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From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Russell King <linux@armlinux.org.uk>,
	Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paul.burton@mips.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Mark Salyzyn <salyzyn@android.com>,
	Peter Collingbourne <pcc@google.com>,
	Mark Salyzyn <salyzyn@google.com>
Subject: [PATCH v3 03/24] arm64: Build vDSO with -ffixed-x18
Date: Thu, 13 Dec 2018 16:57:25 +0000	[thread overview]
Message-ID: <20181213165746.56930-4-vincenzo.frascino@arm.com> (raw)
Message-ID: <20181213165725.dKvlR7w-2Z0XXYzJN9FdgI56nzYRYFAmORwBAgPhPW0@z> (raw)
In-Reply-To: <20181213165746.56930-1-vincenzo.frascino@arm.com>

From: Peter Collingbourne <pcc@google.com>

The vDSO needs to be build with x18 reserved in order to accommodate
userspace platform ABIs built on top of Linux that use the register
to carry inter-procedural state, as provided for by the AAPCS.
An example of such a platform ABI is the one that will be used by an
upcoming version of Android.

Although this change is currently a no-op due to the fact that the vDSO
is currently implemented in pure assembly on arm64, it is necessary
in order to prepare for another change [1] that will add C code to
the vDSO.

[1] https://patchwork.kernel.org/patch/10044501/

Signed-off-by: Peter Collingbourne <pcc@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Mark Salyzyn <salyzyn@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/kernel/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index b215c712d897..8cd4707f832a 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -12,7 +12,7 @@ obj-vdso := gettimeofday.o note.o sigreturn.o
 targets := $(obj-vdso) vdso.so vdso.so.dbg
 obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 
-ccflags-y := -shared -fno-common -fno-builtin
+ccflags-y := -shared -fno-common -fno-builtin -ffixed-x18
 ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \
 		$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
 
-- 
2.19.2

  parent reply	other threads:[~2018-12-13 16:59 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-13 16:57 [PATCH v3 00/24] Unify vDSOs across more architectures Vincenzo Frascino
2018-12-13 16:57 ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 01/24] kernel: Standardize vdso_datapage Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 02/24] kernel: Define gettimeofday vdso common code Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-14 18:15   ` Mark Salyzyn
2018-12-14 18:15     ` Mark Salyzyn
2019-01-10 10:36     ` Vincenzo Frascino
2019-01-10 10:36       ` Vincenzo Frascino
2018-12-13 16:57 ` Vincenzo Frascino [this message]
2018-12-13 16:57   ` [PATCH v3 03/24] arm64: Build vDSO with -ffixed-x18 Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 04/24] arm64: Substitute gettimeofday with C implementation Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 05/24] arm64: compat: Alloc separate pages for vectors and sigpage Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 06/24] arm64: compat: Split kuser32 Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 07/24] arm64: compat: Refactor aarch32_alloc_vdso_pages() Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 08/24] arm64: compat: Add KUSER_HELPERS config option Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 09/24] arm64: compat: Add missing syscall numbers Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 10/24] arm64: compat: Expose signal related structures Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 11/24] arm64: compat: Generate asm offsets for signals Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 12/24] lib: vdso: Add compat support Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 13/24] arm64: compat: Add vDSO Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 14/24] arm64: Refactor vDSO code Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 15/24] arm64: compat: vDSO setup for compat layer Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 16/24] arm64: elf: vDSO code page discovery Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 17/24] arm64: compat: Get sigreturn trampolines from vDSO Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 18/24] arm64: Add vDSO compat support Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-17 15:26   ` Mark Salyzyn
2018-12-17 15:26     ` Mark Salyzyn
2019-01-10 10:39     ` Vincenzo Frascino
2019-01-10 10:39       ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 19/24] arm64: Enable compat vDSO support Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 20/24] arm: Add support for generic vDSO Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 21/24] mips: Introduce vdso_direct Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 22/24] clock: csrc-4k: Add support for vdso_direct Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 23/24] clock: gic-timer: " Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino
2018-12-13 16:57 ` [PATCH v3 24/24] mips: Add support for generic vDSO Vincenzo Frascino
2018-12-13 16:57   ` Vincenzo Frascino

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