From: "Laszlo Ersek" <lersek@redhat.com>
To: devel@edk2.groups.io, ard.biesheuvel@linaro.org
Cc: leif.lindholm@linaro.org
Subject: Re: [edk2-devel] [PATCH] ArmVirtPkg/ArmVirtPrePiUniCoreRelocatable: revert to PIE linking
Date: Thu, 5 Sep 2019 21:33:05 +0200 [thread overview]
Message-ID: <7dff2d0c-eb94-62a8-f07a-705050a71645@redhat.com> (raw)
In-Reply-To: <20190904230423.24661-1-ard.biesheuvel@linaro.org>
On 09/05/19 01:04, Ard Biesheuvel wrote:
> In some cases, the CLANG38 toolchain profile in LTO mode emits GOT
> based relocations in spite of our attempts to avoid this, by using
> hidden visibility, -Bsymbolic etc.
>
> On AARCH64, we managed to work around this by processing the GOT
> based relocations in GenFw. As it turns out, the same issue exists
> on 32-bit ARM, but unfortunately, we cannot use a similar trick to
> get rid of the GOT entry, and the relocation metadata is insufficient
> to locate the GOT entry in the binary.
>
> A bit of trial and error reveals that switching the linker options from
> -pie to -shared in commit e07092edca8442db4a941dbeea0cd196c7bf8ec9 was
> not the best approach, and instead, we can pass -pie to the linker
> directly (using -Wl,xxx) rather than to the compiler directly, which
> turns out to massage the linker in the right way, and prevents if from
> emitting GOT based relocations. Your mileage may vary ...
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> Let's test this on a couple of different Clang versions. If it still
> produces problems, the only other way I see is to disable the builds
> of platforms that incorporate this module for ARM/CLANG38 [which is
> not the end of the world]
>
> ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf b/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf
> index 683397b7afd1..9e58e56fce09 100755
> --- a/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf
> +++ b/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf
> @@ -97,4 +97,4 @@
> gArmTokenSpaceGuid.PcdFvBaseAddress
>
> [BuildOptions]
> - GCC:*_*_*_DLINK_FLAGS = -shared -Wl,-Bsymbolic -Wl,-T,$(MODULE_DIR)/Scripts/PrePi-PIE.lds
> + GCC:*_*_*_DLINK_FLAGS = -Wl,-Bsymbolic,-pie,-T,$(MODULE_DIR)/Scripts/PrePi-PIE.lds
>
Sorry for being late to this patch, I can see [*] it's upstream alrady.
Nonetheless:
Acked-by: Laszlo Ersek <lersek@redhat.com>
[*] Not from my inbox though -- I've got again too much on my plate and
am fetching email in batches. But, between my rebasing of
"ArmVirtPkg/PlatformBootManagerLib: unload image on
EFI_SECURITY_VIOLATION", building it, and attempting to push it, you had
pushed this one -- and I did notice that. :)
Thanks,
Laszlo
next prev parent reply other threads:[~2019-09-05 19:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-04 23:04 [PATCH] ArmVirtPkg/ArmVirtPrePiUniCoreRelocatable: revert to PIE linking Ard Biesheuvel
2019-09-05 14:19 ` Leif Lindholm
2019-09-05 14:25 ` Ard Biesheuvel
2019-09-05 15:55 ` Leif Lindholm
2019-09-05 17:06 ` Ard Biesheuvel
2019-09-05 17:16 ` Leif Lindholm
2019-09-05 17:19 ` Ard Biesheuvel
2019-09-05 14:27 ` Ard Biesheuvel
2019-09-05 19:33 ` Laszlo Ersek [this message]
2019-09-06 22:47 ` [edk2-devel] " Ard Biesheuvel
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