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Commit ab4ead02 authored by Kevin Hao's avatar Kevin Hao Committed by Steven Rostedt
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ftrace/x86: skip over the breakpoint for ftrace caller 



In commit 8a4d0a68 "ftrace: Use breakpoint method to update ftrace
caller", we choose to use breakpoint method to update the ftrace
caller. But we also need to skip over the breakpoint in function
ftrace_int3_handler() for them. Otherwise weird things would happen.

Cc: stable@vger.kernel.org # 3.5+
Signed-off-by: default avatarKevin Hao <haokexin@gmail.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 9cd804ac

arch/x86/kernel/ftrace.c

+13 −1
Original line number Diff line number Diff line
@@ -248,6 +248,15 @@ int ftrace_update_ftrace_func(ftrace_func_t func) 
	return ret;

}



static int is_ftrace_caller(unsigned long ip)

{

	if (ip == (unsigned long)(&ftrace_call) ||

		ip == (unsigned long)(&ftrace_regs_call))

		return 1;



	return 0;

}



/*

 * A breakpoint was added to the code address we are about to

 * modify, and this is the handle that will just skip over it.
@@ -257,10 +266,13 @@ int ftrace_update_ftrace_func(ftrace_func_t func) 
 */

int ftrace_int3_handler(struct pt_regs *regs)

{

	unsigned long ip;



	if (WARN_ON_ONCE(!regs))

		return 0;



	if (!ftrace_location(regs->ip - 1))

	ip = regs->ip - 1;

	if (!ftrace_location(ip) && !is_ftrace_caller(ip))

		return 0;



	regs->ip += MCOUNT_INSN_SIZE - 1;