On Fri, Dec 14, 2018 at 04:34:23PM -0500, Joe Lawrence wrote: > On 12/14/2018 11:56 AM, Nicholas Mc Guire wrote: > > Sparse reported warnings about non-static symbols. For the variables a > > simple static attribute is fine - for those symbols referenced by > > livepatch via klp_func the symbol-names must be unmodified in the > > relocation table - to resolve this the __noclone attribute (as > ^^^^^^^^^^ > nit: symbol table that should have been relocation section as described in Documentation/livepatch/module-elf-format.txt - atleast that is how I currently undderstand the livepatch mechanism and its seperate relocation section. > > > suggested by Joe Lawrence <joe.lawrence@xxxxxxxxxx>) is used > > for the statically declared functions. > > > > Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx> > > Link: https://lkml.org/lkml/2018/12/13/827 > > --- > > > > sparse reported the following warnings: > > > > CHECK samples/livepatch/livepatch-shadow-fix1.c > > samples/livepatch/livepatch-shadow-fix1.c:74:14: warning: symbol > > 'livepatch_fix1_dummy alloc' was not declared. Should it be static? > > samples/livepatch/livepatch-shadow-fix1.c:116:6: warning: symbol > > 'livepatch_fix1_dummy free' was not declared. Should it be static? > > > > CHECK samples/livepatch/livepatch-shadow-mod.c > > samples/livepatch/livepatch-shadow-mod.c:99:1: warning: symbol > > 'dummy_list' was not declared. Should it be static? > > samples/livepatch/livepatch-shadow-mod.c:100:1: warning: symbol > > 'dummy_list_mutex' was not declared. Should it be static? > > samples/livepatch/livepatch-shadow-mod.c:107:23: warning: symbol > > 'dummy_alloc' was not declared. Should it be static? > > samples/livepatch/livepatch-shadow-mod.c:132:15: warning: symbol > > 'dummy_free' was not declared. Should it be static? > > samples/livepatch/livepatch-shadow-mod.c:140:15: warning: symbol > > 'dummy_check' was not declared. Should it be static? > > > > Patch was compile tested with: x86_64_defconfig + FTRACE=y > > FUNCTION_TRACER=y, EXPERT=y, LATENCYTOP=y, SAMPLES=y, > > SAMPLE_LIVEPATCH=y > > > > Patch was runtested on an Intel i3 with: > > insmod samples/livepatch/livepatch-shadow-mod.ko > > insmod samples/livepatch/livepatch-shadow-fix1.ko > > insmod samples/livepatch/livepatch-shadow-fix2.ko > > echo 0 > /sys/kernel/livepatch/livepatch_shadow_fix2/enabled > > echo 0 > /sys/kernel/livepatch/livepatch_shadow_fix1/enabled > > rmmod livepatch-shadow-fix2 > > rmmod livepatch-shadow-fix1 > > rmmod livepatch-shadow-mod > > and dmesg output checked. > > > > Patch is against 4.20-rc6 (localversion-next is next-20181214) > > Great testing notes, thanks for including these! > > > samples/livepatch/livepatch-shadow-fix1.c | 4 ++-- > > samples/livepatch/livepatch-shadow-mod.c | 16 +++++++++++----- > > 2 files changed, 13 insertions(+), 7 deletions(-) > > Almost. We should only need to annotate with __noclone for those > function definitions which the samples will be patching. As the commit > message says, these correlate to klp_func.old_name functions found in > klp_object.name objects (.ko modules or NULL for vmlinux). > > For the functions defined in samples/livepatch/*.c those would be: > > livepatch-callbacks-busymod.c :: busymod_work_func() > livepatch-shadow-mod.c :: dummy_alloc() > livepatch-shadow-mod.c :: dummy_free() > livepatch-shadow-mod.c :: dummy_check() > > So even though livepatch-shadow-fix2 further refines > livepatch-shadow-fix1, the livepatch core is going to redirect the > original dummy_*() calls defined by livepatch-shadow-mod.c in both fix1 > and fix2 cases. Ie, the fixes modules aren't patched, only the original. > thanks for your patience - so I did not yet understand how this really works together - will give it a rerun and repost a hopefully proper solution. thx! hofrat > > > > diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c > > index 49b1355..eaab10f 100644 > > --- a/samples/livepatch/livepatch-shadow-fix1.c > > +++ b/samples/livepatch/livepatch-shadow-fix1.c > > @@ -71,7 +71,7 @@ static int shadow_leak_ctor(void *obj, void *shadow_data, void *ctor_data) > > return 0; > > } > > > > -struct dummy *livepatch_fix1_dummy_alloc(void) > > +static __noclone struct dummy *livepatch_fix1_dummy_alloc(void) > > { > > struct dummy *d; > > void *leak; > > @@ -108,7 +108,7 @@ static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data) > > __func__, d, *shadow_leak); > > } > > > > -void livepatch_fix1_dummy_free(struct dummy *d) > > +static __noclone void livepatch_fix1_dummy_free(struct dummy *d) > > { > > void **shadow_leak; > > > > diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c > > index 4c54b25..0a72bc2 100644 > > --- a/samples/livepatch/livepatch-shadow-mod.c > > +++ b/samples/livepatch/livepatch-shadow-mod.c > > @@ -30,6 +30,11 @@ > > * memory leak, please load these modules at your own risk -- some > > * amount of memory may leaked before the bug is patched. > > * > > + * NOTE - the __noclone attribute to those functions that are to be > > + * shared with other modules while being declared static. As livepatch > > + * needs the unmodified symbol names and the usual "static" would > > + * invoke gccs cloning mechanism that renames the functions this > > + * needs to be suppressed with the additional __noclone attribute. > > I like the idea of providing the sample code reader this information, > but since the compiler might also optimize livepatch-callbacks-busymod.c > :: busymod_work_func(), it too should be annotated __noclone. Would > that file deserve a similar comment? > > I don't have a strong opinion, but would throw my vote at leaving this > in the commit message only. > > > BTW, Petr/Miroslav/Josh, should we be annotating the selftests in > similar fashion? > > > [ ... snip ... ] > > Thanks for working on this, > > -- Joe
