Re: [PATCH V7 13/20] riscv: compat: process: Add UXL_32 support in start_thread

[Ben Dooks]

On 11/03/2022 02:38, Guo Ren wrote:
> Hi Arnd,
>
> On Mon, Feb 28, 2022 at 12:30 AM <guoren@xxxxxxxxxx> wrote:
> > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> >
> > If the current task is in COMPAT mode, set SR_UXL_32 in status for
> > returning userspace. We need CONFIG _COMPAT to prevent compiling
> > errors with rv32 defconfig.
> >
> > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> > Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
> > Cc: Arnd Bergmann <arnd@xxxxxxxx>
> > Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
> > ---
> >   arch/riscv/kernel/process.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> >
> > diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
> > index 03ac3aa611f5..54787ca9806a 100644
> > --- a/arch/riscv/kernel/process.c
> > +++ b/arch/riscv/kernel/process.c
> > @@ -97,6 +97,11 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
> >          }
> >          regs->epc = pc;
> >          regs->sp = sp;
> > +
> FIxup:
>
> + #ifdef CONFIG_COMPAT
> > +       if (is_compat_task())
> > +               regs->status = (regs->status & ~SR_UXL) | SR_UXL_32;
> > +       else
> > +               regs->status = (regs->status & ~SR_UXL) | SR_UXL_64;
> + #endif
>
> We still need "#ifdef CONFIG_COMPAT" here, because for rv32 we can't
> set SR_UXL at all. SR_UXL is BIT[32, 33].

would an if (IS_ENABLED(CONFIG_COMPAT)) { } around the lot be better
than an #ifdef here?

> >   }
> >
> >   void flush_thread(void)
> > --
> > 2.25.1


--
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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