From: Nathan Chancellor <natechancellor@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>
Subject: [PATCH v2] arm64: vdso32: Allow ld.lld to properly link the VDSO
Date: Mon, 19 Oct 2020 18:14:07 -0700 [thread overview]
Message-ID: <20201020011406.1818918-1-natechancellor@gmail.com> (raw)
In-Reply-To: <20201013033947.2257501-1-natechancellor@gmail.com>
As it stands now, the vdso32 Makefile hardcodes the linker to ld.bfd
using -fuse-ld=bfd with $(CC). This was taken from the arm vDSO
Makefile, as the comment notes, done in commit d2b30cd4b722 ("ARM:
8384/1: VDSO: force use of BFD linker").
Commit fe00e50b2db8 ("ARM: 8858/1: vdso: use $(LD) instead of $(CC) to
link VDSO") changed that Makefile to use $(LD) directly instead of
through $(CC), which matches how the rest of the kernel operates. Since
then, LD=ld.lld means that the arm vDSO will be linked with ld.lld,
which has shown no problems so far.
Allow ld.lld to link this vDSO as we do the regular arm vDSO. To do
this, we need to do a few things:
* Add a LD_COMPAT variable, which defaults to $(CROSS_COMPILE_COMPAT)ld
with gcc and $(LD) if LLVM is 1, which will be ld.lld, or
$(CROSS_COMPILE_COMPAT)ld if not, which matches the logic of the main
Makefile. It is overrideable for further customization and avoiding
breakage.
* Eliminate cc32-ldoption, which matches commit 055efab3120b ("kbuild:
drop support for cc-ldoption").
With those, we can use $(LD_COMPAT) in cmd_ldvdso and change the flags
from compiler linker flags to linker flags directly. We eliminate
-mfloat-abi=soft because it is not handled by the linker.
Link: https://github.com/ClangBuiltLinux/linux/issues/1033
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
v1 -> v2:
* Change ifeq ($(LLVM),1) to ifneq ($(LLVM),) to match the main Makefile
per Vincenzo.
* Carry forward Nick and Vincenzo's tags.
arch/arm64/kernel/vdso32/Makefile | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index 7f96a1a9f68c..79280c53b9a6 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -22,16 +22,21 @@ endif
CC_COMPAT ?= $(CC)
CC_COMPAT += $(CC_COMPAT_CLANG_FLAGS)
+
+ifneq ($(LLVM),)
+LD_COMPAT ?= $(LD)
+else
+LD_COMPAT ?= $(CROSS_COMPILE_COMPAT)ld
+endif
else
CC_COMPAT ?= $(CROSS_COMPILE_COMPAT)gcc
+LD_COMPAT ?= $(CROSS_COMPILE_COMPAT)ld
endif
cc32-option = $(call try-run,\
$(CC_COMPAT) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
cc32-disable-warning = $(call try-run,\
$(CC_COMPAT) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
-cc32-ldoption = $(call try-run,\
- $(CC_COMPAT) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
cc32-as-instr = $(call try-run,\
printf "%b\n" "$(1)" | $(CC_COMPAT) $(VDSO_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
@@ -122,14 +127,10 @@ dmbinstr := $(call cc32-as-instr,dmb ishld,-DCONFIG_AS_DMB_ISHLD=1)
VDSO_CFLAGS += $(dmbinstr)
VDSO_AFLAGS += $(dmbinstr)
-VDSO_LDFLAGS := $(VDSO_CPPFLAGS)
# From arm vDSO Makefile
-VDSO_LDFLAGS += -Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1
-VDSO_LDFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
-VDSO_LDFLAGS += -nostdlib -shared -mfloat-abi=soft
-VDSO_LDFLAGS += -Wl,--hash-style=sysv
-VDSO_LDFLAGS += -Wl,--build-id=sha1
-VDSO_LDFLAGS += $(call cc32-ldoption,-fuse-ld=bfd)
+VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1
+VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096
+VDSO_LDFLAGS += -nostdlib -shared --hash-style=sysv --build-id=sha1
# Borrow vdsomunge.c from the arm vDSO
@@ -189,8 +190,8 @@ quiet_cmd_vdsold_and_vdso_check = LD32 $@
cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check)
quiet_cmd_vdsold = LD32 $@
- cmd_vdsold = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_LDFLAGS) \
- -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@
+ cmd_vdsold = $(LD_COMPAT) $(VDSO_LDFLAGS) \
+ -T $(filter %.lds,$^) $(filter %.o,$^) -o $@
quiet_cmd_vdsocc = CC32 $@
cmd_vdsocc = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_CFLAGS) -c -o $@ $<
quiet_cmd_vdsocc_gettimeofday = CC32 $@
base-commit: 0fa21cf4489fe11737d56f8056dda1ba0257bd8d
--
2.29.0
next prev parent reply other threads:[~2020-10-20 1:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 3:39 [PATCH] arm64: vdso32: Allow ld.lld to properly link the VDSO Nathan Chancellor
2020-10-13 22:37 ` Nick Desaulniers
2020-10-19 9:59 ` Vincenzo Frascino
2020-10-20 1:07 ` Nathan Chancellor
2020-10-20 1:14 ` Nathan Chancellor [this message]
2020-10-20 11:37 ` [PATCH v2] " Will Deacon
2020-10-26 14:22 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201020011406.1818918-1-natechancellor@gmail.com \
--to=natechancellor@gmail.com \
--cc=catalin.marinas@arm.com \
--cc=clang-built-linux@googlegroups.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=ndesaulniers@google.com \
--cc=vincenzo.frascino@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).