On Tue, Sep 11, 2018 at 04:01:28PM +0300, Andrey Ryabinin wrote: > > > On 09/10/2018 04:06 PM, Will Deacon wrote: > > On Mon, Sep 10, 2018 at 01:53:03PM +0100, Mark Rutland wrote: > >> On Mon, Sep 10, 2018 at 12:33:22PM +0100, Mark Rutland wrote: > >>> On Fri, Sep 07, 2018 at 06:48:10PM +0300, Andrey Ryabinin wrote: > >>>> On 09/07/2018 05:56 PM, Will Deacon wrote: > >>>>> I don't understand this bit: efistub uses the __pi_ prefixed > >>>>> versions of the routines, so why do we need to declare them as weak? > >>>> > >>>> Weak needed because we can't have two non-weak functions with the same > >>>> name. > >>>> > >>>> Alternative approach would be to never use e.g. "strlen" name for asm > >>>> implementation of strlen() under CONFIG_KASAN=y. But that would > >>>> require adding some special ENDPIPROC_KASAN() macro since we want > >>>> __pi_strlen() to point to the asm_strlen(). > >>> > >>> Somehow, what we have today works with CONFIG_FORTIFY_SOURCE, which > >>> AFAICT would suffer from texactly the same problem with things like > >>> memcpy. > >>> > > FORTIFY_SOURCE seems uses "extern inline" to redefine functions. > I obviously cannot make the whole lib/string.c 'extern inline'. > > > >>> So either we're getting away with that by chance already (and should fix > >>> that regardless of this patch), or this is not actually a problem. > >> > >> I now see those functions are marked weak in the assembly > >> implementation; sorry for the noise. > >> > >> Regardless, I still think it's preferable to avoid weak wherever > >> possible. > > > > I was thinking along the same lines, but having played around with the code, > > I agree with Andrey that this appears to be the cleanest solution. > > > > Andrey -- could you respin using WEAK instead of .weak, removing any > > redundant uses of ENTRY in the process? We might also need to throw an > > ALIGN directive into the WEAK definition. > > > > Actually I come up with something that looks decent, without using weak > symbols, see below. > "#ifndef CONFIG_KASAN" could be moved to the header. In that ALIAS probably > should be renamed to > something like NOKASAN_ALIAS().
Hmm, to be honest, I'd kinda got used to the version using weak symbols and I reckon it'd be cleaner still if you respin it using WEAK. Will