Commit 0fa97e94 authored by Nathan Chancellor's avatar Nathan Chancellor Committed by Will Deacon

arm64: vdso32: Allow ld.lld to properly link the VDSO

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 d2b30cd4 ("ARM:
8384/1: VDSO: force use of BFD linker").

Commit fe00e50b ("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 055efab3 ("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.
Reported-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Tested-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: default avatarVincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1033
Link: https://lore.kernel.org/r/20201020011406.1818918-1-natechancellor@gmail.comSigned-off-by: default avatarWill Deacon <will@kernel.org>
parent 3650b228
......@@ -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 $@
......
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