On 01/17/2017 03:30 PM, Stafford Horne wrote: > On Tue, Jan 17, 2017 at 02:44:54PM +0100, Peter Zijlstra wrote: >> On Tue, Jan 17, 2017 at 02:07:36PM +0100, Vlastimil Babka wrote: >> >>> Anyway I'm not sure if this patch is safe. Hopefully Peter can judge >>> this better... >>> >>>> Cc: Vlastimil Babka <[email protected]> >>>> Signed-off-by: Stafford Horne <[email protected]> >>>> --- >>>> init/main.c | 3 +-- >>>> 1 file changed, 1 insertion(+), 2 deletions(-) >>>> >>>> diff --git a/init/main.c b/init/main.c >>>> index 8b1adb6e..d1ca7cb 100644 >>>> --- a/init/main.c >>>> +++ b/init/main.c >>>> @@ -513,6 +513,7 @@ asmlinkage __visible void __init start_kernel(void) >>>> boot_cpu_state_init(); >>>> smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */ >>>> >>>> + jump_label_init(); >>>> build_all_zonelists(NULL, NULL); >>>> page_alloc_init(); >>>> >>>> @@ -526,8 +527,6 @@ asmlinkage __visible void __init start_kernel(void) >>>> parse_args("Setting init args", after_dashes, NULL, 0, -1, -1, >>>> NULL, set_init_arg); >>>> >>>> - jump_label_init(); >>>> - >> >> Urgh, that means auditing all archs that implement this. The thing >> you're looking for is if the self-modifying code cruft can be done that >> early. >> >> x86 looks to be fine, because this is after setup_arch() which is >> required for ideal_nops[] to be initialied and we use text_poke_early() >> which doesn't really need anything else. >> >> I've not gone through the other arches... > > Vlastimil, > > Will you be able to look into that? Openrisc doesnt have jump_label > support, so its no issue at the moment. > > Archs that do have it: > > arch/arm64/Kconfig: select HAVE_ARCH_JUMP_LABEL > arch/mips/Kconfig: select HAVE_ARCH_JUMP_LABEL > arch/s390/Kconfig: select HAVE_ARCH_JUMP_LABEL > arch/sparc/Kconfig: select HAVE_ARCH_JUMP_LABEL if SPARC64 > arch/tile/Kconfig: select HAVE_ARCH_JUMP_LABEL > arch/x86/Kconfig: select HAVE_ARCH_JUMP_LABEL > arch/arm/Kconfig: select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && > !CPU_ENDIAN_BE32 && MMU > arch/powerpc/Kconfig: select HAVE_ARCH_JUMP_LABEL > > I looked at a few (arm, tile) and I dont see their arch_jump_label_transform* > implementations depending on global state like ideal_nops from x86. They > should be ok.
Thanks, I'll try. > If no time, Should you change your patch to not use static keys for > build_all_zonelists at least? Yes that would be uglier but possible if I find issues or I'm not confident enough with the auditing...
