On Tue, 2007-03-13 at 16:57 +0100, Andi Kleen wrote: > On Tue, Mar 13, 2007 at 05:23:52PM +1100, Rusty Russell wrote: > > In particular, it's been put in GCC 4.1 for > > CONFIG_CC_STACKPROTECTOR, which assumes %gs:40 will give the stack > > canary. > > Yes that was always ugly, but I don't know a better way.
Well, "%gs:__gcc_stack_protector" would have been better. We could have defined __gcc_stack_protector as an absolute symbol (0x40) at the moment, and made it a real per-cpu var later. > > For the record: the PDA should never have existed, that's what percpu > > vars were supposed to be for. Something went wrong here 8( > > PDA predates per cpu. Indeed, but I should have converted it over back in 2003 (?) when the per-cpu stuff went in 8( > > The ideal solution has always been to use __thread, but no architecture > > has yet managed it (I tried for i386, and it quickly caused unbearable > > I tried it too, but __thread is hopeless for kernel code > > > pain). On x86-64 that uses "%fs" on x86-64, not "%gs" as the kernel > > does, but I might try that if I feel particularly masochistic soon... > > Then swapgs wouldn't work anymore (there is no swapfs) Good point. Thanks, Rusty. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/