diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-08-18 15:57:49 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-09-01 09:58:06 +0200 |
| commit | 5b06fd3bb9cdce4f3e731c48eb5b74c4acc47997 (patch) | |
| tree | 533fcad5bdd98fd31ccd3956dec2e3478f15ca91 /kernel/static_call.c | |
| parent | static_call: Add static_call_cond() (diff) | |
| download | linux-5b06fd3bb9cdce4f3e731c48eb5b74c4acc47997.tar.xz linux-5b06fd3bb9cdce4f3e731c48eb5b74c4acc47997.zip | |
static_call: Handle tail-calls
GCC can turn our static_call(name)(args...) into a tail call, in which
case we get a JMP.d32 into the trampoline (which then does a further
tail-call).
Teach objtool to recognise and mark these in .static_call_sites and
adjust the code patching to deal with this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135805.101186767@infradead.org
Diffstat (limited to 'kernel/static_call.c')
| -rw-r--r-- | kernel/static_call.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/kernel/static_call.c b/kernel/static_call.c index 97142cb6bfa6..d98e0e4272c1 100644 --- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -15,8 +15,6 @@ extern struct static_call_site __start_static_call_sites[], static bool static_call_initialized; -#define STATIC_CALL_INIT 1UL - /* mutex to protect key modules/sites */ static DEFINE_MUTEX(static_call_mutex); @@ -39,18 +37,23 @@ static inline void *static_call_addr(struct static_call_site *site) 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_INIT); + (((long)site->key + (long)&site->key) & ~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_INIT; + return ((long)site->key + (long)&site->key) & 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; } static inline void static_call_set_init(struct static_call_site *site) { - site->key = ((long)static_call_key(site) | STATIC_CALL_INIT) - + site->key = ((long)static_call_key(site) | STATIC_CALL_SITE_INIT) - (long)&site->key; } @@ -104,7 +107,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) key->func = func; - arch_static_call_transform(NULL, tramp, func); + arch_static_call_transform(NULL, tramp, func, false); /* * If uninitialized, we'll not update the callsites, but they still @@ -154,7 +157,8 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func) continue; } - arch_static_call_transform(site_addr, NULL, func); + arch_static_call_transform(site_addr, NULL, func, + static_call_is_tail(site)); } } @@ -198,7 +202,8 @@ static int __static_call_init(struct module *mod, key->mods = site_mod; } - arch_static_call_transform(site_addr, NULL, key->func); + arch_static_call_transform(site_addr, NULL, key->func, + static_call_is_tail(site)); } return 0; |