Commit 28bb030f authored by Guo Ren's avatar Guo Ren
Browse files

csky/ftrace: Add dynamic function tracer (include graph tracer) 



Support dynamic ftrace including dynamic graph tracer. Gcc-csky with -pg
will produce call site in every function prologue and we can use these
call site to hook trace function.

gcc with -pg origin call site:
	push	lr
	jbsr	_mcount
	nop32
	nop32

If the (callee - caller)'s offset is in range of bsr instruction, we'll
modify code with:
	push	lr
	bsr	_mcount
	nop32
	nop32
Else if the (callee - caller)'s offset is out of bsr instrunction, we'll
modify code with:
	push	lr
	movih	r26, ...
	ori	r26, ...
	jsr	r26

(r26 is reserved for jsr link reg in csky abiv2 spec.)

Signed-off-by: default avatarGuo Ren <ren_guo@c-sky.com>
parent 3dfc242f

arch/csky/Kconfig

+2 −1
Original line number Diff line number Diff line
@@ -29,13 +29,14 @@ config CSKY 
	select GENERIC_SCHED_CLOCK

	select GENERIC_SMP_IDLE_THREAD

	select HAVE_ARCH_TRACEHOOK

	select HAVE_DYNAMIC_FTRACE

	select HAVE_FUNCTION_TRACER

	select HAVE_FUNCTION_GRAPH_TRACER

	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_LZO

	select HAVE_KERNEL_LZMA

	select HAVE_PERF_EVENTS

	select HAVE_C_RECORDMCOUNT

	select HAVE_DMA_API_DEBUG

	select HAVE_DMA_CONTIGUOUS

	select MAY_HAVE_SPARSE_IRQ

arch/csky/abiv2/mcount.S

+37 −2
Original line number Diff line number Diff line
@@ -61,10 +61,17 @@ 
	addi	sp, 16

.endm



.macro nop32_stub

	nop32

	nop32

	nop32

.endm



ENTRY(ftrace_stub)

	jmp	lr

END(ftrace_stub)



#ifndef CONFIG_DYNAMIC_FTRACE

ENTRY(_mcount)

	mcount_enter
@@ -76,7 +83,7 @@ ENTRY(_mcount) 
	bf	skip_ftrace



	mov	a0, lr

	subi	a0, MCOUNT_INSN_SIZE

	subi	a0, 4

	ldw	a1, (sp, 24)



	jsr	r26
@@ -101,13 +108,41 @@ skip_ftrace: 
	mcount_exit

#endif

END(_mcount)

#else /* CONFIG_DYNAMIC_FTRACE */

ENTRY(_mcount)

	mov	t1, lr

	ldw	lr, (sp, 0)

	addi	sp, 4

	jmp	t1

ENDPROC(_mcount)



ENTRY(ftrace_caller)

	mcount_enter



	ldw	a0, (sp, 16)

	subi	a0, 4

	ldw	a1, (sp, 24)



	nop

GLOBAL(ftrace_call)

	nop32_stub



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	nop

GLOBAL(ftrace_graph_call)

	nop32_stub

#endif



	mcount_exit

ENDPROC(ftrace_caller)

#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

ENTRY(ftrace_graph_caller)

	mov	a0, sp

	addi	a0, 24

	ldw	a1, (sp, 16)

	subi	a1, MCOUNT_INSN_SIZE

	subi	a1, 4

	mov	a2, r8

	lrw	r26, prepare_ftrace_return

	jsr	r26

arch/csky/include/asm/ftrace.h

+17 −1
Original line number Diff line number Diff line
@@ -4,10 +4,26 @@ 
#ifndef __ASM_CSKY_FTRACE_H

#define __ASM_CSKY_FTRACE_H



#define MCOUNT_INSN_SIZE 4

#define MCOUNT_INSN_SIZE	14



#define HAVE_FUNCTION_GRAPH_FP_TEST



#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR



#define MCOUNT_ADDR	((unsigned long)_mcount)



#ifndef __ASSEMBLY__



extern void _mcount(unsigned long);



extern void ftrace_graph_call(void);



static inline unsigned long ftrace_call_adjust(unsigned long addr)

{

	return addr;

}



struct dyn_arch_ftrace {

};

#endif /* !__ASSEMBLY__ */

#endif /* __ASM_CSKY_FTRACE_H */

arch/csky/kernel/ftrace.c

+146 −2
Original line number Diff line number Diff line
@@ -3,6 +3,137 @@ 


#include <linux/ftrace.h>

#include <linux/uaccess.h>

#include <asm/cacheflush.h>



#ifdef CONFIG_DYNAMIC_FTRACE



#define NOP		0x4000

#define NOP32_HI	0xc400

#define NOP32_LO	0x4820

#define PUSH_LR		0x14d0

#define MOVIH_LINK	0xea3a

#define ORI_LINK	0xef5a

#define JSR_LINK	0xe8fa

#define BSR_LINK	0xe000



/*

 * Gcc-csky with -pg will insert stub in function prologue:

 *	push	lr

 *	jbsr	_mcount

 *	nop32

 *	nop32

 *

 * If the (callee - current_pc) is less then 64MB, we'll use bsr:

 *	push	lr

 *	bsr	_mcount

 *	nop32

 *	nop32

 * else we'll use (movih + ori + jsr):

 *	push	lr

 *	movih	r26, ...

 *	ori	r26, ...

 *	jsr	r26

 *

 * (r26 is our reserved link-reg)

 *

 */

static inline void make_jbsr(unsigned long callee, unsigned long pc,

			     uint16_t *call, bool nolr)

{

	long offset;



	call[0]	= nolr ? NOP : PUSH_LR;



	offset = (long) callee - (long) pc;



	if (unlikely(offset < -67108864 || offset > 67108864)) {

		call[1] = MOVIH_LINK;

		call[2] = callee >> 16;

		call[3] = ORI_LINK;

		call[4] = callee & 0xffff;

		call[5] = JSR_LINK;

		call[6] = 0;

	} else {

		offset = offset >> 1;



		call[1] = BSR_LINK |

			 ((uint16_t)((unsigned long) offset >> 16) & 0x3ff);

		call[2] = (uint16_t)((unsigned long) offset & 0xffff);

		call[3] = call[5] = NOP32_HI;

		call[4] = call[6] = NOP32_LO;

	}

}



static uint16_t nops[7] = {NOP, NOP32_HI, NOP32_LO, NOP32_HI, NOP32_LO,

				NOP32_HI, NOP32_LO};

static int ftrace_check_current_nop(unsigned long hook)

{

	uint16_t olds[7];

	unsigned long hook_pos = hook - 2;



	if (probe_kernel_read((void *)olds, (void *)hook_pos, sizeof(nops)))

		return -EFAULT;



	if (memcmp((void *)nops, (void *)olds, sizeof(nops))) {

		pr_err("%p: nop but get (%04x %04x %04x %04x %04x %04x %04x)\n",

			(void *)hook_pos,

			olds[0], olds[1], olds[2], olds[3], olds[4], olds[5],

			olds[6]);



		return -EINVAL;

	}



	return 0;

}



static int ftrace_modify_code(unsigned long hook, unsigned long target,

			      bool enable, bool nolr)

{

	uint16_t call[7];



	unsigned long hook_pos = hook - 2;

	int ret = 0;



	make_jbsr(target, hook, call, nolr);



	ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,

				 sizeof(nops));

	if (ret)

		return -EPERM;



	flush_icache_range(hook_pos, hook_pos + MCOUNT_INSN_SIZE);



	return 0;

}



int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)

{

	int ret = ftrace_check_current_nop(rec->ip);



	if (ret)

		return ret;



	return ftrace_modify_code(rec->ip, addr, true, false);

}



int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,

		    unsigned long addr)

{

	return ftrace_modify_code(rec->ip, addr, false, false);

}



int ftrace_update_ftrace_func(ftrace_func_t func)

{

	int ret = ftrace_modify_code((unsigned long)&ftrace_call,

				(unsigned long)func, true, true);

	return ret;

}



int __init ftrace_dyn_arch_init(void)

{

	return 0;

}

#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
@@ -43,8 +174,21 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
			*(unsigned long *)frame_pointer = return_hooker;

	}

}

#endif



#ifdef CONFIG_DYNAMIC_FTRACE

int ftrace_enable_ftrace_graph_caller(void)

{

	return ftrace_modify_code((unsigned long)&ftrace_graph_call,

			(unsigned long)&ftrace_graph_caller, true, true);

}



int ftrace_disable_ftrace_graph_caller(void)

{

	return ftrace_modify_code((unsigned long)&ftrace_graph_call,

			(unsigned long)&ftrace_graph_caller, false, true);

}

#endif /* CONFIG_DYNAMIC_FTRACE */

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



/* _mcount is defined in abi's mcount.S */

extern void _mcount(void);

EXPORT_SYMBOL(_mcount);

scripts/recordmcount.pl

+3 −0
Original line number Diff line number Diff line
@@ -397,6 +397,9 @@ if ($arch eq "x86_64") { 
} elsif ($arch eq "nds32") {

    $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_NDS32_HI20_RELA\\s+_mcount\$";

    $alignment = 2;

} elsif ($arch eq "csky") {

    $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_CKCORE_PCREL_JSR_IMM26BY2\\s+_mcount\$";

    $alignment = 2;

} else {

    die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";

}

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