Laurent Desnogues wrote: > A recent compiler (gcc 4.4.0) produces this code for a statically > compiled program: > > 00000000005779e0 <time>: > 5779e0: 48 83 ec 08 sub $0x8,%rsp > 5779e4: 48 c7 c0 00 04 60 ff mov $0xffffffffff600400,%rax > 5779eb: ff d0 callq *%rax > 5779ed: 48 83 c4 08 add $0x8,%rsp > 5779f1: c3 retq
Yes. It's a fixed address. See the kernel at linux/arch/x86/kernel/vsyscall_64.c. There are only 3 vsyscall functions defined: vgettimeofday, vtime and vgetcpu. Even though it's a statically linked program, I'm not sure if the above code will work on really old kernels. The vsyscall page is different from the vdso, which has variable address, and the address is supplied to Glibc. vdso provides nearly the same functions in a different way. -- Jamie
