On Tue, 2019-10-01 at 17:37 +0900, Masahiro Yamada wrote: > KernelCI reports that bcm2835_defconfig is no longer booting since > commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING > forcibly") (https://lkml.org/lkml/2019/9/26/825). > > I also received a regression report from Nicolas Saenz Julienne > (https://lkml.org/lkml/2019/9/27/263). > > This problem has cropped up on bcm2835_defconfig because it enables > CONFIG_CC_OPTIMIZE_FOR_SIZE. The compiler tends to prefer not inlining > functions with -Os. I was able to reproduce it with other boards and > defconfig files by manually enabling CONFIG_CC_OPTIMIZE_FOR_SIZE. > > The __get_user_check() specifically uses r0, r1, r2 registers. > So, uaccess_save_and_enable() and uaccess_restore() must be inlined. > Otherwise, those register assignments would be entirely dropped, > according to my analysis of the disassembly. > > Prior to commit 9012d011660e ("compiler: allow all arches to enable > CONFIG_OPTIMIZE_INLINING"), the 'inline' marker was always enough for > inlining functions, except on x86. > > Since that commit, all architectures can enable CONFIG_OPTIMIZE_INLINING. > So, __always_inline is now the only guaranteed way of forcible inlining. > > I also added __always_inline to 4 functions in the call-graph from the > __get_user_check() macro. > > Fixes: 9012d011660e ("compiler: allow all arches to enable > CONFIG_OPTIMIZE_INLINING") > Reported-by: "kernelci.org bot" > Reported-by: Nicolas Saenz Julienne > Signed-off-by: Masahiro Yamada Tested-by: Nicolas Saenz Julienne