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The stack frame 栈帧

1. Definition

A Stack Frame is a temporary, private workspace in memory allocated for a single function call.

  • Created: When a function is called.

  • Destroyed: When the function returns.

  • Location: Resides in the Stack Segment.

2. Anatomy (High Address -> Low Address)

A typical stack frame consists of four layers. The frame is bounded by two CPU registers: EBP (top/anchor) and ESP (bottom).

Section Content Description
1. Arguments func(a, b) Passed by the Caller. Located above EBP.
2. Return Address 0x401... Where to jump back to after the function finishes. Pushed automatically by CALL.
3. Saved EBP Old EBP The Caller's stack base. This links the current frame to the previous one (forming the stack trace).
4. Local Variables int x; Private variables for this function. Located below EBP.

3. Key Registers

  • EBP (Base Pointer): The Anchor. It remains fixed during the function execution. Used to access locals (e.g., EBP - 4) and arguments (e.g., EBP + 8).

  • ESP (Stack Pointer): The Moving Top. It changes as data is pushed/popped or as memory is allocated for locals.

4. Lifecycle (Assembly View)

A. Construction (Prologue)
Sets up the "house".

push ebp      ; Save the Caller's EBP
mov ebp, esp  ; Set current ESP as the new EBP (Anchor)
sub esp, N    ; Allocate N bytes for local variables

B. Destruction (Epilogue)
Tears down the "house".

mov esp, ebp  ; Restore ESP (Free locals instantly)
pop ebp       ; Restore Caller's EBP (Go back to previous frame)
ret           ; Pop Return Address into Instruction Pointer

5. Key Concepts

  • Isolation: Each function call gets its own frame. main cannot touch func's variables.

  • Recursion: If a function calls itself, a new stack frame is created for that specific call. This preserves the state of previous calls.

  • Stack Overflow: Occurs when too many frames are created (e.g., infinite recursion), exhausting the stack memory.

[[Anatomy of a function call in memory]]