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1 /*
2  * Copyright (C) 2000, 2002-2003 Hewlett-Packard Co
3  *	David Mosberger-Tang <davidm@hpl.hp.com>
4  *
5  * Kernel unwind support.
6  */
7 
8 #define UNW_VER(x)		((x) >> 48)
9 #define UNW_FLAG_MASK		0x0000ffff00000000
10 #define UNW_FLAG_OSMASK		0x0000f00000000000
11 #define UNW_FLAG_EHANDLER(x)	((x) & 0x0000000100000000L)
12 #define UNW_FLAG_UHANDLER(x)	((x) & 0x0000000200000000L)
13 #define UNW_LENGTH(x)		((x) & 0x00000000ffffffffL)
14 
15 enum unw_register_index {
16 	/* primary unat: */
17 	UNW_REG_PRI_UNAT_GR,
18 	UNW_REG_PRI_UNAT_MEM,
19 
20 	/* register stack */
21 	UNW_REG_BSP,					/* register stack pointer */
22 	UNW_REG_BSPSTORE,
23 	UNW_REG_PFS,					/* previous function state */
24 	UNW_REG_RNAT,
25 	/* memory stack */
26 	UNW_REG_PSP,					/* previous memory stack pointer */
27 	/* return pointer: */
28 	UNW_REG_RP,
29 
30 	/* preserved registers: */
31 	UNW_REG_R4, UNW_REG_R5, UNW_REG_R6, UNW_REG_R7,
32 	UNW_REG_UNAT, UNW_REG_PR, UNW_REG_LC, UNW_REG_FPSR,
33 	UNW_REG_B1, UNW_REG_B2, UNW_REG_B3, UNW_REG_B4, UNW_REG_B5,
34 	UNW_REG_F2, UNW_REG_F3, UNW_REG_F4, UNW_REG_F5,
35 	UNW_REG_F16, UNW_REG_F17, UNW_REG_F18, UNW_REG_F19,
36 	UNW_REG_F20, UNW_REG_F21, UNW_REG_F22, UNW_REG_F23,
37 	UNW_REG_F24, UNW_REG_F25, UNW_REG_F26, UNW_REG_F27,
38 	UNW_REG_F28, UNW_REG_F29, UNW_REG_F30, UNW_REG_F31,
39 	UNW_NUM_REGS
40 };
41 
42 struct unw_info_block {
43 	u64 header;
44 	u64 desc[0];		/* unwind descriptors */
45 	/* personality routine and language-specific data follow behind descriptors */
46 };
47 
48 struct unw_table {
49 	struct unw_table *next;		/* must be first member! */
50 	const char *name;
51 	unsigned long gp;		/* global pointer for this load-module */
52 	unsigned long segment_base;	/* base for offsets in the unwind table entries */
53 	unsigned long start;
54 	unsigned long end;
55 	const struct unw_table_entry *array;
56 	unsigned long length;
57 };
58 
59 enum unw_where {
60 	UNW_WHERE_NONE,			/* register isn't saved at all */
61 	UNW_WHERE_GR,			/* register is saved in a general register */
62 	UNW_WHERE_FR,			/* register is saved in a floating-point register */
63 	UNW_WHERE_BR,			/* register is saved in a branch register */
64 	UNW_WHERE_SPREL,		/* register is saved on memstack (sp-relative) */
65 	UNW_WHERE_PSPREL,		/* register is saved on memstack (psp-relative) */
66 	/*
67 	 * At the end of each prologue these locations get resolved to
68 	 * UNW_WHERE_PSPREL and UNW_WHERE_GR, respectively:
69 	 */
70 	UNW_WHERE_SPILL_HOME,		/* register is saved in its spill home */
71 	UNW_WHERE_GR_SAVE		/* register is saved in next general register */
72 };
73 
74 #define UNW_WHEN_NEVER	0x7fffffff
75 
76 struct unw_reg_info {
77 	unsigned long val;		/* save location: register number or offset */
78 	enum unw_where where;		/* where the register gets saved */
79 	int when;			/* when the register gets saved */
80 };
81 
82 struct unw_reg_state {
83 	struct unw_reg_state *next;		/* next (outer) element on state stack */
84 	struct unw_reg_info reg[UNW_NUM_REGS];	/* register save locations */
85 };
86 
87 struct unw_labeled_state {
88 	struct unw_labeled_state *next;		/* next labeled state (or NULL) */
89 	unsigned long label;			/* label for this state */
90 	struct unw_reg_state saved_state;
91 };
92 
93 struct unw_state_record {
94 	unsigned int first_region : 1;	/* is this the first region? */
95 	unsigned int done : 1;		/* are we done scanning descriptors? */
96 	unsigned int any_spills : 1;	/* got any register spills? */
97 	unsigned int in_body : 1;	/* are we inside a body (as opposed to a prologue)? */
98 	unsigned long flags;		/* see UNW_FLAG_* in unwind.h */
99 
100 	u8 *imask;			/* imask of spill_mask record or NULL */
101 	unsigned long pr_val;		/* predicate values */
102 	unsigned long pr_mask;		/* predicate mask */
103 	long spill_offset;		/* psp-relative offset for spill base */
104 	int region_start;
105 	int region_len;
106 	int epilogue_start;
107 	int epilogue_count;
108 	int when_target;
109 
110 	u8 gr_save_loc;			/* next general register to use for saving a register */
111 	u8 return_link_reg;		/* branch register in which the return link is passed */
112 
113 	struct unw_labeled_state *labeled_states;	/* list of all labeled states */
114 	struct unw_reg_state curr;	/* current state */
115 };
116 
117 enum unw_nat_type {
118 	UNW_NAT_NONE,		/* NaT not represented */
119 	UNW_NAT_VAL,		/* NaT represented by NaT value (fp reg) */
120 	UNW_NAT_MEMSTK,		/* NaT value is in unat word at offset OFF  */
121 	UNW_NAT_REGSTK		/* NaT is in rnat */
122 };
123 
124 enum unw_insn_opcode {
125 	UNW_INSN_ADD,			/* s[dst] += val */
126 	UNW_INSN_ADD_PSP,		/* s[dst] = (s.psp + val) */
127 	UNW_INSN_ADD_SP,		/* s[dst] = (s.sp + val) */
128 	UNW_INSN_MOVE,			/* s[dst] = s[val] */
129 	UNW_INSN_MOVE2,			/* s[dst] = s[val]; s[dst+1] = s[val+1] */
130 	UNW_INSN_MOVE_STACKED,		/* s[dst] = ia64_rse_skip(*s.bsp, val) */
131 	UNW_INSN_SETNAT_MEMSTK,		/* s[dst+1].nat.type = MEMSTK;
132 					   s[dst+1].nat.off = *s.pri_unat - s[dst] */
133 	UNW_INSN_SETNAT_TYPE,		/* s[dst+1].nat.type = val */
134 	UNW_INSN_LOAD,			/* s[dst] = *s[val] */
135 	UNW_INSN_MOVE_SCRATCH,		/* s[dst] = scratch reg "val" */
136 	UNW_INSN_MOVE_CONST,            /* s[dst] = constant reg "val" */
137 };
138 
139 struct unw_insn {
140 	unsigned int opc	:  4;
141 	unsigned int dst	:  9;
142 	signed int val		: 19;
143 };
144 
145 /*
146  * Preserved general static registers (r4-r7) give rise to two script
147  * instructions; everything else yields at most one instruction; at
148  * the end of the script, the psp gets popped, accounting for one more
149  * instruction.
150  */
151 #define UNW_MAX_SCRIPT_LEN	(UNW_NUM_REGS + 5)
152 
153 struct unw_script {
154 	unsigned long ip;		/* ip this script is for */
155 	unsigned long pr_mask;		/* mask of predicates script depends on */
156 	unsigned long pr_val;		/* predicate values this script is for */
157 	rwlock_t lock;
158 	unsigned int flags;		/* see UNW_FLAG_* in unwind.h */
159 	unsigned short lru_chain;	/* used for least-recently-used chain */
160 	unsigned short coll_chain;	/* used for hash collisions */
161 	unsigned short hint;		/* hint for next script to try (or -1) */
162 	unsigned short count;		/* number of instructions in script */
163 	struct unw_insn insn[UNW_MAX_SCRIPT_LEN];
164 };
165