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#include <syscall-nr.h>
#include <stdio.h>
#include "tests/lib.h"
#include "tests/main.h"
/**
* From threads/vaddr.h:
*/
#define BITMASK(SHIFT, CNT) (((1ul << (CNT)) - 1) << (SHIFT))
#define PGSHIFT 0 /* Index of first offset bit. */
#define PGBITS 12 /* Number of offset bits. */
#define PGSIZE (1 << PGBITS) /* Bytes in a page. */
#define PGMASK BITMASK(PGSHIFT, PGBITS) /* Page offset bits (0:12). */
static inline void *pg_round_up (const void *va) {
return (void *) (((uintptr_t) va + PGSIZE - 1) & ~PGMASK);
}
/**
* External symbol which address is the first address after all data in the BSS segment.
*/
extern int _end_bss;
void test_main(void)
{
// Get the address of the first unmapped page in the process.
unsigned page = (unsigned)pg_round_up(&_end_bss);
// Reserve space for the syscall number and a part of the exit code (1 out of 4 bytes).
unsigned base = page - sizeof(int) - 1;
// Call a syscall.
asm volatile (
"movl %%esp, %%edi;" // Save the stack pointer in case we survive.
"movl %0, %%esp;" // Set stack pointer.
"movl %1, (%%esp);" // Try to call SYS_EXIT
"movb $1, 4(%%esp);" // Set the first byte of the syscall number to zero.
"int $0x30;" // Trigger syscall.
"movl %%edi, %%esp;" // Restore the old stack if we survivied.
:
: "r" (base),
"i" (SYS_EXIT)
: "%esp", "%eax", "%edi");
fail("should have died.");
}
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