| Date | Wed, 1 Nov 2017 11:23:46 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 17/18] x86/asm/64: Remove thread_struct::sp0 |
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On Thu, Oct 26, 2017 at 01:26:49AM -0700, Andy Lutomirski wrote: > On x86_64, we can easily calculate sp0 when needed instead of > storing it in thread_struct. > > On x86_32, a similar cleanup would be possible, but it would require > cleaning up the vm86 code first, and that can wait for a later > cleanup series. > > Signed-off-by: Andy Lutomirski <luto@kernel.org>
...
> @@ -816,23 +825,6 @@ static inline void spin_lock_prefetch(const void *x) > .addr_limit = KERNEL_DS, \ > } > > -/* > - * TOP_OF_KERNEL_STACK_PADDING reserves 8 bytes on top of the ring0 stack. > - * This is necessary to guarantee that the entire "struct pt_regs" > - * is accessible even if the CPU haven't stored the SS/ESP registers > - * on the stack (interrupt gate does not save these registers > - * when switching to the same priv ring). > - * Therefore beware: accessing the ss/esp fields of the > - * "struct pt_regs" is possible, but they may contain the > - * completely wrong values. > - */
Why are we removing the explaination of TOP_OF_KERNEL_STACK_PADDING? Is that going to change later?
-- Regards/Gruss, Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
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