From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Matthias Kaehlcke <mka@chromium.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Matt Fleming <matt@codeblueprint.co.uk>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH 4.9 31/59] efi/libstub/arm64: Set -fpie when building the EFI stub
Date: Wed, 21 Nov 2018 20:06:46 +0100 [thread overview]
Message-ID: <20181121183509.471221312@linuxfoundation.org> (raw)
In-Reply-To: <20181121183508.262873520@linuxfoundation.org>
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
commit 91ee5b21ee026c49e4e7483de69b55b8b47042be upstream.
Clang may emit absolute symbol references when building in non-PIC mode,
even when using the default 'small' code model, which is already mostly
position independent to begin with, due to its use of adrp/add pairs
that have a relative range of +/- 4 GB. The remedy is to pass the -fpie
flag, which can be done safely now that the code has been updated to avoid
GOT indirections (which may be emitted due to the compiler assuming that
the PIC/PIE code may end up in a shared library that is subject to ELF
symbol preemption)
Passing -fpie when building code that needs to execute at an a priori
unknown offset is arguably an improvement in any case, and given that
the recent visibility changes allow the PIC build to pass with GCC as
well, let's add -fpie for all arm64 builds rather than only for Clang.
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170818194947.19347-5-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/firmware/efi/libstub/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -10,7 +10,7 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__K
-fPIC -fno-strict-aliasing -mno-red-zone \
-mno-mmx -mno-sse
-cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS))
+cflags-$(CONFIG_ARM64) := $(subst -pg,,$(KBUILD_CFLAGS)) -fpie
cflags-$(CONFIG_ARM) := $(subst -pg,,$(KBUILD_CFLAGS)) \
-fno-builtin -fpic -mno-single-pic-base
prev parent reply other threads:[~2018-11-21 19:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181121183508.262873520@linuxfoundation.org>
2018-11-21 19:06 ` [PATCH 4.9 28/59] efi/libstub/arm64: Use hidden attribute for struct screen_info reference Greg Kroah-Hartman
2018-11-21 19:06 ` [PATCH 4.9 29/59] efi/libstub/arm64: Force hidden visibility for section markers Greg Kroah-Hartman
2018-11-21 19:06 ` [PATCH 4.9 30/59] efi/libstub: Preserve .debug sections after absolute relocation check Greg Kroah-Hartman
2018-11-21 19:06 ` Greg Kroah-Hartman [this message]
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