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tracing: Define MCOUNT_INSN_SIZE when not defined without direct calls 

In order to handle direct calls along side of function graph tracer, a check
is made to see if the address being traced by the function graph tracer is a
direct call or not. To get the address used by direct callers, the return
address is subtracted by MCOUNT_INSN_SIZE.

For some archs with certain configurations, MCOUNT_INSN_SIZE is undefined
here. But these should not be using direct calls anyway. Just define
MCOUNT_INSN_SIZE to zero in this case.

Link: https://lore.kernel.org/r/202001020219.zvE3vsty%lkp@intel.com

Reported-by: kbuild test robot <lkp@intel.com>
Fixes: ff205766db ("ftrace: Fix function_graph tracer interaction with BPF trampoline")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2020-01-02 21:56:44 -05:00
parent 02f4e01ce7
commit d2ccbccb54
1 changed files with 14 additions and 0 deletions
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14
kernel/trace/fgraph.c
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@ -96,6 +96,20 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
return 0;
}
/*
* Not all archs define MCOUNT_INSN_SIZE which is used to look for direct
* functions. But those archs currently don't support direct functions
* anyway, and ftrace_find_rec_direct() is just a stub for them.
* Define MCOUNT_INSN_SIZE to keep those archs compiling.
*/
#ifndef MCOUNT_INSN_SIZE
/* Make sure this only works without direct calls */
# ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
# error MCOUNT_INSN_SIZE not defined with direct calls enabled
# endif
# define MCOUNT_INSN_SIZE 0
#endif
int function_graph_enter(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp)
{