diff options
| -rw-r--r-- | kernel/trace/ftrace.c | 40 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 106 |
2 files changed, 110 insertions, 36 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 639b6ab1f04..ce8c3d68292 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -158,25 +158,15 @@ ftrace_global_list_func(unsigned long ip, unsigned long parent_ip, { int bit; - if (in_interrupt()) { - if (in_nmi()) - bit = TRACE_GLOBAL_NMI_BIT; - - else if (in_irq()) - bit = TRACE_GLOBAL_IRQ_BIT; - else - bit = TRACE_GLOBAL_SIRQ_BIT; - } else - bit = TRACE_GLOBAL_BIT; - - if (unlikely(trace_recursion_test(bit))) + bit = trace_test_and_set_recursion(TRACE_GLOBAL_START, TRACE_GLOBAL_MAX); + if (bit < 0) return; - trace_recursion_set(bit); do_for_each_ftrace_op(op, ftrace_global_list) { op->func(ip, parent_ip, op, regs); } while_for_each_ftrace_op(op); - trace_recursion_clear(bit); + + trace_clear_recursion(bit); } static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip, @@ -4145,26 +4135,14 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ignored, struct pt_regs *regs) { struct ftrace_ops *op; - unsigned int bit; + int bit; if (function_trace_stop) return; - if (in_interrupt()) { - if (in_nmi()) - bit = TRACE_INTERNAL_NMI_BIT; - - else if (in_irq()) - bit = TRACE_INTERNAL_IRQ_BIT; - else - bit = TRACE_INTERNAL_SIRQ_BIT; - } else - bit = TRACE_INTERNAL_BIT; - - if (unlikely(trace_recursion_test(bit))) - return; - - trace_recursion_set(bit); + bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX); + if (bit < 0) + return; /* * Some of the ops may be dynamically allocated, @@ -4176,7 +4154,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, op->func(ip, parent_ip, op, regs); } while_for_each_ftrace_op(op); preempt_enable_notrace(); - trace_recursion_clear(bit); + trace_clear_recursion(bit); } /* diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 5a095d6f088..c203a51dd41 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -297,18 +297,49 @@ struct tracer { /* Ring buffer has the 10 LSB bits to count */ #define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff) -/* for function tracing recursion */ +/* + * For function tracing recursion: + * The order of these bits are important. + * + * When function tracing occurs, the following steps are made: + * If arch does not support a ftrace feature: + * call internal function (uses INTERNAL bits) which calls... + * If callback is registered to the "global" list, the list + * function is called and recursion checks the GLOBAL bits. + * then this function calls... + * The function callback, which can use the FTRACE bits to + * check for recursion. + * + * Now if the arch does not suppport a feature, and it calls + * the global list function which calls the ftrace callback + * all three of these steps will do a recursion protection. + * There's no reason to do one if the previous caller already + * did. The recursion that we are protecting against will + * go through the same steps again. + * + * To prevent the multiple recursion checks, if a recursion + * bit is set that is higher than the MAX bit of the current + * check, then we know that the check was made by the previous + * caller, and we can skip the current check. + */ enum { - TRACE_INTERNAL_BIT = 11, - TRACE_INTERNAL_NMI_BIT, - TRACE_INTERNAL_IRQ_BIT, - TRACE_INTERNAL_SIRQ_BIT, + TRACE_FTRACE_BIT = 11, + TRACE_FTRACE_NMI_BIT, + TRACE_FTRACE_IRQ_BIT, + TRACE_FTRACE_SIRQ_BIT, + /* GLOBAL_BITs must be greater than FTRACE_BITs */ TRACE_GLOBAL_BIT, TRACE_GLOBAL_NMI_BIT, TRACE_GLOBAL_IRQ_BIT, TRACE_GLOBAL_SIRQ_BIT, + /* INTERNAL_BITs must be greater than GLOBAL_BITs */ + TRACE_INTERNAL_BIT, + TRACE_INTERNAL_NMI_BIT, + TRACE_INTERNAL_IRQ_BIT, + TRACE_INTERNAL_SIRQ_BIT, + TRACE_CONTROL_BIT, /* @@ -325,6 +356,71 @@ enum { #define trace_recursion_clear(bit) do { (current)->trace_recursion &= ~(1<<(bit)); } while (0) #define trace_recursion_test(bit) ((current)->trace_recursion & (1<<(bit))) +#define TRACE_CONTEXT_BITS 4 + +#define TRACE_FTRACE_START TRACE_FTRACE_BIT +#define TRACE_FTRACE_MAX ((1 << (TRACE_FTRACE_START + TRACE_CONTEXT_BITS)) - 1) + +#define TRACE_GLOBAL_START TRACE_GLOBAL_BIT +#define TRACE_GLOBAL_MAX ((1 << (TRACE_GLOBAL_START + TRACE_CONTEXT_BITS)) - 1) + +#define TRACE_LIST_START TRACE_INTERNAL_BIT +#define TRACE_LIST_MAX ((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1) + +#define TRACE_CONTEXT_MASK TRACE_LIST_MAX + +static __always_inline int trace_get_context_bit(void) +{ + int bit; + + if (in_interrupt()) { + if (in_nmi()) + bit = 0; + + else if (in_irq()) + bit = 1; + else + bit = 2; + } else + bit = 3; + + return bit; +} + +static __always_inline int trace_test_and_set_recursion(int start, int max) +{ + unsigned int val = current->trace_recursion; + int bit; + + /* A previous recursion check was made */ + if ((val & TRACE_CONTEXT_MASK) > max) + return 0; + + bit = trace_get_context_bit() + start; + if (unlikely(val & (1 << bit))) + return -1; + + val |= 1 << bit; + current->trace_recursion = val; + barrier(); + + return bit; +} + +static __always_inline void trace_clear_recursion(int bit) +{ + unsigned int val = current->trace_recursion; + + if (!bit) + return; + + bit = 1 << bit; + val &= ~bit; + + barrier(); + current->trace_recursion = val; +} + #define TRACE_PIPE_ALL_CPU -1 static inline struct ring_buffer_iter * |