| From foo@baz Wed Nov 21 18:50:25 CET 2018 |
| From: Ard Biesheuvel <ard.biesheuvel@linaro.org> |
| Date: Fri, 18 Aug 2017 20:49:37 +0100 |
| Subject: efi/libstub/arm64: Set -fpie when building the EFI stub |
| |
| 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 |
| |
