From 68b1eddd421d2b16c6655eceb48918a1e896bbbc Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 18 Mar 2021 11:27:19 +0100 Subject: static_call: Fix static_call_set_init() It turns out that static_call_set_init() does not preserve the other flags; IOW. it clears TAIL if it was set. Fixes: 9183c3f9ed710 ("static_call: Add inline static call infrastructure") Reported-by: Sumit Garg Signed-off-by: Peter Zijlstra (Intel) Acked-by: Jarkko Sakkinen Tested-by: Sumit Garg Link: https://lkml.kernel.org/r/20210318113610.519406371@infradead.org --- kernel/static_call.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) (limited to 'kernel/static_call.c') diff --git a/kernel/static_call.c b/kernel/static_call.c index ae825295cf68..080c8a9ddfaf 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -35,27 +35,30 @@ static inline void *static_call_addr(struct static_call_site *site) return (void *)((long)site->addr + (long)&site->addr); } +static inline unsigned long __static_call_key(const struct static_call_site *site) +{ + return (long)site->key + (long)&site->key; +} static inline struct static_call_key *static_call_key(const struct static_call_site *site) { - return (struct static_call_key *) - (((long)site->key + (long)&site->key) & ~STATIC_CALL_SITE_FLAGS); + return (void *)(__static_call_key(site) & ~STATIC_CALL_SITE_FLAGS); } /* These assume the key is word-aligned. */ static inline bool static_call_is_init(struct static_call_site *site) { - return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_INIT; + return __static_call_key(site) & STATIC_CALL_SITE_INIT; } static inline bool static_call_is_tail(struct static_call_site *site) { - return ((long)site->key + (long)&site->key) & STATIC_CALL_SITE_TAIL; + return __static_call_key(site) & STATIC_CALL_SITE_TAIL; } static inline void static_call_set_init(struct static_call_site *site) { - site->key = ((long)static_call_key(site) | STATIC_CALL_SITE_INIT) - + site->key = (__static_call_key(site) | STATIC_CALL_SITE_INIT) - (long)&site->key; } @@ -190,7 +193,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) } arch_static_call_transform(site_addr, NULL, func, - static_call_is_tail(site)); + static_call_is_tail(site)); } } @@ -349,7 +352,7 @@ static int static_call_add_module(struct module *mod) struct static_call_site *site; for (site = start; site != stop; site++) { - unsigned long s_key = (long)site->key + (long)&site->key; + unsigned long s_key = __static_call_key(site); unsigned long addr = s_key & ~STATIC_CALL_SITE_FLAGS; unsigned long key; -- cgit v1.2.3 From 698bacefe993ad2922c9d3b1380591ad489355e9 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 18 Mar 2021 11:29:56 +0100 Subject: static_call: Align static_call_is_init() patching condition The intent is to avoid writing init code after init (because the text might have been freed). The code is needlessly different between jump_label and static_call and not obviously correct. The existing code relies on the fact that the module loader clears the init layout, such that within_module_init() always fails, while jump_label relies on the module state which is more obvious and matches the kernel logic. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Jarkko Sakkinen Tested-by: Sumit Garg Link: https://lkml.kernel.org/r/20210318113610.636651340@infradead.org --- kernel/static_call.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) (limited to 'kernel/static_call.c') diff --git a/kernel/static_call.c b/kernel/static_call.c index 080c8a9ddfaf..fc2259047be2 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -149,6 +149,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) }; for (site_mod = &first; site_mod; site_mod = site_mod->next) { + bool init = system_state < SYSTEM_RUNNING; struct module *mod = site_mod->mod; if (!site_mod->sites) { @@ -168,6 +169,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) if (mod) { stop = mod->static_call_sites + mod->num_static_call_sites; + init = mod->state == MODULE_STATE_COMING; } #endif @@ -175,16 +177,8 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) site < stop && static_call_key(site) == key; site++) { void *site_addr = static_call_addr(site); - if (static_call_is_init(site)) { - /* - * Don't write to call sites which were in - * initmem and have since been freed. - */ - if (!mod && system_state >= SYSTEM_RUNNING) - continue; - if (mod && !within_module_init((unsigned long)site_addr, mod)) - continue; - } + if (!init && static_call_is_init(site)) + continue; if (!kernel_text_address((unsigned long)site_addr)) { WARN_ONCE(1, "can't patch static call site at %pS", -- cgit v1.2.3 From 38c93587375053c5b9ef093f4a5ea754538cba32 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 18 Mar 2021 11:31:51 +0100 Subject: static_call: Fix static_call_update() sanity check Sites that match init_section_contains() get marked as INIT. For built-in code init_sections contains both __init and __exit text. OTOH kernel_text_address() only explicitly includes __init text (and there are no __exit text markers). Match what jump_label already does and ignore the warning for INIT sites. Also see the excellent changelog for commit: 8f35eaa5f2de ("jump_label: Don't warn on __exit jump entries") Fixes: 9183c3f9ed710 ("static_call: Add inline static call infrastructure") Reported-by: Sumit Garg Signed-off-by: Peter Zijlstra (Intel) Acked-by: Jarkko Sakkinen Tested-by: Sumit Garg Link: https://lkml.kernel.org/r/20210318113610.739542434@infradead.org --- kernel/static_call.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'kernel/static_call.c') diff --git a/kernel/static_call.c b/kernel/static_call.c index fc2259047be2..2c5950b0b90e 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -181,7 +181,16 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) continue; if (!kernel_text_address((unsigned long)site_addr)) { - WARN_ONCE(1, "can't patch static call site at %pS", + /* + * This skips patching built-in __exit, which + * is part of init_section_contains() but is + * not part of kernel_text_address(). + * + * Skipping built-in __exit is fine since it + * will never be executed. + */ + WARN_ONCE(!static_call_is_init(site), + "can't patch static call site at %pS", site_addr); continue; } -- cgit v1.2.3