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tracing/kprobe: bpf: Check error injectable event is on function entry

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Check whether error injectable event is on function entry or not.
Currently it checks the event is ftrace-based kprobes or not,
but that is wrong. It should check if the event is on the entry
of target function. Since error injection will override a function
to just return with modified return value, that operation must
be done before the target function starts making stackframe.

As a side effect, bpf error injection is no need to depend on
function-tracer. It can work with sw-breakpoint based kprobe
events too.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Masami Hiramatsu
2018-01-13 02:54:04 +09:00
committed by Alexei Starovoitov
parent daaf24c634
commit b4da3340ea
7 changed files with 31 additions and 32 deletions
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12
kernel/trace/trace_probe.h
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@@ -252,8 +252,8 @@ struct symbol_cache;
unsigned long update_symbol_cache(struct symbol_cache *sc);
void free_symbol_cache(struct symbol_cache *sc);
struct symbol_cache *alloc_symbol_cache(const char *sym, long offset);
int trace_kprobe_ftrace(struct trace_event_call *call);
int trace_kprobe_error_injectable(struct trace_event_call *call);
bool trace_kprobe_on_func_entry(struct trace_event_call *call);
bool trace_kprobe_error_injectable(struct trace_event_call *call);
#else
/* uprobes do not support symbol fetch methods */
#define fetch_symbol_u8 NULL
@@ -280,14 +280,14 @@ alloc_symbol_cache(const char *sym, long offset)
return NULL;
}
static inline int trace_kprobe_ftrace(struct trace_event_call *call)
static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
return 0;
return false;
}
static inline int trace_kprobe_error_injectable(struct trace_event_call *call)
static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
{
return 0;
return false;
}
#endif /* CONFIG_KPROBE_EVENTS */