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Commit 0029ff87 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

powerpc: ftrace, use create_branch 



Impact: clean up

Paul Mackerras pointed out that the code to determine if the branch
can reach the destination is incorrect. Michael Ellerman suggested
to pull out the code from create_branch and use that.

Simply using create_branch is probably the best.

Reported-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Reported-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ec682cef

arch/powerpc/kernel/ftrace.c

+12 −42
Original line number Original line Diff line number Diff line
@@ -114,19 +114,9 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, 
 */

 */

static int test_24bit_addr(unsigned long ip, unsigned long addr)

static int test_24bit_addr(unsigned long ip, unsigned long addr)

{

{

	long diff;





	/*

	/* use the create_branch to verify that this offset can be branched */

	 * Can we get to addr from ip in 24 bits?

	return create_branch((unsigned int *)ip, addr, 0);

	 *  (26 really, since we mulitply by 4 for 4 byte alignment)

	 */

	diff = addr - ip;



	/*

	 * Return true if diff is less than 1 << 25

	 *  and greater than -1 << 26.

	 */

	return (diff < (1 << 25)) && (diff > (-1 << 26));

}

}





static int is_bl_op(unsigned int op)

static int is_bl_op(unsigned int op)
@@ -134,11 +124,6 @@ static int is_bl_op(unsigned int op) 
	return (op & 0xfc000003) == 0x48000001;

	return (op & 0xfc000003) == 0x48000001;

}

}





static int test_offset(unsigned long offset)

{

	return (offset + 0x2000000 > 0x3ffffff) || ((offset & 3) != 0);

}



static unsigned long find_bl_target(unsigned long ip, unsigned int op)

static unsigned long find_bl_target(unsigned long ip, unsigned int op)

{

{

	static int offset;

	static int offset;
@@ -151,12 +136,6 @@ static unsigned long find_bl_target(unsigned long ip, unsigned int op) 
	return ip + (long)offset;

	return ip + (long)offset;

}

}





static unsigned int branch_offset(unsigned long offset)

{

	/* return "bl ip+offset" */

	return 0x48000001 | (offset & 0x03fffffc);

}



#ifdef CONFIG_PPC64

#ifdef CONFIG_PPC64

static int

static int

__ftrace_make_nop(struct module *mod,

__ftrace_make_nop(struct module *mod,
@@ -402,7 +381,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
{

{

	unsigned int op[2];

	unsigned int op[2];

	unsigned long ip = rec->ip;

	unsigned long ip = rec->ip;

	unsigned long offset;





	/* read where this goes */

	/* read where this goes */

	if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))

	if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2))
@@ -424,17 +402,14 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
		return -EINVAL;

		return -EINVAL;

	}

	}





	/* now calculate a jump to the ftrace caller trampoline */

	/* create the branch to the trampoline */

	offset = rec->arch.mod->arch.tramp - ip;

	op[0] = create_branch((unsigned int *)ip,



			      rec->arch.mod->arch.tramp, BRANCH_SET_LINK);

	if (test_offset(offset)) {

	if (!op[0]) {

		printk(KERN_ERR "REL24 %li out of range!\n",

		printk(KERN_ERR "REL24 out of range!\n");

		       (long int)offset);

		return -EINVAL;

		return -EINVAL;

	}

	}





	/* Set to "bl addr" */

	op[0] = branch_offset(offset);

	/* ld r2,40(r1) */

	/* ld r2,40(r1) */

	op[1] = 0xe8410028;

	op[1] = 0xe8410028;
@@ -453,7 +428,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
{

{

	unsigned int op;

	unsigned int op;

	unsigned long ip = rec->ip;

	unsigned long ip = rec->ip;

	unsigned long offset;





	/* read where this goes */

	/* read where this goes */

	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))

	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
@@ -471,18 +445,14 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
		return -EINVAL;

		return -EINVAL;

	}

	}





	/* now calculate a jump to the ftrace caller trampoline */

	/* create the branch to the trampoline */

	offset = rec->arch.mod->arch.tramp - ip;

	op = create_branch((unsigned int *)ip,



			   rec->arch.mod->arch.tramp, BRANCH_SET_LINK);

	if (test_offset(offset)) {

	if (!op) {

		printk(KERN_ERR "REL24 %li out of range!\n",

		printk(KERN_ERR "REL24 out of range!\n");

		       (long int)offset);

		return -EINVAL;

		return -EINVAL;

	}

	}





	/* Set to "bl addr" */

	op = branch_offset(offset);



	DEBUGP("write to %lx\n", rec->ip);

	DEBUGP("write to %lx\n", rec->ip);





	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))

	if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE))