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 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) samples/livepatch/livepatch-shadow-fix1.c | 4 ++-- samples/livepatch/livepatch-shadow-mod.c | 16 +++++++++++----- 2 files changed, 13 insertions(+), 7 deletions(-) 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. * * Usage * ----- @@ -96,15 +101,15 @@ 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 __noclone noinline struct dummy *dummy_alloc(void) { struct dummy *d; void *leak; @@ -125,7 +130,7 @@ noinline struct dummy *dummy_alloc(void) return d; } -noinline void dummy_free(struct dummy *d) +static __noclone noinline void dummy_free(struct dummy *d) { pr_info("%s: dummy @ %p, expired = %lx\n", __func__, d, d->jiffies_expire); @@ -133,7 +138,8 @@ noinline void dummy_free(struct dummy *d) kfree(d); } -noinline bool dummy_check(struct dummy *d, unsigned long jiffies) +static __noclone noinline bool dummy_check(struct dummy *d, + unsigned long jiffies) { return time_after(jiffies, d->jiffies_expire); } -- 2.1.4
