Re: [PATCH 1/2] powerpc/entry: convert to common and generic entry

[Christophe Leroy]

Le 13/09/2024 à 03:40, Luming Yu a écrit :
> On Thu, Sep 12, 2024 at 12:23:29PM +0200, Christophe Leroy wrote:
> > Le 12/09/2024 à 10:24, Luming Yu a écrit :
> > > From: Yu Luming <luming.yu@xxxxxxxxx>
> > >
> > > convert powerpc entry code in syscall and fault to use syscall_work
> > > and irqentry_state as well as common calls from generic entry infrastructure.
> > >
> > > Signed-off-by: Luming Yu <luming.yu@xxxxxxxxxxxx>
> > > ---
> > >    arch/powerpc/Kconfig                   | 1 +
> > >    arch/powerpc/include/asm/hw_irq.h      | 5 +++++
> > >    arch/powerpc/include/asm/processor.h   | 6 ++++++
> > >    arch/powerpc/include/asm/syscall.h     | 5 +++++
> > >    arch/powerpc/include/asm/thread_info.h | 1 +
> > >    arch/powerpc/kernel/syscall.c          | 6 +++++-
> > >    arch/powerpc/mm/fault.c                | 5 +++++
> > >    7 files changed, 28 insertions(+), 1 deletion(-)
> >
> > There is another build problem:
> >
> >    CC      kernel/entry/common.o
> > kernel/entry/common.c: In function 'irqentry_exit':
> > kernel/entry/common.c:335:21: error: implicit declaration of function
> > 'regs_irqs_disabled'; did you mean 'raw_irqs_disabled'?
> > [-Werror=implicit-function-declaration]
> >    335 |         } else if (!regs_irqs_disabled(regs)) {
> >        |                     ^~~~~~~~~~~~~~~~~~
> >        |                     raw_irqs_disabled
> >
> >
> > You have put regs_irqs_disabled() in a section dedicated to PPC64, so it
> > fails on PPC32.
> >
> >
> > After fixing this problem and providing an empty asm/entry-common.h it is
> > now possible to build the kernel. But that's not enough, the board is stuck
> > after:
> >
> > ...
> > [    2.871391] Freeing unused kernel image (initmem) memory: 1228K
> > [    2.877990] Run /init as init process
>
> Thanks for these questions. :-)
> I haven't gotten chance to run it in ppc32 qemu.
> the common syscall trace enter lost this hunk
> -       if (!is_32bit_task())
> -               audit_syscall_entry(regs->gpr[0], regs->gpr[3], regs->gpr[4],
> -                                   regs->gpr[5], regs->gpr[6]);
> -       else
> -               audit_syscall_entry(regs->gpr[0],
> -                                   regs->gpr[3] & 0xffffffff,
> -                                   regs->gpr[4] & 0xffffffff,
> -                                   regs->gpr[5] & 0xffffffff,
> -                                   regs->gpr[6] & 0xffffffff);
> which I don't understand whether we need a arch callbacks for it.

I don't thing so.

As far as I can see, audit_syscall_entry() is called by 
syscall_enter_audit() in kernel/entry/common.c

And the masking of arguments based on is_32bit_task() is done in 
syscall_get_arguments() with is called by
syscall_enter_audit() just before calling audit_syscall_entry() and 
which is an arch callback that does the same as the removed hunk.
> Before I sent out the RFC patch set, the very limited compile and boot test goes well with a ppc64 qemu VM. Surely, there will be a lot of test, debug and following up patch set update that is necessary to make it a complete convert.

Even on ppc64 it doesn't build, at the first place because 
arch/powerpc/include/asm/entry-common.h is missing in your patch. Did 
you forget to 'git add' it ?

And same as with PPC32, when I build PPC64 with an empty 
asm/entry-common.h, it doesn't work. So, I guess you had some needed 
code in that file and you have to send it.