Selftest for dynamic ftrace requres to pass address of the first
calling instruction because hash function is calculated from it.
ftrace_update_ftrace_func setups pointer to function which is called
in _mcount function. trace_selftest is not aware about instruction
size (for microblaze 8 - imm and addik) and that's why we have
to pass in r5 address of imm not addik which is in r15.12
For more info look at ftrace_ops_list_func/ftrace.c.
Signed-off-by: Michal Simek <monstr@monstr.eu>
This patch add support for dynamic function graph tracer.
There is one my expactation that I can do flush_icache after
all code modification. On microblaze is this safer than do
flush for every entry. For icache is used name flush but
correct should be invalidation - this will be fix in upcomming
new cache implementaion and WB support.
Signed-off-by: Michal Simek <monstr@monstr.eu>
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action. When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.
Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).
In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl.
For more information please look at code and Documentation/trace folder.
Steven ACK that scripts/recordmcount.pl part.
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Michal Simek <monstr@monstr.eu>
If -pg of gcc is enabled with CONFIG_FUNCTION_TRACER=y. a calling to
_mcount will be inserted into each kernel function. so, there is a
possibility to trace the kernel functions in _mcount.
This patch add the specific _mcount support for static function
tracing. by default, ftrace_trace_function is initialized as
ftrace_stub(an empty function), so, the default _mcount will introduce
very little overhead. after enabling ftrace in user-space, it will jump
to a real tracing function and do static function tracing for us.
Commit message from Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
