xref: /freebsd/sys/cddl/dev/fbt/aarch64/fbt_isa.c (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
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 			continue;
61 
62 		cpu->cpu_dtrace_caller = addr;
63 
64 		if (fbt->fbtp_roffset == 0) {
65 			dtrace_probe(fbt->fbtp_id, frame->tf_x[0],
66 			    frame->tf_x[1], frame->tf_x[2],
67 			    frame->tf_x[3], frame->tf_x[4]);
68 		} else {
69 			dtrace_probe(fbt->fbtp_id, fbt->fbtp_roffset, rval,
70 			    0, 0, 0);
71 		}
72 		cpu->cpu_dtrace_caller = 0;
73 		return (fbt->fbtp_savedval);
74 	}
75 
76 	return (0);
77 }
78 
79 void
80 fbt_patch_tracepoint(fbt_probe_t *fbt, fbt_patchval_t val)
81 {
82 	vm_offset_t addr;
83 
84 	if (!arm64_get_writable_addr((vm_offset_t)fbt->fbtp_patchpoint, &addr))
85 		panic("%s: Unable to write new instruction", __func__);
86 
87 	*(fbt_patchval_t *)addr = val;
88 	cpu_icache_sync_range((vm_offset_t)fbt->fbtp_patchpoint, 4);
89 }
90 
91 int
92 fbt_provide_module_function(linker_file_t lf, int symindx,
93     linker_symval_t *symval, void *opaque)
94 {
95 	fbt_probe_t *fbt, *retfbt;
96 	uint32_t *target, *start;
97 	uint32_t *instr, *limit;
98 	const char *name;
99 	char *modname;
100 	bool found;
101 	int offs;
102 
103 	modname = opaque;
104 	name = symval->name;
105 
106 	/* Check if function is excluded from instrumentation */
107 	if (fbt_excluded(name))
108 		return (0);
109 
110 	/*
111 	 * Instrumenting certain exception handling functions can lead to FBT
112 	 * recursion, so exclude from instrumentation.
113 	 */
114 	 if (strcmp(name, "handle_el1h_sync") == 0 ||
115 	    strcmp(name, "do_el1h_sync") == 0)
116 		return (1);
117 
118 	instr = (uint32_t *)(symval->value);
119 	limit = (uint32_t *)(symval->value + symval->size);
120 
121 	/* Look for stp (pre-indexed) operation */
122 	found = false;
123 	/*
124 	 * If the first instruction is a nop it's a specially marked
125 	 * asm function. We only support a nop first as it's not a normal
126 	 * part of the function prologue.
127 	 */
128 	if (*instr == NOP_INSTR)
129 		found = true;
130 	if (!found) {
131 		for (; instr < limit; instr++) {
132 			/*
133 			 * Some functions start with
134 			 * "stp xt1, xt2, [xn, <const>]!"
135 			 */
136 			if ((*instr & LDP_STP_MASK) == STP_64) {
137 				/*
138 				 * Assume any other store of this type means we
139 				 * are past the function prolog.
140 				 */
141 				if (((*instr >> ADDR_SHIFT) & ADDR_MASK) == 31)
142 					found = true;
143 				break;
144 			}
145 
146 			/*
147 			 * Some functions start with a "sub sp, sp, <const>"
148 			 * Sometimes the compiler will have a sub instruction
149 			 * that is not of the above type so don't stop if we
150 			 * see one.
151 			 */
152 			if ((*instr & SUB_MASK) == SUB_INSTR &&
153 			    ((*instr >> SUB_RD_SHIFT) & SUB_R_MASK) == 31 &&
154 			    ((*instr >> SUB_RN_SHIFT) & SUB_R_MASK) == 31) {
155 				found = true;
156 				break;
157 			}
158 		}
159 	}
160 
161 	if (!found)
162 		return (0);
163 
164 	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
165 	fbt->fbtp_name = name;
166 	fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
167 	    name, FBT_ENTRY, FBT_AFRAMES, fbt);
168 	fbt->fbtp_patchpoint = instr;
169 	fbt->fbtp_ctl = lf;
170 	fbt->fbtp_loadcnt = lf->loadcnt;
171 	fbt->fbtp_savedval = *instr;
172 	fbt->fbtp_patchval = FBT_PATCHVAL;
173 	if ((*instr & SUB_MASK) == SUB_INSTR)
174 		fbt->fbtp_rval = DTRACE_INVOP_SUB;
175 	else
176 		fbt->fbtp_rval = DTRACE_INVOP_STP;
177 	fbt->fbtp_symindx = symindx;
178 
179 	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
180 	fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;
181 
182 	lf->fbt_nentries++;
183 
184 	retfbt = NULL;
185 again:
186 	for (; instr < limit; instr++) {
187 		if (*instr == RET_INSTR)
188 			break;
189 		else if ((*instr & B_MASK) == B_INSTR) {
190 			offs = (*instr & B_DATA_MASK);
191 			offs *= 4;
192 			target = (instr + offs);
193 			start = (uint32_t *)symval->value;
194 			if (target >= limit || target < start)
195 				break;
196 		}
197 	}
198 
199 	if (instr >= limit)
200 		return (0);
201 
202 	/*
203 	 * We have a winner!
204 	 */
205 	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
206 	fbt->fbtp_name = name;
207 	if (retfbt == NULL) {
208 		fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
209 		    name, FBT_RETURN, FBT_AFRAMES, fbt);
210 	} else {
211 		retfbt->fbtp_probenext = fbt;
212 		fbt->fbtp_id = retfbt->fbtp_id;
213 	}
214 	retfbt = fbt;
215 
216 	fbt->fbtp_patchpoint = instr;
217 	fbt->fbtp_ctl = lf;
218 	fbt->fbtp_loadcnt = lf->loadcnt;
219 	fbt->fbtp_symindx = symindx;
220 	if ((*instr & B_MASK) == B_INSTR)
221 		fbt->fbtp_rval = DTRACE_INVOP_B;
222 	else
223 		fbt->fbtp_rval = DTRACE_INVOP_RET;
224 	fbt->fbtp_roffset = (uintptr_t)instr - (uintptr_t)symval->value;
225 	fbt->fbtp_savedval = *instr;
226 	fbt->fbtp_patchval = FBT_PATCHVAL;
227 	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
228 	fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;
229 
230 	lf->fbt_nentries++;
231 
232 	instr++;
233 	goto again;
234 }
235