diff options
| -rw-r--r-- | Documentation/trace/ftrace.rst | 25 | ||||
| -rw-r--r-- | include/linux/ftrace.h | 4 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 12 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 2 |
4 files changed, 38 insertions, 5 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index a9c8bce4bc7b..027437b745a0 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -350,6 +350,19 @@ of ftrace. Here is a list of some of the key files: an 'I' will be displayed on the same line as the function that can be overridden. + If a non ftrace trampoline is attached (BPF) a 'D' will be displayed. + Note, normal ftrace trampolines can also be attached, but only one + "direct" trampoline can be attached to a given function at a time. + + Some architectures can not call direct trampolines, but instead have + the ftrace ops function located above the function entry point. In + such cases an 'O' will be displayed. + + If a function had either the "ip modify" or a "direct" call attached to + it in the past, a 'M' will be shown. This flag is never cleared. It is + used to know if a function was every modified by the ftrace infrastructure, + and can be used for debugging. + If the architecture supports it, it will also show what callback is being directly called by the function. If the count is greater than 1 it most likely will be ftrace_ops_list_func(). @@ -359,6 +372,18 @@ of ftrace. Here is a list of some of the key files: its address will be printed as well as the function that the trampoline calls. + touched_functions: + + This file contains all the functions that ever had a function callback + to it via the ftrace infrastructure. It has the same format as + enabled_functions but shows all functions that have every been + traced. + + To see any function that has every been modified by "ip modify" or a + direct trampoline, one can perform the following command: + + grep ' M ' /sys/kernel/tracing/touched_functions + function_profile_enabled: When set it will enable all functions with either the function diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 6954e4ed5bbf..b23bdd414394 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -549,6 +549,7 @@ bool is_ftrace_trampoline(unsigned long addr); * CALL_OPS - the record can use callsite-specific ops * CALL_OPS_EN - the function is set up to use callsite-specific ops * TOUCHED - A callback was added since boot up + * MODIFIED - The function had IPMODIFY or DIRECT attached to it * * When a new ftrace_ops is registered and wants a function to save * pt_regs, the rec->flags REGS is set. When the function has been @@ -569,9 +570,10 @@ enum { FTRACE_FL_CALL_OPS = (1UL << 22), FTRACE_FL_CALL_OPS_EN = (1UL << 21), FTRACE_FL_TOUCHED = (1UL << 20), + FTRACE_FL_MODIFIED = (1UL << 19), }; -#define FTRACE_REF_MAX_SHIFT 20 +#define FTRACE_REF_MAX_SHIFT 19 #define FTRACE_REF_MAX ((1UL << FTRACE_REF_MAX_SHIFT) - 1) #define ftrace_rec_count(rec) ((rec)->flags & FTRACE_REF_MAX) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 76973a70ab9d..764668467155 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -46,7 +46,8 @@ #include "trace_stat.h" /* Flags that do not get reset */ -#define FTRACE_NOCLEAR_FLAGS (FTRACE_FL_DISABLED | FTRACE_FL_TOUCHED) +#define FTRACE_NOCLEAR_FLAGS (FTRACE_FL_DISABLED | FTRACE_FL_TOUCHED | \ + FTRACE_FL_MODIFIED) #define FTRACE_INVALID_FUNCTION "__ftrace_invalid_address__" @@ -2273,6 +2274,10 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update) rec->flags &= ~FTRACE_FL_TRAMP_EN; } + /* Keep track of anything that modifies the function */ + if (rec->flags & (FTRACE_FL_DIRECT | FTRACE_FL_IPMODIFY)) + rec->flags |= FTRACE_FL_MODIFIED; + if (flag & FTRACE_FL_DIRECT) { /* * If there's only one user (direct_ops helper) @@ -3866,12 +3871,13 @@ static int t_show(struct seq_file *m, void *v) if (iter->flags & (FTRACE_ITER_ENABLED | FTRACE_ITER_TOUCHED)) { struct ftrace_ops *ops; - seq_printf(m, " (%ld)%s%s%s%s", + seq_printf(m, " (%ld)%s%s%s%s%s", ftrace_rec_count(rec), rec->flags & FTRACE_FL_REGS ? " R" : " ", rec->flags & FTRACE_FL_IPMODIFY ? " I" : " ", rec->flags & FTRACE_FL_DIRECT ? " D" : " ", - rec->flags & FTRACE_FL_CALL_OPS ? " O" : " "); + rec->flags & FTRACE_FL_CALL_OPS ? " O" : " ", + rec->flags & FTRACE_FL_MODIFIED ? " M " : " "); if (rec->flags & FTRACE_FL_TRAMP_EN) { ops = ftrace_find_tramp_ops_any(rec); if (ops) { diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 427da2341bf0..ebc59781456a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9661,7 +9661,7 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) tr->buffer_percent = 50; - trace_create_file("buffer_percent", TRACE_MODE_READ, d_tracer, + trace_create_file("buffer_percent", TRACE_MODE_WRITE, d_tracer, tr, &buffer_percent_fops); create_trace_options_dir(tr); |