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From: Qian Cai <cai@lca.pw>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Nick Desaulniers <ndesaulniers@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: "arm64: vdso: Substitute gettimeofday() with C implementation" breaks clang build
Date: Tue, 25 Jun 2019 13:31:28 -0400	[thread overview]
Message-ID: <1561483888.5154.78.camel@lca.pw> (raw)
In-Reply-To: <193c179e-16ca-4b4e-2584-75e8f6c1819f@arm.com>

On Tue, 2019-06-25 at 18:00 +0100, Vincenzo Frascino wrote:
> Hi Nick,
> 
> On 25/06/2019 17:26, Nick Desaulniers wrote:
> > On Tue, Jun 25, 2019 at 7:54 AM Vincenzo Frascino
> > <vincenzo.frascino@arm.com> wrote:
> > > 
> > > Hi Qian,
> > > 
> > > ...
> > > 
> > > > 
> > > > but clang 7.0 is still use in many distros by default, so maybe this
> > > > commit can
> > > > be fixed by adding a conditional check to use "small" if clang version <
> > > > 8.0.
> > > > 
> > > 
> > > Could you please verify that the patch below works for you?
> > 
> > Should it be checking against CONFIG_CLANG_VERSION, or better yet be
> > using cc-option macro?
> > 
> 
> This is what I did in my proposed patch, but I was surprised that clang-7
> generates relocations that clang-8 does not.
> 
>   LD      arch/arm64/kernel/vdso/vdso.so.dbg
>   VDSOCHK arch/arm64/kernel/vdso/vdso.so.dbg
> 00000000000009d0 R_AARCH64_JUMP_SLOT  _mcount
> 
> arch/arm64/kernel/vdso/vdso.so.dbg: dynamic relocations are not supported
> make[1]: *** [arch/arm64/kernel/vdso/Makefile:59:
> arch/arm64/kernel/vdso/vdso.so.dbg] Error 1
> make: *** [arch/arm64/Makefile:180: vdso_prepare] Error 2
> 
> This is the the result of the macro I introduced in lib/vdso/Makefile.
> 
> And I just found out why. I forgot to add a "+" in the patch provided :)
> 
> @Qian: Could you please retry with the one provided below?
> 

It works fine.

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WARNING: multiple messages have this Message-ID (diff)
From: Qian Cai <cai@lca.pw>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Nick Desaulniers <ndesaulniers@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will.deacon@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Nathan Chancellor <natechancellor@gmail.com>
Subject: Re: "arm64: vdso: Substitute gettimeofday() with C implementation" breaks clang build
Date: Tue, 25 Jun 2019 13:31:28 -0400	[thread overview]
Message-ID: <1561483888.5154.78.camel@lca.pw> (raw)
In-Reply-To: <193c179e-16ca-4b4e-2584-75e8f6c1819f@arm.com>

On Tue, 2019-06-25 at 18:00 +0100, Vincenzo Frascino wrote:
> Hi Nick,
> 
> On 25/06/2019 17:26, Nick Desaulniers wrote:
> > On Tue, Jun 25, 2019 at 7:54 AM Vincenzo Frascino
> > <vincenzo.frascino@arm.com> wrote:
> > > 
> > > Hi Qian,
> > > 
> > > ...
> > > 
> > > > 
> > > > but clang 7.0 is still use in many distros by default, so maybe this
> > > > commit can
> > > > be fixed by adding a conditional check to use "small" if clang version <
> > > > 8.0.
> > > > 
> > > 
> > > Could you please verify that the patch below works for you?
> > 
> > Should it be checking against CONFIG_CLANG_VERSION, or better yet be
> > using cc-option macro?
> > 
> 
> This is what I did in my proposed patch, but I was surprised that clang-7
> generates relocations that clang-8 does not.
> 
>   LD      arch/arm64/kernel/vdso/vdso.so.dbg
>   VDSOCHK arch/arm64/kernel/vdso/vdso.so.dbg
> 00000000000009d0 R_AARCH64_JUMP_SLOT  _mcount
> 
> arch/arm64/kernel/vdso/vdso.so.dbg: dynamic relocations are not supported
> make[1]: *** [arch/arm64/kernel/vdso/Makefile:59:
> arch/arm64/kernel/vdso/vdso.so.dbg] Error 1
> make: *** [arch/arm64/Makefile:180: vdso_prepare] Error 2
> 
> This is the the result of the macro I introduced in lib/vdso/Makefile.
> 
> And I just found out why. I forgot to add a "+" in the patch provided :)
> 
> @Qian: Could you please retry with the one provided below?
> 

It works fine.

  reply	other threads:[~2019-06-25 17:31 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-25 12:16 "arm64: vdso: Substitute gettimeofday() with C implementation" breaks clang build Qian Cai
2019-06-25 12:16 ` Qian Cai
2019-06-25 12:47 ` Vincenzo Frascino
2019-06-25 12:47   ` Vincenzo Frascino
2019-06-25 12:56   ` Qian Cai
2019-06-25 12:56     ` Qian Cai
2019-06-25 13:40     ` Vincenzo Frascino
2019-06-25 13:40       ` Vincenzo Frascino
2019-06-25 13:51       ` Qian Cai
2019-06-25 13:51         ` Qian Cai
2019-06-25 14:11         ` Vincenzo Frascino
2019-06-25 14:11           ` Vincenzo Frascino
2019-06-25 14:28           ` Qian Cai
2019-06-25 14:28             ` Qian Cai
2019-06-25 14:30             ` Vincenzo Frascino
2019-06-25 14:30               ` Vincenzo Frascino
2019-06-25 14:54             ` Vincenzo Frascino
2019-06-25 14:54               ` Vincenzo Frascino
2019-06-25 15:16               ` Qian Cai
2019-06-25 15:16                 ` Qian Cai
2019-06-25 16:26               ` Nick Desaulniers
2019-06-25 16:26                 ` Nick Desaulniers
2019-06-25 17:00                 ` Vincenzo Frascino
2019-06-25 17:00                   ` Vincenzo Frascino
2019-06-25 17:31                   ` Qian Cai [this message]
2019-06-25 17:31                     ` Qian Cai
2019-06-25 17:33                     ` Vincenzo Frascino
2019-06-25 17:33                       ` Vincenzo Frascino
2019-06-26  9:38                   ` Will Deacon
2019-06-26  9:38                     ` Will Deacon
2019-06-26  9:45                     ` Vincenzo Frascino
2019-06-26  9:45                       ` Vincenzo Frascino

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