1/*
2 * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
3 */
4
5/*
6 * This file is included up to twice from vdso2c.c.  It generates code for
7 * 32-bit and 64-bit vDSOs.  We will eventually need both for 64-bit builds,
8 * since 32-bit vDSOs will then be built for 32-bit userspace.
9 */
10
11static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
12			 void *stripped_addr, size_t stripped_len,
13			 FILE *outfile, const char *name)
14{
15	int found_load = 0;
16	unsigned long load_size = -1;  /* Work around bogus warning */
17	unsigned long mapping_size;
18	int i;
19	unsigned long j;
20	ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr;
21	ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr;
22	ELF(Dyn) *dyn = 0, *dyn_end = 0;
23	INT_BITS syms[NSYMS] = {};
24
25	ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_BE(&hdr->e_phoff));
26
27	/* Walk the segment table. */
28	for (i = 0; i < GET_BE(&hdr->e_phnum); i++) {
29		if (GET_BE(&pt[i].p_type) == PT_LOAD) {
30			if (found_load)
31				fail("multiple PT_LOAD segs\n");
32
33			if (GET_BE(&pt[i].p_offset) != 0 ||
34			    GET_BE(&pt[i].p_vaddr) != 0)
35				fail("PT_LOAD in wrong place\n");
36
37			if (GET_BE(&pt[i].p_memsz) != GET_BE(&pt[i].p_filesz))
38				fail("cannot handle memsz != filesz\n");
39
40			load_size = GET_BE(&pt[i].p_memsz);
41			found_load = 1;
42		} else if (GET_BE(&pt[i].p_type) == PT_DYNAMIC) {
43			dyn = raw_addr + GET_BE(&pt[i].p_offset);
44			dyn_end = raw_addr + GET_BE(&pt[i].p_offset) +
45				GET_BE(&pt[i].p_memsz);
46		}
47	}
48	if (!found_load)
49		fail("no PT_LOAD seg\n");
50
51	if (stripped_len < load_size)
52		fail("stripped input is too short\n");
53
54	/* Walk the dynamic table */
55	for (i = 0; dyn + i < dyn_end &&
56		     GET_BE(&dyn[i].d_tag) != DT_NULL; i++) {
57		typeof(dyn[i].d_tag) tag = GET_BE(&dyn[i].d_tag);
58		typeof(dyn[i].d_un.d_val) val = GET_BE(&dyn[i].d_un.d_val);
59
60		if ((tag == DT_RELSZ || tag == DT_RELASZ) && (val != 0))
61			fail("vdso image contains dynamic relocations\n");
62	}
63
64	/* Walk the section table */
65	for (i = 0; i < GET_BE(&hdr->e_shnum); i++) {
66		ELF(Shdr) *sh = raw_addr + GET_BE(&hdr->e_shoff) +
67			GET_BE(&hdr->e_shentsize) * i;
68		if (GET_BE(&sh->sh_type) == SHT_SYMTAB)
69			symtab_hdr = sh;
70	}
71
72	if (!symtab_hdr)
73		fail("no symbol table\n");
74
75	strtab_hdr = raw_addr + GET_BE(&hdr->e_shoff) +
76		GET_BE(&hdr->e_shentsize) * GET_BE(&symtab_hdr->sh_link);
77
78	/* Walk the symbol table */
79	for (i = 0;
80	     i < GET_BE(&symtab_hdr->sh_size) / GET_BE(&symtab_hdr->sh_entsize);
81	     i++) {
82		int k;
83
84		ELF(Sym) *sym = raw_addr + GET_BE(&symtab_hdr->sh_offset) +
85			GET_BE(&symtab_hdr->sh_entsize) * i;
86		const char *name = raw_addr + GET_BE(&strtab_hdr->sh_offset) +
87			GET_BE(&sym->st_name);
88
89		for (k = 0; k < NSYMS; k++) {
90			if (!strcmp(name, required_syms[k].name)) {
91				if (syms[k]) {
92					fail("duplicate symbol %s\n",
93					     required_syms[k].name);
94				}
95
96				/*
97				 * Careful: we use negative addresses, but
98				 * st_value is unsigned, so we rely
99				 * on syms[k] being a signed type of the
100				 * correct width.
101				 */
102				syms[k] = GET_BE(&sym->st_value);
103			}
104		}
105	}
106
107	/* Validate mapping addresses. */
108	if (syms[sym_vvar_start] % 8192)
109		fail("vvar_begin must be a multiple of 8192\n");
110
111	if (!name) {
112		fwrite(stripped_addr, stripped_len, 1, outfile);
113		return;
114	}
115
116	mapping_size = (stripped_len + 8191) / 8192 * 8192;
117
118	fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n");
119	fprintf(outfile, "#include <linux/cache.h>\n");
120	fprintf(outfile, "#include <asm/vdso.h>\n");
121	fprintf(outfile, "\n");
122	fprintf(outfile,
123		"static unsigned char raw_data[%lu] __ro_after_init __aligned(8192)= {",
124		mapping_size);
125	for (j = 0; j < stripped_len; j++) {
126		if (j % 10 == 0)
127			fprintf(outfile, "\n\t");
128		fprintf(outfile, "0x%02X, ",
129			(int)((unsigned char *)stripped_addr)[j]);
130	}
131	fprintf(outfile, "\n};\n\n");
132
133	fprintf(outfile, "const struct vdso_image %s_builtin = {\n", name);
134	fprintf(outfile, "\t.data = raw_data,\n");
135	fprintf(outfile, "\t.size = %lu,\n", mapping_size);
136	for (i = 0; i < NSYMS; i++) {
137		if (required_syms[i].export && syms[i])
138			fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
139				required_syms[i].name, (int64_t)syms[i]);
140	}
141	fprintf(outfile, "};\n");
142}
143