On Thu, Sep 26, 2019 at 10:43:38PM +0100, Vincenzo Frascino wrote: > As reported by Will Deacon the .config file and the generated > include/config/auto.conf can end up out of sync after a set of > commands since CONFIG_CROSS_COMPILE_COMPAT_VDSO is not updated > correctly. > > The sequence can be reproduced as follows: > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig > [...] > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig > [set CONFIG_CROSS_COMPILE_COMPAT_VDSO="arm-linux-gnueabihf-"] > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- > > Which results in: > > arch/arm64/Makefile:62: CROSS_COMPILE_COMPAT not defined or empty, > the compat vDSO will not be built > > even though the compat vDSO has been built: > > $ file arch/arm64/kernel/vdso32/vdso.so > arch/arm64/kernel/vdso32/vdso.so: ELF 32-bit LSB pie executable, ARM, > EABI5 version 1 (SYSV), dynamically linked, > BuildID[sha1]=c67f6c786f2d2d6f86c71f708595594aa25247f6, stripped > > A similar case that involves changing the configuration parameter multiple > times can be reconducted to the same family of problems. > > The reason behind it comes from the fact that the master Makefile includes > that architecture Makefile twice, once before the syncconfig and one after. > Since the synchronization of the files happens only upon syncconfig, the > architecture Makefile included before this event does not see the change in > configuration. > > As a consequence of this it is not possible to handle the cross compiler > definitions inside the architecture Makefile. > > Address the problem removing CONFIG_CROSS_COMPILE_COMPAT_VDSO and moving > the detection of the correct compiler into Kconfig via COMPAT_CC_IS_GCC. > > As a consequence of this it is not possible anymore to set the compat > cross compiler from menuconfig but it requires to be exported via > command line. > > E.g.: > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- > CROSS_COMPILE_COMPAT=arm-linux-gnueabihf > > Cc: Will Deacon <w...@kernel.org> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frasc...@arm.com> > --- > arch/arm64/Kconfig | 5 ++++- > arch/arm64/Makefile | 18 +++++------------- > arch/arm64/kernel/vdso32/Makefile | 2 -- > 3 files changed, 9 insertions(+), 16 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 37c610963eee..0e5beb928af5 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -110,7 +110,7 @@ config ARM64 > select GENERIC_STRNLEN_USER > select GENERIC_TIME_VSYSCALL > select GENERIC_GETTIMEOFDAY > - select GENERIC_COMPAT_VDSO if (!CPU_BIG_ENDIAN && COMPAT) > + select GENERIC_COMPAT_VDSO if (!CPU_BIG_ENDIAN && COMPAT && > COMPATCC_IS_ARM_GCC) > select HANDLE_DOMAIN_IRQ > select HARDIRQS_SW_RESEND > select HAVE_PCI > @@ -313,6 +313,9 @@ config KASAN_SHADOW_OFFSET > default 0xeffffff900000000 if ARM64_VA_BITS_36 && KASAN_SW_TAGS > default 0xffffffffffffffff > > +config COMPATCC_IS_ARM_GCC > + def_bool $(success,$(COMPATCC) --version | head -n 1 | grep -q > "arm-.*-gcc")
I've seen toolchains where the first part of the tuple is "armv7-", so they won't get detected here. However, do we really need to detect this? If somebody passes a duff compiler, then the build will fail in the same way as if they passed it to CROSS_COMPILE=. I'd prefer to drop this check altogether. Will
