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Commit a0d3e665 authored by Michal Simek's avatar Michal Simek
Browse files

microblaze: ftrace: add function graph support 



For more information look at Documentation/trace folder.

Signed-off-by: default avatarMichal Simek <monstr@monstr.eu>
parent 7d241ff0

arch/microblaze/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ config MICROBLAZE 
	select HAVE_LMB

	select HAVE_FUNCTION_TRACER

	select HAVE_FUNCTION_TRACE_MCOUNT_TEST

	select HAVE_FUNCTION_GRAPH_TRACER

	select HAVE_DYNAMIC_FTRACE

	select HAVE_FTRACE_MCOUNT_RECORD

	select USB_ARCH_HAS_EHCI

arch/microblaze/kernel/ftrace.c

+58 −0
Original line number Diff line number Diff line
@@ -14,6 +14,64 @@ 
#include <asm/cacheflush.h>

#include <linux/ftrace.h>



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

/*

 * Hook the return address and push it in the stack of return addrs

 * in current thread info.

 */

void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)

{

	unsigned long old;

	int faulted, err;

	struct ftrace_graph_ent trace;

	unsigned long return_hooker = (unsigned long)

				&return_to_handler;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;



	/*

	 * Protect against fault, even if it shouldn't

	 * happen. This tool is too much intrusive to

	 * ignore such a protection.

	 */

	asm volatile("	1:	lwi	%0, %2, 0;		\

			2:	swi	%3, %2, 0;		\

				addik	%1, r0, 0;		\

			3:					\

				.section .fixup, \"ax\";	\

			4:	brid	3b;			\

				addik	%1, r0, 1;		\

				.previous;			\

				.section __ex_table,\"a\";	\

				.word	1b,4b;			\

				.word	2b,4b;			\

				.previous;"			\

			: "=&r" (old), "=r" (faulted)

			: "r" (parent), "r" (return_hooker)

	);



	if (unlikely(faulted)) {

		ftrace_graph_stop();

		WARN_ON(1);

		return;

	}



	err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);

	if (err == -EBUSY) {

		*parent = old;

		return;

	}



	trace.func = self_addr;

	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		*parent = old;

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



#ifdef CONFIG_DYNAMIC_FTRACE

/* save value to addr - it is save to do it in asm */

static int ftrace_modify_code(unsigned long addr, unsigned int value)

arch/microblaze/kernel/mcount.S

+41 −0
Original line number Diff line number Diff line
@@ -96,6 +96,27 @@ ENTRY(ftrace_caller) 
	bneid	r5, end;

	nop;

	/* MS: HAVE_FUNCTION_TRACE_MCOUNT_TEST end of checking */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	lwi	r5, r0, ftrace_graph_return;

	addik	r6, r0, ftrace_stub; /* asm implementation */

	cmpu	r5, r5, r6; /* ftrace_graph_return != ftrace_stub */

	beqid	r5, end_graph_tracer;

	nop;



	lwi	r6, r0, ftrace_graph_entry;

	addik	r5, r0, ftrace_graph_entry_stub; /* implemented in C */

	cmpu	r5, r5, r6; /* ftrace_graph_entry != ftrace_graph_entry_stub */

	beqid	r5, end_graph_tracer;

	nop;

	addik	r5, r1, 120; /* MS: load parent addr */

	addik	r6, r15, 0; /* MS: load current function addr */

	bralid	r15, prepare_ftrace_return;

	nop;

	/* MS: graph was taken that's why - can jump over function trace */

	brid	end;

	nop;

end_graph_tracer:

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#ifndef CONFIG_DYNAMIC_FTRACE

	/* MS: test function trace if is taken or not */

	lwi	r20, r0, ftrace_trace_function;
@@ -121,3 +142,23 @@ end: 


	rtsd	r15, 8; /* MS: jump back */

	nop;



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

ENTRY(return_to_handler)

	nop; /* MS: just barrier for rtsd r15, 8 */

	nop;

	SAVE_REGS

	swi	r15, r1, 0;



	/* MS: find out returning address */

	bralid	r15, ftrace_return_to_handler;

	nop;



	/* MS: return value from ftrace_return_to_handler is my returning addr

	 * must be before restore regs because I have to restore r3 content */

	addik	r15, r3, 0;

	RESTORE_REGS



	rtsd	r15, 8; /* MS: jump back */

	nop;

#endif	/* CONFIG_FUNCTION_TRACER */