linux-kernel - Re: [RFC PATCH 3/4] riscv: Introduce is_compat

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Date: Fri, 22 Dec 2023 14:14:21 -0300
From: Leonardo Bras <leobras@...hat.com>
To: Guo Ren <guoren@...nel.org>
Cc: Leonardo Bras <leobras@...hat.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Eric Biederman <ebiederm@...ssion.com>,
	Kees Cook <keescook@...omium.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Andy Chiu <andy.chiu@...ive.com>,
	Greg Ungerer <gerg@...nel.org>,
	Vincent Chen <vincent.chen@...ive.com>,
	Xiao Wang <xiao.w.wang@...el.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Kemeng Shi <shikemeng@...weicloud.com>,
	David Hildenbrand <david@...hat.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Qinglin Pan <panqinglin2020@...as.ac.cn>,
	Greentime Hu <greentime.hu@...ive.com>,
	Björn Töpel <bjorn@...osinc.com>,
	Clément Léger <cleger@...osinc.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [RFC PATCH 3/4] riscv: Introduce is_compat_thread() into compat.h

On Fri, Dec 22, 2023 at 07:20:36PM +0800, Guo Ren wrote:
> On Fri, Dec 22, 2023 at 3:47 PM Leonardo Bras <leobras@...hat.com> wrote:
> >
> > task_user_regset_view() makes use of a function very similar to
> > is_compat_task(), but pointing to a any thread.
> >
> > In arm64 asm/compat.h there is a function very similar to that:
> > is_compat_thread(struct thread_info *thread)
> >
> > Copy this function to riscv asm/compat.h and make use of it into
> > task_user_regset_view().
> >
> > Also, introduce a compile-time test for CONFIG_COMPAT and simplify the
> > function code by removing the #ifdef.
> >
> > Signed-off-by: Leonardo Bras <leobras@...hat.com>
> > ---
> >  arch/riscv/include/asm/compat.h | 8 ++++++++
> >  arch/riscv/kernel/ptrace.c      | 6 +++---
> >  2 files changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/compat.h b/arch/riscv/include/asm/compat.h
> > index 91517b51b8e27..da4b28cd01a95 100644
> > --- a/arch/riscv/include/asm/compat.h
> > +++ b/arch/riscv/include/asm/compat.h
> > @@ -20,6 +20,14 @@ static inline int is_compat_task(void)
> >         return test_thread_flag(TIF_32BIT);
> >  }
> >
> > +static inline int is_compat_thread(struct thread_info *thread)
> > +{
> > +       if (!IS_ENABLED(CONFIG_COMPAT))
> > +               return 0;
> We also could put this into is_compat_task().
> 

Yeah! it's done in a previous patch. :)

> > +
> > +       return test_ti_thread_flag(thread, TIF_32BIT);
> > +}
> > +
> >  struct compat_user_regs_struct {
> >         compat_ulong_t pc;
> >         compat_ulong_t ra;
> > diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
> > index 2afe460de16a6..f362832123616 100644
> > --- a/arch/riscv/kernel/ptrace.c
> > +++ b/arch/riscv/kernel/ptrace.c
> > @@ -374,14 +374,14 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
> >
> >         return ret;
> >  }
> > +#else
> > +static const struct user_regset_view compat_riscv_user_native_view = {};
> >  #endif /* CONFIG_COMPAT */
> >
> >  const struct user_regset_view *task_user_regset_view(struct task_struct *task)
> >  {
> > -#ifdef CONFIG_COMPAT
> > -       if (test_tsk_thread_flag(task, TIF_32BIT))
> > +       if (is_compat_thread(&task->thread_info))
> >                 return &compat_riscv_user_native_view;
> >         else
> > -#endif
> >                 return &riscv_user_native_view;
> >  }
> > --
> > 2.43.0
> >
> LGTM
> 
> Reviewed-by: Guo Ren <guoren@...nel.org>

Thanks!
Leo

> 
> -- 
> Best Regards
>  Guo Ren
>