On Tue, Jan 17, 2012 at 9:05 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > On 01/17, Andrew Lutomirski wrote: >> >> (is_compat_task says whether the executable was marked as 32-bit. The >> actual execution mode is determined by the cs register, which the user >> can control. > > Confused... Afaics, TIF_IA32 says that the binary is 32-bit (this comes > along with TS_COMPAT). > > TS_COMPAT says that, say, the task did "int 80" to enters the kernel. > 64-bit or not, we should treat is as 32-bit in this case. I think you're right, and checking which entry was used is better than checking the cs register (since 64-bit code can use int80). That's what I get for insufficiently careful reading of the assembly. (And for going from memory from when I wrote the vsyscall emulation code -- that code is entered from a page fault, so the entry point used is irrelevant.) --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
