1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 2000, 2002-2003 Hewlett-Packard Co
4  *	David Mosberger-Tang <davidm@hpl.hp.com>
5  *
6  * Kernel unwind support.
7  */
8 
9 #define UNW_VER(x)		((x) >> 48)
10 #define UNW_FLAG_MASK		0x0000ffff00000000
11 #define UNW_FLAG_OSMASK		0x0000f00000000000
12 #define UNW_FLAG_EHANDLER(x)	((x) & 0x0000000100000000L)
13 #define UNW_FLAG_UHANDLER(x)	((x) & 0x0000000200000000L)
14 #define UNW_LENGTH(x)		((x) & 0x00000000ffffffffL)
15 
16 enum unw_register_index {
17 	/* primary unat: */
18 	UNW_REG_PRI_UNAT_GR,
19 	UNW_REG_PRI_UNAT_MEM,
20 
21 	/* register stack */
22 	UNW_REG_BSP,					/* register stack pointer */
23 	UNW_REG_BSPSTORE,
24 	UNW_REG_PFS,					/* previous function state */
25 	UNW_REG_RNAT,
26 	/* memory stack */
27 	UNW_REG_PSP,					/* previous memory stack pointer */
28 	/* return pointer: */
29 	UNW_REG_RP,
30 
31 	/* preserved registers: */
32 	UNW_REG_R4, UNW_REG_R5, UNW_REG_R6, UNW_REG_R7,
33 	UNW_REG_UNAT, UNW_REG_PR, UNW_REG_LC, UNW_REG_FPSR,
34 	UNW_REG_B1, UNW_REG_B2, UNW_REG_B3, UNW_REG_B4, UNW_REG_B5,
35 	UNW_REG_F2, UNW_REG_F3, UNW_REG_F4, UNW_REG_F5,
36 	UNW_REG_F16, UNW_REG_F17, UNW_REG_F18, UNW_REG_F19,
37 	UNW_REG_F20, UNW_REG_F21, UNW_REG_F22, UNW_REG_F23,
38 	UNW_REG_F24, UNW_REG_F25, UNW_REG_F26, UNW_REG_F27,
39 	UNW_REG_F28, UNW_REG_F29, UNW_REG_F30, UNW_REG_F31,
40 	UNW_NUM_REGS
41 };
42 
43 struct unw_info_block {
44 	u64 header;
45 	u64 desc[];		/* unwind descriptors */
46 	/* personality routine and language-specific data follow behind descriptors */
47 };
48 
49 struct unw_table {
50 	struct unw_table *next;		/* must be first member! */
51 	const char *name;
52 	unsigned long gp;		/* global pointer for this load-module */
53 	unsigned long segment_base;	/* base for offsets in the unwind table entries */
54 	unsigned long start;
55 	unsigned long end;
56 	const struct unw_table_entry *array;
57 	unsigned long length;
58 };
59 
60 enum unw_where {
61 	UNW_WHERE_NONE,			/* register isn't saved at all */
62 	UNW_WHERE_GR,			/* register is saved in a general register */
63 	UNW_WHERE_FR,			/* register is saved in a floating-point register */
64 	UNW_WHERE_BR,			/* register is saved in a branch register */
65 	UNW_WHERE_SPREL,		/* register is saved on memstack (sp-relative) */
66 	UNW_WHERE_PSPREL,		/* register is saved on memstack (psp-relative) */
67 	/*
68 	 * At the end of each prologue these locations get resolved to
69 	 * UNW_WHERE_PSPREL and UNW_WHERE_GR, respectively:
70 	 */
71 	UNW_WHERE_SPILL_HOME,		/* register is saved in its spill home */
72 	UNW_WHERE_GR_SAVE		/* register is saved in next general register */
73 };
74 
75 #define UNW_WHEN_NEVER	0x7fffffff
76 
77 struct unw_reg_info {
78 	unsigned long val;		/* save location: register number or offset */
79 	enum unw_where where;		/* where the register gets saved */
80 	int when;			/* when the register gets saved */
81 };
82 
83 struct unw_reg_state {
84 	struct unw_reg_state *next;		/* next (outer) element on state stack */
85 	struct unw_reg_info reg[UNW_NUM_REGS];	/* register save locations */
86 };
87 
88 struct unw_labeled_state {
89 	struct unw_labeled_state *next;		/* next labeled state (or NULL) */
90 	unsigned long label;			/* label for this state */
91 	struct unw_reg_state saved_state;
92 };
93 
94 struct unw_state_record {
95 	unsigned int first_region : 1;	/* is this the first region? */
96 	unsigned int done : 1;		/* are we done scanning descriptors? */
97 	unsigned int any_spills : 1;	/* got any register spills? */
98 	unsigned int in_body : 1;	/* are we inside a body (as opposed to a prologue)? */
99 	unsigned long flags;		/* see UNW_FLAG_* in unwind.h */
100 
101 	u8 *imask;			/* imask of spill_mask record or NULL */
102 	unsigned long pr_val;		/* predicate values */
103 	unsigned long pr_mask;		/* predicate mask */
104 	long spill_offset;		/* psp-relative offset for spill base */
105 	int region_start;
106 	int region_len;
107 	int epilogue_start;
108 	int epilogue_count;
109 	int when_target;
110 
111 	u8 gr_save_loc;			/* next general register to use for saving a register */
112 	u8 return_link_reg;		/* branch register in which the return link is passed */
113 
114 	struct unw_labeled_state *labeled_states;	/* list of all labeled states */
115 	struct unw_reg_state curr;	/* current state */
116 };
117 
118 enum unw_nat_type {
119 	UNW_NAT_NONE,		/* NaT not represented */
120 	UNW_NAT_VAL,		/* NaT represented by NaT value (fp reg) */
121 	UNW_NAT_MEMSTK,		/* NaT value is in unat word at offset OFF  */
122 	UNW_NAT_REGSTK		/* NaT is in rnat */
123 };
124 
125 enum unw_insn_opcode {
126 	UNW_INSN_ADD,			/* s[dst] += val */
127 	UNW_INSN_ADD_PSP,		/* s[dst] = (s.psp + val) */
128 	UNW_INSN_ADD_SP,		/* s[dst] = (s.sp + val) */
129 	UNW_INSN_MOVE,			/* s[dst] = s[val] */
130 	UNW_INSN_MOVE2,			/* s[dst] = s[val]; s[dst+1] = s[val+1] */
131 	UNW_INSN_MOVE_STACKED,		/* s[dst] = ia64_rse_skip(*s.bsp, val) */
132 	UNW_INSN_SETNAT_MEMSTK,		/* s[dst+1].nat.type = MEMSTK;
133 					   s[dst+1].nat.off = *s.pri_unat - s[dst] */
134 	UNW_INSN_SETNAT_TYPE,		/* s[dst+1].nat.type = val */
135 	UNW_INSN_LOAD,			/* s[dst] = *s[val] */
136 	UNW_INSN_MOVE_SCRATCH,		/* s[dst] = scratch reg "val" */
137 	UNW_INSN_MOVE_CONST,            /* s[dst] = constant reg "val" */
138 };
139 
140 struct unw_insn {
141 	unsigned int opc	:  4;
142 	unsigned int dst	:  9;
143 	signed int val		: 19;
144 };
145 
146 /*
147  * Preserved general static registers (r4-r7) give rise to two script
148  * instructions; everything else yields at most one instruction; at
149  * the end of the script, the psp gets popped, accounting for one more
150  * instruction.
151  */
152 #define UNW_MAX_SCRIPT_LEN	(UNW_NUM_REGS + 5)
153 
154 struct unw_script {
155 	unsigned long ip;		/* ip this script is for */
156 	unsigned long pr_mask;		/* mask of predicates script depends on */
157 	unsigned long pr_val;		/* predicate values this script is for */
158 	rwlock_t lock;
159 	unsigned int flags;		/* see UNW_FLAG_* in unwind.h */
160 	unsigned short lru_chain;	/* used for least-recently-used chain */
161 	unsigned short coll_chain;	/* used for hash collisions */
162 	unsigned short hint;		/* hint for next script to try (or -1) */
163 	unsigned short count;		/* number of instructions in script */
164 	struct unw_insn insn[UNW_MAX_SCRIPT_LEN];
165 };
166