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From: Will Deacon <will@kernel.org>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, ard.biesheuvel@linaro.org,
	ndesaulniers@google.com, tglx@linutronix.de
Subject: Re: [PATCH v3 1/5] arm64: vdso32: Introduce COMPAT_CC_IS_GCC
Date: Tue, 1 Oct 2019 15:43:54 +0100	[thread overview]
Message-ID: <20191001144353.5rn3bkcc6eyfclh7@willie-the-truck> (raw)
In-Reply-To: <7558914c-fc2d-d05a-ccbe-76ef451670ae@arm.com>

On Tue, Oct 01, 2019 at 03:37:49PM +0100, Vincenzo Frascino wrote:
> On 10/1/19 3:20 PM, Will Deacon wrote:
> > On Tue, Oct 01, 2019 at 03:20:35PM +0100, Vincenzo Frascino wrote:
> >> On 10/1/19 2:27 PM, Catalin Marinas wrote:
> >>> On Tue, Oct 01, 2019 at 02:14:23PM +0100, Will Deacon wrote:
> >>>> On Thu, Sep 26, 2019 at 10:43:38PM +0100, Vincenzo Frascino wrote:
> >>>>> +config COMPATCC_IS_ARM_GCC
> >>>>> +	def_bool $(success,$(COMPATCC) --version | head -n 1 | grep -q "arm-.*-gcc")
> >>>>
> >>>> I've seen toolchains where the first part of the tuple is "armv7-", so they
> >>>> won't get detected here. However, do we really need to detect this? If
> >>>> somebody passes a duff compiler, then the build will fail in the same way as
> >>>> if they passed it to CROSS_COMPILE=.
> >>>
> >>> Not sure what happens if we pass an aarch64 compiler. Can we end up with
> >>> a 64-bit compat vDSO?
> >>>
> >>
> >> I agree with Catalin here. The problem is not only when you pass and aarch64
> >> toolchain but even an x86 and so on.
> > 
> > I disagree. What happens if you do:
> > 
> > $ make ARCH=arm64 CROSS_COMPILE=x86_64-linux-gnu-
> > 
> > on your x86 box?
> >
> 
> The kernel compilation breaks as follows:
> 
> x86_64-linux-gnu-gcc: error: unrecognized command line option ‘-mlittle-endian’;
> did you mean ‘-fconvert=little-endian’?
> /data1/Projects/LinuxKernel/linux/scripts/Makefile.build:265: recipe for target
> 'scripts/mod/empty.o' failed
> make[2]: *** [scripts/mod/empty.o] Error 1
> /data1/Projects/LinuxKernel/linux/Makefile:1128: recipe for target 'prepare0' failed
> make[1]: *** [prepare0] Error 2
> make[1]: Leaving directory '/data1/Projects/LinuxKernel/linux-out'
> Makefile:179: recipe for target 'sub-make' failed
> make: *** [sub-make] Error 2
> 
> Similar issue in the compat vdso library compilation if I do (without the check):
> 
> $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
> CROSS_COMPILE_COMPAT=x86_64-linux-gnu-
> 
> With this check the compilation completes correctly but the compat vdso does not
> get built (unless my environment is playing me tricks ;) ).

My point was that we don't attempt to sanitise the compiler passed via
CROSS_COMPILE, so I don't think we should do anything special for COMPATCC
either.

Will

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: ard.biesheuvel@linaro.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	ndesaulniers@google.com, linux-kernel@vger.kernel.org,
	tglx@linutronix.de, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/5] arm64: vdso32: Introduce COMPAT_CC_IS_GCC
Date: Tue, 1 Oct 2019 15:43:54 +0100	[thread overview]
Message-ID: <20191001144353.5rn3bkcc6eyfclh7@willie-the-truck> (raw)
In-Reply-To: <7558914c-fc2d-d05a-ccbe-76ef451670ae@arm.com>

On Tue, Oct 01, 2019 at 03:37:49PM +0100, Vincenzo Frascino wrote:
> On 10/1/19 3:20 PM, Will Deacon wrote:
> > On Tue, Oct 01, 2019 at 03:20:35PM +0100, Vincenzo Frascino wrote:
> >> On 10/1/19 2:27 PM, Catalin Marinas wrote:
> >>> On Tue, Oct 01, 2019 at 02:14:23PM +0100, Will Deacon wrote:
> >>>> On Thu, Sep 26, 2019 at 10:43:38PM +0100, Vincenzo Frascino wrote:
> >>>>> +config COMPATCC_IS_ARM_GCC
> >>>>> +	def_bool $(success,$(COMPATCC) --version | head -n 1 | grep -q "arm-.*-gcc")
> >>>>
> >>>> I've seen toolchains where the first part of the tuple is "armv7-", so they
> >>>> won't get detected here. However, do we really need to detect this? If
> >>>> somebody passes a duff compiler, then the build will fail in the same way as
> >>>> if they passed it to CROSS_COMPILE=.
> >>>
> >>> Not sure what happens if we pass an aarch64 compiler. Can we end up with
> >>> a 64-bit compat vDSO?
> >>>
> >>
> >> I agree with Catalin here. The problem is not only when you pass and aarch64
> >> toolchain but even an x86 and so on.
> > 
> > I disagree. What happens if you do:
> > 
> > $ make ARCH=arm64 CROSS_COMPILE=x86_64-linux-gnu-
> > 
> > on your x86 box?
> >
> 
> The kernel compilation breaks as follows:
> 
> x86_64-linux-gnu-gcc: error: unrecognized command line option ‘-mlittle-endian’;
> did you mean ‘-fconvert=little-endian’?
> /data1/Projects/LinuxKernel/linux/scripts/Makefile.build:265: recipe for target
> 'scripts/mod/empty.o' failed
> make[2]: *** [scripts/mod/empty.o] Error 1
> /data1/Projects/LinuxKernel/linux/Makefile:1128: recipe for target 'prepare0' failed
> make[1]: *** [prepare0] Error 2
> make[1]: Leaving directory '/data1/Projects/LinuxKernel/linux-out'
> Makefile:179: recipe for target 'sub-make' failed
> make: *** [sub-make] Error 2
> 
> Similar issue in the compat vdso library compilation if I do (without the check):
> 
> $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
> CROSS_COMPILE_COMPAT=x86_64-linux-gnu-
> 
> With this check the compilation completes correctly but the compat vdso does not
> get built (unless my environment is playing me tricks ;) ).

My point was that we don't attempt to sanitise the compiler passed via
CROSS_COMPILE, so I don't think we should do anything special for COMPATCC
either.

Will

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  reply	other threads:[~2019-10-01 14:44 UTC|newest]

Thread overview: 127+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-20 14:27 Problems with arm64 compat vdso Will Deacon
2019-09-20 16:33 ` Vincenzo Frascino
2019-09-23 16:41   ` Ard Biesheuvel
2019-09-24 12:11     ` Vincenzo Frascino
2019-09-24 18:06       ` Nick Desaulniers
2019-09-24 20:42         ` Vincenzo Frascino
2019-09-25 15:58     ` Ard Biesheuvel
2019-09-26  6:03 ` [PATCH 0/4] arm64: vdso32: Address various issues Vincenzo Frascino
2019-09-26  6:03   ` Vincenzo Frascino
2019-09-26  6:03   ` [PATCH 1/4] arm64: vdso32: Introduce COMPAT_CC_IS_GCC Vincenzo Frascino
2019-09-26  6:03     ` Vincenzo Frascino
2019-09-26  8:06     ` Catalin Marinas
2019-09-26  8:06       ` Catalin Marinas
2019-09-26 10:56       ` Vincenzo Frascino
2019-09-26 10:56         ` Vincenzo Frascino
2019-09-26 11:02         ` Vincenzo Frascino
2019-09-26 11:02           ` Vincenzo Frascino
2019-09-26 15:23           ` Catalin Marinas
2019-09-26 15:23             ` Catalin Marinas
2019-09-26 12:22         ` Vincenzo Frascino
2019-09-26 12:22           ` Vincenzo Frascino
2019-09-26 15:17           ` Catalin Marinas
2019-09-26 15:17             ` Catalin Marinas
2019-09-26 20:17             ` Vincenzo Frascino
2019-09-26 20:17               ` Vincenzo Frascino
2019-09-26  6:03   ` [PATCH 2/4] arm64: vdso32: Detect binutils support for dmb ishld Vincenzo Frascino
2019-09-26  6:03     ` Vincenzo Frascino
2019-09-26  8:30     ` Catalin Marinas
2019-09-26  8:30       ` Catalin Marinas
2019-09-26 10:59       ` Vincenzo Frascino
2019-09-26 10:59         ` Vincenzo Frascino
2019-09-26  6:03   ` [PATCH 3/4] arm64: vdso32: Fix compilation warning Vincenzo Frascino
2019-09-26  6:03     ` Vincenzo Frascino
2019-09-26  8:32     ` Catalin Marinas
2019-09-26  8:32       ` Catalin Marinas
2019-09-26 11:03       ` Vincenzo Frascino
2019-09-26 11:03         ` Vincenzo Frascino
2019-09-26  6:03   ` [PATCH 4/4] arm64: Remove gettimeofday.S Vincenzo Frascino
2019-09-26  6:03     ` Vincenzo Frascino
2019-09-26  8:34     ` Catalin Marinas
2019-09-26  8:34       ` Catalin Marinas
2019-09-26 13:38 ` [PATCH v2 0/4] arm64: vdso32: Address various issues Vincenzo Frascino
2019-09-26 13:38   ` Vincenzo Frascino
2019-09-26 13:38   ` [PATCH v2 1/4] arm64: vdso32: Introduce COMPAT_CC_IS_GCC Vincenzo Frascino
2019-09-26 13:38     ` Vincenzo Frascino
2019-09-26 15:13     ` Catalin Marinas
2019-09-26 15:13       ` Catalin Marinas
2019-09-26 13:38   ` [PATCH v2 2/4] arm64: vdso32: Detect binutils support for dmb ishld Vincenzo Frascino
2019-09-26 13:38     ` Vincenzo Frascino
2019-09-26 14:26     ` Catalin Marinas
2019-09-26 14:26       ` Catalin Marinas
2019-09-26 20:19       ` Vincenzo Frascino
2019-09-26 20:19         ` Vincenzo Frascino
2019-09-26 15:59     ` Catalin Marinas
2019-09-26 15:59       ` Catalin Marinas
2019-09-26 21:17       ` Vincenzo Frascino
2019-09-26 21:17         ` Vincenzo Frascino
2019-09-26 16:23     ` Nick Desaulniers
2019-09-26 16:23       ` Nick Desaulniers
2019-09-26 13:38   ` [PATCH v2 3/4] arm64: vdso32: Fix compilation warning Vincenzo Frascino
2019-09-26 13:38     ` Vincenzo Frascino
2019-09-26 15:22     ` Catalin Marinas
2019-09-26 15:22       ` Catalin Marinas
2019-09-26 13:38   ` [PATCH v2 4/4] arm64: Remove gettimeofday.S Vincenzo Frascino
2019-09-26 13:38     ` Vincenzo Frascino
2019-09-26 15:31   ` [PATCH v2 0/4] arm64: vdso32: Address various issues Catalin Marinas
2019-09-26 15:31     ` Catalin Marinas
2019-09-26 20:29     ` Vincenzo Frascino
2019-09-26 20:29       ` Vincenzo Frascino
2019-09-26 21:43 ` [PATCH v3 0/5]arm64: " Vincenzo Frascino
2019-09-26 21:43   ` Vincenzo Frascino
2019-09-26 21:43   ` [PATCH v3 1/5] arm64: vdso32: Introduce COMPAT_CC_IS_GCC Vincenzo Frascino
2019-09-26 21:43     ` Vincenzo Frascino
2019-09-27  9:24     ` Catalin Marinas
2019-09-27  9:24       ` Catalin Marinas
2019-10-01 13:14     ` Will Deacon
2019-10-01 13:14       ` Will Deacon
2019-10-01 13:27       ` Catalin Marinas
2019-10-01 13:27         ` Catalin Marinas
2019-10-01 14:20         ` Vincenzo Frascino
2019-10-01 14:20           ` Vincenzo Frascino
2019-10-01 14:20           ` Will Deacon
2019-10-01 14:20             ` Will Deacon
2019-10-01 14:37             ` Vincenzo Frascino
2019-10-01 14:37               ` Vincenzo Frascino
2019-10-01 14:43               ` Will Deacon [this message]
2019-10-01 14:43                 ` Will Deacon
2019-10-01 14:59                 ` Vincenzo Frascino
2019-10-01 14:59                   ` Vincenzo Frascino
2019-10-01 15:30                 ` Catalin Marinas
2019-10-01 15:30                   ` Catalin Marinas
2019-10-01 16:46                   ` Will Deacon
2019-10-01 16:46                     ` Will Deacon
2019-10-01 16:59                     ` Nick Desaulniers
2019-10-01 16:59                       ` Nick Desaulniers
2019-10-01 17:07                       ` Will Deacon
2019-10-01 17:07                         ` Will Deacon
2019-10-01 17:12                         ` Nick Desaulniers
2019-10-01 17:12                           ` Nick Desaulniers
2019-10-01 17:14                           ` Will Deacon
2019-10-01 17:14                             ` Will Deacon
2019-09-26 21:43   ` [PATCH v3 2/5] arm64: vdso32: Detect binutils support for dmb ishld Vincenzo Frascino
2019-09-26 21:43     ` Vincenzo Frascino
2019-09-27  9:25     ` Catalin Marinas
2019-09-27  9:25       ` Catalin Marinas
2019-10-01 13:26     ` Will Deacon
2019-10-01 13:26       ` Will Deacon
2019-10-01 14:23       ` Vincenzo Frascino
2019-10-01 14:23         ` Vincenzo Frascino
2019-09-26 21:43   ` [PATCH v3 3/5] arm64: vdso32: Fix compilation warning Vincenzo Frascino
2019-09-26 21:43     ` Vincenzo Frascino
2019-09-27  9:26     ` Catalin Marinas
2019-09-27  9:26       ` Catalin Marinas
2019-10-01 13:21     ` Will Deacon
2019-10-01 13:21       ` Will Deacon
2019-10-01 14:41       ` Vincenzo Frascino
2019-10-01 14:41         ` Vincenzo Frascino
2019-09-26 21:43   ` [PATCH v3 4/5] arm64: Remove gettimeofday.S Vincenzo Frascino
2019-09-26 21:43     ` Vincenzo Frascino
2019-09-26 21:43   ` [PATCH v3 5/5] arm64: vdso32: Remove jump label config option in Makefile Vincenzo Frascino
2019-09-26 21:43     ` Vincenzo Frascino
2019-09-27  9:27     ` Catalin Marinas
2019-09-27  9:27       ` Catalin Marinas
2019-09-27 10:46   ` [PATCH v3 0/5]arm64: vdso32: Address various issues Catalin Marinas
2019-09-27 10:46     ` Catalin Marinas
2019-10-01 13:27   ` Will Deacon
2019-10-01 13:27     ` Will Deacon

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