linux-kernel - Re: [PATCH v6 4/6] powerpc/64: make buildable without CONFIG

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Message-ID: <20190830223535.7ef0b76f@kitsune.suse.cz>
Date:   Fri, 30 Aug 2019 22:35:35 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     linuxppc-dev@...ts.ozlabs.org,
        David Hildenbrand <david@...hat.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        David Howells <dhowells@...hat.com>,
        Paul Mackerras <paulus@...ba.org>,
        Breno Leitao <leitao@...ian.org>,
        Michael Neuling <mikey@...ling.org>,
        Nicolai Stange <nstange@...e.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Allison Randal <allison@...utok.net>,
        Firoz Khan <firoz.khan@...aro.org>,
        Joel Stanley <joel@....id.au>, Arnd Bergmann <arnd@...db.de>,
        Nicholas Piggin <npiggin@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Christian Brauner <christian@...uner.io>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Hari Bathini <hbathini@...ux.ibm.com>
Subject: Re: [PATCH v6 4/6] powerpc/64: make buildable without CONFIG_COMPAT

On Fri, 30 Aug 2019 22:21:09 +0200
Christophe Leroy <christophe.leroy@....fr> wrote:

> Le 30/08/2019 à 20:57, Michal Suchanek a écrit :
> > There are numerous references to 32bit functions in generic and 64bit
> > code so ifdef them out.
> > 
> > Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> > ---
> > v2:
> > - fix 32bit ifdef condition in signal.c
> > - simplify the compat ifdef condition in vdso.c - 64bit is redundant
> > - simplify the compat ifdef condition in callchain.c - 64bit is redundant
> > v3:
> > - use IS_ENABLED and maybe_unused where possible
> > - do not ifdef declarations
> > - clean up Makefile
> > v4:
> > - further makefile cleanup
> > - simplify is_32bit_task conditions
> > - avoid ifdef in condition by using return
> > v5:
> > - avoid unreachable code on 32bit
> > - make is_current_64bit constant on !COMPAT
> > - add stub perf_callchain_user_32 to avoid some ifdefs
> > v6:
> > - consolidate current_is_64bit
> > ---
> >   arch/powerpc/include/asm/thread_info.h |  4 +--
> >   arch/powerpc/kernel/Makefile           |  7 +++--
> >   arch/powerpc/kernel/entry_64.S         |  2 ++
> >   arch/powerpc/kernel/signal.c           |  3 +--
> >   arch/powerpc/kernel/syscall_64.c       |  6 ++---
> >   arch/powerpc/kernel/vdso.c             |  5 ++--
> >   arch/powerpc/perf/callchain.c          | 37 +++++++++++++++-----------
> >   7 files changed, 33 insertions(+), 31 deletions(-)
> >   
> 
> [...]
> 
> > diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> > index b7cdcce20280..788ad2c63f18 100644
> > --- a/arch/powerpc/perf/callchain.c
> > +++ b/arch/powerpc/perf/callchain.c
> > @@ -15,7 +15,7 @@
> >   #include <asm/sigcontext.h>
> >   #include <asm/ucontext.h>
> >   #include <asm/vdso.h>
> > -#ifdef CONFIG_PPC64
> > +#ifdef CONFIG_COMPAT
> >   #include "../kernel/ppc32.h"
> >   #endif
> >   #include <asm/pte-walk.h>
> > @@ -268,16 +268,6 @@ static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
> >   	}
> >   }
> >   
> > -static inline int current_is_64bit(void)
> > -{
> > -	/*
> > -	 * We can't use test_thread_flag() here because we may be on an
> > -	 * interrupt stack, and the thread flags don't get copied over
> > -	 * from the thread_info on the main stack to the interrupt stack.
> > -	 */
> > -	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
> > -}
> > -
> >   #else  /* CONFIG_PPC64 */
> >   static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> >   {
> > @@ -314,11 +304,6 @@ static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry
> >   {
> >   }
> >   
> > -static inline int current_is_64bit(void)
> > -{
> > -	return 0;
> > -}
> > -
> >   static inline int valid_user_sp(unsigned long sp, int is_64)
> >   {
> >   	if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
> > @@ -334,6 +319,7 @@ static inline int valid_user_sp(unsigned long sp, int is_64)
> >   
> >   #endif /* CONFIG_PPC64 */
> >   
> > +#if defined(CONFIG_PPC32) || defined(CONFIG_COMPAT)
> >   /*
> >    * Layout for non-RT signal frames
> >    */
> > @@ -475,6 +461,25 @@ static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
> >   		sp = next_sp;
> >   	}
> >   }
> > +#else /* 32bit */
> > +static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
> > +				   struct pt_regs *regs)
> > +{
> > +	(void)&read_user_stack_32; /* unused if !COMPAT */  
> 
> You don't need that anymore do you ?

Yes, this part is not needed. It was removed later anyway but this
state is broken.

Thanks

Michal

> 
> Christophe
> 
> > +}
> > +#endif /* 32bit */
> > +
> > +static inline int current_is_64bit(void)
> > +{
> > +	if (!IS_ENABLED(CONFIG_COMPAT))
> > +		return IS_ENABLED(CONFIG_PPC64);
> > +	/*
> > +	 * We can't use test_thread_flag() here because we may be on an
> > +	 * interrupt stack, and the thread flags don't get copied over
> > +	 * from the thread_info on the main stack to the interrupt stack.
> > +	 */
> > +	return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
> > +}
> >   
> >   void
> >   perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
> >