A program that tests valgrind's '--max-stackframe' option on an x86-64 running Linux

tst-stack-switch-x86_64-linux.c

/*
$ gcc -Wall -pedantic -o test-stack-switching test-stack-switching.c
$ valgrind ./test-stack-switching

Expected program output:
> 55
> 55
> 55

Expected valgrind output: Three warnings that look like;
> client switching stacks?  SP change: 0xffefff880 --> 0x5101b78
*/

#include <stdio.h>
#include <stdlib.h>

#define STACK_SIZE 2500000

int buf[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

__attribute__ ((noreturn))
void callee (int *);

__attribute__ ((noreturn))
void call_on_new_stack (char *, void (*)(int *), int *);

char *prepare_new_stack (void);

int
main (void)
{
  char *new_stack;

  new_stack = prepare_new_stack ();
  call_on_new_stack (new_stack, callee, buf);
  return 0;
}

void
callee (int *arr)
{
  int i, sum = 0;
  static int remaining_calls = 2;
  char *new_stack;

  for (i = 0; i < 10; i++)
    {
      sum += arr[i];
    }
  printf ("%d\n", sum);

  if (remaining_calls--)
    {
      new_stack = prepare_new_stack ();
      call_on_new_stack (new_stack, callee, buf);
    }
  exit (0);
}

void
call_on_new_stack (char *stack, void (*f) (int *), int *arg)
{
  asm ("movq %rdi, %rsp\n\t"    /* Set stack.  */
       "pushq $0\n\t"           /* Return address is 0, we'll never return.  */
       "movq %rdx, %rdi\n\t"    /* arg for f.  */
       "pushq %rsi\n\t"         /* push function addr for use by 'ret' insn.  */
       "ret\n\t"                /* this will pop 'f's addr and execute it.  */
       "ud2");                  /* invalid opcode. Should never be executed.  */
  exit (0);
}

char *
prepare_new_stack (void)
{
  static char *block = NULL;
  static char *stacks[3];
  static int call_count = 0;

  if (!block)
    {
      block = malloc (4 * STACK_SIZE);
      /* We expect three calls, each in a new stack.  */
      stacks[0] = block + 2 * STACK_SIZE;
      stacks[1] = block + 3 * STACK_SIZE; /* Guarantees huge increase in sp.  */
      stacks[2] = block + 1 * STACK_SIZE; /* Guarantees huge decrease in sp.  */
    }
  return stacks[call_count++];
}