From: "Steven Rostedt (VMware)" rostedt@goodmis.org
mainline inclusion from mainline-v5.12-rc1 commit d9a1be1be331fc857d3fe29f86c3a305950b35a9 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4RCS8 CVE: NA
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With static calls, a tracepoint can call the callback directly if there is only one callback registered to that tracepoint. When there is more than one, the static call will call the tracepoint's "iterator" function, which needs to reload the tracepoint's "funcs" array again, as it could have changed since the first time it was loaded.
But an arch without static calls is punished by having to load the tracepoint's "funcs" array twice. Once in the DO_TRACE macro, and once again in the iterator macro.
For archs without static calls, there's no reason to load the array macro in the first place, since the iterator function will do it anyway.
Change the __DO_TRACE_CALL() macro to do the load and call of the tracepoints funcs array only for architectures with static calls, and just call the iterator function directly for architectures without static calls.
Link: https://lkml.kernel.org/r/20210208201050.909329787@goodmis.org
Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com Reviewed-by: Wei Li liwei391@huawei.com Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- include/linux/tracepoint.h | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index b4b2cc56be8d..45b24a3965e9 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -162,9 +162,19 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) #ifdef TRACEPOINTS_ENABLED
#ifdef CONFIG_HAVE_STATIC_CALL -#define __DO_TRACE_CALL(name) static_call(tp_func_##name) +#define __DO_TRACE_CALL(name, args) \ + do { \ + struct tracepoint_func *it_func_ptr; \ + void *__data; \ + it_func_ptr = \ + rcu_dereference_raw((&__tracepoint_##name)->funcs); \ + if (it_func_ptr) { \ + __data = (it_func_ptr)->data; \ + static_call(tp_func_##name)(__data, args); \ + } \ + } while (0) #else -#define __DO_TRACE_CALL(name) __traceiter_##name +#define __DO_TRACE_CALL(name, args) __traceiter_##name(NULL, args) #endif /* CONFIG_HAVE_STATIC_CALL */
/* @@ -173,9 +183,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) */ #define __DO_TRACE(name, args, cond, rcuidle) \ do { \ - struct tracepoint_func *it_func_ptr; \ int __maybe_unused __idx = 0; \ - void *__data; \ \ if (!(cond)) \ return; \ @@ -195,12 +203,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) rcu_irq_enter_irqson(); \ } \ \ - it_func_ptr = \ - rcu_dereference_raw((&__tracepoint_##name)->funcs); \ - if (it_func_ptr) { \ - __data = (it_func_ptr)->data; \ - __DO_TRACE_CALL(name)(__data, args); \ - } \ + __DO_TRACE_CALL(name, TP_ARGS(args)); \ \ if (rcuidle) { \ rcu_irq_exit_irqson(); \