Messages in this thread | | | Subject | Re: _proxy_pda still makes linking modules fail | From | Rusty Russell <> | Date | Wed, 14 Mar 2007 13:17:03 +1100 |
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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.
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