On Mon, Sep 30, 2019 at 8:45 PM Will Deacon <w...@kernel.org> wrote: > > This reverts commit ac7c3e4ff401b304489a031938dbeaab585bfe0a for ARM and > arm64. > > Building an arm64 kernel with CONFIG_OPTIMIZE_INLINING=y has been shown > to violate fixed register allocations of local variables passed to > inline assembly with GCC prior to version 9 which can lead to subtle > failures at runtime: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91111 > > A very similar has been reported for 32-bit ARM as well: > > > https://lkml.kernel.org/r/f5c221f5749e5768c9f0d909175a14910d349456.ca...@suse.de
For reviewers: The main discussion is here: https://lore.kernel.org/patchwork/patch/1122097/ > Although GCC 9.1 appears to work for the specific case in the bugzilla > above, the exact issue has not been root-caused so play safe and disable > the option for now on these architectures. > > Cc: Nicolas Saenz Julienne <nsaenzjulie...@suse.de> > Cc: Linus Torvalds <torva...@linux-foundation.org> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: Russell King <li...@armlinux.org.uk> > Cc: Masahiro Yamada <yamada.masah...@socionext.com>, > Cc: Arnd Bergmann <a...@arndb.de> > Signed-off-by: Will Deacon <w...@kernel.org> > --- > lib/Kconfig.debug | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 93d97f9b0157..c37c72adaeff 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -312,6 +312,7 @@ config HEADERS_CHECK > > config OPTIMIZE_INLINING > def_bool y > + depends on !(ARM || ARM64) # > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91111 This is a too big hammer. For ARM, it is not a compiler bug, so I am trying to fix the kernel code. For ARM64, even if it is a compiler bug, you can add __always_inline to the functions in question. (arch_atomic64_dec_if_positive in this case). You do not need to force __always_inline globally. > help > This option determines if the kernel forces gcc to inline the > functions > developers have marked 'inline'. Doing so takes away freedom from > gcc to > -- > 2.23.0.444.g18eeb5a265-goog > -- Best Regards Masahiro Yamada
