我有由 frameCount 调用的汇编代码，需要返回 frameCount，但不确定如何检索（然后导航）前一帧的指针引用。

获取FP.s

  .globl getFP
getFP:
  movq %rbp, %rax
  ret

帧数

int frameCount() {
  int count = 0;
  uint64_t fp = getFP();
  uint64_t *sp = &fp;
  
  // how do I get the pointer/offset to pointer to the previous stack frame from here?
  
  return count;
}

更新：

我已经更新了 frameCount 函数以包含一个遍历堆栈帧链接列表的循环，但是在调用 frameCount 时出现分段错误。

主文件

#include <stdio.h>
#include <inttypes.h>
#include "framecount.c"

int main() {
  printf("Number of Frames: %dn", frameCount());

  return(0);
}

帧数

#include <stdio.h>
#include <inttypes.h>

uint64_t* getFP();

int frameCount() {
  uint64_t* fp = getFP();
  uint64_t registerValue1 = *fp;

  while (registerValue1 != 0) {
    printf("current register value %" PRIx64 "n", registerValue1);
    printf("next register value %" PRIx64 "n", *(volatile uint64_t *)registerValue1);
    count++;
    registerValue1 = *(volatile uint64_t *)registerValue1;
  }

  printf("count=%dn", count);

  return count;
}

输出

current register value 7ffca7c147b0
next register value 401230
current register value 401230
next register value 8d4c5741fa1e0ff3
current register value 8d4c5741fa1e0ff3
Segmentation fault (core dumped)

但是，当我执行以下操作时，我没有收到分段错误，但计数似乎不正确：（更新：删除了虚假示例）

更新 2：

即使在使用选项-O0或-fno-omit-frame-pointer以下是初始第一次更新的程序集输出时，仍然会出现分段错误：

    .file   "lab7.c"
    .text
    .section    .rodata
.LC0:
    .string "%d"
    .text
    .globl  frameCount
    .type   frameCount, @function
frameCount:
.LFB0:
    .cfi_startproc
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    subq    $32, %rsp
    movl    $0, -4(%rbp)
    movl    $0, %eax
    call    getFP
    movq    %rax, -24(%rbp)
    movq    -24(%rbp), %rax
    movq    (%rax), %rax
    movq    %rax, -16(%rbp)
    jmp .L2
.L3:
    addl    $1, -4(%rbp)
    movl    -4(%rbp), %eax
    movl    %eax, %esi
    movl    $.LC0, %edi
    movl    $0, %eax
    call    printf
    movq    -16(%rbp), %rax
    movq    (%rax), %rax
    movq    %rax, -16(%rbp)
.L2:
    cmpq    $0, -16(%rbp)
    jne .L3
    movl    -4(%rbp), %eax
    leave
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size   frameCount, .-frameCount
    .section    .rodata
.LC1:
    .string "Number of Frames: %dn"
    .text
    .globl  main
    .type   main, @function
main:
.LFB1:
    .cfi_startproc
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    movl    $0, %eax
    call    frameCount
    movl    %eax, %esi
    movl    $.LC1, %edi
    movl    $0, %eax
    call    printf
    movl    $0, %eax
    popq    %rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE1:
    .size   main, .-main
    .ident  "GCC: (GNU) 10.2.1 20200723 (Red Hat 10.2.1-1)"
    .section    .note.GNU-stack,"",@progbits

回答

    pushq   %rbp
    movq    %rsp, %rbp

for (uint64_t *fp = getFP(); fp; fp = (uint64_t *)*fp) count++;