Messages in this thread | | | Date | Fri, 25 Feb 2022 14:46:19 -0800 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v2 16/39] x86/bpf: Add ENDBR instructions to prologue and trampoline |
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On Fri, Feb 25, 2022 at 01:24:58PM +0100, Peter Zijlstra wrote: > On Thu, Feb 24, 2022 at 03:37:31PM -0800, Josh Poimboeuf wrote: > > > > @@ -2028,10 +2052,11 @@ int arch_prepare_bpf_trampoline(struct b > > > /* skip patched call instruction and point orig_call to actual > > > * body of the kernel function. > > > */ > > > - orig_call += X86_PATCH_SIZE; > > > + orig_call += X86_PATCH_SIZE + 4*HAS_KERNEL_IBT; > > > > All the "4*HAS_KERNEL_IBT" everywhere is cute, but you might as well > > just have IBT_ENDBR_SIZE (here and in other patches). > > So there's two forms of this, only one has the 4 included: > > (x * (1 + HAS_KERNEL_IBT)) > (x + 4*HAS_KERNEL_IBT) > > If I include the 4, then the first form would become something like: > > (x * (1 + !!IBT_ENDBR_SIZE)) > > that ok?
I don't have a strong preference, but there's no harming in having both IBT_ENDBR_SIZE and HAS_KERNEL_IBT if it would help readability.
-- Josh
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