On Wed, Feb 23, 2022 at 9:42 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote: > > On Tue, 01 Feb 2022 07:05:37 PST (-0800), 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..1a666ad299b4 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; > > + > > +#ifdef CONFIG_COMPAT > > + if (is_compat_task()) > > + regs->status |= SR_UXL_32; > > Not sure if I'm just misunderstanding the bit ops here, but aren't we > trying to set the UXL field to 1 (for UXL=32)? That should be a bit > field set op, not just an OR. You are right, I would modify like this: + if (is_compat_task()) + regs->status = （regs->status & ~SR_UXL) | SR_UXL_32; + else +. regs->status = （regs->status & ~SR_UXL) | SR_UXL_64; > > > +#endif > > } > > > > void flush_thread(void) > > Additionally: this isn't really an issue so much with this patch, but it > does bring up that we're relying on someone else to have set UXL=64 on > CONFIG_COMPAT=n systems. I don't see that in any spec anywhere, so we > should really be setting UXL in Linux for all systems (ie, not just those with > COMPAT=y). -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/
