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Commit 0df2c90e authored by Vincenzo Frascino's avatar Vincenzo Frascino Committed by Will Deacon
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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: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarVincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Tested-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 37a50760

arch/arm64/include/asm/vdso/compat_barrier.h

+1 −1
Original line number Diff line number Diff line
@@ -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)

arch/arm64/kernel/vdso32/Makefile

+9 −0
Original line number Diff line number Diff line
@@ -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