Re: [PATCH RFC bpf-next 1/8] kasan: expose generic kasan helpers

Alexei Starovoitov
2026-04-14T14:36:18Z

On Tue, Apr 14, 2026 at 6:13 AM Alexis Lothoré
<alexis.lothore@bootlin.com> wrote:
>
> Hi Andrey, thanks for the prompt review !
>
> On Tue Apr 14, 2026 at 12:19 AM CEST, Andrey Konovalov wrote:
> > On Mon, Apr 13, 2026 at 8:29 PM Alexis Lothoré (eBPF Foundation)
> > <alexis.lothore@bootlin.com> wrote:
> >>
>
> [...]
>
> >> +#ifdef CONFIG_KASAN_GENERIC
> >> +void __asan_load1(void *p);
> >> +void __asan_store1(void *p);
> >> +void __asan_load2(void *p);
> >> +void __asan_store2(void *p);
> >> +void __asan_load4(void *p);
> >> +void __asan_store4(void *p);
> >> +void __asan_load8(void *p);
> >> +void __asan_store8(void *p);
> >> +void __asan_load16(void *p);
> >> +void __asan_store16(void *p);
> >> +#endif /* CONFIG_KASAN_GENERIC */
> >
> > This looks ugly, let's not do this unless it's really required.
> >
> > You can just use kasan_check_read/write() instead - these are public
> > wrappers around the same shadow memory checking functions. And they
> > also work with the SW_TAGS mode, in case the BPF would want to use
> > that mode at some point. (For HW_TAGS, we only have kasan_check_byte()
> > that checks a single byte, but it can be extended in the future if
> > required to be used by BPF.)
>
> ACK, I'll try to use those kasan_check_read and kasan_check_write rather
> than __asan_{load,store}X.

No. The performance penalty will be too high.
hw_tags won't work without corresponding JIT work.
I see no point sacrificing performance for aesthetics.
__asan_load/storeX is what compilers emit.
In that sense JIT is a compiler it should emit exactly the same.