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arm64: vdso32: Detect binutils support for dmb ishld 

Older versions of binutils (prior to 2.24) do not support the "ISHLD"
option for memory barrier instructions, which leads to a build failure
when assembling the vdso32 library.

Add a compilation time mechanism that detects if binutils supports those
instructions and configure the kernel accordingly.

Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Vincenzo Frascino 2019-10-03 18:48:34 +01:00 committed by Will Deacon
parent 37a5076098
commit 0df2c90eba
2 changed files with 10 additions and 1 deletions
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2
arch/arm64/include/asm/vdso/compat_barrier.h
View File

@ -20,7 +20,7 @@
#define dmb(option) __asm__ __volatile__ ("dmb " #option : : : "memory")
#if __LINUX_ARM_ARCH__ >= 8
#if __LINUX_ARM_ARCH__ >= 8 && defined(CONFIG_AS_DMB_ISHLD)
#define aarch32_smp_mb() dmb(ish)
#define aarch32_smp_rmb() dmb(ishld)
#define aarch32_smp_wmb() dmb(ishst)

9
arch/arm64/kernel/vdso32/Makefile
View File

@ -15,6 +15,8 @@ cc32-disable-warning = $(call try-run,\
$(COMPATCC) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
cc32-ldoption = $(call try-run,\
$(COMPATCC) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
cc32-as-instr = $(call try-run,\
printf "%b\n" "$(1)" | $(COMPATCC) $(VDSO_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))
# We cannot use the global flags to compile the vDSO files, the main reason
# being that the 32-bit compiler may be older than the main (64-bit) compiler
@ -53,6 +55,7 @@ endif
VDSO_CAFLAGS += -fPIC -fno-builtin -fno-stack-protector
VDSO_CAFLAGS += -DDISABLE_BRANCH_PROFILING
# Try to compile for ARMv8. If the compiler is too old and doesn't support it,
# fall back to v7. There is no easy way to check for what architecture the code
# is being compiled, so define a macro specifying that (see arch/arm/Makefile).
@ -89,6 +92,12 @@ VDSO_CFLAGS += -Wno-int-to-pointer-cast
VDSO_AFLAGS := $(VDSO_CAFLAGS)
VDSO_AFLAGS += -D__ASSEMBLY__
# Check for binutils support for dmb ishld
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