From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: [PATCH v5 0/3] extern inline native_save_fl for paravirt Date: Tue, 19 Jun 2018 17:03:26 +0200 Message-ID: <6a36db0d-e790-48d6-183a-263c355531b6@suse.com> References: <20180613210518.113983-1-ndesaulniers@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180613210518.113983-1-ndesaulniers@google.com> Content-Language: de-DE List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Nick Desaulniers , akpm@linux-foundation.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de Cc: kstewart@linuxfoundation.org, andrea.parri@amarulasolutions.com, linux-efi@vger.kernel.org, brijesh.singh@amd.com, jan.kiszka@siemens.com, will.deacon@arm.com, jarkko.sakkinen@linux.intel.com, linux-kernel@vger.kernel.org, yamada.masahiro@socionext.com, manojgupta@google.com, akataria@vmware.com, tweek@google.com, mawilcox@microsoft.com, x86@kernel.org, ghackmann@google.com, mka@chromium.org, geert@linux-m68k.org, rientjes@google.com, aryabinin@virtuozzo.com, thomas.lendacky@amd.com, arnd@arndb.de, linux-kbuild@vger.kernel.org, keescook@google.com, rostedt@goodmis.org, acme@redhat.com, caoj.fnst@cn.fujitsu.com, jpoimboe@redhat.com, sedat.dilek@gmail.com, boris.ostrovsky@oracle.com, virtualization@lists.linux-foundation.org, michal.lkml@markovi.net, tstellar@redhat.com, gregkh@linuxfoundation.org, ard.biesheuvel@linaro.org, astrachan@google.com, mjg59@google.com, pombre List-Id: virtualization@lists.linuxfoundation.org On 13/06/18 23:05, Nick Desaulniers wrote: > paravirt depends on a custom calling convention (callee saved), but > expects this from a static inline function that it then forces to be > outlined. This is problematic because different compilers or flags can > then add a stack guard that violates the calling conventions. > > Uses extern inline with the out-of-line definition in assembly to > prevent compilers from adding stack guards to the outlined version. > > Other parts of the codebase overwrite KBUILD_CFLAGS, which is *extremely > problematic* for extern inline, as the sematics are completely the > opposite depending on what C standard is used. > http://blahg.josefsipek.net/?p=529 > > Changes since v4: > Take Arnd's and hpa's suggestions properly feature detect gnu_inline > attribute to support gcc 4.1. > > Changes since v3: > Take Joe's suggestion to hoist __inline__ and __inline out of > conditional block. > > Changes since v2: > Take hpa's _ASM_ARG patch into the set in order to simplify cross > 32b/64b x86 assembly and rebase my final patch to use it. Apply > Sedat's typo fix to commit message and sign off on it. Take Joe's > suggestion to simplify __inline__ and __inline. Add Arnd to list of > folks who made helpful suggestions. > > Changes since v1: > Prefer gnu_inline function attribute instead of explicitly setting C > standard compiler flag in problematic Makefiles. We should instead > carefully evaluate if those Makefiles should be overwriting > KBUILD_CFLAGS at all. Dropped the previous first two patches and added > a new first patch. > > H. Peter Anvin (1): > x86/asm: add _ASM_ARG* constants for argument registers to > > Nick Desaulniers (2): > compiler-gcc.h: add gnu_inline to all inline declarations > x86: paravirt: make native_save_fl extern inline > > arch/x86/include/asm/asm.h | 59 +++++++++++++++++++++++++++++++++ > arch/x86/include/asm/irqflags.h | 2 +- > arch/x86/kernel/Makefile | 1 + > arch/x86/kernel/irqflags.S | 26 +++++++++++++++ > include/linux/compiler-gcc.h | 29 ++++++++++++---- > 5 files changed, 109 insertions(+), 8 deletions(-) > create mode 100644 arch/x86/kernel/irqflags.S > For the series: Acked-by: Juergen Gross Juergen