linux/kernel/trace/trace_uprobe.c, branch v5.0

tracing/uprobes: Fix output for multiple string arguments

2019-01-17T15:54:08Z

When printing multiple uprobe arguments as strings the output for the earlier arguments would also include all later string arguments. This is best explained in an example: Consider adding a uprobe to a function receiving two strings as parameters which is at offset 0xa0 in strlib.so and we want to print both parameters when the uprobe is hit (on x86_64): $ echo 'p:func /lib/strlib.so:0xa0 +0(%di):string +0(%si):string' > \ /sys/kernel/debug/tracing/uprobe_events When the function is called as func("foo", "bar") and we hit the probe, the trace file shows a line like the following: [...] func: (0x7f7e683706a0) arg1="foobar" arg2="bar" Note the extra "bar" printed as part of arg1. This behaviour stacks up for additional string arguments. The strings are stored in a dynamically growing part of the uprobe buffer by fetch_store_string() after copying them from userspace via strncpy_from_user(). The return value of strncpy_from_user() is then directly used as the required size for the string. However, this does not take the terminating null byte into account as the documentation for strncpy_from_user() cleary states that it "[...] returns the length of the string (not including the trailing NUL)" even though the null byte will be copied to the destination. Therefore, subsequent calls to fetch_store_string() will overwrite the terminating null byte of the most recently fetched string with the first character of the current string, leading to the "accumulation" of strings in earlier arguments in the output. Fix this by incrementing the return value of strncpy_from_user() by one if we did not hit the maximum buffer size. Link: http://lkml.kernel.org/r/20190116141629.5752-1-andreas.ziegler@fau.de Cc: Ingo Molnar Cc: stable@vger.kernel.org Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes") Acked-by: Masami Hiramatsu Signed-off-by: Andreas Ziegler Signed-off-by: Steven Rostedt (VMware)

tracing: uprobes: Fix typo in pr_fmt string

2019-01-17T14:51:42Z

The subsystem-specific message prefix for uprobes was also "trace_kprobe: " instead of "trace_uprobe: " as described in the original commit message. Link: http://lkml.kernel.org/r/20190117133023.19292-1-andreas.ziegler@fau.de Cc: Ingo Molnar Cc: stable@vger.kernel.org Acked-by: Masami Hiramatsu Fixes: 7257634135c24 ("tracing/probe: Show subsystem name in messages") Signed-off-by: Andreas Ziegler Signed-off-by: Steven Rostedt (VMware)

tracing: Consolidate trace_add/remove_event_call back to the nolock functions

2018-12-10T17:22:10Z

The trace_add/remove_event_call_nolock() functions were added to allow the tace_add/remove_event_call() code be called when the event_mutex lock was already taken. Now that all callers are done within the event_mutex, there's no reason to have two different interfaces. Remove the current wrapper trace_add/remove_event_call()s and rename the _nolock versions back to the original names. Link: http://lkml.kernel.org/r/154140866955.17322.2081425494660638846.stgit@devbox Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/uprobes: Use dyn_event framework for uprobe events

2018-12-09T01:54:10Z

Use dyn_event framework for uprobe events. This shows uprobe events on "dynamic_events" file. User can also define new uprobe events via dynamic_events. Link: http://lkml.kernel.org/r/154140858481.17322.9091293846515154065.stgit@devbox Reviewed-by: Tom Zanussi Tested-by: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: Integrate similar probe argument parsers

2018-12-09T01:54:09Z

Integrate similar argument parsers for kprobes and uprobes events into traceprobe_parse_probe_arg(). Link: http://lkml.kernel.org/r/154140850016.17322.9836787731210512176.stgit@devbox Reviewed-by: Tom Zanussi Tested-by: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/uprobes: Add busy check when cleanup all uprobes

2018-12-09T01:54:08Z

Add a busy check loop in cleanup_all_probes() before trying to remove all events in uprobe_events, the same way that kprobe_events does. Without this change, writing null to uprobe_events will try to remove events but if one of them is enabled, it will stop there leaving some events cleared and others not clceared. With this change, writing null to uprobe_events makes sure all events are not enabled before removing events. So, it clears all events, or returns an error (-EBUSY) with keeping all events. Link: http://lkml.kernel.org/r/154140841557.17322.12653952888762532401.stgit@devbox Reviewed-by: Tom Zanussi Tested-by: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/uprobes: Fix to return -EFAULT if copy_from_user failed

2018-10-11T02:19:11Z

Fix probe_mem_read() to return -EFAULT if copy_from_user() failed. The copy_from_user() returns remaining bytes when it failed, but probe_mem_read() caller expects it returns error code like as probe_kernel_read(). Link: http://lkml.kernel.org/r/153547306719.26502.8353484532699160223.stgit@devbox Reported-by: Dan Carpenter Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: probeevent: Add $argN for accessing function args

2018-10-11T02:19:11Z

Add $argN special fetch variable for accessing function arguments. This allows user to trace the Nth argument easily at the function entry. Note that this returns most probably assignment of registers and stacks. In some case, it may not work well. If you need to access correct registers or stacks you should use perf-probe. Link: http://lkml.kernel.org/r/152465888632.26224.3412465701570253696.stgit@devbox Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: probeevent: Unify fetch_insn processing common part

2018-10-11T02:19:09Z

Unify the fetch_insn bottom process (from stage 2: dereference indirect data) from kprobe and uprobe events, since those are mostly same. Link: http://lkml.kernel.org/r/152465879965.26224.8547240824606804815.stgit@devbox Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: probeevent: Append traceprobe_ for exported function

2018-10-11T02:19:09Z

Append traceprobe_ for exported function set_print_fmt() as same as other functions. Link: http://lkml.kernel.org/r/152465877071.26224.11143125027282999726.stgit@devbox Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)