From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Will Deacon <will@kernel.org>, Geoff Levand <geoff@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] arm64/vdso: Remove unused makefile variable
Date: Tue, 28 Apr 2020 11:46:03 +0100 [thread overview]
Message-ID: <c3c48a79-6a0c-2bae-16a8-507f05ee5473@arm.com> (raw)
In-Reply-To: <20200427203520.GA23186@willie-the-truck>
Hi Will,
thank you for pointing this out.
On 4/27/20 9:35 PM, Will Deacon wrote:
> [+Vincenzo]
>
> On Fri, Apr 24, 2020 at 08:58:49AM -0700, Geoff Levand wrote:
>> The vdso makefile variable VDSO_LDFLAGS is defined, but never used,
>> so remove it.
>>
>> Signed-off-by: Geoff Levand <geoff@infradead.org>
>> ---
>>
>> Hi,
>>
>> This seems to be left over from a code cleanup that missed it.
>
> While I agree that this isn't used, I'm wondering why '-Bsymbolic' is used
> to link the compat vDSO but not the native one. It seems weird to differ
> in this regard.
>
> Vincenzo? Looks like you added this unused variable in 28b1a824a4f44
> ("arm64: vdso: Substitute gettimeofday() with C implementation").
>
My understanding is that "-Bsymbolic" is required by both compat and normal vdso
because when the shared library is built it adds a flag in the dynamic section
of the binary called DT_SYMBOLIC which alters the dynamic linker's symbol
resolution algorithm to search for references for a symbol inside the library
first and then into the executable.
This becomes useful for example when an executable built with -fPIC is trying to
call a public vDSO function from assembly (bl symbol).
The issue here seems to be that I used VDSO_LDFLAGS instead of ldflags-y. I can
post a patch and Cc stable. Adding Geoff as Reported-by.
> Will
>
--
Regards,
Vincenzo
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next prev parent reply other threads:[~2020-04-28 10:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-24 15:58 [PATCH] arm64/vdso: Remove unused makefile variable Geoff Levand
2020-04-27 20:35 ` Will Deacon
2020-04-28 10:46 ` Vincenzo Frascino [this message]
2020-04-28 11:52 ` Ard Biesheuvel
2020-04-28 12:43 ` Will Deacon
2020-04-28 13:02 ` Ard Biesheuvel
2020-04-28 13:16 ` Will Deacon
2020-04-28 13:21 ` Vincenzo Frascino
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