xref: /freebsd/sys/cddl/dev/fbt/aarch64/fbt_isa.c (revision 3332f1b444d4a73238e9f59cca27bfc95fe936bd)
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 (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  *
21  * Portions Copyright 2006-2008 John Birrell jb@freebsd.org
22  * Portions Copyright 2013 Justin Hibbits jhibbits@freebsd.org
23  * Portions Copyright 2013 Howard Su howardsu@freebsd.org
24  * Portions Copyright 2015 Ruslan Bukin <br@bsdpad.com>
25  *
26  * $FreeBSD$
27  */
28 
29 /*
30  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
31  * Use is subject to license terms.
32  */
33 
34 #include <sys/cdefs.h>
35 #include <sys/param.h>
36 
37 #include <sys/dtrace.h>
38 
39 #include "fbt.h"
40 
41 #define	AARCH64_BRK		0xd4200000
42 #define	AARCH64_BRK_IMM16_SHIFT	5
43 #define	AARCH64_BRK_IMM16_VAL	(0x40d << AARCH64_BRK_IMM16_SHIFT)
44 #define	FBT_PATCHVAL		(AARCH64_BRK | AARCH64_BRK_IMM16_VAL)
45 #define	FBT_ENTRY	"entry"
46 #define	FBT_RETURN	"return"
47 #define	FBT_AFRAMES	4
48 
49 int
50 fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
51 {
52 	solaris_cpu_t *cpu;
53 	fbt_probe_t *fbt;
54 
55 	cpu = &solaris_cpu[curcpu];
56 	fbt = fbt_probetab[FBT_ADDR2NDX(addr)];
57 
58 	for (; fbt != NULL; fbt = fbt->fbtp_hashnext) {
59 		if ((uintptr_t)fbt->fbtp_patchpoint == addr) {
60 			cpu->cpu_dtrace_caller = addr;
61 
62 			dtrace_probe(fbt->fbtp_id, frame->tf_x[0],
63 			    frame->tf_x[1], frame->tf_x[2],
64 			    frame->tf_x[3], frame->tf_x[4]);
65 
66 			cpu->cpu_dtrace_caller = 0;
67 			return (fbt->fbtp_savedval);
68 		}
69 	}
70 
71 	return (0);
72 }
73 
74 void
75 fbt_patch_tracepoint(fbt_probe_t *fbt, fbt_patchval_t val)
76 {
77 	vm_offset_t addr;
78 
79 	if (!arm64_get_writable_addr((vm_offset_t)fbt->fbtp_patchpoint, &addr))
80 		panic("%s: Unable to write new instruction", __func__);
81 
82 	*(fbt_patchval_t *)addr = val;
83 	cpu_icache_sync_range((vm_offset_t)fbt->fbtp_patchpoint, 4);
84 }
85 
86 int
87 fbt_provide_module_function(linker_file_t lf, int symindx,
88     linker_symval_t *symval, void *opaque)
89 {
90 	fbt_probe_t *fbt, *retfbt;
91 	uint32_t *target, *start;
92 	uint32_t *instr, *limit;
93 	const char *name;
94 	char *modname;
95 	bool found;
96 	int offs;
97 
98 	modname = opaque;
99 	name = symval->name;
100 
101 	/* Check if function is excluded from instrumentation */
102 	if (fbt_excluded(name))
103 		return (0);
104 
105 	/*
106 	 * Instrumenting certain exception handling functions can lead to FBT
107 	 * recursion, so exclude from instrumentation.
108 	 */
109 	 if (strcmp(name, "handle_el1h_sync") == 0 ||
110 	    strcmp(name, "do_el1h_sync") == 0)
111 		return (1);
112 
113 	instr = (uint32_t *)(symval->value);
114 	limit = (uint32_t *)(symval->value + symval->size);
115 
116 	/* Look for stp (pre-indexed) operation */
117 	found = false;
118 	/*
119 	 * If the first instruction is a nop it's a specially marked
120 	 * asm function. We only support a nop first as it's not a normal
121 	 * part of the function prologue.
122 	 */
123 	if (*instr == NOP_INSTR)
124 		found = true;
125 	if (!found) {
126 		for (; instr < limit; instr++) {
127 			/*
128 			 * Some functions start with
129 			 * "stp xt1, xt2, [xn, <const>]!"
130 			 */
131 			if ((*instr & LDP_STP_MASK) == STP_64) {
132 				/*
133 				 * Assume any other store of this type means we
134 				 * are past the function prolog.
135 				 */
136 				if (((*instr >> ADDR_SHIFT) & ADDR_MASK) == 31)
137 					found = true;
138 				break;
139 			}
140 
141 			/*
142 			 * Some functions start with a "sub sp, sp, <const>"
143 			 * Sometimes the compiler will have a sub instruction
144 			 * that is not of the above type so don't stop if we
145 			 * see one.
146 			 */
147 			if ((*instr & SUB_MASK) == SUB_INSTR &&
148 			    ((*instr >> SUB_RD_SHIFT) & SUB_R_MASK) == 31 &&
149 			    ((*instr >> SUB_RN_SHIFT) & SUB_R_MASK) == 31) {
150 				found = true;
151 				break;
152 			}
153 		}
154 	}
155 
156 	if (!found)
157 		return (0);
158 
159 	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
160 	fbt->fbtp_name = name;
161 	fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
162 	    name, FBT_ENTRY, FBT_AFRAMES, fbt);
163 	fbt->fbtp_patchpoint = instr;
164 	fbt->fbtp_ctl = lf;
165 	fbt->fbtp_loadcnt = lf->loadcnt;
166 	fbt->fbtp_savedval = *instr;
167 	fbt->fbtp_patchval = FBT_PATCHVAL;
168 	if ((*instr & SUB_MASK) == SUB_INSTR)
169 		fbt->fbtp_rval = DTRACE_INVOP_SUB;
170 	else
171 		fbt->fbtp_rval = DTRACE_INVOP_STP;
172 	fbt->fbtp_symindx = symindx;
173 
174 	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
175 	fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;
176 
177 	lf->fbt_nentries++;
178 
179 	retfbt = NULL;
180 again:
181 	for (; instr < limit; instr++) {
182 		if (*instr == RET_INSTR)
183 			break;
184 		else if ((*instr & B_MASK) == B_INSTR) {
185 			offs = (*instr & B_DATA_MASK);
186 			offs *= 4;
187 			target = (instr + offs);
188 			start = (uint32_t *)symval->value;
189 			if (target >= limit || target < start)
190 				break;
191 		}
192 	}
193 
194 	if (instr >= limit)
195 		return (0);
196 
197 	/*
198 	 * We have a winner!
199 	 */
200 	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
201 	fbt->fbtp_name = name;
202 	if (retfbt == NULL) {
203 		fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
204 		    name, FBT_RETURN, FBT_AFRAMES, fbt);
205 	} else {
206 		retfbt->fbtp_probenext = fbt;
207 		fbt->fbtp_id = retfbt->fbtp_id;
208 	}
209 	retfbt = fbt;
210 
211 	fbt->fbtp_patchpoint = instr;
212 	fbt->fbtp_ctl = lf;
213 	fbt->fbtp_loadcnt = lf->loadcnt;
214 	fbt->fbtp_symindx = symindx;
215 	if ((*instr & B_MASK) == B_INSTR)
216 		fbt->fbtp_rval = DTRACE_INVOP_B;
217 	else
218 		fbt->fbtp_rval = DTRACE_INVOP_RET;
219 	fbt->fbtp_savedval = *instr;
220 	fbt->fbtp_patchval = FBT_PATCHVAL;
221 	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
222 	fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;
223 
224 	lf->fbt_nentries++;
225 
226 	instr++;
227 	goto again;
228 }
229