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@xxxxxxxxx> Suggested-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> Acked-by: Miroslav Benes <mbenes@xxxxxxx> Link: https://lore.kernel.org/lkml/1544965657-26804-1-git-send-email-hofrat@xxxxxxxxx/ --- 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@xxxxxxxxxx> - thanks ! V3: fix the wording as proposed by Joe Lawrence <joe.lawrence@xxxxxxxxxx> 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@xxxxxxxxxx>. 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); } -- 2.1.4
