Gentle ping for review. On Fri, Jun 17, 2022 at 11:08:46AM -0700, Nathan Chancellor wrote: > Chimera Linux notes that CONFIG_CC_HAS_SANE_STACKPROTECTOR cannot be > enabled when cross compiling an x86_64 kernel with clang, even though it > does work when natively compiling. > > When building on aarch64: > > $ make -sj"$(nproc)" ARCH=x86_64 LLVM=1 defconfig > > $ grep STACKPROTECTOR .config > > When building on x86_64: > > $ make -sj"$(nproc)" ARCH=x86_64 LLVM=1 defconfig > > $ grep STACKPROTECTOR .config > CONFIG_CC_HAS_SANE_STACKPROTECTOR=y > CONFIG_HAVE_STACKPROTECTOR=y > CONFIG_STACKPROTECTOR=y > CONFIG_STACKPROTECTOR_STRONG=y > > When clang is invoked without a '--target' flag, code is generated for > the default target, which is usually the host (it is configurable via > cmake). As a result, the has-stack-protector scripts will generate code > for the default target but check for x86 specific segment registers, > which cannot succeed if the default target is not x86. > > $(CLANG_FLAGS) contains an explicit '--target' flag so pass that > variable along to the has-stack-protector scripts so that the stack > protector can be enabled when cross compiling with clang. The 32-bit > stack protector cannot currently be enabled with clang, as it does not > support '-mstack-protector-guard-symbol', so this results in no > functional change for ARCH=i386 when cross compiling. > > Link: https://github.com/chimera-linux/cports/commit/0fb7e506d5f83fdf2104feb22cdac34934561226 > Link: https://github.com/llvm/llvm-project/issues/48553 > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > --- > > Fixes: 2a61f4747eea ("stack-protector: test compiler capability in Kconfig and drop AUTO mode") > > might be appropriate; I am conflicted on fixes tags for problems that > that arise due to use cases that were not considered at the time of a > change, as it feels wrong to blame the commit for not looking far enough > into the future where it might be common for people to have workstations > running another architecture other than x86_64. > > Chimera appears to use a 5.15 kernel so a > > Cc: stable@xxxxxxxxxxxxxxx > > might be nice but some maintainers are picky about that so I leave it up > to you all. > > arch/x86/Kconfig | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index be0b95e51df6..076adde7ead9 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -391,8 +391,8 @@ config PGTABLE_LEVELS > > config CC_HAS_SANE_STACKPROTECTOR > bool > - default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT > - default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC)) > + default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT > + default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) > help > We have to make sure stack protector is unconditionally disabled if > the compiler produces broken code or if it does not let us control > > base-commit: b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 > -- > 2.36.1 > >
