Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 3 Nov 2022 09:48:52 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Sathvika Vasireddy <sv@linux.ibm.com>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "jpoimboe@redhat.com" <jpoimboe@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "aik@ozlabs.ru" <aik@ozlabs.ru>,
        "mpe@ellerman.id.au" <mpe@ellerman.id.au>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "rostedt@goodmis.org" <rostedt@goodmis.org>,
        "mbenes@suse.cz" <mbenes@suse.cz>,
        "npiggin@gmail.com" <npiggin@gmail.com>,
        "chenzhongjin@huawei.com" <chenzhongjin@huawei.com>,
        "naveen.n.rao@linux.vnet.ibm.com" <naveen.n.rao@linux.vnet.ibm.com>
Subject: Re: [PATCH v5 02/16] powerpc: Override __ALIGN and __ALIGN_STR macros
Message-ID: <Y2OAdHBIGXVnN5Ud@hirez.programming.kicks-ass.net>
References: <20221028143346.183569-1-sv@linux.ibm.com>
 <20221028143346.183569-3-sv@linux.ibm.com>
 <327c371a-a8f4-1676-3da8-f454612b5c58@csgroup.eu>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <327c371a-a8f4-1676-3da8-f454612b5c58@csgroup.eu>
Precedence: bulk

On Wed, Nov 02, 2022 at 12:35:07PM +0000, Christophe Leroy wrote:
> 
> 
> Le 28/10/2022 ? 16:33, Sathvika Vasireddy a ?crit?:
> > In a subsequent patch, we would want to annotate powerpc assembly functions
> > with SYM_FUNC_START_LOCAL macro. This macro depends on __ALIGN macro.
> > 
> > The default expansion of __ALIGN macro is:
> >          #define __ALIGN      .align 4,0x90
> > 
> > So, override __ALIGN and __ALIGN_STR macros to use the same alignment as
> > that of the existing _GLOBAL macro. Also, do not pad with 0x90, because
> > repeated 0x90s are not a nop or trap on powerpc.
> 
> By the way, do we know what the instruction 0x90909090 is on powerpc ? 
> Is that something valid or not ?

Please also look at the version that's in tip/x86/core (and next). This
stuff should be gone now.

include/linux/linkage.h now reads like:

#ifndef __ALIGN
#define __ALIGN                 .balign CONFIG_FUNCTION_ALIGNMENT
#define __ALIGN_STR             __stringify(__ALIGN)
#endif