linux-kernel - Re: [PATCH] arm64/efi: Make strrchr() available to the EFI namespace

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Message-ID: <CAKv+Gu8E=wg-=KCtsR=GFEwT1SsEaGFujBx8PNq0JkCAmJYktw@mail.gmail.com>
Date:   Thu, 1 Mar 2018 17:10:38 +0000
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Rob Herring <robh@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64/efi: Make strrchr() available to the EFI namespace

On 1 March 2018 at 17:08, Will Deacon <will.deacon@....com> wrote:
> On Thu, Mar 01, 2018 at 10:28:03AM -0600, Rob Herring wrote:
>> libfdt gained a new dependency on strrchr, so make it available to the
>> EFI namespace before we update libfdt.
>>
>> Thanks to Ard for providing this fix.
>>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Will Deacon <will.deacon@....com>
>> Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>> Signed-off-by: Rob Herring <robh@...nel.org>
>> ---
>> Please ack. This is a dependency on a dtc upstream sync.
>
> Acked-by: Will Deacon <will.deacon@....com>
>
> As an aside, I noticed that this __efistub prefixing is also being
> applied to mapping symbols, so we get crazy stuff like __efistub_$x. I
> didn't get round to working out whether that's going to be problematic,
> but maybe it's all fine...
>

Ugh. Those mapping symbols.

We can filter them explicitly in scripts/kallsyms, I guess, or even
better, get rid of all __efistub_ symbols entirely (since they are
either aliases or part of __init code)


>>
>>  arch/arm64/kernel/image.h | 1 +
>>  arch/arm64/lib/strrchr.S  | 2 +-
>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h
>> index c7fcb232fe47..a820ed07fb80 100644
>> --- a/arch/arm64/kernel/image.h
>> +++ b/arch/arm64/kernel/image.h
>> @@ -103,6 +103,7 @@ __efistub_strlen          = KALLSYMS_HIDE(__pi_strlen);
>>  __efistub_strnlen            = KALLSYMS_HIDE(__pi_strnlen);
>>  __efistub_strcmp             = KALLSYMS_HIDE(__pi_strcmp);
>>  __efistub_strncmp            = KALLSYMS_HIDE(__pi_strncmp);
>> +__efistub_strrchr            = KALLSYMS_HIDE(__pi_strrchr);
>>  __efistub___flush_dcache_area        = KALLSYMS_HIDE(__pi___flush_dcache_area);
>>
>>  #ifdef CONFIG_KASAN
>> diff --git a/arch/arm64/lib/strrchr.S b/arch/arm64/lib/strrchr.S
>> index 61eabd9a289a..f8e2784d5752 100644
>> --- a/arch/arm64/lib/strrchr.S
>> +++ b/arch/arm64/lib/strrchr.S
>> @@ -40,4 +40,4 @@ ENTRY(strrchr)
>>       b       1b
>>  2:   mov     x0, x3
>>       ret
>> -ENDPROC(strrchr)
>> +ENDPIPROC(strrchr)
>> --
>> 2.14.1
>>