summaryrefslogtreecommitdiffstats
path: root/arch/ppc64/kernel/vdso.c
blob: efa985f05aca2ebfe45be32ff4cd1e6b339ce1d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
/*
 *  linux/arch/ppc64/kernel/vdso.c
 *
 *    Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
 *			 <benh@kernel.crashing.org>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/security.h>
#include <linux/bootmem.h>

#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/machdep.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/vdso.h>

#undef DEBUG

#ifdef DEBUG
#define DBG(fmt...) printk(fmt)
#else
#define DBG(fmt...)
#endif


/*
 * The vDSOs themselves are here
 */
extern char vdso64_start, vdso64_end;
extern char vdso32_start, vdso32_end;

static void *vdso64_kbase = &vdso64_start;
static void *vdso32_kbase = &vdso32_start;

unsigned int vdso64_pages;
unsigned int vdso32_pages;

/* Signal trampolines user addresses */

unsigned long vdso64_rt_sigtramp;
unsigned long vdso32_sigtramp;
unsigned long vdso32_rt_sigtramp;

/* Format of the patch table */
struct vdso_patch_def
{
	u32		pvr_mask, pvr_value;
	const char	*gen_name;
	const char	*fix_name;
};

/* Table of functions to patch based on the CPU type/revision
 *
 * TODO: Improve by adding whole lists for each entry
 */
static struct vdso_patch_def vdso_patches[] = {
	{
		0xffff0000, 0x003a0000,		/* POWER5 */
		"__kernel_sync_dicache", "__kernel_sync_dicache_p5"
	},
	{
		0xffff0000, 0x003b0000,		/* POWER5 */
		"__kernel_sync_dicache", "__kernel_sync_dicache_p5"
	},
};

/*
 * Some infos carried around for each of them during parsing at
 * boot time.
 */
struct lib32_elfinfo
{
	Elf32_Ehdr	*hdr;		/* ptr to ELF */
	Elf32_Sym	*dynsym;	/* ptr to .dynsym section */
	unsigned long	dynsymsize;	/* size of .dynsym section */
	char		*dynstr;	/* ptr to .dynstr section */
	unsigned long	text;		/* offset of .text section in .so */
};

struct lib64_elfinfo
{
	Elf64_Ehdr	*hdr;
	Elf64_Sym	*dynsym;
	unsigned long	dynsymsize;
	char		*dynstr;
	unsigned long	text;
};


#ifdef __DEBUG
static void dump_one_vdso_page(struct page *pg, struct page *upg)
{
	printk("kpg: %p (c:%d,f:%08lx)", __va(page_to_pfn(pg) << PAGE_SHIFT),
	       page_count(pg),
	       pg->flags);
	if (upg/* && pg != upg*/) {
		printk(" upg: %p (c:%d,f:%08lx)", __va(page_to_pfn(upg) << PAGE_SHIFT),
		       page_count(upg),
		       upg->flags);
	}
	printk("\n");
}

static void dump_vdso_pages(struct vm_area_struct * vma)
{
	int i;

	if (!vma || test_thread_flag(TIF_32BIT)) {
		printk("vDSO32 @ %016lx:\n", (unsigned long)vdso32_kbase);
		for (i=0; i<vdso32_pages; i++) {
			struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
			struct page *upg = (vma && vma->vm_mm) ?
				follow_page(vma->vm_mm, vma->vm_start + i*PAGE_SIZE, 0)
				: NULL;
			dump_one_vdso_page(pg, upg);
		}
	}
	if (!vma || !test_thread_flag(TIF_32BIT)) {
		printk("vDSO64 @ %016lx:\n", (unsigned long)vdso64_kbase);
		for (i=0; i<vdso64_pages; i++) {
			struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
			struct page *upg = (vma && vma->vm_mm) ?
				follow_page(vma->vm_mm, vma->vm_start + i*PAGE_SIZE, 0)
				: NULL;
			dump_one_vdso_page(pg, upg);
		}
	}
}
#endif /* DEBUG */

/*
 * Keep a dummy vma_close for now, it will prevent VMA merging.
 */
static void vdso_vma_close(struct vm_area_struct * vma)
{
}

/*
 * Our nopage() function, maps in the actual vDSO kernel pages, they will
 * be mapped read-only by do_no_page(), and eventually COW'ed, either
 * right away for an initial write access, or by do_wp_page().
 */
static struct page * vdso_vma_nopage(struct vm_area_struct * vma,
				     unsigned long address, int *type)
{
	unsigned long offset = address - vma->vm_start;
	struct page *pg;
	void *vbase = test_thread_flag(TIF_32BIT) ? vdso32_kbase : vdso64_kbase;

	DBG("vdso_vma_nopage(current: %s, address: %016lx, off: %lx)\n",
	    current->comm, address, offset);

	if (address < vma->vm_start || address > vma->vm_end)
		return NOPAGE_SIGBUS;

	/*
	 * Last page is systemcfg, special handling here, no get_page() a
	 * this is a reserved page
	 */
	if ((vma->vm_end - address) <= PAGE_SIZE)
		return virt_to_page(systemcfg);

	pg = virt_to_page(vbase + offset);
	get_page(pg);
	DBG(" ->page count: %d\n", page_count(pg));

	return pg;
}

static struct vm_operations_struct vdso_vmops = {
	.close	= vdso_vma_close,
	.nopage	= vdso_vma_nopage,
};

/*
 * This is called from binfmt_elf, we create the special vma for the
 * vDSO and insert it into the mm struct tree
 */
int arch_setup_additional_pages(struct linux_binprm *bprm, int executable_stack)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long vdso_pages;
	unsigned long vdso_base;

	if (test_thread_flag(TIF_32BIT)) {
		vdso_pages = vdso32_pages;
		vdso_base = VDSO32_MBASE;
	} else {
		vdso_pages = vdso64_pages;
		vdso_base = VDSO64_MBASE;
	}

	current->thread.vdso_base = 0;

	/* vDSO has a problem and was disabled, just don't "enable" it for the
	 * process
	 */
	if (vdso_pages == 0)
		return 0;

	vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
	if (vma == NULL)
		return -ENOMEM;

	memset(vma, 0, sizeof(*vma));

	/*
	 * pick a base address for the vDSO in process space. We try to put it
	 * at vdso_base which is the "natural" base for it, but we might fail
	 * and end up putting it elsewhere.
	 */
	vdso_base = get_unmapped_area(NULL, vdso_base,
				      vdso_pages << PAGE_SHIFT, 0, 0);
	if (vdso_base & ~PAGE_MASK) {
		kmem_cache_free(vm_area_cachep, vma);
		return (int)vdso_base;
	}

	current->thread.vdso_base = vdso_base;

	vma->vm_mm = mm;
	vma->vm_start = current->thread.vdso_base;

	/*
	 * the VMA size is one page more than the vDSO since systemcfg
	 * is mapped in the last one
	 */
	vma->vm_end = vma->vm_start + ((vdso_pages + 1) << PAGE_SHIFT);

	/*
	 * our vma flags don't have VM_WRITE so by default, the process isn't allowed
	 * to write those pages.
	 * gdb can break that with ptrace interface, and thus trigger COW on those
	 * pages but it's then your responsibility to never do that on the "data" page
	 * of the vDSO or you'll stop getting kernel updates and your nice userland
	 * gettimeofday will be totally dead. It's fine to use that for setting
	 * breakpoints in the vDSO code pages though
	 */
	vma->vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
	vma->vm_flags |= mm->def_flags;
	vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
	vma->vm_ops = &vdso_vmops;

	down_write(&mm->mmap_sem);
	if (insert_vm_struct(mm, vma)) {
		up_write(&mm->mmap_sem);
		kmem_cache_free(vm_area_cachep, vma);
		return -ENOMEM;
	}
	mm->total_vm += (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	up_write(&mm->mmap_sem);

	return 0;
}

static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
				  unsigned long *size)
{
	Elf32_Shdr *sechdrs;
	unsigned int i;
	char *secnames;

	/* Grab section headers and strings so we can tell who is who */
	sechdrs = (void *)ehdr + ehdr->e_shoff;
	secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;

	/* Find the section they want */
	for (i = 1; i < ehdr->e_shnum; i++) {
		if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) {
			if (size)
				*size = sechdrs[i].sh_size;
			return (void *)ehdr + sechdrs[i].sh_offset;
		}
	}
	*size = 0;
	return NULL;
}

static void * __init find_section64(Elf64_Ehdr *ehdr, const char *secname,
				  unsigned long *size)
{
	Elf64_Shdr *sechdrs;
	unsigned int i;
	char *secnames;

	/* Grab section headers and strings so we can tell who is who */
	sechdrs = (void *)ehdr + ehdr->e_shoff;
	secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;

	/* Find the section they want */
	for (i = 1; i < ehdr->e_shnum; i++) {
		if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) {
			if (size)
				*size = sechdrs[i].sh_size;
			return (void *)ehdr + sechdrs[i].sh_offset;
		}
	}
	if (size)
		*size = 0;
	return NULL;
}

static Elf32_Sym * __init find_symbol32(struct lib32_elfinfo *lib, const char *symname)
{
	unsigned int i;
	char name[32], *c;

	for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
		if (lib->dynsym[i].st_name == 0)
			continue;
		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name, 32);
		c = strchr(name, '@');
		if (c)
			*c = 0;
		if (strcmp(symname, name) == 0)
			return &lib->dynsym[i];
	}
	return NULL;
}

static Elf64_Sym * __init find_symbol64(struct lib64_elfinfo *lib, const char *symname)
{
	unsigned int i;
	char name[32], *c;

	for (i = 0; i < (lib->dynsymsize / sizeof(Elf64_Sym)); i++) {
		if (lib->dynsym[i].st_name == 0)
			continue;
		strlcpy(name, lib->dynstr + lib->dynsym[i].st_name, 32);
		c = strchr(name, '@');
		if (c)
			*c = 0;
		if (strcmp(symname, name) == 0)
			return &lib->dynsym[i];
	}
	return NULL;
}

/* Note that we assume the section is .text and the symbol is relative to
 * the library base
 */
static unsigned long __init find_function32(struct lib32_elfinfo *lib, const char *symname)
{
	Elf32_Sym *sym = find_symbol32(lib, symname);

	if (sym == NULL) {
		printk(KERN_WARNING "vDSO32: function %s not found !\n", symname);
		return 0;
	}
	return sym->st_value - VDSO32_LBASE;
}

/* Note that we assume the section is .text and the symbol is relative to
 * the library base
 */
static unsigned long __init find_function64(struct lib64_elfinfo *lib, const char *symname)
{
	Elf64_Sym *sym = find_symbol64(lib, symname);

	if (sym == NULL) {
		printk(KERN_WARNING "vDSO64: function %s not found !\n", symname);
		return 0;
	}
#ifdef VDS64_HAS_DESCRIPTORS
	return *((u64 *)(vdso64_kbase + sym->st_value - VDSO64_LBASE)) - VDSO64_LBASE;
#else
	return sym->st_value - VDSO64_LBASE;
#endif
}


static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
					struct lib64_elfinfo *v64)
{
	void *sect;

	/*
	 * Locate symbol tables & text section
	 */

	v32->dynsym = find_section32(v32->hdr, ".dynsym", &v32->dynsymsize);
	v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
	if (v32->dynsym == NULL || v32->dynstr == NULL) {
		printk(KERN_ERR "vDSO32: a required symbol section was not found\n");
		return -1;
	}
	sect = find_section32(v32->hdr, ".text", NULL);
	if (sect == NULL) {
		printk(KERN_ERR "vDSO32: the .text section was not found\n");
		return -1;
	}
	v32->text = sect - vdso32_kbase;

	v64->dynsym = find_section64(v64->hdr, ".dynsym", &v64->dynsymsize);
	v64->dynstr = find_section64(v64->hdr, ".dynstr", NULL);
	if (v64->dynsym == NULL || v64->dynstr == NULL) {
		printk(KERN_ERR "vDSO64: a required symbol section was not found\n");
		return -1;
	}
	sect = find_section64(v64->hdr, ".text", NULL);
	if (sect == NULL) {
		printk(KERN_ERR "vDSO64: the .text section was not found\n");
		return -1;
	}
	v64->text = sect - vdso64_kbase;

	return 0;
}

static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32,
					  struct lib64_elfinfo *v64)
{
	/*
	 * Find signal trampolines
	 */

	vdso64_rt_sigtramp	= find_function64(v64, "__kernel_sigtramp_rt64");
	vdso32_sigtramp		= find_function32(v32, "__kernel_sigtramp32");
	vdso32_rt_sigtramp	= find_function32(v32, "__kernel_sigtramp_rt32");
}

static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
				       struct lib64_elfinfo *v64)
{
	Elf32_Sym *sym32;
	Elf64_Sym *sym64;

	sym32 = find_symbol32(v32, "__kernel_datapage_offset");
	if (sym32 == NULL) {
		printk(KERN_ERR "vDSO32: Can't find symbol __kernel_datapage_offset !\n");
		return -1;
	}
	*((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
		(vdso32_pages << PAGE_SHIFT) - (sym32->st_value - VDSO32_LBASE);

       	sym64 = find_symbol64(v64, "__kernel_datapage_offset");
	if (sym64 == NULL) {
		printk(KERN_ERR "vDSO64: Can't find symbol __kernel_datapage_offset !\n");
		return -1;
	}
	*((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) =
		(vdso64_pages << PAGE_SHIFT) - (sym64->st_value - VDSO64_LBASE);

	return 0;
}

static int vdso_do_func_patch32(struct lib32_elfinfo *v32,
				struct lib64_elfinfo *v64,
				const char *orig, const char *fix)
{
	Elf32_Sym *sym32_gen, *sym32_fix;

	sym32_gen = find_symbol32(v32, orig);
	if (sym32_gen == NULL) {
		printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", orig);
		return -1;
	}
	sym32_fix = find_symbol32(v32, fix);
	if (sym32_fix == NULL) {
		printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", fix);
		return -1;
	}
	sym32_gen->st_value = sym32_fix->st_value;
	sym32_gen->st_size = sym32_fix->st_size;
	sym32_gen->st_info = sym32_fix->st_info;
	sym32_gen->st_other = sym32_fix->st_other;
	sym32_gen->st_shndx = sym32_fix->st_shndx;

	return 0;
}

static int vdso_do_func_patch64(struct lib32_elfinfo *v32,
				struct lib64_elfinfo *v64,
				const char *orig, const char *fix)
{
	Elf64_Sym *sym64_gen, *sym64_fix;

	sym64_gen = find_symbol64(v64, orig);
	if (sym64_gen == NULL) {
		printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", orig);
		return -1;
	}
	sym64_fix = find_symbol64(v64, fix);
	if (sym64_fix == NULL) {
		printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", fix);
		return -1;
	}
	sym64_gen->st_value = sym64_fix->st_value;
	sym64_gen->st_size = sym64_fix->st_size;
	sym64_gen->st_info = sym64_fix->st_info;
	sym64_gen->st_other = sym64_fix->st_other;
	sym64_gen->st_shndx = sym64_fix->st_shndx;

	return 0;
}

static __init int vdso_fixup_alt_funcs(struct lib32_elfinfo *v32,
				       struct lib64_elfinfo *v64)
{
	u32 pvr;
	int i;

	pvr = mfspr(SPRN_PVR);
	for (i = 0; i < ARRAY_SIZE(vdso_patches); i++) {
		struct vdso_patch_def *patch = &vdso_patches[i];
		int match = (pvr & patch->pvr_mask) == patch->pvr_value;

		DBG("patch %d (mask: %x, pvr: %x) : %s\n",
		    i, patch->pvr_mask, patch->pvr_value, match ? "match" : "skip");

		if (!match)
			continue;

		DBG("replacing %s with %s...\n", patch->gen_name, patch->fix_name);

		/*
		 * Patch the 32 bits and 64 bits symbols. Note that we do not patch
		 * the "." symbol on 64 bits. It would be easy to do, but doesn't
		 * seem to be necessary, patching the OPD symbol is enough.
		 */
		vdso_do_func_patch32(v32, v64, patch->gen_name, patch->fix_name);
		vdso_do_func_patch64(v32, v64, patch->gen_name, patch->fix_name);
	}

	return 0;
}


static __init int vdso_setup(void)
{
	struct lib32_elfinfo	v32;
	struct lib64_elfinfo	v64;

	v32.hdr = vdso32_kbase;
	v64.hdr = vdso64_kbase;

	if (vdso_do_find_sections(&v32, &v64))
		return -1;

	if (vdso_fixup_datapage(&v32, &v64))
		return -1;

	if (vdso_fixup_alt_funcs(&v32, &v64))
		return -1;

	vdso_setup_trampolines(&v32, &v64);

	return 0;
}

void __init vdso_init(void)
{
	int i;

	vdso64_pages = (&vdso64_end - &vdso64_start) >> PAGE_SHIFT;
	vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT;

	DBG("vdso64_kbase: %p, 0x%x pages, vdso32_kbase: %p, 0x%x pages\n",
	       vdso64_kbase, vdso64_pages, vdso32_kbase, vdso32_pages);

	/*
	 * Initialize the vDSO images in memory, that is do necessary
	 * fixups of vDSO symbols, locate trampolines, etc...
	 */
	if (vdso_setup()) {
		printk(KERN_ERR "vDSO setup failure, not enabled !\n");
		/* XXX should free pages here ? */
		vdso64_pages = vdso32_pages = 0;
		return;
	}

	/* Make sure pages are in the correct state */
	for (i = 0; i < vdso64_pages; i++) {
		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
	}
	for (i = 0; i < vdso32_pages; i++) {
		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
	}
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}

int in_gate_area(struct task_struct *task, unsigned long addr)
{
	return 0;
}

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
	return NULL;
}