[PATCH] riscv: Align on L1_CACHE_BYTES when STRICT_KERNEL_RWX

[Atish Patra]

On Mon, Jan 11, 2021 at 11:40 AM Atish Patra <atishp at atishpatra.org> wrote:
>
> On Sat, Jan 9, 2021 at 1:35 AM Geert Uytterhoeven <geert at linux-m68k.org> wrote:
> >
> > Hi Atish,
> >
> > On Fri, Jan 8, 2021 at 8:12 PM Atish Patra <atishp at atishpatra.org> wrote:
> > > On Fri, Jan 8, 2021 at 8:37 AM Geert Uytterhoeven <geert at linux-m68k.org> wrote:
> > > > On Mon, Nov 16, 2020 at 1:59 PM Sebastien Van Cauwenberghe
> > > > <svancau at gmail.com> wrote:
> > > > > From 5690c2f91d87a007babb13e2d2c9c45d1ff68b7a Mon Sep 17 00:00:00 2001
> > > > > From: Sebastien Van Cauwenberghe <svancau at gmail.com>
> > > > > Date: Mon, 16 Nov 2020 13:37:32 +0100
> > > > > Subject: [PATCH] riscv: Align on L1_CACHE_BYTES when STRICT_KERNEL_RWX is
> > > > >  disabled
> > > > >
> > > > > Allows the sections to be aligned on smaller boundaries and
> > > > > therefore results in a smaller kernel image size.
> > > > >
> > > > > Signed-off-by: Sebastien Van Cauwenberghe <svancau at gmail.com>
> > > >
> > > > Thanks for your patch!
> > > >
> > > > > --- a/arch/riscv/include/asm/set_memory.h
> > > > > +++ b/arch/riscv/include/asm/set_memory.h
> > > > > @@ -27,14 +27,14 @@ int set_direct_map_default_noflush(struct page *page);
> > > > >
> > > > >  #endif /* __ASSEMBLY__ */
> > > > >
> > > > > -#ifdef CONFIG_ARCH_HAS_STRICT_KERNEL_RWX
> > > > > +#ifdef CONFIG_STRICT_KERNEL_RWX
> > > > >  #ifdef CONFIG_64BIT
> > > > >  #define SECTION_ALIGN (1 << 21)
> > > > >  #else
> > > > >  #define SECTION_ALIGN (1 << 22)
> > > > >  #endif
> > > > > -#else /* !CONFIG_ARCH_HAS_STRICT_KERNEL_RWX */
> > > > > +#else /* !CONFIG_STRICT_KERNEL_RWX */
> > > > >  #define SECTION_ALIGN L1_CACHE_BYTES
> > > > > -#endif /* CONFIG_ARCH_HAS_STRICT_KERNEL_RWX */
> > > > > +#endif /* CONFIG_STRICT_KERNEL_RWX */
> > > > >
> > > > >  #endif /* _ASM_RISCV_SET_MEMORY_H */
> > > >
> > > > Since commit 19a00869028f4a28 ("RISC-V: Protect all kernel sections
> > > > including init early"), you also need (whitespace-damaged-gmail-patch):
> > > >
> > > > --- a/arch/riscv/kernel/setup.c
> > > > +++ b/arch/riscv/kernel/setup.c
> > > > @@ -293,6 +293,8 @@ void free_initmem(void)
> > > >         unsigned long init_begin = (unsigned long)__init_begin;
> > > >         unsigned long init_end = (unsigned long)__init_end;
> > > >
> > > > -       set_memory_rw_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
> > > > +       if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
> > > > +               set_memory_rw_nx(init_begin,
> > > > +                                (init_end - init_begin) >> PAGE_SHIFT);
> > > >         free_initmem_default(POISON_FREE_INITMEM);
> > > >  }
> > > >
> > >
> > > Thanks for the fix. I guess you need to disable
> > > CONFIG_STRICT_KERNEL_RWX explicitly
> > > to notice this issue.
> >
> > Indeed.
> >
> > > > Else it crashes here without any kernel output.
> > > >
> > > > Feel free to fold this into your patch.
> > > >
> > >
> > > IMO, this can be a separate patch with Fixes tag.
> >
> > Why? Sebastien's patch (which hasn't been applied yet) no longer works
> > due to interaction with a commit in v5.11-rc1.
> >
>
> Technically, Sebastien's patch was an improvement while this one fixes
> an issue so that the Fixes tag can be added.
> But the original patch was merged in this cycle only. So these changes
> can be a single change as long as it is sent as an rc fix.
> I am fine with either way.
>
> @Sebastien: Can you send the updated patch soon so that palmer can
> pull this one as an RC fix?
>

I have sent the fixes to the mailing list with appropriate tags.

>
> > Gr{oetje,eeting}s,
> >
> >                         Geert
> >
> > --
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
> >
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                 -- Linus Torvalds
>
>
>
> --
> Regards,
> Atish



-- 
Regards,
Atish