The Linux VirtualMemory Map (as seen by a UserSpace program)
| Starts at | Contains | ffffffff |< End of the universe | ffffe000 |< vsyscall table (new in 2.5.x) | c0000000 |< Off limits, reserved for the kernel | bfffffff |< 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
$ 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)
$ cat > x.c
- 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.)
$ cat > x2.c
- include <stdio.h>
int main(void) {char c;printf("%p\n", &c); return 0;} $ gcc -o x2 x2.c && ./x2 0xbffffab7
$ perl -e 'my $var; print \$var . "\n"'
SCALAR(0x814f38c)
(note that this is the address in the Perl interpreter)
$ cat > x3.c
- include <stdio.h>
- include <stdlib.h>
int main(void) {char *p=!malloc(3);printf("%p\n", p); return 0;} $ gcc -o x3 x3.c && ./x3 0x8049628
Also,
cat /proc/pid/maps
gives you the memory map for a program :)
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