Messages in this thread | | | Subject | Re: [PATCH V4] livepatch: non static warnings fix | From | Joe Lawrence <> | Date | Thu, 24 Jan 2019 12:05:57 -0500 |
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On 1/23/19 8:48 PM, Nicholas Mc Guire wrote: > Sparse reported warnings about non-static symbols. For the variables > a simple static attribute is fine - for the functions referenced by > livepatch via klp_func the symbol-names must be unmodified in the > symbol table and the patchable code has to be emitted. The resolution > is to attach __used attribute to the shared statically declared functions. > > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> > Suggested-by: Joe Lawrence <joe.lawrence@redhat.com> > Acked-by: Miroslav Benes <mbenes@suse.cz> > Link: https://lore.kernel.org/lkml/1544965657-26804-1-git-send-email-hofrat@osadl.org/
Hi Nicholas, thanks for re-posting this fix, the __used attribute change was particularly interesting to learn about.
I think Miroslav requested a re-ordering of these tags, perhaps we could do the shuffle when we apply the patch to the tree?
Link: Suggested-by: Signed-off-by: Acked-by:
With that,
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
> --- > > V2: not all static functions shared need to carry the __noclone > attribute only those that need to be resolved at runtime by > livepatch - so drop the unnecessary __noclone attributes as > well as the Note on __noclone as suggested by Joe Lawrence > <joe.lawrence@redhat.com> - thanks ! > > V3: fix the wording as proposed by Joe Lawrence > <joe.lawrence@redhat.com> to address that this is not only > about how to fix sparse warnings but also to ensure > traceable/patchable code still being emitted. > > V4: fix up the Link to point to the proper page as suggested > by Joe Lawrence <joe.lawrence@redhat.com>.
Credit to Miroslav for these last two change suggestions.
-- Joe
> Sparse reported the following findings in 5.0-rc3: > > 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? > > 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-fix2.c > samples/livepatch/livepatch-shadow-fix2.c:53:6: warning: symbol 'livepatch_fix2_dummy_check' was not declared. Should it be static? > samples/livepatch/livepatch-shadow-fix2.c:81:6: warning: symbol 'livepatch_fix2_dummy_free' was not declared. Should it be static? > > Patch was compile tested with: x86_64_defconfig + FTRACE=y > FUNCTION_TRACER=y, SAMPLES=y, LIVEPATCH=y SAMPLE_LIVEPATCH=m > (looks sparse, smatch claan, one coccichek warning left - fix later today) > > Patch was runtested 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 compared to previous run. > > Patch is against 5.0-rc3 (localversion-next is next-20190123) > > samples/livepatch/livepatch-shadow-fix1.c | 4 ++-- > samples/livepatch/livepatch-shadow-fix2.c | 4 ++-- > samples/livepatch/livepatch-shadow-mod.c | 11 ++++++----- > 3 files changed, 10 insertions(+), 9 deletions(-) > > diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c > index a5a5cac..67a73e5 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 struct dummy *livepatch_fix1_dummy_alloc(void) > { > struct dummy *d; > void *leak; > @@ -113,7 +113,7 @@ 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 void livepatch_fix1_dummy_free(struct dummy *d) > { > void **shadow_leak; > > diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c > index 52de947..91c21d5 100644 > --- a/samples/livepatch/livepatch-shadow-fix2.c > +++ b/samples/livepatch/livepatch-shadow-fix2.c > @@ -50,7 +50,7 @@ struct dummy { > unsigned long jiffies_expire; > }; > > -bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies) > +static bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies) > { > int *shadow_count; > > @@ -78,7 +78,7 @@ static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data) > __func__, d, *shadow_leak); > } > > -void livepatch_fix2_dummy_free(struct dummy *d) > +static void livepatch_fix2_dummy_free(struct dummy *d) > { > void **shadow_leak; > int *shadow_count; > diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c > index 4aa8a88..4d79c6dc 100644 > --- a/samples/livepatch/livepatch-shadow-mod.c > +++ b/samples/livepatch/livepatch-shadow-mod.c > @@ -96,15 +96,15 @@ MODULE_DESCRIPTION("Buggy module for shadow variable demo"); > * Keep a list of all the dummies so we can clean up any residual ones > * on module exit > */ > -LIST_HEAD(dummy_list); > -DEFINE_MUTEX(dummy_list_mutex); > +static LIST_HEAD(dummy_list); > +static DEFINE_MUTEX(dummy_list_mutex); > > struct dummy { > struct list_head list; > unsigned long jiffies_expire; > }; > > -noinline struct dummy *dummy_alloc(void) > +static __used noinline struct dummy *dummy_alloc(void) > { > struct dummy *d; > void *leak; > @@ -129,7 +129,7 @@ noinline struct dummy *dummy_alloc(void) > return d; > } > > -noinline void dummy_free(struct dummy *d) > +static __used noinline void dummy_free(struct dummy *d) > { > pr_info("%s: dummy @ %p, expired = %lx\n", > __func__, d, d->jiffies_expire); > @@ -137,7 +137,8 @@ noinline void dummy_free(struct dummy *d) > kfree(d); > } > > -noinline bool dummy_check(struct dummy *d, unsigned long jiffies) > +static __used noinline bool dummy_check(struct dummy *d, > + unsigned long jiffies) > { > return time_after(jiffies, d->jiffies_expire); > } >
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