From: Dmitry Osipenko <digetx@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@armlinux.org.uk>,
Nick Desaulniers <ndesaulniers@google.com>,
Ingo Molnar <mingo@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH v1] ARM: vfp: Use long jump to fix THUMB2 kernel compilation error
Date: Thu, 22 Oct 2020 03:00:06 +0300 [thread overview]
Message-ID: <773fbdb0-5fc4-ab39-e72d-89845faa4c6d@gmail.com> (raw)
In-Reply-To: <202010211637.7CFD8435@keescook>
22.10.2020 02:40, Kees Cook пишет:
> On Thu, Oct 22, 2020 at 01:57:37AM +0300, Dmitry Osipenko wrote:
>> The vfp_kmode_exception() function now is unreachable using relative
>> branching in THUMB2 kernel configuration, resulting in a "relocation
>> truncated to fit: R_ARM_THM_JUMP19 against symbol `vfp_kmode_exception'"
>> linker error. Let's use long jump in order to fix the issue.
>
> Eek. Is this with gcc or clang?
GCC 9.3.0
>> Fixes: eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections")
>
> Are you sure it wasn't 512dd2eebe55 ("arm/build: Add missing sections") ?
> That commit may have implicitly moved the location of .vfp11_veneer,
> though I thought I had chosen the correct position.
I re-checked that the fixes tag is correct.
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>> arch/arm/vfp/vfphw.S | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
>> index 4fcff9f59947..6e2b29f0c48d 100644
>> --- a/arch/arm/vfp/vfphw.S
>> +++ b/arch/arm/vfp/vfphw.S
>> @@ -82,7 +82,8 @@ ENTRY(vfp_support_entry)
>> ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions
>> and r3, r3, #MODE_MASK @ are supported in kernel mode
>> teq r3, #USR_MODE
>> - bne vfp_kmode_exception @ Returns through lr
>> + ldr r1, =vfp_kmode_exception
>> + bxne r1 @ Returns through lr
>>
>> VFPFMRX r1, FPEXC @ Is the VFP enabled?
>> DBGSTR1 "fpexc %08x", r1
>
> This seems like a workaround though? I suspect the vfp11_veneer needs
> moving?
>
I don't know where it needs to be moved. Please feel free to make a
patch if you have a better idea, I'll be glad to test it.
next prev parent reply other threads:[~2020-10-22 0:00 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 22:57 [PATCH v1] ARM: vfp: Use long jump to fix THUMB2 kernel compilation error Dmitry Osipenko
2020-10-21 23:40 ` Kees Cook
2020-10-22 0:00 ` Dmitry Osipenko [this message]
2020-10-22 3:28 ` Kees Cook
2020-10-22 7:06 ` Ard Biesheuvel
2020-10-22 15:57 ` Dmitry Osipenko
2020-10-22 16:06 ` Ard Biesheuvel
2020-10-22 16:11 ` Russell King - ARM Linux admin
2020-10-22 16:20 ` Ard Biesheuvel
2020-10-22 16:23 ` Russell King - ARM Linux admin
2020-10-22 16:33 ` Ard Biesheuvel
2020-10-22 17:48 ` Russell King - ARM Linux admin
2020-10-22 17:59 ` Ard Biesheuvel
2020-10-26 8:58 ` Ard Biesheuvel
2020-10-29 9:56 ` Ard Biesheuvel
2020-11-03 7:24 ` Ard Biesheuvel
2020-11-03 8:43 ` Dmitry Osipenko
2020-11-09 7:25 ` Ard Biesheuvel
2020-11-10 7:44 ` Dmitry Osipenko
2020-11-10 7:45 ` Ard Biesheuvel
2020-10-22 16:34 ` Dmitry Osipenko
2020-10-22 17:38 ` Russell King - ARM Linux admin
2020-10-22 17:47 ` Ard Biesheuvel
2020-10-22 17:50 ` Russell King - ARM Linux admin
2020-10-22 17:51 ` Ard Biesheuvel
2020-10-22 19:05 ` Dmitry Osipenko
2020-10-22 14:57 ` Russell King - ARM Linux admin
2020-10-22 15:56 ` Dmitry Osipenko
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