[PATCH 1/2] riscv: Fix asan-stack clang build

[Palmer Dabbelt]

On Wed, 27 Oct 2021 21:15:28 PDT (-0700), alexandre.ghiti at canonical.com wrote:
> On Thu, Oct 28, 2021 at 1:06 AM Palmer Dabbelt <palmer at dabbelt.com> wrote:
>>
>> On Tue, 26 Oct 2021 21:58:42 PDT (-0700), alexandre.ghiti at canonical.com wrote:
>> > Nathan reported that because KASAN_SHADOW_OFFSET was not defined in
>> > Kconfig, it prevents asan-stack from getting disabled with clang even
>> > when CONFIG_KASAN_STACK is disabled: fix this by defining the
>> > corresponding config.
>> >
>> > Reported-by: Nathan Chancellor <nathan at kernel.org>
>> > Signed-off-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
>> > ---
>> >  arch/riscv/Kconfig             | 6 ++++++
>> >  arch/riscv/include/asm/kasan.h | 3 +--
>> >  arch/riscv/mm/kasan_init.c     | 3 +++
>> >  3 files changed, 10 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> > index c1abbc876e5b..79250b1ed54e 100644
>> > --- a/arch/riscv/Kconfig
>> > +++ b/arch/riscv/Kconfig
>> > @@ -162,6 +162,12 @@ config PAGE_OFFSET
>> >       default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
>> >       default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
>> >
>> > +config KASAN_SHADOW_OFFSET
>> > +     hex
>> > +     depends on KASAN_GENERIC
>> > +     default 0xdfffffc800000000 if 64BIT
>> > +     default 0xffffffff if 32BIT
>>
>> I thought I posted this somewhere, but this is exactly what my first
>> guess was.  The problem is that it's hanging on boot for me.  I don't
>> really have anything exotic going on, it's just a defconfig with
>> CONFIG_KASAN=y running in QEMU.
>>
>> Does this boot for you?
>
> Yes with the 2nd patch of this series which fixes the issue
> encountered here. And that's true I copied/pasted this part of your
> patch which was better than what I had initially done, sorry I should
> have mentioned you did that, please add a Codeveloped-by or something
> like that.

Not sure if I'm missing something, but it's still not booting for me.  
I've put what I'm testing on palmer/to-test, it's these two on top of 
fixes and merged into Linus' tree

    *   6d7d351902ff - (HEAD -> to-test, palmer/to-test) Merge remote-tracking branch 'palmer/fixes' into to-test (7 minutes ago) <Palmer Dabbelt>
    |\
    | * 782551edf8f8 - (palmer/fixes) riscv: Fix CONFIG_KASAN_STACK build (6 hours ago) <Alexandre Ghiti>
    | * 47383e5b3c4f - riscv: Fix asan-stack clang build (6 hours ago) <Alexandre Ghiti>
    | * 64a19591a293 - (riscv/fixes) riscv: fix misalgned trap vector base address (9 hours ago) <Chen Lu>
    * |   1fc596a56b33 - (palmer/master, linus/master, linus/HEAD, master) Merge tag 'trace-v5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace (11 hours ago) <Linus Torvalds>

Am I missing something else?

>
> Thanks,
>
> Alex
>
>>
>> > +
>> >  config ARCH_FLATMEM_ENABLE
>> >       def_bool !NUMA
>> >
>> > diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h
>> > index a2b3d9cdbc86..b00f503ec124 100644
>> > --- a/arch/riscv/include/asm/kasan.h
>> > +++ b/arch/riscv/include/asm/kasan.h
>> > @@ -30,8 +30,7 @@
>> >  #define KASAN_SHADOW_SIZE    (UL(1) << ((CONFIG_VA_BITS - 1) - KASAN_SHADOW_SCALE_SHIFT))
>> >  #define KASAN_SHADOW_START   KERN_VIRT_START
>> >  #define KASAN_SHADOW_END     (KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
>> > -#define KASAN_SHADOW_OFFSET  (KASAN_SHADOW_END - (1ULL << \
>> > -                                     (64 - KASAN_SHADOW_SCALE_SHIFT)))
>> > +#define KASAN_SHADOW_OFFSET  _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
>> >
>> >  void kasan_init(void);
>> >  asmlinkage void kasan_early_init(void);
>> > diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
>> > index d7189c8714a9..8175e98b9073 100644
>> > --- a/arch/riscv/mm/kasan_init.c
>> > +++ b/arch/riscv/mm/kasan_init.c
>> > @@ -17,6 +17,9 @@ asmlinkage void __init kasan_early_init(void)
>> >       uintptr_t i;
>> >       pgd_t *pgd = early_pg_dir + pgd_index(KASAN_SHADOW_START);
>> >
>> > +     BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
>> > +             KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
>> > +
>> >       for (i = 0; i < PTRS_PER_PTE; ++i)
>> >               set_pte(kasan_early_shadow_pte + i,
>> >                       mk_pte(virt_to_page(kasan_early_shadow_page),