xref: /illumos-gate/usr/src/uts/sparc/dtrace/fbt.c (revision a1b5e537)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <sys/errno.h>
30 #include <sys/stat.h>
31 #include <sys/modctl.h>
32 #include <sys/conf.h>
33 #include <sys/systm.h>
34 #include <sys/ddi.h>
35 #include <sys/sunddi.h>
36 #include <sys/cpuvar.h>
37 #include <sys/kmem.h>
38 #include <sys/strsubr.h>
39 #include <sys/dtrace.h>
40 #include <sys/kobj.h>
41 #include <sys/modctl.h>
42 #include <sys/atomic.h>
43 #include <vm/seg_kmem.h>
44 #include <sys/stack.h>
45 #include <sys/ctf_api.h>
46 #include <sys/sysmacros.h>
47 
48 static dev_info_t		*fbt_devi;
49 static dtrace_provider_id_t	fbt_id;
50 static uintptr_t		fbt_trampoline;
51 static caddr_t			fbt_trampoline_window;
52 static size_t			fbt_trampoline_size;
53 static int			fbt_verbose = 0;
54 
55 /*
56  * Various interesting bean counters.
57  */
58 static int			fbt_entry;
59 static int			fbt_ret;
60 static int			fbt_retl;
61 static int			fbt_retl_jmptab;
62 static int			fbt_retl_twoinstr;
63 static int			fbt_retl_tailcall;
64 static int			fbt_retl_tailjmpl;
65 static int			fbt_leaf_functions;
66 
67 extern char			stubs_base[];
68 extern char			stubs_end[];
69 
70 #define	FBT_REG_G0		0
71 #define	FBT_REG_G1		1
72 #define	FBT_REG_O0		8
73 #define	FBT_REG_O1		9
74 #define	FBT_REG_O2		10
75 #define	FBT_REG_O3		11
76 #define	FBT_REG_O4		12
77 #define	FBT_REG_O5		13
78 #define	FBT_REG_O6		14
79 #define	FBT_REG_O7		15
80 #define	FBT_REG_I0		24
81 #define	FBT_REG_I1		25
82 #define	FBT_REG_I2		26
83 #define	FBT_REG_I3		27
84 #define	FBT_REG_I4		28
85 #define	FBT_REG_I7		31
86 #define	FBT_REG_L0		16
87 #define	FBT_REG_L1		17
88 #define	FBT_REG_L2		18
89 #define	FBT_REG_L3		19
90 #define	FBT_REG_PC		5
91 
92 #define	FBT_REG_ISGLOBAL(r)	((r) < 8)
93 #define	FBT_REG_ISOUTPUT(r)	((r) >= 8 && (r) < 16)
94 #define	FBT_REG_ISLOCAL(r)	((r) >= 16 && (r) < 24)
95 #define	FBT_REG_ISVOLATILE(r)	\
96 	((FBT_REG_ISGLOBAL(r) || FBT_REG_ISOUTPUT(r)) && (r) != FBT_REG_G0)
97 #define	FBT_REG_NLOCALS		8
98 
99 #define	FBT_REG_MARKLOCAL(locals, r)	\
100 	if (FBT_REG_ISLOCAL(r)) \
101 		(locals)[(r) - FBT_REG_L0] = 1;
102 
103 #define	FBT_REG_INITLOCALS(local, locals)	\
104 	for ((local) = 0; (local) < FBT_REG_NLOCALS; (local)++)  \
105 		(locals)[(local)] = 0; \
106 	(local) = FBT_REG_L0
107 
108 #define	FBT_REG_ALLOCLOCAL(local, locals)	\
109 	while ((locals)[(local) - FBT_REG_L0]) \
110 		(local)++; \
111 	(locals)[(local) - FBT_REG_L0] = 1;
112 
113 #define	FBT_OP_MASK		0xc0000000
114 #define	FBT_OP_SHIFT		30
115 #define	FBT_OP(val)		((val) & FBT_FMT1_MASK)
116 
117 #define	FBT_SIMM13_MASK		0x1fff
118 #define	FBT_SIMM13_MAX		((int32_t)0xfff)
119 #define	FBT_IMM22_MASK		0x3fffff
120 #define	FBT_IMM22_SHIFT		10
121 #define	FBT_IMM10_MASK		0x3ff
122 
123 #define	FBT_DISP30_MASK		0x3fffffff
124 #define	FBT_DISP30(from, to)	\
125 	(((uintptr_t)(to) - (uintptr_t)(from) >> 2) & FBT_DISP30_MASK)
126 
127 #define	FBT_DISP22_MASK		0x3fffff
128 #define	FBT_DISP22(from, to)	\
129 	(((uintptr_t)(to) - (uintptr_t)(from) >> 2) & FBT_DISP22_MASK)
130 
131 #define	FBT_DISP19_MASK		0x7ffff
132 #define	FBT_DISP19(from, to)	\
133 	(((uintptr_t)(to) - (uintptr_t)(from) >> 2) & FBT_DISP19_MASK)
134 
135 #define	FBT_DISP16_HISHIFT	20
136 #define	FBT_DISP16_HIMASK	(0x3 << FBT_DISP16_HISHIFT)
137 #define	FBT_DISP16_LOMASK	(0x3fff)
138 #define	FBT_DISP16_MASK		(FBT_DISP16_HIMASK | FBT_DISP16_LOMASK)
139 #define	FBT_DISP16(val)	\
140 	((((val) & FBT_DISP16_HIMASK) >> 6) | ((val) & FBT_DISP16_LOMASK))
141 
142 #define	FBT_DISP14_MASK		0x3fff
143 #define	FBT_DISP14(from, to)	\
144 	(((uintptr_t)(to) - (uintptr_t)(from) >> 2) & FBT_DISP14_MASK)
145 
146 #define	FBT_OP0			(((uint32_t)0) << FBT_OP_SHIFT)
147 #define	FBT_OP1			(((uint32_t)1) << FBT_OP_SHIFT)
148 #define	FBT_OP2			(((uint32_t)2) << FBT_OP_SHIFT)
149 #define	FBT_ILLTRAP		0
150 
151 #define	FBT_ANNUL_SHIFT		29
152 #define	FBT_ANNUL		(1 << FBT_ANNUL_SHIFT)
153 
154 #define	FBT_FMT3_OP3_SHIFT	19
155 #define	FBT_FMT3_OP_MASK	0xc1f80000
156 #define	FBT_FMT3_OP(val)	((val) & FBT_FMT3_OP_MASK)
157 
158 #define	FBT_FMT3_RD_SHIFT	25
159 #define	FBT_FMT3_RD_MASK	(0x1f << FBT_FMT3_RD_SHIFT)
160 #define	FBT_FMT3_RD(val)	\
161 	(((val) & FBT_FMT3_RD_MASK) >> FBT_FMT3_RD_SHIFT)
162 
163 #define	FBT_FMT3_RS1_SHIFT	14
164 #define	FBT_FMT3_RS1_MASK	(0x1f << FBT_FMT3_RS1_SHIFT)
165 #define	FBT_FMT3_RS1(val)	\
166 	(((val) & FBT_FMT3_RS1_MASK) >> FBT_FMT3_RS1_SHIFT)
167 #define	FBT_FMT3_RS1_SET(val, rs1) \
168 	(val) = ((val) & ~FBT_FMT3_RS1_MASK) | ((rs1) << FBT_FMT3_RS1_SHIFT)
169 
170 #define	FBT_FMT3_RS2_SHIFT	0
171 #define	FBT_FMT3_RS2_MASK	(0x1f << FBT_FMT3_RS2_SHIFT)
172 #define	FBT_FMT3_RS2(val)	\
173 	(((val) & FBT_FMT3_RS2_MASK) >> FBT_FMT3_RS2_SHIFT)
174 #define	FBT_FMT3_RS2_SET(val, rs2) \
175 	(val) = ((val) & ~FBT_FMT3_RS2_MASK) | ((rs2) << FBT_FMT3_RS2_SHIFT)
176 
177 #define	FBT_FMT3_IMM_SHIFT	13
178 #define	FBT_FMT3_IMM		(1 << FBT_FMT3_IMM_SHIFT)
179 #define	FBT_FMT3_SIMM13_MASK	FBT_SIMM13_MASK
180 
181 #define	FBT_FMT3_ISIMM(val)	((val) & FBT_FMT3_IMM)
182 #define	FBT_FMT3_SIMM13(val)	((val) & FBT_FMT3_SIMM13_MASK)
183 
184 #define	FBT_FMT2_OP2_SHIFT	22
185 #define	FBT_FMT2_OP2_MASK	(0x7 << FBT_FMT2_OP2_SHIFT)
186 #define	FBT_FMT2_RD_SHIFT	25
187 
188 #define	FBT_FMT1_OP(val)	((val) & FBT_OP_MASK)
189 #define	FBT_FMT1_DISP30(val)	((val) & FBT_DISP30_MASK)
190 
191 #define	FBT_FMT2_OP2_BPCC	(0x01 << FBT_FMT2_OP2_SHIFT)
192 #define	FBT_FMT2_OP2_BCC	(0x02 << FBT_FMT2_OP2_SHIFT)
193 #define	FBT_FMT2_OP2_BPR	(0x03 << FBT_FMT2_OP2_SHIFT)
194 #define	FBT_FMT2_OP2_SETHI	(0x04 << FBT_FMT2_OP2_SHIFT)
195 
196 #define	FBT_FMT2_COND_SHIFT	25
197 #define	FBT_FMT2_COND_BA	(0x8 << FBT_FMT2_COND_SHIFT)
198 #define	FBT_FMT2_COND_BL	(0x3 << FBT_FMT2_COND_SHIFT)
199 #define	FBT_FMT2_COND_BGE	(0xb << FBT_FMT2_COND_SHIFT)
200 
201 #define	FBT_OP_RESTORE		(FBT_OP2 | (0x3d << FBT_FMT3_OP3_SHIFT))
202 #define	FBT_OP_SAVE		(FBT_OP2 | (0x3c << FBT_FMT3_OP3_SHIFT))
203 #define	FBT_OP_JMPL		(FBT_OP2 | (0x38 << FBT_FMT3_OP3_SHIFT))
204 #define	FBT_OP_RETURN		(FBT_OP2 | (0x39 << FBT_FMT3_OP3_SHIFT))
205 #define	FBT_OP_CALL		FBT_OP1
206 #define	FBT_OP_SETHI		(FBT_OP0 | FBT_FMT2_OP2_SETHI)
207 #define	FBT_OP_ADD		(FBT_OP2 | (0x00 << FBT_FMT3_OP3_SHIFT))
208 #define	FBT_OP_OR		(FBT_OP2 | (0x02 << FBT_FMT3_OP3_SHIFT))
209 #define	FBT_OP_SUB		(FBT_OP2 | (0x04 << FBT_FMT3_OP3_SHIFT))
210 #define	FBT_OP_CC		(FBT_OP2 | (0x10 << FBT_FMT3_OP3_SHIFT))
211 #define	FBT_OP_BA		(FBT_OP0 | FBT_FMT2_OP2_BCC | FBT_FMT2_COND_BA)
212 #define	FBT_OP_BL		(FBT_OP0 | FBT_FMT2_OP2_BCC | FBT_FMT2_COND_BL)
213 #define	FBT_OP_BGE		(FBT_OP0 | FBT_FMT2_OP2_BCC | FBT_FMT2_COND_BGE)
214 #define	FBT_OP_BAPCC		(FBT_OP0 | FBT_FMT2_OP2_BPCC | FBT_FMT2_COND_BA)
215 #define	FBT_OP_RD		(FBT_OP2 | (0x28 << FBT_FMT3_OP3_SHIFT))
216 
217 #define	FBT_ORLO(rs, val, rd) \
218 	(FBT_OP_OR | ((rs) << FBT_FMT3_RS1_SHIFT) | \
219 	((rd) << FBT_FMT3_RD_SHIFT) | FBT_FMT3_IMM | ((val) & FBT_IMM10_MASK))
220 
221 #define	FBT_ORSIMM13(rs, val, rd) \
222 	(FBT_OP_OR | ((rs) << FBT_FMT3_RS1_SHIFT) | \
223 	((rd) << FBT_FMT3_RD_SHIFT) | FBT_FMT3_IMM | ((val) & FBT_SIMM13_MASK))
224 
225 #define	FBT_ADDSIMM13(rs, val, rd) \
226 	(FBT_OP_ADD | ((rs) << FBT_FMT3_RS1_SHIFT) | \
227 	((rd) << FBT_FMT3_RD_SHIFT) | FBT_FMT3_IMM | ((val) & FBT_SIMM13_MASK))
228 
229 #define	FBT_ADD(rs1, rs2, rd) \
230 	(FBT_OP_ADD | ((rs1) << FBT_FMT3_RS1_SHIFT) | \
231 	((rs2) << FBT_FMT3_RS2_SHIFT) | ((rd) << FBT_FMT3_RD_SHIFT))
232 
233 #define	FBT_CMP(rs1, rs2) \
234 	(FBT_OP_SUB | FBT_OP_CC | ((rs1) << FBT_FMT3_RS1_SHIFT) | \
235 	((rs2) << FBT_FMT3_RS2_SHIFT) | (FBT_REG_G0 << FBT_FMT3_RD_SHIFT))
236 
237 #define	FBT_MOV(rs, rd) \
238 	(FBT_OP_OR | (FBT_REG_G0 << FBT_FMT3_RS1_SHIFT) | \
239 	((rs) << FBT_FMT3_RS2_SHIFT) | ((rd) << FBT_FMT3_RD_SHIFT))
240 
241 #define	FBT_SETHI(val, reg)	\
242 	(FBT_OP_SETHI | (reg << FBT_FMT2_RD_SHIFT) | \
243 	((val >> FBT_IMM22_SHIFT) & FBT_IMM22_MASK))
244 
245 #define	FBT_CALL(orig, dest)	(FBT_OP_CALL | FBT_DISP30(orig, dest))
246 
247 #define	FBT_RET \
248 	(FBT_OP_JMPL | (FBT_REG_I7 << FBT_FMT3_RS1_SHIFT) | \
249 	(FBT_REG_G0 << FBT_FMT3_RD_SHIFT) | FBT_FMT3_IMM | (sizeof (pc_t) << 1))
250 
251 #define	FBT_SAVEIMM(rd, val, rs1)	\
252 	(FBT_OP_SAVE | ((rs1) << FBT_FMT3_RS1_SHIFT) | \
253 	((rd) << FBT_FMT3_RD_SHIFT) | FBT_FMT3_IMM | ((val) & FBT_SIMM13_MASK))
254 
255 #define	FBT_RESTORE(rd, rs1, rs2)	\
256 	(FBT_OP_RESTORE | ((rs1) << FBT_FMT3_RS1_SHIFT) | \
257 	((rd) << FBT_FMT3_RD_SHIFT) | ((rs2) << FBT_FMT3_RS2_SHIFT))
258 
259 #define	FBT_RETURN(rs1, val)		\
260 	(FBT_OP_RETURN | ((rs1) << FBT_FMT3_RS1_SHIFT) | \
261 	FBT_FMT3_IMM | ((val) & FBT_SIMM13_MASK))
262 
263 #define	FBT_BA(orig, dest)	(FBT_OP_BA | FBT_DISP22(orig, dest))
264 #define	FBT_BAA(orig, dest)	(FBT_BA(orig, dest) | FBT_ANNUL)
265 #define	FBT_BL(orig, dest)	(FBT_OP_BL | FBT_DISP22(orig, dest))
266 #define	FBT_BGE(orig, dest)	(FBT_OP_BGE | FBT_DISP22(orig, dest))
267 #define	FBT_BDEST(va, instr)	((uintptr_t)(va) + \
268 	(((int32_t)(((instr) & FBT_DISP22_MASK) << 10)) >> 8))
269 #define	FBT_BPCCDEST(va, instr)	((uintptr_t)(va) + \
270 	(((int32_t)(((instr) & FBT_DISP19_MASK) << 13)) >> 11))
271 #define	FBT_BPRDEST(va, instr)	((uintptr_t)(va) + \
272 	(((int32_t)((FBT_DISP16(instr)) << 16)) >> 14))
273 
274 /*
275  * We're only going to treat a save as safe if (a) both rs1 and rd are
276  * %sp and (b) if the instruction has a simm, the value isn't 0.
277  */
278 #define	FBT_IS_SAVE(instr)	\
279 	(FBT_FMT3_OP(instr) == FBT_OP_SAVE && \
280 	FBT_FMT3_RD(instr) == FBT_REG_O6 && \
281 	FBT_FMT3_RS1(instr) == FBT_REG_O6 && \
282 	!(FBT_FMT3_ISIMM(instr) && FBT_FMT3_SIMM13(instr) == 0))
283 
284 #define	FBT_IS_BA(instr)	(((instr) & ~FBT_DISP22_MASK) == FBT_OP_BA)
285 #define	FBT_IS_BAPCC(instr)	(((instr) & ~FBT_DISP22_MASK) == FBT_OP_BAPCC)
286 
287 #define	FBT_IS_RDPC(instr)	((FBT_FMT3_OP(instr) == FBT_OP_RD) && \
288 	(FBT_FMT3_RD(instr) == FBT_REG_PC))
289 
290 #define	FBT_IS_PCRELATIVE(instr)	\
291 	((((instr) & FBT_OP_MASK) == FBT_OP0 && \
292 	((instr) & FBT_FMT2_OP2_MASK) != FBT_FMT2_OP2_SETHI) || \
293 	((instr) & FBT_OP_MASK) == FBT_OP1 || \
294 	FBT_IS_RDPC(instr))
295 
296 #define	FBT_IS_CTI(instr)	\
297 	((((instr) & FBT_OP_MASK) == FBT_OP0 && \
298 	((instr) & FBT_FMT2_OP2_MASK) != FBT_FMT2_OP2_SETHI) || \
299 	((instr) & FBT_OP_MASK) == FBT_OP1 || \
300 	(FBT_FMT3_OP(instr) == FBT_OP_JMPL) || \
301 	(FBT_FMT3_OP(instr) == FBT_OP_RETURN))
302 
303 #define	FBT_PROBENAME_ENTRY	"entry"
304 #define	FBT_PROBENAME_RETURN	"return"
305 #define	FBT_ESTIMATE_ID		(UINT32_MAX)
306 #define	FBT_COUNTER(id, count)	if ((id) != FBT_ESTIMATE_ID) (count)++
307 
308 #define	FBT_ENTENT_MAXSIZE	(16 * sizeof (uint32_t))
309 #define	FBT_RETENT_MAXSIZE	(11 * sizeof (uint32_t))
310 #define	FBT_RETLENT_MAXSIZE	(23 * sizeof (uint32_t))
311 #define	FBT_ENT_MAXSIZE		\
312 	MAX(MAX(FBT_ENTENT_MAXSIZE, FBT_RETENT_MAXSIZE), FBT_RETLENT_MAXSIZE)
313 
314 typedef struct fbt_probe {
315 	char		*fbtp_name;
316 	dtrace_id_t	fbtp_id;
317 	uintptr_t	fbtp_addr;
318 	struct modctl	*fbtp_ctl;
319 	int		fbtp_loadcnt;
320 	int		fbtp_symndx;
321 	int		fbtp_primary;
322 	int		fbtp_return;
323 	uint32_t	*fbtp_patchpoint;
324 	uint32_t	fbtp_patchval;
325 	uint32_t	fbtp_savedval;
326 	struct fbt_probe *fbtp_next;
327 } fbt_probe_t;
328 
329 typedef struct fbt_trampoline {
330 	uintptr_t	fbtt_va;
331 	uintptr_t	fbtt_limit;
332 	uintptr_t	fbtt_next;
333 } fbt_trampoline_t;
334 
335 static caddr_t
336 fbt_trampoline_map(uintptr_t tramp, size_t size)
337 {
338 	uintptr_t offs;
339 	page_t **ppl;
340 
341 	ASSERT(fbt_trampoline_window == NULL);
342 	ASSERT(fbt_trampoline_size == 0);
343 	ASSERT(fbt_trampoline == NULL);
344 
345 	size += tramp & PAGEOFFSET;
346 	fbt_trampoline = tramp & PAGEMASK;
347 	fbt_trampoline_size = (size + PAGESIZE - 1) & PAGEMASK;
348 	fbt_trampoline_window =
349 	    vmem_alloc(heap_arena, fbt_trampoline_size, VM_SLEEP);
350 
351 	(void) as_pagelock(&kas, &ppl, (caddr_t)fbt_trampoline,
352 	    fbt_trampoline_size, S_WRITE);
353 
354 	for (offs = 0; offs < fbt_trampoline_size; offs += PAGESIZE) {
355 		hat_devload(kas.a_hat, fbt_trampoline_window + offs, PAGESIZE,
356 		    hat_getpfnum(kas.a_hat, (caddr_t)fbt_trampoline + offs),
357 		    PROT_READ | PROT_WRITE,
358 		    HAT_LOAD_LOCK | HAT_LOAD_NOCONSIST);
359 	}
360 
361 	as_pageunlock(&kas, ppl, (caddr_t)fbt_trampoline, fbt_trampoline_size,
362 	    S_WRITE);
363 
364 	return (fbt_trampoline_window + (tramp & PAGEOFFSET));
365 }
366 
367 static void
368 fbt_trampoline_unmap()
369 {
370 	ASSERT(fbt_trampoline_window != NULL);
371 	ASSERT(fbt_trampoline_size != 0);
372 	ASSERT(fbt_trampoline != NULL);
373 
374 	membar_enter();
375 	sync_icache((caddr_t)fbt_trampoline, fbt_trampoline_size);
376 	sync_icache(fbt_trampoline_window, fbt_trampoline_size);
377 
378 	hat_unload(kas.a_hat, fbt_trampoline_window, fbt_trampoline_size,
379 	    HAT_UNLOAD_UNLOCK);
380 
381 	vmem_free(heap_arena, fbt_trampoline_window, fbt_trampoline_size);
382 
383 	fbt_trampoline_window = NULL;
384 	fbt_trampoline = NULL;
385 	fbt_trampoline_size = 0;
386 }
387 
388 static uintptr_t
389 fbt_patch_entry(uint32_t *instr, uint32_t id, fbt_trampoline_t *tramp,
390     int nargs)
391 {
392 	uint32_t *tinstr = (uint32_t *)tramp->fbtt_next;
393 	uint32_t first = *instr;
394 	uintptr_t va = tramp->fbtt_va;
395 	uintptr_t base = tramp->fbtt_next;
396 
397 	if (tramp->fbtt_next + FBT_ENTENT_MAXSIZE > tramp->fbtt_limit) {
398 		/*
399 		 * There isn't sufficient room for this entry; return failure.
400 		 */
401 		return (0);
402 	}
403 
404 	FBT_COUNTER(id, fbt_entry);
405 
406 	if (FBT_IS_SAVE(first)) {
407 		*tinstr++ = first;
408 	} else {
409 		*tinstr++ = FBT_SAVEIMM(FBT_REG_O6, -SA(MINFRAME), FBT_REG_O6);
410 	}
411 
412 	if (id > (uint32_t)FBT_SIMM13_MAX) {
413 		*tinstr++ = FBT_SETHI(id, FBT_REG_O0);
414 		*tinstr++ = FBT_ORLO(FBT_REG_O0, id, FBT_REG_O0);
415 	} else {
416 		*tinstr++ = FBT_ORSIMM13(FBT_REG_G0, id, FBT_REG_O0);
417 	}
418 
419 	if (nargs >= 1)
420 		*tinstr++ = FBT_MOV(FBT_REG_I0, FBT_REG_O1);
421 
422 	if (nargs >= 2)
423 		*tinstr++ = FBT_MOV(FBT_REG_I1, FBT_REG_O2);
424 
425 	if (nargs >= 3)
426 		*tinstr++ = FBT_MOV(FBT_REG_I2, FBT_REG_O3);
427 
428 	if (nargs >= 4)
429 		*tinstr++ = FBT_MOV(FBT_REG_I3, FBT_REG_O4);
430 
431 	if (nargs >= 5)
432 		*tinstr++ = FBT_MOV(FBT_REG_I4, FBT_REG_O5);
433 
434 	if (FBT_IS_SAVE(first)) {
435 		uintptr_t ret = (uintptr_t)instr - sizeof (uint32_t);
436 
437 		*tinstr++ = FBT_SETHI(ret, FBT_REG_G1);
438 		*tinstr = FBT_CALL((uintptr_t)tinstr - base + va, dtrace_probe);
439 		tinstr++;
440 		*tinstr++ = FBT_ORLO(FBT_REG_G1, ret, FBT_REG_O7);
441 	} else {
442 		uintptr_t slot = *--tinstr;
443 		uintptr_t ret = (uintptr_t)instr + sizeof (uint32_t);
444 		uint32_t delay = first;
445 
446 		*tinstr = FBT_CALL((uintptr_t)tinstr - base + va, dtrace_probe);
447 		tinstr++;
448 		*tinstr++ = slot;
449 		*tinstr++ = FBT_RESTORE(FBT_REG_G0, FBT_REG_G0, FBT_REG_G0);
450 
451 		if (FBT_IS_BA(first) || FBT_IS_BAPCC(first)) {
452 			/*
453 			 * This is a special case:  we are instrumenting a
454 			 * a non-annulled branch-always (or variant).  We'll
455 			 * return directly to the destination of the branch,
456 			 * copying the instruction in the delay slot here,
457 			 * and then executing it in the slot of a ba.
458 			 */
459 			if (FBT_IS_BA(first)) {
460 				ret = FBT_BDEST(instr, *instr);
461 			} else {
462 				ret = FBT_BPCCDEST(instr, *instr);
463 			}
464 
465 			delay = *(instr + 1);
466 		}
467 
468 		if ((first & FBT_OP_MASK) != FBT_OP0 ||
469 		    (first & FBT_FMT2_OP2_MASK) != FBT_FMT2_OP2_BPR) {
470 			*tinstr = FBT_BA((uintptr_t)tinstr - base + va, ret);
471 			tinstr++;
472 			*tinstr++ = delay;
473 		} else {
474 			/*
475 			 * If this is a branch-on-register, we have a little
476 			 * more work to do:  because the displacement is only
477 			 * sixteen bits, we're going to thunk the branch into
478 			 * the trampoline, and then ba,a to the appropriate
479 			 * destination in the branch targets.  That is, we're
480 			 * constructing this sequence in the trampoline:
481 			 *
482 			 *		br[cc]	%[rs], 1f
483 			 *		<delay-instruction>
484 			 *		ba,a	<not-taken-destination>
485 			 *	1:	ba,a	<taken-destination>
486 			 *
487 			 */
488 			uintptr_t targ = FBT_BPRDEST(instr, first);
489 
490 			*tinstr = first & ~(FBT_DISP16_MASK);
491 			*tinstr |= FBT_DISP14(tinstr, &tinstr[3]);
492 			tinstr++;
493 			*tinstr++ = *(instr + 1);
494 			*tinstr = FBT_BAA((uintptr_t)tinstr - base + va,
495 			    ret + sizeof (uint32_t));
496 			tinstr++;
497 			*tinstr = FBT_BAA((uintptr_t)tinstr - base + va, targ);
498 			tinstr++;
499 		}
500 	}
501 
502 	tramp->fbtt_va += (uintptr_t)tinstr - tramp->fbtt_next;
503 	tramp->fbtt_next = (uintptr_t)tinstr;
504 
505 	return (1);
506 }
507 
508 /*
509  * We are patching control-transfer/restore couplets.  There are three
510  * variants of couplet:
511  *
512  * (a)	return		rs1 + imm
513  *	delay
514  *
515  * (b)	jmpl		rs1 + (rs2 | offset), rd
516  *	restore		rs1, rs2 | imm, rd
517  *
518  * (c)	call		displacement
519  *	restore		rs1, rs2 | imm, rd
520  *
521  * If rs1 in (a) is anything other than %i7, or imm is anything other than 8,
522  * or delay is a DCTI, we fail.  If rd from the jmpl in (b) is something other
523  * than %g0 (a ret or a tail-call through a function pointer) or %o7 (a call
524  * through a register), we fail.
525  *
526  * Note that rs1 and rs2 in the restore instructions in (b) and (c) are
527  * potentially outputs and/or globals.  Because these registers cannot be
528  * relied upon across the call to dtrace_probe(), we move rs1 into an unused
529  * local, ls0, and rs2 into an unused local, ls1, and restructure the restore
530  * to be:
531  *
532  *	restore		ls0, ls1, rd
533  *
534  * Likewise, rs1 and rs2 in the jmpl of case (b) may be outputs and/or globals.
535  * If the jmpl uses outputs or globals, we restructure it to be:
536  *
537  * 	jmpl		ls2 + (ls3 | offset), (%g0 | %o7)
538  *
539  */
540 /*ARGSUSED*/
541 static int
542 fbt_canpatch_return(uint32_t *instr, int offset, const char *name)
543 {
544 	int rd;
545 
546 	if (FBT_FMT3_OP(*instr) == FBT_OP_RETURN) {
547 		uint32_t delay = *(instr + 1);
548 
549 		if (*instr != FBT_RETURN(FBT_REG_I7, 8)) {
550 			/*
551 			 * It's unclear if we should warn about this or not.
552 			 * We really wouldn't expect the compiler to generate
553 			 * return instructions with something other than %i7
554 			 * as rs1 and 8 as the simm13 -- it would just be
555 			 * mean-spirited.  That said, such a construct isn't
556 			 * necessarily incorrect.  Sill, we err on the side of
557 			 * caution and warn about it...
558 			 */
559 			cmn_err(CE_NOTE, "cannot instrument return of %s at "
560 			    "%p: non-canonical return instruction", name,
561 			    (void *)instr);
562 			return (0);
563 		}
564 
565 		if (FBT_IS_CTI(delay)) {
566 			/*
567 			 * This is even weirder -- a DCTI coupled with a
568 			 * return instruction.  Similar constructs are used to
569 			 * return from utraps, but these typically have the
570 			 * return in the slot -- and we wouldn't expect to see
571 			 * it in the kernel regardless.  At any rate, we don't
572 			 * want to try to instrument this construct, whatever
573 			 * it may be.
574 			 */
575 			cmn_err(CE_NOTE, "cannot instrument return of %s at "
576 			    "%p: CTI in delay slot of return instruction",
577 			    name, (void *)instr);
578 			return (0);
579 		}
580 
581 		if (FBT_IS_PCRELATIVE(delay)) {
582 			/*
583 			 * This is also very weird, but might be correct code
584 			 * if the function is (for example) returning the
585 			 * address of the delay instruction of the return as
586 			 * its return value (e.g. "rd %pc, %o0" in the slot).
587 			 * Perhaps correct, but still too weird to not warn
588 			 * about it...
589 			 */
590 			cmn_err(CE_NOTE, "cannot instrument return of %s at "
591 			    "%p: PC-relative instruction in delay slot of "
592 			    "return instruction", name, (void *)instr);
593 			return (0);
594 		}
595 
596 		return (1);
597 	}
598 
599 	if (FBT_FMT3_OP(*(instr + 1)) != FBT_OP_RESTORE)
600 		return (0);
601 
602 	if (FBT_FMT1_OP(*instr) == FBT_OP_CALL)
603 		return (1);
604 
605 	if (FBT_FMT3_OP(*instr) != FBT_OP_JMPL)
606 		return (0);
607 
608 	rd = FBT_FMT3_RD(*instr);
609 
610 	if (rd == FBT_REG_I7 || rd == FBT_REG_O7 || rd == FBT_REG_G0)
611 		return (1);
612 
613 	/*
614 	 * We have encountered a jmpl that is storing the calling %pc in
615 	 * some register besides %i7, %o7 or %g0.  This is strange; emit
616 	 * a warning and fail.
617 	 */
618 	cmn_err(CE_NOTE, "cannot instrument return of %s at %p: unexpected "
619 	    "jmpl destination register", name, (void *)instr);
620 	return (0);
621 }
622 
623 static int
624 fbt_canpatch_retl(uint32_t *instr, int offset, const char *name)
625 {
626 	if (FBT_FMT1_OP(*instr) == FBT_OP_CALL ||
627 	    (FBT_FMT3_OP(*instr) == FBT_OP_JMPL &&
628 	    FBT_FMT3_RD(*instr) == FBT_REG_O7)) {
629 		/*
630 		 * If this is a call (or a jmpl that links into %o7), we can
631 		 * patch it iff the next instruction uses %o7 as a destination
632 		 * register.  Because there is an ABI responsibility to
633 		 * restore %o7 to the value before the call/jmpl, we don't
634 		 * particularly care how this routine is managing to restore
635 		 * it (mov, add, ld or divx for all we care).  If it doesn't
636 		 * seem to be restoring it at all, however, we'll refuse
637 		 * to patch it.
638 		 */
639 		uint32_t delay = *(instr + 1);
640 		uint32_t op, rd;
641 
642 		op = FBT_FMT1_OP(delay);
643 		rd = FBT_FMT3_RD(delay);
644 
645 		if (op != FBT_OP2 || rd != FBT_REG_O7) {
646 			/*
647 			 * This is odd.  Before we assume that we're looking
648 			 * at something bizarre (and warn accordingly), we'll
649 			 * check to see if it's obviously a jump table entry.
650 			 */
651 			if (*instr < (uintptr_t)instr &&
652 			    *instr >= (uintptr_t)instr - offset)
653 				return (0);
654 
655 			cmn_err(CE_NOTE, "cannot instrument return of %s at "
656 			    "%p: leaf jmpl/call delay isn't restoring %%o7",
657 			    name, (void *)instr);
658 			return (0);
659 		}
660 
661 		return (1);
662 	}
663 
664 	if (offset == sizeof (uint32_t)) {
665 		/*
666 		 * If this is the second instruction in the function, we're
667 		 * going to allow it to be patched if the first instruction
668 		 * is a patchable return-from-leaf instruction.
669 		 */
670 		if (fbt_canpatch_retl(instr - 1, 0, name))
671 			return (1);
672 	}
673 
674 	if (FBT_FMT3_OP(*instr) != FBT_OP_JMPL)
675 		return (0);
676 
677 	if (FBT_FMT3_RD(*instr) != FBT_REG_G0)
678 		return (0);
679 
680 	return (1);
681 }
682 
683 /*ARGSUSED*/
684 static uint32_t
685 fbt_patch_return(uint32_t *instr, uint32_t *funcbase, uint32_t *funclim,
686     int offset, uint32_t id, fbt_trampoline_t *tramp, const char *name)
687 {
688 	uint32_t *tinstr = (uint32_t *)tramp->fbtt_next;
689 	uint32_t cti = *instr, restore = *(instr + 1), rs1, dest;
690 	uintptr_t va = tramp->fbtt_va;
691 	uintptr_t base = tramp->fbtt_next;
692 	uint32_t locals[FBT_REG_NLOCALS], local;
693 
694 	if (tramp->fbtt_next + FBT_RETENT_MAXSIZE > tramp->fbtt_limit) {
695 		/*
696 		 * There isn't sufficient room for this entry; return failure.
697 		 */
698 		return (FBT_ILLTRAP);
699 	}
700 
701 	FBT_COUNTER(id, fbt_ret);
702 
703 	if (FBT_FMT3_OP(*instr) == FBT_OP_RETURN) {
704 		/*
705 		 * To handle the case of the return instruction, we'll emit a
706 		 * restore, followed by the instruction in the slot (which
707 		 * we'll transplant here), and then another save.  While it
708 		 * may seem intellectually unsatisfying to emit the additional
709 		 * restore/save couplet, one can take solace in the fact that
710 		 * we don't do this if the instruction in the return delay
711 		 * slot is a nop -- which it is nearly 90% of the time with
712 		 * gcc.  (And besides, this couplet can't induce unnecessary
713 		 * spill/fill traps; rewriting the delay instruction to be
714 		 * in terms of the current window hardly seems worth the
715 		 * trouble -- let alone the risk.)
716 		 */
717 		uint32_t delay = *(instr + 1);
718 		ASSERT(*instr == FBT_RETURN(FBT_REG_I7, 8));
719 
720 		cti = FBT_RET;
721 		restore = FBT_RESTORE(FBT_REG_G0, FBT_REG_G0, FBT_REG_G0);
722 
723 		if (delay != FBT_SETHI(0, FBT_REG_G0)) {
724 			*tinstr++ = restore;
725 			*tinstr++ = delay;
726 			*tinstr++ = FBT_SAVEIMM(FBT_REG_O6,
727 			    -SA(MINFRAME), FBT_REG_O6);
728 		}
729 	}
730 
731 	FBT_REG_INITLOCALS(local, locals);
732 
733 	/*
734 	 * Mark the locals used in the jmpl.
735 	 */
736 	if (FBT_FMT3_OP(cti) == FBT_OP_JMPL) {
737 		uint32_t rs1 = FBT_FMT3_RS1(cti);
738 		FBT_REG_MARKLOCAL(locals, rs1);
739 
740 		if (!FBT_FMT3_ISIMM(cti)) {
741 			uint32_t rs2 = FBT_FMT3_RS2(cti);
742 			FBT_REG_MARKLOCAL(locals, rs2);
743 		}
744 	}
745 
746 	/*
747 	 * And mark the locals used in the restore.
748 	 */
749 	rs1 = FBT_FMT3_RS1(restore);
750 	FBT_REG_MARKLOCAL(locals, rs1);
751 
752 	if (!FBT_FMT3_ISIMM(restore)) {
753 		uint32_t rs2 = FBT_FMT3_RS2(restore);
754 		FBT_REG_MARKLOCAL(locals, rs2);
755 	}
756 
757 	if (FBT_FMT3_OP(cti) == FBT_OP_JMPL) {
758 		uint32_t rs1 = FBT_FMT3_RS1(cti);
759 
760 		if (FBT_REG_ISVOLATILE(rs1)) {
761 			FBT_REG_ALLOCLOCAL(local, locals);
762 			FBT_FMT3_RS1_SET(cti, local);
763 			*tinstr++ = FBT_MOV(rs1, local);
764 		}
765 
766 		if (!FBT_FMT3_ISIMM(cti)) {
767 			uint32_t rs2 = FBT_FMT3_RS2(cti);
768 
769 			if (FBT_REG_ISVOLATILE(rs2)) {
770 				FBT_REG_ALLOCLOCAL(local, locals);
771 				FBT_FMT3_RS2_SET(cti, local);
772 				*tinstr++ = FBT_MOV(rs2, local);
773 			}
774 		}
775 	}
776 
777 	rs1 = FBT_FMT3_RS1(restore);
778 
779 	if (FBT_REG_ISVOLATILE(rs1)) {
780 		FBT_REG_ALLOCLOCAL(local, locals);
781 		FBT_FMT3_RS1_SET(restore, local);
782 		*tinstr++ = FBT_MOV(rs1, local);
783 	}
784 
785 	if (!FBT_FMT3_ISIMM(restore)) {
786 		uint32_t rs2 = FBT_FMT3_RS2(restore);
787 
788 		if (FBT_REG_ISVOLATILE(rs2)) {
789 			FBT_REG_ALLOCLOCAL(local, locals);
790 			FBT_FMT3_RS2_SET(restore, local);
791 			*tinstr++ = FBT_MOV(rs2, local);
792 		}
793 	}
794 
795 	if (id > (uint32_t)FBT_SIMM13_MAX) {
796 		*tinstr++ = FBT_SETHI(id, FBT_REG_O0);
797 		*tinstr++ = FBT_ORLO(FBT_REG_O0, id, FBT_REG_O0);
798 	} else {
799 		*tinstr++ = FBT_ORSIMM13(FBT_REG_G0, id, FBT_REG_O0);
800 	}
801 
802 	if (offset > (uint32_t)FBT_SIMM13_MAX) {
803 		*tinstr++ = FBT_SETHI(offset, FBT_REG_O1);
804 		*tinstr++ = FBT_ORLO(FBT_REG_O1, offset, FBT_REG_O1);
805 	} else {
806 		*tinstr++ = FBT_ORSIMM13(FBT_REG_G0, offset, FBT_REG_O1);
807 	}
808 
809 	*tinstr = FBT_CALL((uintptr_t)tinstr - base + va, dtrace_probe);
810 	tinstr++;
811 
812 	if (FBT_FMT3_RD(restore) == FBT_REG_O0) {
813 		/*
814 		 * If the destination register of the restore is %o0, we
815 		 * need to perform the implied calculation to derive the
816 		 * return value.
817 		 */
818 		uint32_t add = (restore & ~FBT_FMT3_OP_MASK) | FBT_OP_ADD;
819 		add &= ~FBT_FMT3_RD_MASK;
820 		*tinstr++ = add | (FBT_REG_O2 << FBT_FMT3_RD_SHIFT);
821 	} else {
822 		*tinstr++ = FBT_MOV(FBT_REG_I0, FBT_REG_O2);
823 	}
824 
825 	/*
826 	 * If the control transfer instruction is %pc-relative (i.e. a
827 	 * call), we need to reset it appropriately.
828 	 */
829 	if (FBT_FMT1_OP(cti) == FBT_OP_CALL) {
830 		dest = (uintptr_t)instr + (FBT_FMT1_DISP30(cti) << 2);
831 		*tinstr = FBT_CALL((uintptr_t)tinstr - base + va, dest);
832 		tinstr++;
833 	} else {
834 		*tinstr++ = cti;
835 	}
836 
837 	*tinstr++ = restore;
838 	tramp->fbtt_va += (uintptr_t)tinstr - tramp->fbtt_next;
839 	tramp->fbtt_next = (uintptr_t)tinstr;
840 
841 	return (FBT_BAA(instr, va));
842 }
843 
844 static uint32_t
845 fbt_patch_retl(uint32_t *instr, uint32_t *funcbase, uint32_t *funclim,
846     int offset, uint32_t id, fbt_trampoline_t *tramp, const char *name)
847 {
848 	uint32_t *tinstr = (uint32_t *)tramp->fbtt_next;
849 	uintptr_t va = tramp->fbtt_va;
850 	uintptr_t base = tramp->fbtt_next;
851 	uint32_t cti = *instr, dest;
852 	int annul = 0;
853 
854 	FBT_COUNTER(id, fbt_retl);
855 
856 	if (tramp->fbtt_next + FBT_RETLENT_MAXSIZE > tramp->fbtt_limit) {
857 		/*
858 		 * There isn't sufficient room for this entry; return failure.
859 		 */
860 		return (FBT_ILLTRAP);
861 	}
862 
863 	if (offset == sizeof (uint32_t) &&
864 	    fbt_canpatch_retl(instr - 1, 0, name)) {
865 		*tinstr++ = *instr;
866 		annul = 1;
867 		FBT_COUNTER(id, fbt_retl_twoinstr);
868 	} else {
869 		if (FBT_FMT3_OP(cti) == FBT_OP_JMPL &&
870 		    FBT_FMT3_RD(cti) != FBT_REG_O7 &&
871 		    FBT_FMT3_RS1(cti) != FBT_REG_O7) {
872 			annul = 1;
873 			*tinstr++ = *(instr + 1);
874 		}
875 	}
876 
877 	*tinstr++ = FBT_SAVEIMM(FBT_REG_O6, -SA(MINFRAME), FBT_REG_O6);
878 
879 	if (FBT_FMT3_OP(cti) == FBT_OP_JMPL) {
880 		uint32_t rs1, rs2, o2i = FBT_REG_I0 - FBT_REG_O0;
881 
882 		/*
883 		 * If we have a jmpl and it's in terms of output registers, we
884 		 * need to rewrite it to be in terms of the corresponding input
885 		 * registers.  If it's in terms of the globals, we'll rewrite
886 		 * it to be in terms of locals.
887 		 */
888 		rs1 = FBT_FMT3_RS1(cti);
889 
890 		if (FBT_REG_ISOUTPUT(rs1))
891 			rs1 += o2i;
892 
893 		if (FBT_REG_ISGLOBAL(rs1)) {
894 			*tinstr++ = FBT_MOV(rs1, FBT_REG_L0);
895 			rs1 = FBT_REG_L0;
896 		}
897 
898 		FBT_FMT3_RS1_SET(cti, rs1);
899 
900 		if (!FBT_FMT3_ISIMM(cti)) {
901 			rs2 = FBT_FMT3_RS2(cti);
902 
903 			if (FBT_REG_ISOUTPUT(rs2))
904 				rs2 += o2i;
905 
906 			if (FBT_REG_ISGLOBAL(rs2)) {
907 				*tinstr++ = FBT_MOV(rs2, FBT_REG_L1);
908 				rs2 = FBT_REG_L1;
909 			}
910 
911 			FBT_FMT3_RS2_SET(cti, rs2);
912 		}
913 
914 		/*
915 		 * Now we need to check the rd and source register for the jmpl;
916 		 * If neither rd nor the source register is %o7, then we might
917 		 * have a jmp that is actually part of a jump table.  We need
918 		 * to generate the code to compare it to the base and limit of
919 		 * the function.
920 		 */
921 		if (FBT_FMT3_RD(cti) != FBT_REG_O7 && rs1 != FBT_REG_I7) {
922 			uintptr_t base = (uintptr_t)funcbase;
923 			uintptr_t limit = (uintptr_t)funclim;
924 
925 			FBT_COUNTER(id, fbt_retl_jmptab);
926 
927 			if (FBT_FMT3_ISIMM(cti)) {
928 				*tinstr++ = FBT_ADDSIMM13(rs1,
929 				    FBT_FMT3_SIMM13(cti), FBT_REG_L2);
930 			} else {
931 				*tinstr++ = FBT_ADD(rs1, rs2, FBT_REG_L2);
932 			}
933 
934 			*tinstr++ = FBT_SETHI(base, FBT_REG_L3);
935 			*tinstr++ = FBT_ORLO(FBT_REG_L3, base, FBT_REG_L3);
936 			*tinstr++ = FBT_CMP(FBT_REG_L2, FBT_REG_L3);
937 			*tinstr++ = FBT_BL(0, 8 * sizeof (uint32_t));
938 			*tinstr++ = FBT_SETHI(limit, FBT_REG_L3);
939 			*tinstr++ = FBT_ORLO(FBT_REG_L3, limit, FBT_REG_L3);
940 			*tinstr++ = FBT_CMP(FBT_REG_L2, FBT_REG_L3);
941 			*tinstr++ = FBT_BGE(0, 4 * sizeof (uint32_t));
942 			*tinstr++ = FBT_SETHI(0, FBT_REG_G0);
943 			*tinstr++ = cti;
944 			*tinstr++ = FBT_RESTORE(FBT_REG_G0,
945 			    FBT_REG_G0, FBT_REG_G0);
946 		}
947 	}
948 
949 	if (id > (uint32_t)FBT_SIMM13_MAX) {
950 		*tinstr++ = FBT_SETHI(id, FBT_REG_O0);
951 		*tinstr++ = FBT_ORLO(FBT_REG_O0, id, FBT_REG_O0);
952 	} else {
953 		*tinstr++ = FBT_ORSIMM13(FBT_REG_G0, id, FBT_REG_O0);
954 	}
955 
956 	if (offset > (uint32_t)FBT_SIMM13_MAX) {
957 		*tinstr++ = FBT_SETHI(offset, FBT_REG_O1);
958 		*tinstr++ = FBT_ORLO(FBT_REG_O1, offset, FBT_REG_O1);
959 	} else {
960 		*tinstr++ = FBT_ORSIMM13(FBT_REG_G0, offset, FBT_REG_O1);
961 	}
962 
963 	*tinstr = FBT_CALL((uintptr_t)tinstr - base + va, dtrace_probe);
964 	tinstr++;
965 	*tinstr++ = FBT_MOV(FBT_REG_I0, FBT_REG_O2);
966 
967 	/*
968 	 * If the control transfer instruction is %pc-relative (i.e. a
969 	 * call), we need to reset it appropriately.
970 	 */
971 	if (FBT_FMT1_OP(cti) == FBT_OP_CALL) {
972 		FBT_COUNTER(id, fbt_retl_tailcall);
973 		dest = (uintptr_t)instr + (FBT_FMT1_DISP30(cti) << 2);
974 		*tinstr = FBT_CALL((uintptr_t)tinstr - base + va, dest);
975 		tinstr++;
976 		annul = 1;
977 	} else {
978 		if (FBT_FMT3_OP(cti) == FBT_OP_JMPL) {
979 			*tinstr++ = cti;
980 
981 			if (FBT_FMT3_RD(cti) == FBT_REG_O7) {
982 				FBT_COUNTER(id, fbt_retl_tailjmpl);
983 				annul = 1;
984 			}
985 		} else {
986 			*tinstr++ = FBT_RET;
987 		}
988 	}
989 
990 	*tinstr++ = FBT_RESTORE(FBT_REG_G0, FBT_REG_G0, FBT_REG_G0);
991 
992 	tramp->fbtt_va += (uintptr_t)tinstr - tramp->fbtt_next;
993 	tramp->fbtt_next = (uintptr_t)tinstr;
994 
995 	return (annul ? FBT_BAA(instr, va) : FBT_BA(instr, va));
996 }
997 
998 /*ARGSUSED*/
999 static void
1000 fbt_provide_module(void *arg, struct modctl *ctl)
1001 {
1002 	struct module *mp = ctl->mod_mp;
1003 	char *modname = ctl->mod_modname;
1004 	char *str = mp->strings;
1005 	int nsyms = mp->nsyms;
1006 	Shdr *symhdr = mp->symhdr;
1007 	size_t symsize;
1008 	char *name;
1009 	int i;
1010 	fbt_probe_t *fbt, *retfbt;
1011 	fbt_trampoline_t tramp;
1012 	uintptr_t offset;
1013 	int primary = 0;
1014 	ctf_file_t *fp = NULL;
1015 	int error;
1016 	int estimate = 1;
1017 	uint32_t faketramp[50];
1018 	size_t fbt_size = 0;
1019 
1020 	/*
1021 	 * Employees of dtrace and their families are ineligible.  Void
1022 	 * where prohibited.
1023 	 */
1024 	if (strcmp(modname, "dtrace") == 0)
1025 		return;
1026 
1027 	if (ctl->mod_requisites != NULL) {
1028 		struct modctl_list *list;
1029 
1030 		list = (struct modctl_list *)ctl->mod_requisites;
1031 
1032 		for (; list != NULL; list = list->modl_next) {
1033 			if (strcmp(list->modl_modp->mod_modname, "dtrace") == 0)
1034 				return;
1035 		}
1036 	}
1037 
1038 	/*
1039 	 * KMDB is ineligible for instrumentation -- it may execute in
1040 	 * any context, including probe context.
1041 	 */
1042 	if (strcmp(modname, "kmdbmod") == 0)
1043 		return;
1044 
1045 	if (str == NULL || symhdr == NULL || symhdr->sh_addr == NULL) {
1046 		/*
1047 		 * If this module doesn't (yet) have its string or symbol
1048 		 * table allocated, clear out.
1049 		 */
1050 		return;
1051 	}
1052 
1053 	symsize = symhdr->sh_entsize;
1054 
1055 	if (mp->fbt_nentries) {
1056 		/*
1057 		 * This module has some FBT entries allocated; we're afraid
1058 		 * to screw with it.
1059 		 */
1060 		return;
1061 	}
1062 
1063 	if (mp->fbt_tab != NULL)
1064 		estimate = 0;
1065 
1066 	/*
1067 	 * This is a hack for unix/genunix/krtld.
1068 	 */
1069 	primary = vmem_contains(heap_arena, (void *)ctl,
1070 	    sizeof (struct modctl)) == 0;
1071 	kobj_textwin_alloc(mp);
1072 
1073 	/*
1074 	 * Open the CTF data for the module.  We'll use this to determine the
1075 	 * functions that can be instrumented.  Note that this call can fail,
1076 	 * in which case we'll use heuristics to determine the functions that
1077 	 * can be instrumented.  (But in particular, leaf functions will not be
1078 	 * instrumented.)
1079 	 */
1080 	fp = ctf_modopen(mp, &error);
1081 
1082 forreal:
1083 	if (!estimate) {
1084 		tramp.fbtt_next =
1085 		    (uintptr_t)fbt_trampoline_map((uintptr_t)mp->fbt_tab,
1086 		    mp->fbt_size);
1087 		tramp.fbtt_limit = tramp.fbtt_next + mp->fbt_size;
1088 		tramp.fbtt_va = (uintptr_t)mp->fbt_tab;
1089 	}
1090 
1091 	for (i = 1; i < nsyms; i++) {
1092 		ctf_funcinfo_t f;
1093 		uint32_t *instr, *base, *limit;
1094 		Sym *sym = (Sym *)(symhdr->sh_addr + i * symsize);
1095 		int have_ctf = 0, is_leaf = 0, nargs, cti = 0;
1096 		int (*canpatch)(uint32_t *, int, const char *);
1097 		uint32_t (*patch)(uint32_t *, uint32_t *, uint32_t *, int,
1098 		    uint32_t, fbt_trampoline_t *, const char *);
1099 
1100 		if (ELF_ST_TYPE(sym->st_info) != STT_FUNC)
1101 			continue;
1102 
1103 		/*
1104 		 * Weak symbols are not candidates.  This could be made to
1105 		 * work (where weak functions and their underlying function
1106 		 * appear as two disjoint probes), but it's not simple.
1107 		 */
1108 		if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
1109 			continue;
1110 
1111 		name = str + sym->st_name;
1112 
1113 		if (strstr(name, "dtrace_") == name &&
1114 		    strstr(name, "dtrace_safe_") != name) {
1115 			/*
1116 			 * Anything beginning with "dtrace_" may be called
1117 			 * from probe context unless it explitly indicates
1118 			 * that it won't be called from probe context by
1119 			 * using the prefix "dtrace_safe_".
1120 			 */
1121 			continue;
1122 		}
1123 
1124 		if (strstr(name, "kdi_") == name ||
1125 		    strstr(name, "_kdi_") != NULL) {
1126 			/*
1127 			 * Any function name beginning with "kdi_" or
1128 			 * containing the string "_kdi_" is a part of the
1129 			 * kernel debugger interface and may be called in
1130 			 * arbitrary context -- including probe context.
1131 			 */
1132 			continue;
1133 		}
1134 
1135 		if (strstr(name, "__relocatable") != NULL) {
1136 			/*
1137 			 * Anything with the string "__relocatable" anywhere
1138 			 * in the function name is considered to be a function
1139 			 * that may be manually relocated before execution.
1140 			 * Because FBT uses a PC-relative technique for
1141 			 * instrumentation, these functions cannot safely
1142 			 * be instrumented by us.
1143 			 */
1144 			continue;
1145 		}
1146 
1147 		if (strstr(name, "ip_ocsum") == name) {
1148 			/*
1149 			 * The ip_ocsum_* family of routines are all ABI
1150 			 * violators.  (They expect incoming arguments in the
1151 			 * globals!)  Break the ABI?  No soup for you!
1152 			 */
1153 			continue;
1154 		}
1155 
1156 		/*
1157 		 * We want to scan the function for one (and only one) save.
1158 		 * Any more indicates that something fancy is going on.
1159 		 */
1160 		base = (uint32_t *)sym->st_value;
1161 		limit = (uint32_t *)(sym->st_value + sym->st_size);
1162 
1163 		/*
1164 		 * We don't want to interpose on the module stubs.
1165 		 */
1166 		if (base >= (uint32_t *)stubs_base &&
1167 		    base <= (uint32_t *)stubs_end)
1168 			continue;
1169 
1170 		/*
1171 		 * We can't safely trace a zero-length function...
1172 		 */
1173 		if (base == limit)
1174 			continue;
1175 
1176 		/*
1177 		 * Due to 4524008, _init and _fini may have a bloated st_size.
1178 		 * While this bug was fixed quite some time ago, old drivers
1179 		 * may be lurking.  We need to develop a better solution to
1180 		 * this problem, such that correct _init and _fini functions
1181 		 * (the vast majority) may be correctly traced.  One solution
1182 		 * may be to scan through the entire symbol table to see if
1183 		 * any symbol overlaps with _init.  If none does, set a bit in
1184 		 * the module structure that this module has correct _init and
1185 		 * _fini sizes.  This will cause some pain the first time a
1186 		 * module is scanned, but at least it would be O(N) instead of
1187 		 * O(N log N)...
1188 		 */
1189 		if (strcmp(name, "_init") == 0)
1190 			continue;
1191 
1192 		if (strcmp(name, "_fini") == 0)
1193 			continue;
1194 
1195 		instr = base;
1196 
1197 		/*
1198 		 * While we try hard to only trace safe functions (that is,
1199 		 * functions at TL=0), one unsafe function manages to otherwise
1200 		 * appear safe:  prom_trap().  We could discover prom_trap()
1201 		 * if we added an additional rule:  in order to trace a
1202 		 * function, we must either (a) discover a restore or (b)
1203 		 * determine that the function does not have any unlinked
1204 		 * control transfers to another function (i.e., the function
1205 		 * never returns).  Unfortunately, as of this writing, one
1206 		 * legitimate function (resume_from_zombie()) transfers
1207 		 * control to a different function (_resume_from_idle())
1208 		 * without executing a restore.  Barring a rule to figure out
1209 		 * that resume_from_zombie() is safe while prom_trap() is not,
1210 		 * we resort to hard-coding prom_trap() here.
1211 		 */
1212 		if (strcmp(name, "prom_trap") == 0)
1213 			continue;
1214 
1215 		if (fp != NULL && ctf_func_info(fp, i, &f) != CTF_ERR) {
1216 			nargs = f.ctc_argc;
1217 			have_ctf = 1;
1218 		} else {
1219 			nargs = 32;
1220 		}
1221 
1222 		/*
1223 		 * If the first instruction of the function is a branch and
1224 		 * it's not a branch-always-not-annulled, we're going to refuse
1225 		 * to patch it.
1226 		 */
1227 		if ((*instr & FBT_OP_MASK) == FBT_OP0 &&
1228 		    (*instr & FBT_FMT2_OP2_MASK) != FBT_FMT2_OP2_SETHI &&
1229 		    (*instr & FBT_FMT2_OP2_MASK) != FBT_FMT2_OP2_BPR) {
1230 			if (!FBT_IS_BA(*instr) && !FBT_IS_BAPCC(*instr)) {
1231 				if (have_ctf) {
1232 					cmn_err(CE_NOTE, "cannot instrument %s:"
1233 					    " begins with non-ba, "
1234 					    "non-br CTI", name);
1235 				}
1236 				continue;
1237 			}
1238 		}
1239 
1240 		while (!FBT_IS_SAVE(*instr)) {
1241 			/*
1242 			 * Before we assume that this is a leaf routine, check
1243 			 * forward in the basic block for a save.
1244 			 */
1245 			int op = *instr & FBT_OP_MASK;
1246 			int op2 = *instr & FBT_FMT2_OP2_MASK;
1247 
1248 			if (op == FBT_OP0 && op2 != FBT_FMT2_OP2_SETHI) {
1249 				/*
1250 				 * This is a CTI.  If we see a subsequent
1251 				 * save, we will refuse to process this
1252 				 * routine unless both of the following are
1253 				 * true:
1254 				 *
1255 				 *  (a)	The branch is not annulled
1256 				 *
1257 				 *  (b)	The subsequent save is in the delay
1258 				 *	slot of the branch
1259 				 */
1260 				if ((*instr & FBT_ANNUL) ||
1261 				    !FBT_IS_SAVE(*(instr + 1))) {
1262 					cti = 1;
1263 				} else {
1264 					instr++;
1265 					break;
1266 				}
1267 			}
1268 
1269 			if (op == FBT_OP1)
1270 				cti = 1;
1271 
1272 			if (++instr == limit)
1273 				break;
1274 		}
1275 
1276 		if (instr < limit && cti) {
1277 			/*
1278 			 * If we found a CTI before the save, we need to not
1279 			 * do anything.  But if we have CTF information, this
1280 			 * is weird enough that it merits a message.
1281 			 */
1282 			if (!have_ctf)
1283 				continue;
1284 
1285 			cmn_err(CE_NOTE, "cannot instrument %s: "
1286 			    "save not in first basic block", name);
1287 			continue;
1288 		}
1289 
1290 		if (instr == limit) {
1291 			if (!have_ctf)
1292 				continue;
1293 			is_leaf = 1;
1294 
1295 			if (!estimate)
1296 				fbt_leaf_functions++;
1297 
1298 			canpatch = fbt_canpatch_retl;
1299 			patch = fbt_patch_retl;
1300 		} else {
1301 			canpatch = fbt_canpatch_return;
1302 			patch = fbt_patch_return;
1303 		}
1304 
1305 		if (!have_ctf && !is_leaf) {
1306 			/*
1307 			 * Before we assume that this isn't something tricky,
1308 			 * look for other saves.  If we find them, there are
1309 			 * multiple entry points here (or something), and we'll
1310 			 * leave it alone.
1311 			 */
1312 			while (++instr < limit) {
1313 				if (FBT_IS_SAVE(*instr))
1314 					break;
1315 			}
1316 
1317 			if (instr != limit)
1318 				continue;
1319 		}
1320 
1321 		instr = base;
1322 
1323 		if (FBT_IS_CTI(*instr)) {
1324 			/*
1325 			 * If we have a CTI, we want to be sure that we don't
1326 			 * have a CTI or a PC-relative instruction in the
1327 			 * delay slot -- we want to be able to thunk the
1328 			 * instruction into the trampoline without worrying
1329 			 * about either DCTIs or relocations.  It would be
1330 			 * very odd for the compiler to generate this kind of
1331 			 * code, so we warn about it if we have CTF
1332 			 * information.
1333 			 */
1334 			if (FBT_IS_CTI(*(instr + 1))) {
1335 				if (!have_ctf)
1336 					continue;
1337 
1338 				cmn_err(CE_NOTE, "cannot instrument %s: "
1339 				    "CTI in delay slot of first instruction",
1340 				    name);
1341 				continue;
1342 			}
1343 
1344 			if (FBT_IS_PCRELATIVE(*(instr + 1))) {
1345 				if (!have_ctf)
1346 					continue;
1347 
1348 				cmn_err(CE_NOTE, "cannot instrument %s: "
1349 				    "PC-relative instruction in delay slot of"
1350 				    " first instruction", name);
1351 				continue;
1352 			}
1353 		}
1354 
1355 		if (estimate) {
1356 			tramp.fbtt_next = (uintptr_t)faketramp;
1357 			tramp.fbtt_limit = tramp.fbtt_next + sizeof (faketramp);
1358 			(void) fbt_patch_entry(instr, FBT_ESTIMATE_ID,
1359 			    &tramp, nargs);
1360 			fbt_size += tramp.fbtt_next - (uintptr_t)faketramp;
1361 		} else {
1362 			fbt = kmem_zalloc(sizeof (fbt_probe_t), KM_SLEEP);
1363 			fbt->fbtp_name = name;
1364 			fbt->fbtp_ctl = ctl;
1365 			fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
1366 			    name, FBT_PROBENAME_ENTRY, 1, fbt);
1367 			fbt->fbtp_patchval = FBT_BAA(instr, tramp.fbtt_va);
1368 
1369 			if (!fbt_patch_entry(instr, fbt->fbtp_id,
1370 			    &tramp, nargs)) {
1371 				cmn_err(CE_WARN, "unexpectedly short FBT table "
1372 				    "in module %s (sym %d of %d)", modname,
1373 				    i, nsyms);
1374 				break;
1375 			}
1376 
1377 			fbt->fbtp_patchpoint =
1378 			    (uint32_t *)((uintptr_t)mp->textwin +
1379 			    ((uintptr_t)instr - (uintptr_t)mp->text));
1380 			fbt->fbtp_savedval = *instr;
1381 
1382 			fbt->fbtp_loadcnt = ctl->mod_loadcnt;
1383 			fbt->fbtp_primary = primary;
1384 			fbt->fbtp_symndx = i;
1385 			mp->fbt_nentries++;
1386 		}
1387 
1388 		retfbt = NULL;
1389 again:
1390 		if (++instr == limit)
1391 			continue;
1392 
1393 		offset = (uintptr_t)instr - (uintptr_t)base;
1394 
1395 		if (!(*canpatch)(instr, offset, name))
1396 			goto again;
1397 
1398 		if (estimate) {
1399 			tramp.fbtt_next = (uintptr_t)faketramp;
1400 			tramp.fbtt_limit = tramp.fbtt_next + sizeof (faketramp);
1401 			(void) (*patch)(instr, base, limit,
1402 			    offset, FBT_ESTIMATE_ID, &tramp, name);
1403 			fbt_size += tramp.fbtt_next - (uintptr_t)faketramp;
1404 
1405 			goto again;
1406 		}
1407 
1408 		fbt = kmem_zalloc(sizeof (fbt_probe_t), KM_SLEEP);
1409 		fbt->fbtp_name = name;
1410 		fbt->fbtp_ctl = ctl;
1411 
1412 		if (retfbt == NULL) {
1413 			fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
1414 			    name, FBT_PROBENAME_RETURN, 1, fbt);
1415 		} else {
1416 			retfbt->fbtp_next = fbt;
1417 			fbt->fbtp_id = retfbt->fbtp_id;
1418 		}
1419 
1420 		fbt->fbtp_return = 1;
1421 		retfbt = fbt;
1422 
1423 		if ((fbt->fbtp_patchval = (*patch)(instr, base, limit, offset,
1424 		    fbt->fbtp_id, &tramp, name)) == FBT_ILLTRAP) {
1425 			cmn_err(CE_WARN, "unexpectedly short FBT table "
1426 			    "in module %s (sym %d of %d)", modname, i, nsyms);
1427 			break;
1428 		}
1429 
1430 		fbt->fbtp_patchpoint = (uint32_t *)((uintptr_t)mp->textwin +
1431 		    ((uintptr_t)instr - (uintptr_t)mp->text));
1432 		fbt->fbtp_savedval = *instr;
1433 		fbt->fbtp_loadcnt = ctl->mod_loadcnt;
1434 		fbt->fbtp_primary = primary;
1435 		fbt->fbtp_symndx = i;
1436 		mp->fbt_nentries++;
1437 
1438 		goto again;
1439 	}
1440 
1441 	if (estimate) {
1442 		/*
1443 		 * Slosh on another entry's worth...
1444 		 */
1445 		fbt_size += FBT_ENT_MAXSIZE;
1446 		mp->fbt_size = fbt_size;
1447 		mp->fbt_tab = kobj_texthole_alloc(mp->text, fbt_size);
1448 
1449 		if (mp->fbt_tab == NULL) {
1450 			cmn_err(CE_WARN, "couldn't allocate FBT table "
1451 			    "for module %s", modname);
1452 		} else {
1453 			estimate = 0;
1454 			goto forreal;
1455 		}
1456 	} else {
1457 		fbt_trampoline_unmap();
1458 	}
1459 
1460 error:
1461 	if (fp != NULL)
1462 		ctf_close(fp);
1463 }
1464 
1465 /*ARGSUSED*/
1466 static void
1467 fbt_destroy(void *arg, dtrace_id_t id, void *parg)
1468 {
1469 	fbt_probe_t *fbt = parg, *next;
1470 	struct modctl *ctl = fbt->fbtp_ctl;
1471 
1472 	do {
1473 		if (ctl != NULL && ctl->mod_loadcnt == fbt->fbtp_loadcnt) {
1474 			if ((ctl->mod_loadcnt == fbt->fbtp_loadcnt &&
1475 			    ctl->mod_loaded) || fbt->fbtp_primary) {
1476 				((struct module *)
1477 				    (ctl->mod_mp))->fbt_nentries--;
1478 			}
1479 		}
1480 
1481 		next = fbt->fbtp_next;
1482 		kmem_free(fbt, sizeof (fbt_probe_t));
1483 		fbt = next;
1484 	} while (fbt != NULL);
1485 }
1486 
1487 /*ARGSUSED*/
1488 static void
1489 fbt_enable(void *arg, dtrace_id_t id, void *parg)
1490 {
1491 	fbt_probe_t *fbt = parg, *f;
1492 	struct modctl *ctl = fbt->fbtp_ctl;
1493 
1494 	ctl->mod_nenabled++;
1495 
1496 	for (f = fbt; f != NULL; f = f->fbtp_next) {
1497 		if (f->fbtp_patchpoint == NULL) {
1498 			/*
1499 			 * Due to a shortened FBT table, this entry was never
1500 			 * completed; refuse to enable it.
1501 			 */
1502 			if (fbt_verbose) {
1503 				cmn_err(CE_NOTE, "fbt is failing for probe %s "
1504 				    "(short FBT table in %s)",
1505 				    fbt->fbtp_name, ctl->mod_modname);
1506 			}
1507 
1508 			return;
1509 		}
1510 	}
1511 
1512 	/*
1513 	 * If this module has disappeared since we discovered its probes,
1514 	 * refuse to enable it.
1515 	 */
1516 	if (!fbt->fbtp_primary && !ctl->mod_loaded) {
1517 		if (fbt_verbose) {
1518 			cmn_err(CE_NOTE, "fbt is failing for probe %s "
1519 			    "(module %s unloaded)",
1520 			    fbt->fbtp_name, ctl->mod_modname);
1521 		}
1522 
1523 		return;
1524 	}
1525 
1526 	/*
1527 	 * Now check that our modctl has the expected load count.  If it
1528 	 * doesn't, this module must have been unloaded and reloaded -- and
1529 	 * we're not going to touch it.
1530 	 */
1531 	if (ctl->mod_loadcnt != fbt->fbtp_loadcnt) {
1532 		if (fbt_verbose) {
1533 			cmn_err(CE_NOTE, "fbt is failing for probe %s "
1534 			    "(module %s reloaded)",
1535 			    fbt->fbtp_name, ctl->mod_modname);
1536 		}
1537 
1538 		return;
1539 	}
1540 
1541 	for (; fbt != NULL; fbt = fbt->fbtp_next)
1542 		*fbt->fbtp_patchpoint = fbt->fbtp_patchval;
1543 }
1544 
1545 /*ARGSUSED*/
1546 static void
1547 fbt_disable(void *arg, dtrace_id_t id, void *parg)
1548 {
1549 	fbt_probe_t *fbt = parg, *f;
1550 	struct modctl *ctl = fbt->fbtp_ctl;
1551 
1552 	ASSERT(ctl->mod_nenabled > 0);
1553 	ctl->mod_nenabled--;
1554 
1555 	for (f = fbt; f != NULL; f = f->fbtp_next) {
1556 		if (f->fbtp_patchpoint == NULL)
1557 			return;
1558 	}
1559 
1560 	if ((!fbt->fbtp_primary && !ctl->mod_loaded) ||
1561 	    (ctl->mod_loadcnt != fbt->fbtp_loadcnt))
1562 		return;
1563 
1564 	for (; fbt != NULL; fbt = fbt->fbtp_next)
1565 		*fbt->fbtp_patchpoint = fbt->fbtp_savedval;
1566 }
1567 
1568 /*ARGSUSED*/
1569 static void
1570 fbt_suspend(void *arg, dtrace_id_t id, void *parg)
1571 {
1572 	fbt_probe_t *fbt = parg;
1573 	struct modctl *ctl = fbt->fbtp_ctl;
1574 
1575 	if (!fbt->fbtp_primary && !ctl->mod_loaded)
1576 		return;
1577 
1578 	if (ctl->mod_loadcnt != fbt->fbtp_loadcnt)
1579 		return;
1580 
1581 	ASSERT(ctl->mod_nenabled > 0);
1582 
1583 	for (; fbt != NULL; fbt = fbt->fbtp_next)
1584 		*fbt->fbtp_patchpoint = fbt->fbtp_savedval;
1585 }
1586 
1587 /*ARGSUSED*/
1588 static void
1589 fbt_resume(void *arg, dtrace_id_t id, void *parg)
1590 {
1591 	fbt_probe_t *fbt = parg;
1592 	struct modctl *ctl = fbt->fbtp_ctl;
1593 
1594 	if (!fbt->fbtp_primary && !ctl->mod_loaded)
1595 		return;
1596 
1597 	if (ctl->mod_loadcnt != fbt->fbtp_loadcnt)
1598 		return;
1599 
1600 	ASSERT(ctl->mod_nenabled > 0);
1601 
1602 	for (; fbt != NULL; fbt = fbt->fbtp_next)
1603 		*fbt->fbtp_patchpoint = fbt->fbtp_patchval;
1604 }
1605 
1606 /*ARGSUSED*/
1607 static void
1608 fbt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc)
1609 {
1610 	fbt_probe_t *fbt = parg;
1611 	struct modctl *ctl = fbt->fbtp_ctl;
1612 	struct module *mp = ctl->mod_mp;
1613 	ctf_file_t *fp = NULL, *pfp;
1614 	ctf_funcinfo_t f;
1615 	int error;
1616 	ctf_id_t argv[32], type;
1617 	int argc = sizeof (argv) / sizeof (ctf_id_t);
1618 	const char *parent;
1619 
1620 	if (!ctl->mod_loaded || (ctl->mod_loadcnt != fbt->fbtp_loadcnt))
1621 		goto err;
1622 
1623 	if (fbt->fbtp_return && desc->dtargd_ndx == 0) {
1624 		(void) strcpy(desc->dtargd_native, "int");
1625 		return;
1626 	}
1627 
1628 	if ((fp = ctf_modopen(mp, &error)) == NULL) {
1629 		/*
1630 		 * We have no CTF information for this module -- and therefore
1631 		 * no args[] information.
1632 		 */
1633 		goto err;
1634 	}
1635 
1636 	/*
1637 	 * If we have a parent container, we must manually import it.
1638 	 */
1639 	if ((parent = ctf_parent_name(fp)) != NULL) {
1640 		struct modctl *mod;
1641 
1642 		/*
1643 		 * We must iterate over all modules to find the module that
1644 		 * is our parent.
1645 		 */
1646 		for (mod = &modules; mod != NULL; mod = mod->mod_next) {
1647 			if (strcmp(mod->mod_filename, parent) == 0)
1648 				break;
1649 		}
1650 
1651 		if (mod == NULL)
1652 			goto err;
1653 
1654 		if ((pfp = ctf_modopen(mod->mod_mp, &error)) == NULL)
1655 			goto err;
1656 
1657 		if (ctf_import(fp, pfp) != 0) {
1658 			ctf_close(pfp);
1659 			goto err;
1660 		}
1661 
1662 		ctf_close(pfp);
1663 	}
1664 
1665 	if (ctf_func_info(fp, fbt->fbtp_symndx, &f) == CTF_ERR)
1666 		goto err;
1667 
1668 	if (fbt->fbtp_return) {
1669 		if (desc->dtargd_ndx > 1)
1670 			goto err;
1671 
1672 		ASSERT(desc->dtargd_ndx == 1);
1673 		type = f.ctc_return;
1674 	} else {
1675 		if (desc->dtargd_ndx + 1 > f.ctc_argc)
1676 			goto err;
1677 
1678 		if (ctf_func_args(fp, fbt->fbtp_symndx, argc, argv) == CTF_ERR)
1679 			goto err;
1680 
1681 		type = argv[desc->dtargd_ndx];
1682 	}
1683 
1684 	if (ctf_type_name(fp, type, desc->dtargd_native,
1685 	    DTRACE_ARGTYPELEN) != NULL) {
1686 		ctf_close(fp);
1687 		return;
1688 	}
1689 err:
1690 	if (fp != NULL)
1691 		ctf_close(fp);
1692 
1693 	desc->dtargd_ndx = DTRACE_ARGNONE;
1694 }
1695 
1696 static dtrace_pattr_t fbt_attr = {
1697 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_ISA },
1698 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
1699 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
1700 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_ISA },
1701 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
1702 };
1703 
1704 static dtrace_pops_t fbt_pops = {
1705 	NULL,
1706 	fbt_provide_module,
1707 	fbt_enable,
1708 	fbt_disable,
1709 	fbt_suspend,
1710 	fbt_resume,
1711 	fbt_getargdesc,
1712 	NULL,
1713 	NULL,
1714 	fbt_destroy
1715 };
1716 
1717 static int
1718 fbt_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
1719 {
1720 	switch (cmd) {
1721 	case DDI_ATTACH:
1722 		break;
1723 	case DDI_RESUME:
1724 		return (DDI_SUCCESS);
1725 	default:
1726 		return (DDI_FAILURE);
1727 	}
1728 
1729 	if (ddi_create_minor_node(devi, "fbt", S_IFCHR, 0,
1730 	    DDI_PSEUDO, NULL) == DDI_FAILURE ||
1731 	    dtrace_register("fbt", &fbt_attr, DTRACE_PRIV_KERNEL, 0,
1732 	    &fbt_pops, NULL, &fbt_id) != 0) {
1733 		ddi_remove_minor_node(devi, NULL);
1734 		return (DDI_FAILURE);
1735 	}
1736 
1737 	ddi_report_dev(devi);
1738 	fbt_devi = devi;
1739 	return (DDI_SUCCESS);
1740 }
1741 
1742 static int
1743 fbt_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
1744 {
1745 	switch (cmd) {
1746 	case DDI_DETACH:
1747 		break;
1748 	case DDI_SUSPEND:
1749 		return (DDI_SUCCESS);
1750 	default:
1751 		return (DDI_FAILURE);
1752 	}
1753 
1754 	if (dtrace_unregister(fbt_id) != 0)
1755 		return (DDI_FAILURE);
1756 
1757 	ddi_remove_minor_node(devi, NULL);
1758 	return (DDI_SUCCESS);
1759 }
1760 
1761 /*ARGSUSED*/
1762 static int
1763 fbt_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
1764 {
1765 	int error;
1766 
1767 	switch (infocmd) {
1768 	case DDI_INFO_DEVT2DEVINFO:
1769 		*result = (void *)fbt_devi;
1770 		error = DDI_SUCCESS;
1771 		break;
1772 	case DDI_INFO_DEVT2INSTANCE:
1773 		*result = (void *)0;
1774 		error = DDI_SUCCESS;
1775 		break;
1776 	default:
1777 		error = DDI_FAILURE;
1778 	}
1779 	return (error);
1780 }
1781 
1782 /*ARGSUSED*/
1783 static int
1784 fbt_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
1785 {
1786 	return (0);
1787 }
1788 
1789 static struct cb_ops fbt_cb_ops = {
1790 	fbt_open,		/* open */
1791 	nodev,			/* close */
1792 	nulldev,		/* strategy */
1793 	nulldev,		/* print */
1794 	nodev,			/* dump */
1795 	nodev,			/* read */
1796 	nodev,			/* write */
1797 	nodev,			/* ioctl */
1798 	nodev,			/* devmap */
1799 	nodev,			/* mmap */
1800 	nodev,			/* segmap */
1801 	nochpoll,		/* poll */
1802 	ddi_prop_op,		/* cb_prop_op */
1803 	0,			/* streamtab  */
1804 	D_NEW | D_MP		/* Driver compatibility flag */
1805 };
1806 
1807 static struct dev_ops fbt_ops = {
1808 	DEVO_REV,		/* devo_rev */
1809 	0,			/* refcnt */
1810 	fbt_info,		/* get_dev_info */
1811 	nulldev,		/* identify */
1812 	nulldev,		/* probe */
1813 	fbt_attach,		/* attach */
1814 	fbt_detach,		/* detach */
1815 	nodev,			/* reset */
1816 	&fbt_cb_ops,		/* driver operations */
1817 	NULL,			/* bus operations */
1818 	nodev			/* dev power */
1819 };
1820 
1821 /*
1822  * Module linkage information for the kernel.
1823  */
1824 static struct modldrv modldrv = {
1825 	&mod_driverops,		/* module type (this is a pseudo driver) */
1826 	"Function Boundary Tracing",	/* name of module */
1827 	&fbt_ops,		/* driver ops */
1828 };
1829 
1830 static struct modlinkage modlinkage = {
1831 	MODREV_1,
1832 	(void *)&modldrv,
1833 	NULL
1834 };
1835 
1836 int
1837 _init(void)
1838 {
1839 	return (mod_install(&modlinkage));
1840 }
1841 
1842 int
1843 _info(struct modinfo *modinfop)
1844 {
1845 	return (mod_info(&modlinkage, modinfop));
1846 }
1847 
1848 int
1849 _fini(void)
1850 {
1851 	return (mod_remove(&modlinkage));
1852 }
1853