1#ifndef _ASM_POWERPC_CODE_PATCHING_H
2#define _ASM_POWERPC_CODE_PATCHING_H
3
4/*
5 * Copyright 2008, Michael Ellerman, IBM Corporation.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <asm/types.h>
14#include <asm/ppc-opcode.h>
15
16/* Flags for create_branch:
17 * "b"   == create_branch(addr, target, 0);
18 * "ba"  == create_branch(addr, target, BRANCH_ABSOLUTE);
19 * "bl"  == create_branch(addr, target, BRANCH_SET_LINK);
20 * "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
21 */
22#define BRANCH_SET_LINK	0x1
23#define BRANCH_ABSOLUTE	0x2
24
25unsigned int create_branch(const unsigned int *addr,
26			   unsigned long target, int flags);
27unsigned int create_cond_branch(const unsigned int *addr,
28				unsigned long target, int flags);
29int patch_branch(unsigned int *addr, unsigned long target, int flags);
30int patch_instruction(unsigned int *addr, unsigned int instr);
31
32int instr_is_relative_branch(unsigned int instr);
33int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
34unsigned long branch_target(const unsigned int *instr);
35unsigned int translate_branch(const unsigned int *dest,
36			      const unsigned int *src);
37#ifdef CONFIG_PPC_BOOK3E_64
38void __patch_exception(int exc, unsigned long addr);
39#define patch_exception(exc, name) do { \
40	extern unsigned int name; \
41	__patch_exception((exc), (unsigned long)&name); \
42} while (0)
43#endif
44
45#define OP_RT_RA_MASK	0xffff0000UL
46#define LIS_R2		0x3c020000UL
47#define ADDIS_R2_R12	0x3c4c0000UL
48#define ADDI_R2_R2	0x38420000UL
49
50static inline unsigned long ppc_function_entry(void *func)
51{
52#if defined(CONFIG_PPC64)
53#if defined(_CALL_ELF) && _CALL_ELF == 2
54	u32 *insn = func;
55
56	/*
57	 * A PPC64 ABIv2 function may have a local and a global entry
58	 * point. We need to use the local entry point when patching
59	 * functions, so identify and step over the global entry point
60	 * sequence.
61	 *
62	 * The global entry point sequence is always of the form:
63	 *
64	 * addis r2,r12,XXXX
65	 * addi  r2,r2,XXXX
66	 *
67	 * A linker optimisation may convert the addis to lis:
68	 *
69	 * lis   r2,XXXX
70	 * addi  r2,r2,XXXX
71	 */
72	if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
73	     ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
74	    ((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
75		return (unsigned long)(insn + 2);
76	else
77		return (unsigned long)func;
78#else
79	/*
80	 * On PPC64 ABIv1 the function pointer actually points to the
81	 * function's descriptor. The first entry in the descriptor is the
82	 * address of the function text.
83	 */
84	return ((func_descr_t *)func)->entry;
85#endif
86#else
87	return (unsigned long)func;
88#endif
89}
90
91static inline unsigned long ppc_global_function_entry(void *func)
92{
93#if defined(CONFIG_PPC64) && defined(_CALL_ELF) && _CALL_ELF == 2
94	/* PPC64 ABIv2 the global entry point is at the address */
95	return (unsigned long)func;
96#else
97	/* All other cases there is no change vs ppc_function_entry() */
98	return ppc_function_entry(func);
99#endif
100}
101
102#endif /* _ASM_POWERPC_CODE_PATCHING_H */
103