Re: [PATCH v5 5/5] powerpc/perf: split callchain.c by bitness

[Christophe Leroy]

Le 30/08/2019 Ã 09:12, Michal SuchÃnek a ÃcritÂ:
> On Fri, 30 Aug 2019 08:42:25 +0200
> Michal SuchÃnek <msuchanek@xxxxxxx> wrote:
>
> > On Fri, 30 Aug 2019 06:35:11 +0000 (UTC)
> > Christophe Leroy <christophe.leroy@xxxxxx> wrote:
> >
> > > On 08/29/2019 10:28 PM, Michal Suchanek wrote:
>
> > >   obj-$(CONFIG_PPC_PERF_CTRS)	+= core-book3s.o bhrb.o
> > > diff --git a/arch/powerpc/perf/callchain_32.c b/arch/powerpc/perf/callchain_32.c
> > > index 0bd4484eddaa..17c43ae03084 100644
> > > --- a/arch/powerpc/perf/callchain_32.c
> > > +++ b/arch/powerpc/perf/callchain_32.c
> > > @@ -15,50 +15,13 @@
> > >   #include <asm/sigcontext.h>
> > >   #include <asm/ucontext.h>
> > >   #include <asm/vdso.h>
> > > -#ifdef CONFIG_PPC64
> > > -#include "../kernel/ppc32.h"
> > > -#endif
> > >   #include <asm/pte-walk.h>
> > >   
> > >   #include "callchain.h"
> > >   
> > >   #ifdef CONFIG_PPC64
> > > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> > > -{
> > > -	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> > > -	    ((unsigned long)ptr & 3))
> > > -		return -EFAULT;
> > > -
> > > -	pagefault_disable();
> > > -	if (!__get_user_inatomic(*ret, ptr)) {
> > > -		pagefault_enable();
> > > -		return 0;
> > > -	}
> > > -	pagefault_enable();
> > > -
> > > -	return read_user_stack_slow(ptr, ret, 4);
> > > -}
> > > -#else /* CONFIG_PPC64 */
> > > -/*
> > > - * On 32-bit we just access the address and let hash_page create a
> > > - * HPTE if necessary, so there is no need to fall back to reading
> > > - * the page tables.  Since this is called at interrupt level,
> > > - * do_page_fault() won't treat a DSI as a page fault.
> > > - */
> > > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> > > -{
> > > -	int rc;
> > > -
> > > -	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> > > -	    ((unsigned long)ptr & 3))
> > > -		return -EFAULT;
> > > -
> > > -	pagefault_disable();
> > > -	rc = __get_user_inatomic(*ret, ptr);
> > > -	pagefault_enable();
> > > -
> > > -	return rc;
> > > -}
> > > +#include "../kernel/ppc32.h"
> > > +#else
> > >   
> > >   #define __SIGNAL_FRAMESIZE32	__SIGNAL_FRAMESIZE
> > >   #define sigcontext32		sigcontext
> > > @@ -95,6 +58,30 @@ struct rt_signal_frame_32 {
> > >   	int			abigap[56];
> > >   };
> > >   
> > > +/*
> > > + * On 32-bit we just access the address and let hash_page create a
> > > + * HPTE if necessary, so there is no need to fall back to reading
> > > + * the page tables.  Since this is called at interrupt level,
> > > + * do_page_fault() won't treat a DSI as a page fault.
> > > + */
> > > +static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> > > +{
> > > +	int rc;
> > > +
> > > +	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> > > +	    ((unsigned long)ptr & 3))
> > > +		return -EFAULT;
> > > +
> > > +	pagefault_disable();
> > > +	rc = __get_user_inatomic(*ret, ptr);
> > > +	pagefault_enable();
> > > +
> > > +	if (IS_ENABLED(CONFIG_PPC32) || !rc)
> > > +		return rc;
> > > +
> > > +	return read_user_stack_slow(ptr, ret, 4);
> > > +}
> > > +
> > >   static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
> > >   {
> > >   	if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
> >
> > I will leave consolidating this function to somebody who knows what the
> > desired semantic is. With a short ifdef section at the top of the file
> > it is a low-hanging fruit.
>
> It looks ok if done as a separate patch.

Yes, doing it as a separate patch is good.

And if you do it before patch 3, then you don't need anymore this ugly 
hack to hide read_user_stack_32()

Christphe

> Thanks
>
> Michal