caf4b323b0
Impact: add infrastructure for function-return tracing Add low level support for ftrace return tracing. This plug-in stores return addresses on the thread_info structure of the current task. The index of the current return address is initialized when the task is the first one (init) and when a process forks (the child). It is not needed when a task does a sys_execve because after this syscall, it still needs to return on the kernel functions it called. Note that the code of return_to_handler has been suggested by Steven Rostedt as almost all of the ideas of improvements in this V3. For purpose of security, arch/x86/kernel/process_32.c is not traced because __switch_to() changes the current task during its execution. That could cause inconsistency in the stored return address of this function even if I didn't have any crash after testing with tracing on this function enabled. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
50 lines
1.1 KiB
C
50 lines
1.1 KiB
C
#ifndef _ASM_X86_FTRACE_H
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#define _ASM_X86_FTRACE_H
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#ifdef CONFIG_FUNCTION_TRACER
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#define MCOUNT_ADDR ((long)(mcount))
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#define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */
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#ifndef __ASSEMBLY__
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extern void mcount(void);
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static inline unsigned long ftrace_call_adjust(unsigned long addr)
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{
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/*
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* call mcount is "e8 <4 byte offset>"
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* The addr points to the 4 byte offset and the caller of this
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* function wants the pointer to e8. Simply subtract one.
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*/
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return addr - 1;
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}
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_FUNCTION_RET_TRACER
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#define FTRACE_RET_STACK_SIZE 20
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#ifndef __ASSEMBLY__
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/*
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* Stack of return addresses for functions
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* of a thread.
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* Used in struct thread_info
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*/
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struct ftrace_ret_stack {
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unsigned long ret;
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unsigned long func;
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unsigned long long calltime;
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};
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/*
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* Primary handler of a function return.
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* It relays on ftrace_return_to_handler.
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* Defined in entry32.S
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*/
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extern void return_to_handler(void);
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_FUNCTION_RET_TRACER */
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#endif /* _ASM_X86_FTRACE_H */
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