| Message ID | 20190926133805.52348-3-vincenzo.frascino@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: vdso32: Address various issues | expand |
On Thu, Sep 26, 2019 at 02:38:03PM +0100, Vincenzo Frascino wrote: > diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild > index d6465823b281..75cf8c796d0e 100644 > --- a/arch/arm64/Kbuild > +++ b/arch/arm64/Kbuild > @@ -4,3 +4,9 @@ obj-$(CONFIG_NET) += net/ > obj-$(CONFIG_KVM) += kvm/ > obj-$(CONFIG_XEN) += xen/ > obj-$(CONFIG_CRYPTO) += crypto/ > + > +# as-instr-compat > +# Usage: cflags-y += $(call as-instr-compat,instr,option1,option2) > + > +as-instr-compat = $(call try-run,\ > + printf "%b\n" "$(1)" | $(COMPATCC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3)) This doesn't seem to be used anywhere. Was it meant to be replaced by cc32-as-instr?
On Thu, Sep 26, 2019 at 02:38:03PM +0100, Vincenzo Frascino wrote:
> arch/arm64/kernel/vdso32/Makefile | 9 +++++++++
Could you please also remove the unnecessary gcc-goto.sh check in this
file? We don't use jump labels in the vdso (can't run-time patch them).
I found it while forcing COMPATCC=clang with my additional diff and I
get the warning on 'make clean'.
diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index 22f0d31ea528..038357a1e835 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -40,9 +38,6 @@ VDSO_CAFLAGS += $(call cc32-option,-fno-PIE)
ifdef CONFIG_DEBUG_INFO
VDSO_CAFLAGS += -g
endif
-ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(COMPATCC)), y)
-VDSO_CAFLAGS += -DCC_HAVE_ASM_GOTO
-endif
# From arm Makefile
VDSO_CAFLAGS += $(call cc32-option,-fno-dwarf2-cfi-asm)
On Thu, Sep 26, 2019 at 6:38 AM Vincenzo Frascino <vincenzo.frascino@arm.com> wrote: > > As reported by Will Deacon, older versions of binutils that do not > support certain types of memory barriers can cause build failure of the > vdso32 library. Do we know which specific version of binutils has this problem? Documentation/process/changes.rst lists 2.21+ as the supported versions. If it's older than that, it's unsupported. I triple checked android's 2.27 seems ok. $ cat bar.s .text .globl foo dmb ish dmb ishld dmb ishst $ aarch64-linux-gnu-as bar.s $ echo $? 0 $ llvm-objdump -d a.out a.out: file format ELF64-aarch64-little Disassembly of section .text: 0000000000000000 $x: 0: bf 3b 03 d5 dmb ish 4: bf 39 03 d5 dmb ishld 8: bf 3a 03 d5 dmb ishst > > 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> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > --- > arch/arm64/Kbuild | 6 ++++++ > arch/arm64/include/asm/vdso/compat_barrier.h | 2 +- > arch/arm64/kernel/vdso32/Makefile | 9 +++++++++ > 3 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild > index d6465823b281..75cf8c796d0e 100644 > --- a/arch/arm64/Kbuild > +++ b/arch/arm64/Kbuild > @@ -4,3 +4,9 @@ obj-$(CONFIG_NET) += net/ > obj-$(CONFIG_KVM) += kvm/ > obj-$(CONFIG_XEN) += xen/ > obj-$(CONFIG_CRYPTO) += crypto/ > + > +# as-instr-compat > +# Usage: cflags-y += $(call as-instr-compat,instr,option1,option2) > + > +as-instr-compat = $(call try-run,\ > + printf "%b\n" "$(1)" | $(COMPATCC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3)) > diff --git a/arch/arm64/include/asm/vdso/compat_barrier.h b/arch/arm64/include/asm/vdso/compat_barrier.h > index fb60a88b5ed4..3fd8fd6d8fc2 100644 > --- a/arch/arm64/include/asm/vdso/compat_barrier.h > +++ b/arch/arm64/include/asm/vdso/compat_barrier.h > @@ -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) > diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile > index 1fba0776ed40..22f0d31ea528 100644 > --- a/arch/arm64/kernel/vdso32/Makefile > +++ b/arch/arm64/kernel/vdso32/Makefile > @@ -17,6 +17,8 @@ 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 "$$TMP" -,$(2),$(3)) > > # We cannot use the global flags to compile the vDSO files, the main reason > # being that the 32-bit compiler may be older than the main (64-bit) compiler > @@ -55,6 +57,7 @@ endif > VDSO_CAFLAGS += -fPIC -fno-builtin -fno-stack-protector > VDSO_CAFLAGS += -DDISABLE_BRANCH_PROFILING > > + > # Try to compile for ARMv8. If the compiler is too old and doesn't support it, > # fall back to v7. There is no easy way to check for what architecture the code > # is being compiled, so define a macro specifying that (see arch/arm/Makefile). > @@ -91,6 +94,12 @@ VDSO_CFLAGS += -Wno-int-to-pointer-cast > VDSO_AFLAGS := $(VDSO_CAFLAGS) > VDSO_AFLAGS += -D__ASSEMBLY__ > > +# Check for binutils support for dmb ishld > +dmbinstr := $(call cc32-as-instr,dmb ishld,-DCONFIG_AS_DMB_ISHLD=1) > + > +VDSO_CFLAGS += $(dmbinstr) > +VDSO_AFLAGS += $(dmbinstr) > + > VDSO_LDFLAGS := $(VDSO_CPPFLAGS) > # From arm vDSO Makefile > VDSO_LDFLAGS += -Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 > -- > 2.23.0 >
On 9/26/19 3:26 PM, Catalin Marinas wrote: > On Thu, Sep 26, 2019 at 02:38:03PM +0100, Vincenzo Frascino wrote: >> diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild >> index d6465823b281..75cf8c796d0e 100644 >> --- a/arch/arm64/Kbuild >> +++ b/arch/arm64/Kbuild >> @@ -4,3 +4,9 @@ obj-$(CONFIG_NET) += net/ >> obj-$(CONFIG_KVM) += kvm/ >> obj-$(CONFIG_XEN) += xen/ >> obj-$(CONFIG_CRYPTO) += crypto/ >> + >> +# as-instr-compat >> +# Usage: cflags-y += $(call as-instr-compat,instr,option1,option2) >> + >> +as-instr-compat = $(call try-run,\ >> + printf "%b\n" "$(1)" | $(COMPATCC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3)) > > This doesn't seem to be used anywhere. Was it meant to be replaced by > cc32-as-instr? > Forgot to squash a stash here. Will fix in v3. This is not used anymore was just an experiment.
On 9/26/19 4:59 PM, Catalin Marinas wrote: > On Thu, Sep 26, 2019 at 02:38:03PM +0100, Vincenzo Frascino wrote: >> arch/arm64/kernel/vdso32/Makefile | 9 +++++++++ > > Could you please also remove the unnecessary gcc-goto.sh check in this > file? We don't use jump labels in the vdso (can't run-time patch them). > I found it while forcing COMPATCC=clang with my additional diff and I > get the warning on 'make clean'. > I will do it in a separate cleanup patch, I want to keep this only for the error reported by Will. > diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile > index 22f0d31ea528..038357a1e835 100644 > --- a/arch/arm64/kernel/vdso32/Makefile > +++ b/arch/arm64/kernel/vdso32/Makefile > @@ -40,9 +38,6 @@ VDSO_CAFLAGS += $(call cc32-option,-fno-PIE) > ifdef CONFIG_DEBUG_INFO > VDSO_CAFLAGS += -g > endif > -ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(COMPATCC)), y) > -VDSO_CAFLAGS += -DCC_HAVE_ASM_GOTO > -endif > > # From arm Makefile > VDSO_CAFLAGS += $(call cc32-option,-fno-dwarf2-cfi-asm) >
diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild index d6465823b281..75cf8c796d0e 100644 --- a/arch/arm64/Kbuild +++ b/arch/arm64/Kbuild @@ -4,3 +4,9 @@ obj-$(CONFIG_NET) += net/ obj-$(CONFIG_KVM) += kvm/ obj-$(CONFIG_XEN) += xen/ obj-$(CONFIG_CRYPTO) += crypto/ + +# as-instr-compat +# Usage: cflags-y += $(call as-instr-compat,instr,option1,option2) + +as-instr-compat = $(call try-run,\ + printf "%b\n" "$(1)" | $(COMPATCC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3)) diff --git a/arch/arm64/include/asm/vdso/compat_barrier.h b/arch/arm64/include/asm/vdso/compat_barrier.h index fb60a88b5ed4..3fd8fd6d8fc2 100644 --- a/arch/arm64/include/asm/vdso/compat_barrier.h +++ b/arch/arm64/include/asm/vdso/compat_barrier.h @@ -20,7 +20,7 @@ #define dmb(option) __asm__ __volatile__ ("dmb " #option : : : "memory") -#if __LINUX_ARM_ARCH__ >= 8 +#if __LINUX_ARM_ARCH__ >= 8 && defined(CONFIG_AS_DMB_ISHLD) #define aarch32_smp_mb() dmb(ish) #define aarch32_smp_rmb() dmb(ishld) #define aarch32_smp_wmb() dmb(ishst) diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile index 1fba0776ed40..22f0d31ea528 100644 --- a/arch/arm64/kernel/vdso32/Makefile +++ b/arch/arm64/kernel/vdso32/Makefile @@ -17,6 +17,8 @@ cc32-disable-warning = $(call try-run,\ $(COMPATCC) -W$(strip $(1)) -c -x c /dev/null -o "$$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 @@ -55,6 +57,7 @@ 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). @@ -91,6 +94,12 @@ 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
As reported by Will Deacon, older versions of binutils that do not support certain types of memory barriers can cause build failure of 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> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- arch/arm64/Kbuild | 6 ++++++ arch/arm64/include/asm/vdso/compat_barrier.h | 2 +- arch/arm64/kernel/vdso32/Makefile | 9 +++++++++ 3 files changed, 16 insertions(+), 1 deletion(-)