Penguin
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The Linux Virtual Memory Map (as seen by a userspace program)

| Starts at | Contains | ffffffff |< End of the universe | c0000000 |< Off limits, reserved for the kernel | xxxxxxxx |< Process stack (grows down) | bffff000 |< Process heap (grows up) | 40000000 |< Libraries | zzzzzzzz |< Unused | yyyyyyyy |< .bss segment, uninitialised program data | xxxxxxxx |< .data segment, initialised program data | 08048000 |< .text segment, program code | 00000000 |< Unmapped to trap NULL pointers

Practical examples

Library-mapped memory (using ldd(1))

$ ldd /bin/ls

librt.so.1 => /lib/librt.so.1 (0x40026000) libc.so.6 => /lib/libc.so.6 (0x40038000) libpthread.so.0 => /lib/libpthread.so.0 (0x4016a000) /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

Program code

$ cat > x.c

  1. include <stdio.h>

int main(void) {printf("%p\n", main);return 0;} $ gcc -o x x.c && ./x 0x8048344 $

(this is printing the address of the main function.)

Process Heap

$ cat > x2.c

  1. include <stdio.h>

int main(void) {char c;printf("%p\n", &c); return 0;} $ gcc -o x2 x2.c && ./x2 0xbffffab7

Process Data and bss segment

$ perl -e 'my $var; print \$var . "\n"'

SCALAR(0x814f38c)

(note that this is the address in the Perl interpreter)

$ cat > x3.c

  1. include <stdio.h>
  2. include <stdlib.h>

int main(void) {char *p=malloc(3);printf("%p\n", p); return 0;} $ gcc -o x3 x3.c && ./x3 0x8049628