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MASM Macros

 

The latest version of this topic can be found at MASM Macros.

In order to simplify the use of the Raw Pseudo Operations, there are a set of macros, defined in ksamd64.inc, which can be used to create typical procedure prologues and epilogues.

Remarks

Macro Description
alloc_stack(n) Allocates a stack frame of n bytes (using sub rsp, n), and emits the appropriate unwind information (.allocstack n)
save_reg reg, loc Saves a nonvolatile register reg on the stack at RSP offset loc, and emits the appropriate unwind information. (.savereg reg, loc)
push_reg reg Pushes a nonvolatile register reg on the stack, and emits the appropriate unwind information. (.pushreg reg)
rex_push_reg reg Save a nonvolatile register on the stack using a 2 byte push, and emits the appropriate unwind information (.pushreg reg) This should be used if the push is the first instruction in the function to ensure that the function is hot-patchable.
save_xmm128 reg, loc Saves a nonvolatile XMM register reg on the stack at RSP offset loc, and emits the appropriate unwind information (.savexmm128 reg, loc)
set_frame reg, offset Sets the frame register reg to be the RSP + offset (using a mov, or an lea), and emits the appropriate unwind information (.set_frame reg, offset)
push_eflags Pushes the eflags with a pushfq instruction, and emits the appropriate unwind information (.alloc_stack 8)

Here is a sample function prolog with proper usage of the macros:

SkFrame struct   
Fill    dq ?; fill to 8 mod 16   
SavedRdi dq ?; saved register RDI   
SavedRsi dq ?; saved register RSI   
SkFrame ends  
  
sampleFrame struct  
Filldq?; fill to 8 mod 16  
SavedRdidq?; Saved Register RDI   
SavedRsi  dq?; Saved Register RSI  
sampleFrame ends  
  
sample2 PROC FRAME  
alloc_stack(sizeof sampleFrame)  
save_reg rdi, sampleFrame.SavedRdi  
save_reg rsi, sampleFrame.SavedRsi  
.end_prolog  
  
; function body  
  
mov rsi, sampleFrame.SavedRsi[rsp]  
mov rdi, sampleFrame.SavedRdi[rsp]  
  
; Here’s the official epilog  
  
add rsp, (sizeof sampleFrame)  
ret  
sample2 ENDP  

See Also

Unwind Helpers for MASM