xref: /freebsd/lib/libkvm/kvm_powerpc.c (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 2008, Juniper Networks, Inc.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the author nor the names of any co-contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #include <sys/cdefs.h>
32 #include <sys/param.h>
33 #include <sys/endian.h>
34 #include <sys/kerneldump.h>
35 #include <sys/mman.h>
36 
37 #include <elf.h>
38 #include <kvm.h>
39 #include <limits.h>
40 #include <stdlib.h>
41 #include <string.h>
42 
43 #include "kvm_private.h"
44 
45 struct vmstate {
46 	void		*map;
47 	size_t		mapsz;
48 	size_t		dmphdrsz;
49 	Elf32_Ehdr	*eh;
50 	Elf32_Phdr	*ph;
51 };
52 
53 static int
54 valid_elf_header(Elf32_Ehdr *eh)
55 {
56 
57 	if (!IS_ELF(*eh))
58 		return (0);
59 	if (eh->e_ident[EI_CLASS] != ELFCLASS32)
60 		return (0);
61 	if (eh->e_ident[EI_DATA] != ELFDATA2MSB)
62 		return (0);
63 	if (eh->e_ident[EI_VERSION] != EV_CURRENT)
64 		return (0);
65 	if (eh->e_ident[EI_OSABI] != ELFOSABI_STANDALONE)
66 		return (0);
67 	if (be16toh(eh->e_type) != ET_CORE)
68 		return (0);
69 	if (be16toh(eh->e_machine) != EM_PPC)
70 		return (0);
71 	/* Can't think of anything else to check... */
72 	return (1);
73 }
74 
75 static size_t
76 dump_header_size(struct kerneldumpheader *dh)
77 {
78 
79 	if (strcmp(dh->magic, KERNELDUMPMAGIC) != 0)
80 		return (0);
81 	if (strcmp(dh->architecture, "powerpc") != 0)
82 		return (0);
83 	/* That should do it... */
84 	return (sizeof(*dh));
85 }
86 
87 /*
88  * Map the ELF headers into the process' address space. We do this in two
89  * steps: first the ELF header itself and using that information the whole
90  * set of headers.
91  */
92 static int
93 powerpc_maphdrs(kvm_t *kd)
94 {
95 	struct vmstate *vm;
96 	size_t mapsz;
97 
98 	vm = kd->vmst;
99 
100 	vm->mapsz = sizeof(*vm->eh) + sizeof(struct kerneldumpheader);
101 	vm->map = mmap(NULL, vm->mapsz, PROT_READ, MAP_PRIVATE, kd->pmfd, 0);
102 	if (vm->map == MAP_FAILED) {
103 		_kvm_err(kd, kd->program, "cannot map corefile");
104 		return (-1);
105 	}
106 	vm->dmphdrsz = 0;
107 	vm->eh = vm->map;
108 	if (!valid_elf_header(vm->eh)) {
109 		/*
110 		 * Hmmm, no ELF header. Maybe we still have a dump header.
111 		 * This is normal when the core file wasn't created by
112 		 * savecore(8), but instead was dumped over TFTP. We can
113 		 * easily skip the dump header...
114 		 */
115 		vm->dmphdrsz = dump_header_size(vm->map);
116 		if (vm->dmphdrsz == 0)
117 			goto inval;
118 		vm->eh = (void *)((uintptr_t)vm->map + vm->dmphdrsz);
119 		if (!valid_elf_header(vm->eh))
120 			goto inval;
121 	}
122 	mapsz = be16toh(vm->eh->e_phentsize) * be16toh(vm->eh->e_phnum) +
123 	    be32toh(vm->eh->e_phoff);
124 	munmap(vm->map, vm->mapsz);
125 
126 	/* Map all headers. */
127 	vm->mapsz = vm->dmphdrsz + mapsz;
128 	vm->map = mmap(NULL, vm->mapsz, PROT_READ, MAP_PRIVATE, kd->pmfd, 0);
129 	if (vm->map == MAP_FAILED) {
130 		_kvm_err(kd, kd->program, "cannot map corefile headers");
131 		return (-1);
132 	}
133 	vm->eh = (void *)((uintptr_t)vm->map + vm->dmphdrsz);
134 	vm->ph = (void *)((uintptr_t)vm->eh + be32toh(vm->eh->e_phoff));
135 	return (0);
136 
137  inval:
138 	_kvm_err(kd, kd->program, "invalid corefile");
139 	return (-1);
140 }
141 
142 /*
143  * Determine the offset within the corefile corresponding the virtual
144  * address. Return the number of contiguous bytes in the corefile or
145  * 0 when the virtual address is invalid.
146  */
147 static size_t
148 powerpc_va2off(kvm_t *kd, kvaddr_t va, off_t *ofs)
149 {
150 	struct vmstate *vm = kd->vmst;
151 	Elf32_Phdr *ph;
152 	int nph;
153 
154 	ph = vm->ph;
155 	nph = be16toh(vm->eh->e_phnum);
156 	while (nph && (va < be32toh(ph->p_vaddr) ||
157 	    va >= be32toh(ph->p_vaddr) + be32toh(ph->p_memsz))) {
158 		nph--;
159 		ph = (void *)((uintptr_t)ph + be16toh(vm->eh->e_phentsize));
160 	}
161 	if (nph == 0)
162 		return (0);
163 
164 	/* Segment found. Return file offset and range. */
165 	*ofs = vm->dmphdrsz + be32toh(ph->p_offset) +
166 	    (va - be32toh(ph->p_vaddr));
167 	return (be32toh(ph->p_memsz) - (va - be32toh(ph->p_vaddr)));
168 }
169 
170 static void
171 _powerpc_freevtop(kvm_t *kd)
172 {
173 	struct vmstate *vm = kd->vmst;
174 
175 	if (vm->eh != MAP_FAILED)
176 		munmap(vm->eh, vm->mapsz);
177 	free(vm);
178 	kd->vmst = NULL;
179 }
180 
181 static int
182 _powerpc_probe(kvm_t *kd)
183 {
184 
185 	return (_kvm_probe_elf_kernel(kd, ELFCLASS32, EM_PPC) &&
186 	    kd->nlehdr.e_ident[EI_DATA] == ELFDATA2MSB);
187 }
188 
189 static int
190 _powerpc_initvtop(kvm_t *kd)
191 {
192 
193 	kd->vmst = (struct vmstate *)_kvm_malloc(kd, sizeof(*kd->vmst));
194 	if (kd->vmst == NULL)
195 		return (-1);
196 
197 	if (powerpc_maphdrs(kd) == -1)
198 		return (-1);
199 
200 	return (0);
201 }
202 
203 static int
204 _powerpc_kvatop(kvm_t *kd, kvaddr_t va, off_t *ofs)
205 {
206 	struct vmstate *vm;
207 
208 	vm = kd->vmst;
209 	if (be32toh(vm->ph->p_paddr) == 0xffffffff)
210 		return ((int)powerpc_va2off(kd, va, ofs));
211 
212 	_kvm_err(kd, kd->program, "Raw corefile not supported");
213 	return (0);
214 }
215 
216 static int
217 _powerpc_native(kvm_t *kd __unused)
218 {
219 
220 #if defined(__powerpc__) && !defined(__powerpc64__)
221 	return (1);
222 #else
223 	return (0);
224 #endif
225 }
226 
227 static struct kvm_arch kvm_powerpc = {
228 	.ka_probe = _powerpc_probe,
229 	.ka_initvtop = _powerpc_initvtop,
230 	.ka_freevtop = _powerpc_freevtop,
231 	.ka_kvatop = _powerpc_kvatop,
232 	.ka_native = _powerpc_native,
233 };
234 
235 KVM_ARCH(kvm_powerpc);
236