2 * Copyright 2008 Michael Ellerman, IBM Corporation.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
10 #include <linux/kernel.h>
11 #include <asm/code-patching.h>
14 void patch_instruction(unsigned int *addr, unsigned int instr)
17 asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr));
20 void patch_branch(unsigned int *addr, unsigned long target, int flags)
22 patch_instruction(addr, create_branch(addr, target, flags));
25 unsigned int create_branch(const unsigned int *addr,
26 unsigned long target, int flags)
28 unsigned int instruction;
32 if (! (flags & BRANCH_ABSOLUTE))
33 offset = offset - (unsigned long)addr;
35 /* Check we can represent the target in the instruction format */
36 if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3)
39 /* Mask out the flags and target, so they don't step on each other. */
40 instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
45 unsigned int create_cond_branch(const unsigned int *addr,
46 unsigned long target, int flags)
48 unsigned int instruction;
52 if (! (flags & BRANCH_ABSOLUTE))
53 offset = offset - (unsigned long)addr;
55 /* Check we can represent the target in the instruction format */
56 if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
59 /* Mask out the flags and target, so they don't step on each other. */
60 instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
65 static unsigned int branch_opcode(unsigned int instr)
67 return (instr >> 26) & 0x3F;
70 static int instr_is_branch_iform(unsigned int instr)
72 return branch_opcode(instr) == 18;
75 static int instr_is_branch_bform(unsigned int instr)
77 return branch_opcode(instr) == 16;
80 int instr_is_relative_branch(unsigned int instr)
82 if (instr & BRANCH_ABSOLUTE)
85 return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
88 static unsigned long branch_iform_target(const unsigned int *instr)
92 imm = *instr & 0x3FFFFFC;
94 /* If the top bit of the immediate value is set this is negative */
98 if ((*instr & BRANCH_ABSOLUTE) == 0)
99 imm += (unsigned long)instr;
101 return (unsigned long)imm;
104 static unsigned long branch_bform_target(const unsigned int *instr)
108 imm = *instr & 0xFFFC;
110 /* If the top bit of the immediate value is set this is negative */
114 if ((*instr & BRANCH_ABSOLUTE) == 0)
115 imm += (unsigned long)instr;
117 return (unsigned long)imm;
120 unsigned long branch_target(const unsigned int *instr)
122 if (instr_is_branch_iform(*instr))
123 return branch_iform_target(instr);
124 else if (instr_is_branch_bform(*instr))
125 return branch_bform_target(instr);
130 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
132 if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
133 return branch_target(instr) == addr;
138 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
140 unsigned long target;
142 target = branch_target(src);
144 if (instr_is_branch_iform(*src))
145 return create_branch(dest, target, *src);
146 else if (instr_is_branch_bform(*src))
147 return create_cond_branch(dest, target, *src);