
+        
+        mov eax, [ebx]
+        stosd ; mov dword[edi], dword[eax] edi += 4
+        mov eax, 0
+        stosd ; [edi] = 0 edi += 4
+        add ebx, 4 ; srcPtr++
+        dec ecx    ; cnt--
+        jmp CONVERT_PARAMS_LOOP
+        
+@@:     
+        ;mov eax, [ebp + 4*3 + 0x0C] ; Get syscall id
+        call 0x33:X64_START
+X86_RETURN_FROM_X64:    
+        leave
+        pop edx
+        pop ebx
+        pop edi
+        ret
+                        
+;align 16       
+X64_START:
+use64
+        mov eax, dword [ebp + 0x18] ; Get syscall id (4*3 = saved registers, )
+        ; Get args from shadow space
+        mov rcx, [rsp + 8]
+        mov rdx , [rsp + 0x10]
+        mov r8, [rsp + 0x18]
+        mov r9, [rsp + 0x20]
+        
+        mov     r10,rcx
+        syscall
+use32 
+        retf
+```