xref: /illumos-gate/usr/src/uts/common/krtld/kobj_kdi.c (revision 2d6eb4a5e0a47d30189497241345dc5466bb68ab)
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 /*
22  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 /*
27  * The KDI is used to allow the kernel debugger to directly invoke various
28  * kernel functions.  In some cases, such as with kdi_mod_iter(), the
29  * debugger needs to execute functions that use the kernel's linker bindings.
30  * In other cases, the implementation of the KDI functions vary by platform
31  * and/or by CPU.  By embedding the implementation of these functions in
32  * the platmod/cpumod, we can avoid the need for platform-specific knowledge
33  * in the debugger, and can thus have a single debugger binary for all
34  * platforms.
35  *
36  * There are three classes of KDI function:
37  *
38  * 1. Normal - These are functions whose implementations are in the kernel for
39  *    convenience.  An example is the modctl iterator, kdi_mod_iter.  Using the
40  *    modules symbol, this function iterates through the kernel's modctl list,
41  *    invoking a debugger-provided callback for each one.  This function is in
42  *    the KDI because the debugger needs to be able to execute it in order to
43  *    enable symbol resolution.  Without symbol resolution, the debugger can't
44  *    locate the modules symbol.  A chicken-and-egg problem results.  We solve
45  *    this problem by locating the module iterator in the kernel, where run-time
46  *    linking solves the problem for us.
47  *
48  * 2. CPU-specific - Functions in this class have implementations that differ
49  *    by CPU.  For example, the crosscall delivery notification method differs
50  *    between Cheetah and Jalapeno, necessitating a different implementation for
51  *    each.  By locating the KDI implementation of these functions in the
52  *    cpumods, we automatically get the correct implementation, as krtld
53  *    automatically loads the correct cpumod when it starts.  The cpumods
54  *    directly fill in their portion of the kdi_t, using the mandatory
55  *    cpu_kdi_init cpumod entry point.
56  *
57  * 3. Platform-specific - Similar to the CPU-specific class, platform-specific
58  *    KDI functions have implementations that differ from platform to platform.
59  *    As such, the implementations live in the platmods.  Further
60  *    differentiating the platform-specific KDI functions from their
61  *    CPU-dependent brethren, many directly invoke PROM functions.  This poses
62  *    a problem, as the platmods use the kernel's promif functions, rather than
63  *    the lock-free kmdb versions.  We provide an interposition layer for these
64  *    platform-specific calls that disables the pre- and post-processing
65  *    functions used by the kernel to implement kernel-specific functionality
66  *    that must not be executed when kmdb has control of the machine.  Platmods
67  *    fill in a kdi_plat_t using their optional plat_kdi_init entry point.
68  *    krtld provides wrapper functions which suspend the necessary functions in
69  *    the promif layer before invoking the kdi_plat_t functions (if any).
70  */
71 
72 #include <sys/types.h>
73 #include <sys/systm.h>
74 #include <sys/reboot.h>
75 #include <sys/kdi_impl.h>
76 
77 #include <krtld/kobj_kdi.h>
78 
79 #define	KOBJ_KDI_MOD_IDLE	0
80 #define	KOBJ_KDI_MOD_CHANGING	1
81 #define	KOBJ_KDI_MOD_CHANGED	2
82 
83 static int kobj_kdi_mod_state = KOBJ_KDI_MOD_IDLE;
84 
85 extern int standalone;
86 
87 cons_polledio_t *
kobj_kdi_get_polled_io(void)88 kobj_kdi_get_polled_io(void)
89 {
90 	cons_polledio_t **polled_io = &cons_polledio;
91 
92 	return (polled_io == NULL ? NULL : *polled_io);
93 }
94 
95 int
kobj_kdi_mod_iter(int (* func)(struct modctl *,void *),void * arg)96 kobj_kdi_mod_iter(int (*func)(struct modctl *, void *), void *arg)
97 {
98 	int rc;
99 
100 	if (standalone) {
101 		struct modctl_list *lp, **lpp;
102 
103 		for (lpp = kobj_linkmaps; *lpp != NULL; lpp++) {
104 			for (lp = *lpp; lp != NULL; lp = lp->modl_next) {
105 				if ((rc = func(lp->modl_modp, arg)) != 0)
106 					return (rc);
107 			}
108 		}
109 
110 	} else {
111 		struct modctl *modp = &modules;
112 
113 		do {
114 			if ((rc = func(modp, arg)) != 0)
115 				return (rc);
116 		} while ((modp = modp->mod_next) != &modules);
117 	}
118 
119 	return (0);
120 }
121 
122 int
kobj_kdi_mod_isloaded(struct modctl * modp)123 kobj_kdi_mod_isloaded(struct modctl *modp)
124 {
125 	return (modp->mod_mp != NULL);
126 }
127 
128 int
kobj_kdi_mods_changed(void)129 kobj_kdi_mods_changed(void)
130 {
131 	int state;
132 
133 	if ((state = kobj_kdi_mod_state) == KOBJ_KDI_MOD_CHANGED)
134 		kobj_kdi_mod_state = KOBJ_KDI_MOD_IDLE;
135 
136 	return (state != KOBJ_KDI_MOD_IDLE);
137 }
138 
139 /*ARGSUSED1*/
140 void
kobj_kdi_mod_notify(uint_t why,struct modctl * what)141 kobj_kdi_mod_notify(uint_t why, struct modctl *what)
142 {
143 	switch (why) {
144 	case KOBJ_NOTIFY_MODLOADING:
145 		kobj_kdi_mod_state = KOBJ_KDI_MOD_CHANGING;
146 		break;
147 	case KOBJ_NOTIFY_MODLOADED:
148 		kobj_kdi_mod_state = KOBJ_KDI_MOD_CHANGED;
149 		if (boothowto & RB_DEBUG)
150 			kdi_dvec_mod_loaded(what);
151 		break;
152 	case KOBJ_NOTIFY_MODUNLOADING:
153 		kobj_kdi_mod_state = KOBJ_KDI_MOD_CHANGING;
154 		if (boothowto & RB_DEBUG)
155 			kdi_dvec_mod_unloading(what);
156 		break;
157 	case KOBJ_NOTIFY_MODUNLOADED:
158 		kobj_kdi_mod_state = KOBJ_KDI_MOD_CHANGED;
159 		break;
160 	}
161 }
162 
163 /*
164  * Compare two modctl and module snapshots, attempting to determine whether
165  * the module to which they both refer has changed between the time of the first
166  * and the time of the second.  We can't do a straight bcmp, because there are
167  * fields that change in the normal course of operations.  False positives
168  * aren't the end of the world, but it'd be nice to avoid flagging a module
169  * as changed every time someone holds or releases it.
170  */
171 int
kobj_kdi_mod_haschanged(struct modctl * mc1,struct module * mp1,struct modctl * mc2,struct module * mp2)172 kobj_kdi_mod_haschanged(struct modctl *mc1, struct module *mp1,
173     struct modctl *mc2, struct module *mp2)
174 {
175 	if (mc1->mod_loadcnt != mc2->mod_loadcnt || mc1->mod_mp != mc2->mod_mp)
176 		return (1);
177 
178 	if (mc1->mod_mp == NULL)
179 		return (0);
180 
181 	/* Take breath here. */
182 	return (bcmp(&mp1->hdr, &mp2->hdr, sizeof (mp1->hdr)) != 0 ||
183 	    mp1->symhdr != mp2->symhdr || mp1->strhdr != mp2->strhdr ||
184 	    mp1->text != mp2->text || mp1->bss != mp2->bss ||
185 	    mp1->ctfdata != mp2->ctfdata || mp1->ctfsize != mp2->ctfsize);
186 }
187 
188 void
kobj_kdi_system_claim(void)189 kobj_kdi_system_claim(void)
190 {
191 	kobj_kdi.kdi_plat_call(kobj_kdi.pkdi_system_claim);
192 	kobj_kdi.kdi_plat_call(kobj_kdi.pkdi_console_claim);
193 }
194 
195 void
kobj_kdi_system_release(void)196 kobj_kdi_system_release(void)
197 {
198 	kobj_kdi.kdi_plat_call(kobj_kdi.pkdi_console_release);
199 	kobj_kdi.kdi_plat_call(kobj_kdi.pkdi_system_release);
200 }
201 
202 void
kobj_kdi_init(void)203 kobj_kdi_init(void)
204 {
205 	static const char *const initializers[] = {
206 		"cpu_kdi_init", "mach_kdi_init", "plat_kdi_init", NULL
207 	};
208 
209 	Sym *sym;
210 	int i;
211 
212 	for (i = 0; initializers[i] != NULL; i++) {
213 		if ((sym = kobj_lookup_kernel(initializers[i])) != NULL)
214 			((void (*)(kdi_t *))sym->st_value)(&kobj_kdi);
215 	}
216 }
217 
218 kdi_t kobj_kdi = {
219 	KDI_VERSION,
220 	kobj_kdi_mods_changed,
221 	kobj_kdi_mod_iter,
222 	kobj_kdi_mod_isloaded,
223 	kobj_kdi_mod_haschanged,
224 	kobj_kdi_system_claim,
225 	kobj_kdi_system_release,
226 	kdi_pread,
227 	kdi_pwrite,
228 	kdi_flush_caches,
229 	kdi_range_is_nontoxic,
230 	kobj_kdi_get_polled_io,
231 	kdi_vtop,
232 	kdi_dtrace_get_state,
233 	kdi_dtrace_set,
234 	/*
235 	 * The rest are filled in by cpu_kdi_init, mach_kdi_init, and/or
236 	 * plat_kdi_init.
237 	 */
238 	NULL,			/* kdi_plat_call */
239 	NULL,			/* kdi_kmdb_enter */
240 	{ NULL },		/* kdi_arch */
241 	{ NULL }		/* kdi_plat */
242 };
243