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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:50746) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1iFZwT-0007aT-6L; Wed, 02 Oct 2019 09:25:01 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1iFZwM-0000Wl-RU; Wed, 02 Oct 2019 09:24:54 +0100 Date: Wed, 2 Oct 2019 09:24:54 +0100 From: Russell King - ARM Linux admin To: Nick Desaulniers Subject: Re: [PATCH v2] ARM: add __always_inline to functions called from __get_user_check() Message-ID: <20191002082454.GQ25745@shell.armlinux.org.uk> References: <20191001083701.27207-1-yamada.masahiro@socionext.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191002_012515_475348_EDACA1CC X-CRM114-Status: GOOD ( 25.33 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kate Stewart , Arnd Bergmann , Enrico Weigelt , Vincent Whitchurch , Allison Randal , LKML , Stefan Agner , Masahiro Yamada , Linux ARM , Greg Kroah-Hartman , Olof Johansson , Thomas Gleixner , Julien Thierry , Linus Torvalds , Nicolas Saenz Julienne Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 01, 2019 at 10:03:50AM -0700, Nick Desaulniers wrote: > On Tue, Oct 1, 2019 at 1:37 AM Masahiro Yamada > wrote: > > > > KernelCI reports that bcm2835_defconfig is no longer booting since > > commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING > > forcibly") (https://lkml.org/lkml/2019/9/26/825). > > > > I also received a regression report from Nicolas Saenz Julienne > > (https://lkml.org/lkml/2019/9/27/263). > > > > This problem has cropped up on bcm2835_defconfig because it enables > > CONFIG_CC_OPTIMIZE_FOR_SIZE. The compiler tends to prefer not inlining > > functions with -Os. I was able to reproduce it with other boards and > > defconfig files by manually enabling CONFIG_CC_OPTIMIZE_FOR_SIZE. > > > > The __get_user_check() specifically uses r0, r1, r2 registers. > > So, uaccess_save_and_enable() and uaccess_restore() must be inlined. > > Otherwise, those register assignments would be entirely dropped, > > according to my analysis of the disassembly. > > > > Prior to commit 9012d011660e ("compiler: allow all arches to enable > > CONFIG_OPTIMIZE_INLINING"), the 'inline' marker was always enough for > > inlining functions, except on x86. > > > > Since that commit, all architectures can enable CONFIG_OPTIMIZE_INLINING. > > So, __always_inline is now the only guaranteed way of forcible inlining. > > No, the C preprocessor is the only guaranteed way of inlining. I > preferred v1; if you're going to play with > firewrite assembly, don't get burned. It seems we disagree on that. Masahiro Yamada, please send this to the patch system, thanks. > > > > > I also added __always_inline to 4 functions in the call-graph from the > > __get_user_check() macro. > > > > Fixes: 9012d011660e ("compiler: allow all arches to enable CONFIG_OPTIMIZE_INLINING") > > Reported-by: "kernelci.org bot" > > Reported-by: Nicolas Saenz Julienne > > Signed-off-by: Masahiro Yamada > > --- > > > > Changes in v2: > > - Use __always_inline instead of changing the function call places > > (per Russell King) > > - The previous submission is: https://lore.kernel.org/patchwork/patch/1132459/ > > > > arch/arm/include/asm/domain.h | 8 ++++---- > > arch/arm/include/asm/uaccess.h | 4 ++-- > > 2 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h > > index 567dbede4785..f1d0a7807cd0 100644 > > --- a/arch/arm/include/asm/domain.h > > +++ b/arch/arm/include/asm/domain.h > > @@ -82,7 +82,7 @@ > > #ifndef __ASSEMBLY__ > > > > #ifdef CONFIG_CPU_CP15_MMU > > -static inline unsigned int get_domain(void) > > +static __always_inline unsigned int get_domain(void) > > { > > unsigned int domain; > > > > @@ -94,7 +94,7 @@ static inline unsigned int get_domain(void) > > return domain; > > } > > > > -static inline void set_domain(unsigned val) > > +static __always_inline void set_domain(unsigned int val) > > { > > asm volatile( > > "mcr p15, 0, %0, c3, c0 @ set domain" > > @@ -102,12 +102,12 @@ static inline void set_domain(unsigned val) > > isb(); > > } > > #else > > -static inline unsigned int get_domain(void) > > +static __always_inline unsigned int get_domain(void) > > { > > return 0; > > } > > > > -static inline void set_domain(unsigned val) > > +static __always_inline void set_domain(unsigned int val) > > { > > } > > #endif > > diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h > > index 303248e5b990..98c6b91be4a8 100644 > > --- a/arch/arm/include/asm/uaccess.h > > +++ b/arch/arm/include/asm/uaccess.h > > @@ -22,7 +22,7 @@ > > * perform such accesses (eg, via list poison values) which could then > > * be exploited for priviledge escalation. > > */ > > -static inline unsigned int uaccess_save_and_enable(void) > > +static __always_inline unsigned int uaccess_save_and_enable(void) > > { > > #ifdef CONFIG_CPU_SW_DOMAIN_PAN > > unsigned int old_domain = get_domain(); > > @@ -37,7 +37,7 @@ static inline unsigned int uaccess_save_and_enable(void) > > #endif > > } > > > > -static inline void uaccess_restore(unsigned int flags) > > +static __always_inline void uaccess_restore(unsigned int flags) > > { > > #ifdef CONFIG_CPU_SW_DOMAIN_PAN > > /* Restore the user access mask */ > > -- > > 2.17.1 > > > > > -- > Thanks, > ~Nick Desaulniers > -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel