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 
25 unsigned int create_branch(const unsigned int *addr,
26 			   unsigned long target, int flags);
27 unsigned int create_cond_branch(const unsigned int *addr,
28 				unsigned long target, int flags);
29 int patch_branch(unsigned int *addr, unsigned long target, int flags);
30 int patch_instruction(unsigned int *addr, unsigned int instr);
31 
32 int instr_is_relative_branch(unsigned int instr);
33 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
34 unsigned long branch_target(const unsigned int *instr);
35 unsigned int translate_branch(const unsigned int *dest,
36 			      const unsigned int *src);
37 #ifdef CONFIG_PPC_BOOK3E_64
38 void __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 
50 static 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 
91 static 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