Messages in this thread Patch in this message | | | Date | Fri, 13 Dec 2019 21:49:46 +0100 | Subject | [PATCH RESEND -rcu/kcsan] kcsan: Prefer __always_inline for fast-path | From | Marco Elver <> |
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Prefer __always_inline for fast-path functions that are called outside of user_access_save, to avoid generating UACCESS warnings when optimizing for size (CC_OPTIMIZE_FOR_SIZE). It will also avoid future surprises with compiler versions that change the inlining heuristic even when optimizing for performance.
Report: http://lkml.kernel.org/r/58708908-84a0-0a81-a836-ad97e33dbb62@infradead.org Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Signed-off-by: Marco Elver <elver@google.com> --- Version rebased on -rcu/kcsan.
There are 3 locations that would conflict with the style cleanup in -tip/locking/kcsan: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=locking/kcsan&id=5cbaefe9743bf14c9d3106db0cc19f8cb0a3ca22
For the conflicting locations the better style is carried over, so that upon eventual merge the resolution should be trivial. --- kernel/kcsan/atomic.h | 2 +- kernel/kcsan/core.c | 17 ++++++++--------- kernel/kcsan/encoding.h | 11 +++++------ 3 files changed, 14 insertions(+), 16 deletions(-)
diff --git a/kernel/kcsan/atomic.h b/kernel/kcsan/atomic.h index c9c3fe628011..466e6777533e 100644 --- a/kernel/kcsan/atomic.h +++ b/kernel/kcsan/atomic.h @@ -18,7 +18,7 @@ * than cast to volatile. Eventually, we hope to be able to remove this * function. */ -static inline bool kcsan_is_atomic(const volatile void *ptr) +static __always_inline bool kcsan_is_atomic(const volatile void *ptr) { /* only jiffies for now */ return ptr == &jiffies; diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index d9410d58c93e..69870645b631 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -78,9 +78,8 @@ static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS - 1]; */ static DEFINE_PER_CPU(long, kcsan_skip); -static inline atomic_long_t *find_watchpoint(unsigned long addr, size_t size, - bool expect_write, - long *encoded_watchpoint) +static __always_inline atomic_long_t * +find_watchpoint(unsigned long addr, size_t size, bool expect_write, long *encoded_watchpoint) { const int slot = watchpoint_slot(addr); const unsigned long addr_masked = addr & WATCHPOINT_ADDR_MASK; @@ -150,8 +149,8 @@ static inline atomic_long_t *insert_watchpoint(unsigned long addr, size_t size, * 2. the thread that set up the watchpoint already removed it; * 3. the watchpoint was removed and then re-used. */ -static inline bool try_consume_watchpoint(atomic_long_t *watchpoint, - long encoded_watchpoint) +static __always_inline bool +try_consume_watchpoint(atomic_long_t *watchpoint, long encoded_watchpoint) { return atomic_long_try_cmpxchg_relaxed(watchpoint, &encoded_watchpoint, CONSUMED_WATCHPOINT); @@ -166,7 +165,7 @@ static inline bool remove_watchpoint(atomic_long_t *watchpoint) CONSUMED_WATCHPOINT; } -static inline struct kcsan_ctx *get_ctx(void) +static __always_inline struct kcsan_ctx *get_ctx(void) { /* * In interrupt, use raw_cpu_ptr to avoid unnecessary checks, that would @@ -175,7 +174,7 @@ static inline struct kcsan_ctx *get_ctx(void) return in_task() ? ¤t->kcsan_ctx : raw_cpu_ptr(&kcsan_cpu_ctx); } -static inline bool is_atomic(const volatile void *ptr) +static __always_inline bool is_atomic(const volatile void *ptr) { struct kcsan_ctx *ctx = get_ctx(); @@ -199,7 +198,7 @@ static inline bool is_atomic(const volatile void *ptr) return kcsan_is_atomic(ptr); } -static inline bool should_watch(const volatile void *ptr, int type) +static __always_inline bool should_watch(const volatile void *ptr, int type) { /* * Never set up watchpoints when memory operations are atomic. @@ -232,7 +231,7 @@ static inline void reset_kcsan_skip(void) this_cpu_write(kcsan_skip, skip_count); } -static inline bool kcsan_is_enabled(void) +static __always_inline bool kcsan_is_enabled(void) { return READ_ONCE(kcsan_enabled) && get_ctx()->disable_count == 0; } diff --git a/kernel/kcsan/encoding.h b/kernel/kcsan/encoding.h index e17bdac0e54b..e527e83ce825 100644 --- a/kernel/kcsan/encoding.h +++ b/kernel/kcsan/encoding.h @@ -58,9 +58,8 @@ static inline long encode_watchpoint(unsigned long addr, size_t size, (addr & WATCHPOINT_ADDR_MASK)); } -static inline bool decode_watchpoint(long watchpoint, - unsigned long *addr_masked, size_t *size, - bool *is_write) +static __always_inline bool +decode_watchpoint(long watchpoint, unsigned long *addr_masked, size_t *size, bool *is_write) { if (watchpoint == INVALID_WATCHPOINT || watchpoint == CONSUMED_WATCHPOINT) @@ -77,13 +76,13 @@ static inline bool decode_watchpoint(long watchpoint, /* * Return watchpoint slot for an address. */ -static inline int watchpoint_slot(unsigned long addr) +static __always_inline int watchpoint_slot(unsigned long addr) { return (addr / PAGE_SIZE) % CONFIG_KCSAN_NUM_WATCHPOINTS; } -static inline bool matching_access(unsigned long addr1, size_t size1, - unsigned long addr2, size_t size2) +static __always_inline bool matching_access(unsigned long addr1, size_t size1, + unsigned long addr2, size_t size2) { unsigned long end_range1 = addr1 + size1 - 1; unsigned long end_range2 = addr2 + size2 - 1; -- 2.24.1.735.g03f4e72817-goog
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