Messages in this thread | | | Date | Tue, 15 Aug 2023 17:10:32 -0700 | From | Josh Poimboeuf <> | Subject | Re: [PATCH] x86/static_call: Fix __static_call_fixup() |
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On Wed, Aug 16, 2023 at 01:08:09AM +0200, Peter Zijlstra wrote: > bool __static_call_fixup(void *tramp, u8 op, void *dest) > { > + /* > + * Not all .return_sites are a static_call trampoline (most are not). > + * Check if the next 3 bytes are still kernel text, if not, then this
s/3/7 ?
> + * definitely is not a trampoline and we need not worry further. > + * > + * This avoids the memcmp() below tripping over pagefaults etc.. > + */ > + if (!kernel_text_address(tramp+7)) > + return false; > + > if (memcmp(tramp+5, tramp_ud, 3)) { > /* Not a trampoline site, not our problem. */ > return false;
kernel_text_address() can be quite heavyweight to call in a loop during module loading. Maybe that doesn't matter much. But it would be a lot faster to only call kernel_text_address() if tramp+7 is on the next page.
-- Josh
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