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From:   LEROY Christophe <christophe.leroy@csgroup.eu>
To:     Weizhao Ouyang <o451686892@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>
CC:     Rich Felker <dalias@libc.org>,
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        Guo Ren <guoren@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
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        Will Deacon <will@kernel.org>,
        "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Helge Deller <deller@gmx.de>,
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        <linux-arm-kernel@lists.infradead.org>,
        Michal Simek <monstr@monstr.eu>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
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        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Mackerras <paulus@samba.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "David S. Miller" <davem@davemloft.net>
Subject: RE: [PATCH v3] ftrace: Cleanup ftrace_dyn_arch_init()
Thread-Topic: [PATCH v3] ftrace: Cleanup ftrace_dyn_arch_init()
Thread-Index: AQHXo9AGcZMAst5pGUmuiVdX2ZKaD6uYuHhw
Date:   Tue, 7 Sep 2021 15:55:58 +0000
Message-ID: <MRZP264MB298824D80E6C0ADCB5EA1D9AEDD39@MRZP264MB2988.FRAP264.PROD.OUTLOOK.COM>
References: <20210907100524.1454928-1-o451686892@gmail.com>
In-Reply-To: <20210907100524.1454928-1-o451686892@gmail.com>
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> -----Message d'origine-----
> De : Linuxppc-dev <linuxppc-dev-
> bounces+christophe.leroy=3Dcsgroup.eu@lists.ozlabs.org> De la part de Wei=
zhao
> Ouyang
>
> Most of ARCHs use empty ftrace_dyn_arch_init(), introduce a weak common
> ftrace_dyn_arch_init() to cleanup them.
>
> Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
> Acked-by: Heiko Carstens <hca@linux.ibm.com> (s390)
> Acked-by: Helge Deller <deller@gmx.de> (parisc)
>
> ---
> Changes in v3:
> -- fix unrecognized opcode on PowerPC
>
> Changes in v2:
> -- correct CONFIG_DYNAMIC_FTRACE on PowerPC
> -- add Acked-by tag
>
> ---
>  arch/arm/kernel/ftrace.c          | 5 -----
>  arch/arm64/kernel/ftrace.c        | 5 -----
>  arch/csky/kernel/ftrace.c         | 5 -----
>  arch/ia64/kernel/ftrace.c         | 6 ------
>  arch/microblaze/kernel/ftrace.c   | 5 -----
>  arch/mips/include/asm/ftrace.h    | 2 ++
>  arch/nds32/kernel/ftrace.c        | 5 -----
>  arch/parisc/kernel/ftrace.c       | 5 -----
>  arch/powerpc/include/asm/ftrace.h | 4 ++++
>  arch/riscv/kernel/ftrace.c        | 5 -----
>  arch/s390/kernel/ftrace.c         | 5 -----
>  arch/sh/kernel/ftrace.c           | 5 -----
>  arch/sparc/kernel/ftrace.c        | 5 -----
>  arch/x86/kernel/ftrace.c          | 5 -----
>  include/linux/ftrace.h            | 1 -
>  kernel/trace/ftrace.c             | 5 +++++
>  16 files changed, 11 insertions(+), 62 deletions(-)
>
> diff --git a/arch/mips/include/asm/ftrace.h b/arch/mips/include/asm/ftrac=
e.h
> index b463f2aa5a61..ed013e767390 100644
> --- a/arch/mips/include/asm/ftrace.h
> +++ b/arch/mips/include/asm/ftrace.h
> @@ -76,6 +76,8 @@ do {                                                \
>
>
>  #ifdef CONFIG_DYNAMIC_FTRACE
> +int __init ftrace_dyn_arch_init(void);
> +

Why ?


>  static inline unsigned long ftrace_call_adjust(unsigned long addr)
>  {
>       return addr;
> diff --git a/arch/powerpc/include/asm/ftrace.h
> b/arch/powerpc/include/asm/ftrace.h
> index debe8c4f7062..b05c43f13a4d 100644
> --- a/arch/powerpc/include/asm/ftrace.h
> +++ b/arch/powerpc/include/asm/ftrace.h
> @@ -126,6 +126,10 @@ static inline void this_cpu_enable_ftrace(void) { }
>  static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled) { }
>  static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; }
>  #endif /* CONFIG_PPC64 */
> +
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +int __init ftrace_dyn_arch_init(void);
> +#endif /* CONFIG_DYNAMIC_FTRACE */

Why ?

>  #endif /* !__ASSEMBLY__ */
>
>  #endif /* _ASM_POWERPC_FTRACE */
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 832e65f06754..f1eca123d89d 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -573,7 +573,6 @@ ftrace_set_early_filter(struct ftrace_ops *ops, char
> *buf, int enable);
>
>  /* defined in arch */
>  extern int ftrace_ip_converted(unsigned long ip);
> -extern int ftrace_dyn_arch_init(void);

Why removing that ?

Have you tried to build kernel/trace/ftrace.o with C=3D2 ? It will likely t=
ell you that the function is not declared and that it should be static

We could eventually consider that in the past, this generic declaration was=
 unrelevant because the definitions where in the arch specific sections.
Now that you are implementing a generic weak version of this function, it w=
ould make sense to have a generic declaration as well.

I really don't see the point in duplicating the declaration of the function=
 in the arch specific headers.

>  extern void ftrace_replace_code(int enable);
>  extern int ftrace_update_ftrace_func(ftrace_func_t func);
>  extern void ftrace_caller(void);

Christophe

CS Group - Document Interne