Re: [PATCH -fixes] riscv: Re-introduce global icache flush in patch_text_XXX()

[Palmer Dabbelt]

On Thu, 01 Aug 2024 10:32:28 PDT (-0700), samuel.holland@xxxxxxxxxx wrote:
> Hi Alex,
>
> On 2024-07-30 8:59 AM, Alexandre Ghiti wrote:
> > commit edf2d546bfd6 ("riscv: patch: Flush the icache right after
> > patching to avoid illegal insns") mistakenly removed the global icache
> > flush in patch_text_nosync() and patch_text_set_nosync() functions, so
> > reintroduce them.
> >
> > Fixes: edf2d546bfd6 ("riscv: patch: Flush the icache right after patching to avoid illegal insns")
> > Reported-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
> > Closes: https://lore.kernel.org/linux-riscv/CAHVXubh8Adb4=-vN4cSh0FrZ16TeOKJbLj4AF09QC241bRk1Jg@xxxxxxxxxxxxxx/T/#m800757c26f72a1d45c240cb815650430166c82ea
>
> Shouldn't this use the permalink for the specific message, not the thread?
>
> > Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
> > ---
> >  arch/riscv/kernel/patch.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
> > index ab03732d06c4..91edfd764ed9 100644
> > --- a/arch/riscv/kernel/patch.c
> > +++ b/arch/riscv/kernel/patch.c
> > @@ -205,6 +205,9 @@ int patch_text_set_nosync(void *addr, u8 c, size_t len)
> >
> >  	ret = patch_insn_set(tp, c, len);
> >
> > +	if (!ret)
> > +		flush_icache_range((uintptr_t)tp, (uintptr_t)tp + len);
>
> This patch was based on an old tree from before
> https://git.kernel.org/riscv/c/47742484ee16 removed the "tp" variable. While it
> still compiles because flush_icache_range() is a macro that discards its
> arguments, it will be confusing to anyone reading the code.

Thanks.  Alex is going to spin a new one, so I dropped this.

> Regards,
> Samuel
>
> > +
> >  	return ret;
> >  }
> >  NOKPROBE_SYMBOL(patch_text_set_nosync);
> > @@ -237,6 +240,9 @@ int patch_text_nosync(void *addr, const void *insns, size_t len)
> >
> >  	ret = patch_insn_write(tp, insns, len);
> >
> > +	if (!ret)
> > +		flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len);
> > +
> >  	return ret;
> >  }
> >  NOKPROBE_SYMBOL(patch_text_nosync);