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    Subject[PATCH] Partially revert "compiler: enable CONFIG_OPTIMIZE_INLINING forcibly"
    Date
    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.camel@suse.de

    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 <nsaenzjulienne@suse.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Masahiro Yamada <yamada.masahiro@socionext.com>,
    Cc: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Will Deacon <will@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
    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
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