Commit 88dbd203 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

[S390] ftrace: add function graph tracer support 



Function graph tracer support for s390.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 8b4488f8

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ config S390 
	select HAVE_FUNCTION_TRACE_MCOUNT_TEST

	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_DYNAMIC_FTRACE

	select HAVE_FUNCTION_GRAPH_TRACER

	select HAVE_DEFAULT_NO_SPIN_MUTEXES

	select HAVE_OPROFILE

	select HAVE_KPROBES

arch/s390/include/asm/ftrace.h

+6 −4
Original line number Diff line number Diff line
@@ -11,9 +11,11 @@ struct dyn_arch_ftrace { }; 
#define MCOUNT_ADDR ((long)_mcount)



#ifdef CONFIG_64BIT

#define MCOUNT_OFFSET_RET 18

#define MCOUNT_INSN_SIZE  24

#define MCOUNT_OFFSET	  14

#else

#define MCOUNT_OFFSET_RET 26

#define MCOUNT_INSN_SIZE  30

#define MCOUNT_OFFSET	   8

#endif

arch/s390/kernel/Makefile

+2 −4
Original line number Diff line number Diff line
@@ -3,11 +3,8 @@ 
#



ifdef CONFIG_FUNCTION_TRACER

# Do not trace early boot code

# Don't trace early setup code and tracing code

CFLAGS_REMOVE_early.o = -pg

endif



ifdef CONFIG_DYNAMIC_FTRACE

CFLAGS_REMOVE_ftrace.o = -pg

endif
@@ -46,6 +43,7 @@ obj-$(CONFIG_STACKTRACE) += stacktrace.o 
obj-$(CONFIG_KPROBES)		+= kprobes.o

obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o

obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o



# Kexec part

S390_KEXEC_OBJS := machine_kexec.o crash.o

arch/s390/kernel/ftrace.c

+72 −0
Original line number Diff line number Diff line
@@ -7,13 +7,17 @@ 
 *

 */



#include <linux/hardirq.h>

#include <linux/uaccess.h>

#include <linux/ftrace.h>

#include <linux/kernel.h>

#include <linux/types.h>

#include <asm/lowcore.h>



#ifdef CONFIG_DYNAMIC_FTRACE



void ftrace_disable_code(void);

void ftrace_disable_return(void);

void ftrace_call_code(void);

void ftrace_nop_code(void);
@@ -28,6 +32,7 @@ asm( 
	"	.word	0x0024\n"

	"	lg	%r1,"__stringify(__LC_FTRACE_FUNC)"\n"

	"	basr	%r14,%r1\n"

	"ftrace_disable_return:\n"

	"	lg	%r14,8(15)\n"

	"	lgr	%r0,%r0\n"

	"0:\n");
@@ -50,6 +55,7 @@ asm( 
	"	j	0f\n"

	"	l	%r1,"__stringify(__LC_FTRACE_FUNC)"\n"

	"	basr	%r14,%r1\n"

	"ftrace_disable_return:\n"

	"	l	%r14,4(%r15)\n"

	"	j	0f\n"

	"	bcr	0,%r7\n"
@@ -130,3 +136,69 @@ int __init ftrace_dyn_arch_init(void *data) 
	*(unsigned long *)data = 0;

	return 0;

}



#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

#ifdef CONFIG_DYNAMIC_FTRACE

/*

 * Patch the kernel code at ftrace_graph_caller location:

 * The instruction there is branch relative on condition. The condition mask

 * is either all ones (always branch aka disable ftrace_graph_caller) or all

 * zeroes (nop aka enable ftrace_graph_caller).

 * Instruction format for brc is a7m4xxxx where m is the condition mask.

 */

int ftrace_enable_ftrace_graph_caller(void)

{

	unsigned short opcode = 0xa704;



	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));

}



int ftrace_disable_ftrace_graph_caller(void)

{

	unsigned short opcode = 0xa7f4;



	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));

}



static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)

{

	return addr - (ftrace_disable_return - ftrace_disable_code);

}



#else /* CONFIG_DYNAMIC_FTRACE */



static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)

{

	return addr - MCOUNT_OFFSET_RET;

}



#endif /* CONFIG_DYNAMIC_FTRACE */



/*

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

 * in current thread info.

 */

unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)

{

	struct ftrace_graph_ent trace;



	/* Nmi's are currently unsupported. */

	if (unlikely(in_nmi()))

		goto out;

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

		goto out;

	if (ftrace_push_return_trace(parent, ip, &trace.depth) == -EBUSY)

		goto out;

	trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;

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

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		goto out;

	}

	parent = (unsigned long)return_to_handler;

out:

	return parent;

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/s390/kernel/mcount.S

+79 −0
Original line number Diff line number Diff line
@@ -34,6 +34,18 @@ ftrace_caller: 
	larl	%r14,ftrace_dyn_func

	lg	%r14,0(%r14)

	basr	%r14,%r14

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	.globl	ftrace_graph_caller

ftrace_graph_caller:

	# This unconditional branch gets runtime patched. Change only if

	# you know what you are doing. See ftrace_enable_graph_caller().

	j	0f

	lg	%r2,272(%r15)

	lg	%r3,168(%r15)

	brasl	%r14,prepare_ftrace_return

	stg	%r2,168(%r15)

0:

#endif

	aghi	%r15,160

	lmg	%r2,%r5,32(%r15)

	lg	%r14,112(%r15)
@@ -62,6 +74,12 @@ _mcount: 
	larl	%r14,ftrace_trace_function

	lg	%r14,0(%r14)

	basr	%r14,%r14

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	lg	%r2,272(%r15)

	lg	%r3,168(%r15)

	brasl	%r14,prepare_ftrace_return

	stg	%r2,168(%r15)

#endif

	aghi	%r15,160

	lmg	%r2,%r5,32(%r15)

	lg	%r14,112(%r15)
@@ -69,6 +87,22 @@ _mcount: 


#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER



	.globl	return_to_handler

return_to_handler:

	stmg	%r2,%r5,32(%r15)

	lgr	%r1,%r15

	aghi	%r15,-160

	stg	%r1,__SF_BACKCHAIN(%r15)

	brasl	%r14,ftrace_return_to_handler

	aghi	%r15,160

	lgr	%r14,%r2

	lmg	%r2,%r5,32(%r15)

	br	%r14



#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



#else /* CONFIG_64BIT */



#ifdef CONFIG_DYNAMIC_FTRACE
@@ -96,6 +130,21 @@ ftrace_caller: 
	l	%r14,0b-0b(%r1)

	l	%r14,0(%r14)

	basr	%r14,%r14

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	.globl	ftrace_graph_caller

ftrace_graph_caller:

	# This unconditional branch gets runtime patched. Change only if

	# you know what you are doing. See ftrace_enable_graph_caller().

	j	1f

	bras	%r1,0f

	.long	prepare_ftrace_return

0:	l	%r2,152(%r15)

	l	%r4,0(%r1)

	l	%r3,100(%r15)

	basr	%r14,%r4

	st	%r2,100(%r15)

1:

#endif

	ahi	%r15,96

	l	%r14,56(%r15)

3:	lm	%r2,%r5,16(%r15)
@@ -128,10 +177,40 @@ _mcount: 
	l	%r14,0b-0b(%r1)

	l	%r14,0(%r14)

	basr	%r14,%r14

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	bras	%r1,0f

	.long	prepare_ftrace_return

0:	l	%r2,152(%r15)

	l	%r4,0(%r1)

	l	%r3,100(%r15)

	basr	%r14,%r4

	st	%r2,100(%r15)

#endif

	ahi	%r15,96

	l	%r14,56(%r15)

3:	lm	%r2,%r5,16(%r15)

	br	%r14



#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER



	.globl	return_to_handler

return_to_handler:

	stm	%r2,%r5,16(%r15)

	st	%r14,56(%r15)

	lr	%r0,%r15

	ahi	%r15,-96

	st	%r0,__SF_BACKCHAIN(%r15)

	bras	%r1,0f

	.long	ftrace_return_to_handler

0:	l	%r2,0b-0b(%r1)

	basr	%r14,%r2

	lr	%r14,%r2

	ahi	%r15,96

	lm	%r2,%r5,16(%r15)

	br	%r14



#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



#endif /* CONFIG_64BIT */