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Commit a14a07b8 authored by Shaohua Li's avatar Shaohua Li Committed by Ingo Molnar
Browse files

ftrace, ia64: IA64 dynamic ftrace support 



IA64 dynamic ftrace support.
The original _mcount stub for each function is like:
	alloc r40=ar.pfs,12,8,0
	mov r43=r0;;
	mov r42=b0
	mov r41=r1
	nop.i 0x0
	br.call.sptk.many b0 = _mcount;;

The patch convert it to below for nop:
	[MII] nop.m 0x0
	mov r3=ip
	nop.i 0x0
	[MLX] nop.m 0x0
	nop.x 0x0;;
This isn't completely nop, as there is one instuction 'mov r3=ip', but
it should be light and harmless for code follow it.

And below is for call
	[MII] nop.m 0x0
	mov r3=ip
	nop.i 0x0
	[MLX] nop.m 0x0
	brl.many .;;
In this way, only one instruction is changed to convert code between nop
and call. This should meet dyn-ftrace's requirement.
But this requires CPU support brl instruction, so dyn-ftrace isn't
supported for old Itanium system. Assume there are quite few such old
system running.

Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d3e75ff1

arch/ia64/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -21,6 +21,8 @@ config IA64 
	select HAVE_OPROFILE

	select HAVE_KPROBES

	select HAVE_KRETPROBES

	select HAVE_FTRACE_MCOUNT_RECORD

	select HAVE_DYNAMIC_FTRACE if (!ITANIUM)

	select HAVE_FUNCTION_TRACER

	select HAVE_DMA_ATTRS

	select HAVE_KVM

arch/ia64/include/asm/ftrace.h

+13 −0
Original line number Diff line number Diff line
@@ -8,6 +8,19 @@ 
extern void _mcount(unsigned long pfs, unsigned long r1, unsigned long b0, unsigned long r0);

#define mcount _mcount



#include <asm/kprobes.h>

/* In IA64, MCOUNT_ADDR is set in link time, so it's not a constant at compile time */

#define MCOUNT_ADDR (((struct fnptr *)mcount)->ip)

#define FTRACE_ADDR (((struct fnptr *)ftrace_caller)->ip)



static inline unsigned long ftrace_call_adjust(unsigned long addr)

{

	/* second bundle, insn 2 */

	return addr - 0x12;

}



struct dyn_arch_ftrace {

};

#endif



#endif /* CONFIG_FUNCTION_TRACER */

arch/ia64/kernel/Makefile

+5 −0
Original line number Diff line number Diff line
@@ -2,6 +2,10 @@ 
# Makefile for the linux kernel.

#



ifdef CONFIG_DYNAMIC_FTRACE

CFLAGS_REMOVE_ftrace.o = -pg

endif



extra-y	:= head.o init_task.o vmlinux.lds



obj-y := acpi.o entry.o efi.o efi_stub.o gate-data.o fsys.o ia64_ksyms.o irq.o irq_ia64.o	\
@@ -28,6 +32,7 @@ obj-$(CONFIG_IA64_CYCLONE) += cyclone.o 
obj-$(CONFIG_CPU_FREQ)		+= cpufreq/

obj-$(CONFIG_IA64_MCA_RECOVERY)	+= mca_recovery.o

obj-$(CONFIG_KPROBES)		+= kprobes.o jprobes.o

obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o crash.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o

obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR)	+= uncached.o

arch/ia64/kernel/entry.S

+51 −0
Original line number Diff line number Diff line
@@ -1406,6 +1406,56 @@ GLOBAL_ENTRY(unw_init_running) 
END(unw_init_running)



#ifdef CONFIG_FUNCTION_TRACER

#ifdef CONFIG_DYNAMIC_FTRACE

GLOBAL_ENTRY(_mcount)

	br ftrace_stub

END(_mcount)



.here:

	br.ret.sptk.many b0



GLOBAL_ENTRY(ftrace_caller)

	alloc out0 = ar.pfs, 8, 0, 4, 0

	mov out3 = r0

	;;

	mov out2 = b0

	add r3 = 0x20, r3

	mov out1 = r1;

	br.call.sptk.many b0 = ftrace_patch_gp

	//this might be called from module, so we must patch gp

ftrace_patch_gp:

	movl gp=__gp

	mov b0 = r3

	;;

.global ftrace_call;

ftrace_call:

{

	.mlx

	nop.m 0x0

	movl r3 = .here;;

}

	alloc loc0 = ar.pfs, 4, 4, 2, 0

	;;

	mov loc1 = b0

	mov out0 = b0

	mov loc2 = r8

	mov loc3 = r15

	;;

	adds out0 = -MCOUNT_INSN_SIZE, out0

	mov out1 = in2

	mov b6 = r3



	br.call.sptk.many b0 = b6

	;;

	mov ar.pfs = loc0

	mov b0 = loc1

	mov r8 = loc2

	mov r15 = loc3

	br ftrace_stub

	;;

END(ftrace_caller)



#else

GLOBAL_ENTRY(_mcount)

	movl r2 = ftrace_stub

	movl r3 = ftrace_trace_function;;
@@ -1435,6 +1485,7 @@ GLOBAL_ENTRY(_mcount) 
	br ftrace_stub

	;;

END(_mcount)

#endif



GLOBAL_ENTRY(ftrace_stub)

	mov r3 = b0

arch/ia64/kernel/ftrace.c

0 → 100644
+206 −0
Original line number Diff line number Diff line 
/*

 * Dynamic function tracing support.

 *

 * Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>

 *

 * For licencing details, see COPYING.

 *

 * Defines low-level handling of mcount calls when the kernel

 * is compiled with the -pg flag. When using dynamic ftrace, the

 * mcount call-sites get patched lazily with NOP till they are

 * enabled. All code mutation routines here take effect atomically.

 */



#include <linux/uaccess.h>

#include <linux/ftrace.h>



#include <asm/cacheflush.h>

#include <asm/patch.h>



/* In IA64, each function will be added below two bundles with -pg option */

static unsigned char __attribute__((aligned(8)))

ftrace_orig_code[MCOUNT_INSN_SIZE] = {

	0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */

	0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */

	0x05, 0x00, 0xc4, 0x00,             /* mov r42=b0 */

	0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */

	0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */

	0x08, 0x00, 0x00, 0x50              /* br.call.sptk.many b0 = _mcount;; */

};



struct ftrace_orig_insn {

	u64 dummy1, dummy2, dummy3;

	u64 dummy4:64-41+13;

	u64 imm20:20;

	u64 dummy5:3;

	u64 sign:1;

	u64 dummy6:4;

};



/* mcount stub will be converted below for nop */

static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {

	0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */

	0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */

	0x00, 0x00, 0x04, 0x00,             /* nop.i 0x0 */

	0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */

	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */

	0x00, 0x00, 0x04, 0x00

};



static unsigned char *ftrace_nop_replace(void)

{

	return ftrace_nop_code;

}



/*

 * mcount stub will be converted below for call

 * Note: Just the last instruction is changed against nop

 * */

static unsigned char __attribute__((aligned(8)))

ftrace_call_code[MCOUNT_INSN_SIZE] = {

	0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */

	0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */

	0x00, 0x00, 0x04, 0x00,             /* nop.i 0x0 */

	0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */

	0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/

	0xf8, 0xff, 0xff, 0xc8

};



struct ftrace_call_insn {

	u64 dummy1, dummy2;

	u64 dummy3:48;

	u64 imm39_l:16;

	u64 imm39_h:23;

	u64 dummy4:13;

	u64 imm20:20;

	u64 dummy5:3;

	u64 i:1;

	u64 dummy6:4;

};



static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)

{

	struct ftrace_call_insn *code = (void *)ftrace_call_code;

	unsigned long offset = addr - (ip + 0x10);



	code->imm39_l = offset >> 24;

	code->imm39_h = offset >> 40;

	code->imm20 = offset >> 4;

	code->i = offset >> 63;

	return ftrace_call_code;

}



static int

ftrace_modify_code(unsigned long ip, unsigned char *old_code,

		   unsigned char *new_code, int do_check)

{

	unsigned char replaced[MCOUNT_INSN_SIZE];



	/*

	 * Note: Due to modules and __init, code can

	 *  disappear and change, we need to protect against faulting

	 *  as well as code changing. We do this by using the

	 *  probe_kernel_* functions.

	 *

	 * No real locking needed, this code is run through

	 * kstop_machine, or before SMP starts.

	 */



	if (!do_check)

		goto skip_check;



	/* read the text we want to modify */

	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))

		return -EFAULT;



	/* Make sure it is what we expect it to be */

	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)

		return -EINVAL;



skip_check:

	/* replace the text with the new text */

	if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))

		return -EPERM;

	flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);



	return 0;

}



static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)

{

	unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];

	unsigned long ip = rec->ip;



	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))

		return -EFAULT;

	if (rec->flags & FTRACE_FL_CONVERTED) {

		struct ftrace_call_insn *call_insn, *tmp_call;



		call_insn = (void *)ftrace_call_code;

		tmp_call = (void *)replaced;

		call_insn->imm39_l = tmp_call->imm39_l;

		call_insn->imm39_h = tmp_call->imm39_h;

		call_insn->imm20 = tmp_call->imm20;

		call_insn->i = tmp_call->i;

		if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)

			return -EINVAL;

		return 0;

	} else {

		struct ftrace_orig_insn *call_insn, *tmp_call;



		call_insn = (void *)ftrace_orig_code;

		tmp_call = (void *)replaced;

		call_insn->sign = tmp_call->sign;

		call_insn->imm20 = tmp_call->imm20;

		if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)

			return -EINVAL;

		return 0;

	}

}



int ftrace_make_nop(struct module *mod,

		    struct dyn_ftrace *rec, unsigned long addr)

{

	int ret;

	char *new;



	ret = ftrace_make_nop_check(rec, addr);

	if (ret)

		return ret;

	new = ftrace_nop_replace();

	return ftrace_modify_code(rec->ip, NULL, new, 0);

}



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

{

	unsigned long ip = rec->ip;

	unsigned char *old, *new;



	old=  ftrace_nop_replace();

	new = ftrace_call_replace(ip, addr);

	return ftrace_modify_code(ip, old, new, 1);

}



/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */

int ftrace_update_ftrace_func(ftrace_func_t func)

{

	unsigned long ip;

	unsigned long addr = ((struct fnptr *)ftrace_call)->ip;



	if (func == ftrace_stub)

		return 0;

	ip = ((struct fnptr *)func)->ip;



	ia64_patch_imm64(addr + 2, ip);



	flush_icache_range(addr, addr + 16);

	return 0;

}



/* run from kstop_machine */

int __init ftrace_dyn_arch_init(void *data)

{

	*(unsigned long *)data = 0;



	return 0;

}