1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * tools/testing/selftests/kvm/lib/elf.c
4 *
5 * Copyright (C) 2018, Google LLC.
6 */
7
8#include "test_util.h"
9
10#include <bits/endian.h>
11#include <linux/elf.h>
12
13#include "kvm_util.h"
14
15static void elfhdr_get(const char *filename, Elf64_Ehdr *hdrp)
16{
17	off_t offset_rv;
18
19	/* Open the ELF file. */
20	int fd;
21	fd = open(filename, O_RDONLY);
22	TEST_ASSERT(fd >= 0, "Failed to open ELF file,\n"
23		"  filename: %s\n"
24		"  rv: %i errno: %i", filename, fd, errno);
25
26	/* Read in and validate ELF Identification Record.
27	 * The ELF Identification record is the first 16 (EI_NIDENT) bytes
28	 * of the ELF header, which is at the beginning of the ELF file.
29	 * For now it is only safe to read the first EI_NIDENT bytes.  Once
30	 * read and validated, the value of e_ehsize can be used to determine
31	 * the real size of the ELF header.
32	 */
33	unsigned char ident[EI_NIDENT];
34	test_read(fd, ident, sizeof(ident));
35	TEST_ASSERT((ident[EI_MAG0] == ELFMAG0) && (ident[EI_MAG1] == ELFMAG1)
36		&& (ident[EI_MAG2] == ELFMAG2) && (ident[EI_MAG3] == ELFMAG3),
37		"ELF MAGIC Mismatch,\n"
38		"  filename: %s\n"
39		"  ident[EI_MAG0 - EI_MAG3]: %02x %02x %02x %02x\n"
40		"  Expected: %02x %02x %02x %02x",
41		filename,
42		ident[EI_MAG0], ident[EI_MAG1], ident[EI_MAG2], ident[EI_MAG3],
43		ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3);
44	TEST_ASSERT(ident[EI_CLASS] == ELFCLASS64,
45		"Current implementation only able to handle ELFCLASS64,\n"
46		"  filename: %s\n"
47		"  ident[EI_CLASS]: %02x\n"
48		"  expected: %02x",
49		filename,
50		ident[EI_CLASS], ELFCLASS64);
51	TEST_ASSERT(((BYTE_ORDER == LITTLE_ENDIAN)
52			&& (ident[EI_DATA] == ELFDATA2LSB))
53		|| ((BYTE_ORDER == BIG_ENDIAN)
54			&& (ident[EI_DATA] == ELFDATA2MSB)), "Current "
55		"implementation only able to handle\n"
56		"cases where the host and ELF file endianness\n"
57		"is the same:\n"
58		"  host BYTE_ORDER: %u\n"
59		"  host LITTLE_ENDIAN: %u\n"
60		"  host BIG_ENDIAN: %u\n"
61		"  ident[EI_DATA]: %u\n"
62		"  ELFDATA2LSB: %u\n"
63		"  ELFDATA2MSB: %u",
64		BYTE_ORDER, LITTLE_ENDIAN, BIG_ENDIAN,
65		ident[EI_DATA], ELFDATA2LSB, ELFDATA2MSB);
66	TEST_ASSERT(ident[EI_VERSION] == EV_CURRENT,
67		"Current implementation only able to handle current "
68		"ELF version,\n"
69		"  filename: %s\n"
70		"  ident[EI_VERSION]: %02x\n"
71		"  expected: %02x",
72		filename, ident[EI_VERSION], EV_CURRENT);
73
74	/* Read in the ELF header.
75	 * With the ELF Identification portion of the ELF header
76	 * validated, especially that the value at EI_VERSION is
77	 * as expected, it is now safe to read the entire ELF header.
78	 */
79	offset_rv = lseek(fd, 0, SEEK_SET);
80	TEST_ASSERT(offset_rv == 0, "Seek to ELF header failed,\n"
81		"  rv: %zi expected: %i", offset_rv, 0);
82	test_read(fd, hdrp, sizeof(*hdrp));
83	TEST_ASSERT(hdrp->e_phentsize == sizeof(Elf64_Phdr),
84		"Unexpected physical header size,\n"
85		"  hdrp->e_phentsize: %x\n"
86		"  expected: %zx",
87		hdrp->e_phentsize, sizeof(Elf64_Phdr));
88	TEST_ASSERT(hdrp->e_shentsize == sizeof(Elf64_Shdr),
89		"Unexpected section header size,\n"
90		"  hdrp->e_shentsize: %x\n"
91		"  expected: %zx",
92		hdrp->e_shentsize, sizeof(Elf64_Shdr));
93	close(fd);
94}
95
96/* VM ELF Load
97 *
98 * Input Args:
99 *   filename - Path to ELF file
100 *
101 * Output Args: None
102 *
103 * Input/Output Args:
104 *   vm - Pointer to opaque type that describes the VM.
105 *
106 * Return: None, TEST_ASSERT failures for all error conditions
107 *
108 * Loads the program image of the ELF file specified by filename,
109 * into the virtual address space of the VM pointed to by vm.  On entry
110 * the VM needs to not be using any of the virtual address space used
111 * by the image and it needs to have sufficient available physical pages, to
112 * back the virtual pages used to load the image.
113 */
114void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename)
115{
116	off_t offset, offset_rv;
117	Elf64_Ehdr hdr;
118
119	/* Open the ELF file. */
120	int fd;
121	fd = open(filename, O_RDONLY);
122	TEST_ASSERT(fd >= 0, "Failed to open ELF file,\n"
123		"  filename: %s\n"
124		"  rv: %i errno: %i", filename, fd, errno);
125
126	/* Read in the ELF header. */
127	elfhdr_get(filename, &hdr);
128
129	/* For each program header.
130	 * The following ELF header members specify the location
131	 * and size of the program headers:
132	 *
133	 *   e_phoff - File offset to start of program headers
134	 *   e_phentsize - Size of each program header
135	 *   e_phnum - Number of program header entries
136	 */
137	for (unsigned int n1 = 0; n1 < hdr.e_phnum; n1++) {
138		/* Seek to the beginning of the program header. */
139		offset = hdr.e_phoff + (n1 * hdr.e_phentsize);
140		offset_rv = lseek(fd, offset, SEEK_SET);
141		TEST_ASSERT(offset_rv == offset,
142			"Failed to seek to beginning of program header %u,\n"
143			"  filename: %s\n"
144			"  rv: %jd errno: %i",
145			n1, filename, (intmax_t) offset_rv, errno);
146
147		/* Read in the program header. */
148		Elf64_Phdr phdr;
149		test_read(fd, &phdr, sizeof(phdr));
150
151		/* Skip if this header doesn't describe a loadable segment. */
152		if (phdr.p_type != PT_LOAD)
153			continue;
154
155		/* Allocate memory for this segment within the VM. */
156		TEST_ASSERT(phdr.p_memsz > 0, "Unexpected loadable segment "
157			"memsize of 0,\n"
158			"  phdr index: %u p_memsz: 0x%" PRIx64,
159			n1, (uint64_t) phdr.p_memsz);
160		vm_vaddr_t seg_vstart = align_down(phdr.p_vaddr, vm->page_size);
161		vm_vaddr_t seg_vend = phdr.p_vaddr + phdr.p_memsz - 1;
162		seg_vend |= vm->page_size - 1;
163		size_t seg_size = seg_vend - seg_vstart + 1;
164
165		vm_vaddr_t vaddr = __vm_vaddr_alloc(vm, seg_size, seg_vstart,
166						    MEM_REGION_CODE);
167		TEST_ASSERT(vaddr == seg_vstart, "Unable to allocate "
168			"virtual memory for segment at requested min addr,\n"
169			"  segment idx: %u\n"
170			"  seg_vstart: 0x%lx\n"
171			"  vaddr: 0x%lx",
172			n1, seg_vstart, vaddr);
173		memset(addr_gva2hva(vm, vaddr), 0, seg_size);
174		/* TODO(lhuemill): Set permissions of each memory segment
175		 * based on the least-significant 3 bits of phdr.p_flags.
176		 */
177
178		/* Load portion of initial state that is contained within
179		 * the ELF file.
180		 */
181		if (phdr.p_filesz) {
182			offset_rv = lseek(fd, phdr.p_offset, SEEK_SET);
183			TEST_ASSERT(offset_rv == phdr.p_offset,
184				"Seek to program segment offset failed,\n"
185				"  program header idx: %u errno: %i\n"
186				"  offset_rv: 0x%jx\n"
187				"  expected: 0x%jx",
188				n1, errno, (intmax_t) offset_rv,
189				(intmax_t) phdr.p_offset);
190			test_read(fd, addr_gva2hva(vm, phdr.p_vaddr),
191				phdr.p_filesz);
192		}
193	}
194	close(fd);
195}
196