2 * linux/arch/ppc64/kernel/vdso.c
4 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
5 * <benh@kernel.crashing.org>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 #include <linux/config.h>
14 #include <linux/module.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
17 #include <linux/kernel.h>
19 #include <linux/smp.h>
20 #include <linux/smp_lock.h>
21 #include <linux/stddef.h>
22 #include <linux/unistd.h>
23 #include <linux/slab.h>
24 #include <linux/user.h>
25 #include <linux/elf.h>
26 #include <linux/security.h>
27 #include <linux/bootmem.h>
29 #include <asm/pgtable.h>
30 #include <asm/system.h>
31 #include <asm/processor.h>
33 #include <asm/mmu_context.h>
34 #include <asm/machdep.h>
35 #include <asm/cputable.h>
36 #include <asm/sections.h>
37 #include <asm/systemcfg.h>
43 #define DBG(fmt...) printk(fmt)
50 * The vDSOs themselves are here
52 extern char vdso64_start
, vdso64_end
;
53 extern char vdso32_start
, vdso32_end
;
55 static void *vdso64_kbase
= &vdso64_start
;
56 static void *vdso32_kbase
= &vdso32_start
;
58 unsigned int vdso64_pages
;
59 unsigned int vdso32_pages
;
61 /* Signal trampolines user addresses */
63 unsigned long vdso64_rt_sigtramp
;
64 unsigned long vdso32_sigtramp
;
65 unsigned long vdso32_rt_sigtramp
;
67 /* Format of the patch table */
70 u32 pvr_mask
, pvr_value
;
75 /* Table of functions to patch based on the CPU type/revision
77 * TODO: Improve by adding whole lists for each entry
79 static struct vdso_patch_def vdso_patches
[] = {
81 0xffff0000, 0x003a0000, /* POWER5 */
82 "__kernel_sync_dicache", "__kernel_sync_dicache_p5"
85 0xffff0000, 0x003b0000, /* POWER5 */
86 "__kernel_sync_dicache", "__kernel_sync_dicache_p5"
91 * Some infos carried around for each of them during parsing at
96 Elf32_Ehdr
*hdr
; /* ptr to ELF */
97 Elf32_Sym
*dynsym
; /* ptr to .dynsym section */
98 unsigned long dynsymsize
; /* size of .dynsym section */
99 char *dynstr
; /* ptr to .dynstr section */
100 unsigned long text
; /* offset of .text section in .so */
107 unsigned long dynsymsize
;
114 static void dump_one_vdso_page(struct page
*pg
, struct page
*upg
)
116 printk("kpg: %p (c:%d,f:%08lx)", __va(page_to_pfn(pg
) << PAGE_SHIFT
),
119 if (upg
/* && pg != upg*/) {
120 printk(" upg: %p (c:%d,f:%08lx)", __va(page_to_pfn(upg
) << PAGE_SHIFT
),
127 static void dump_vdso_pages(struct vm_area_struct
* vma
)
131 if (!vma
|| test_thread_flag(TIF_32BIT
)) {
132 printk("vDSO32 @ %016lx:\n", (unsigned long)vdso32_kbase
);
133 for (i
=0; i
<vdso32_pages
; i
++) {
134 struct page
*pg
= virt_to_page(vdso32_kbase
+ i
*PAGE_SIZE
);
135 struct page
*upg
= (vma
&& vma
->vm_mm
) ?
136 follow_page(vma
->vm_mm
, vma
->vm_start
+ i
*PAGE_SIZE
, 0)
138 dump_one_vdso_page(pg
, upg
);
141 if (!vma
|| !test_thread_flag(TIF_32BIT
)) {
142 printk("vDSO64 @ %016lx:\n", (unsigned long)vdso64_kbase
);
143 for (i
=0; i
<vdso64_pages
; i
++) {
144 struct page
*pg
= virt_to_page(vdso64_kbase
+ i
*PAGE_SIZE
);
145 struct page
*upg
= (vma
&& vma
->vm_mm
) ?
146 follow_page(vma
->vm_mm
, vma
->vm_start
+ i
*PAGE_SIZE
, 0)
148 dump_one_vdso_page(pg
, upg
);
155 * Keep a dummy vma_close for now, it will prevent VMA merging.
157 static void vdso_vma_close(struct vm_area_struct
* vma
)
162 * Our nopage() function, maps in the actual vDSO kernel pages, they will
163 * be mapped read-only by do_no_page(), and eventually COW'ed, either
164 * right away for an initial write access, or by do_wp_page().
166 static struct page
* vdso_vma_nopage(struct vm_area_struct
* vma
,
167 unsigned long address
, int *type
)
169 unsigned long offset
= address
- vma
->vm_start
;
171 void *vbase
= test_thread_flag(TIF_32BIT
) ? vdso32_kbase
: vdso64_kbase
;
173 DBG("vdso_vma_nopage(current: %s, address: %016lx, off: %lx)\n",
174 current
->comm
, address
, offset
);
176 if (address
< vma
->vm_start
|| address
> vma
->vm_end
)
177 return NOPAGE_SIGBUS
;
180 * Last page is systemcfg.
182 if ((vma
->vm_end
- address
) <= PAGE_SIZE
)
183 pg
= virt_to_page(_systemcfg
);
185 pg
= virt_to_page(vbase
+ offset
);
188 DBG(" ->page count: %d\n", page_count(pg
));
193 static struct vm_operations_struct vdso_vmops
= {
194 .close
= vdso_vma_close
,
195 .nopage
= vdso_vma_nopage
,
199 * This is called from binfmt_elf, we create the special vma for the
200 * vDSO and insert it into the mm struct tree
202 int arch_setup_additional_pages(struct linux_binprm
*bprm
, int executable_stack
)
204 struct mm_struct
*mm
= current
->mm
;
205 struct vm_area_struct
*vma
;
206 unsigned long vdso_pages
;
207 unsigned long vdso_base
;
209 if (test_thread_flag(TIF_32BIT
)) {
210 vdso_pages
= vdso32_pages
;
211 vdso_base
= VDSO32_MBASE
;
213 vdso_pages
= vdso64_pages
;
214 vdso_base
= VDSO64_MBASE
;
217 current
->thread
.vdso_base
= 0;
219 /* vDSO has a problem and was disabled, just don't "enable" it for the
225 vma
= kmem_cache_alloc(vm_area_cachep
, SLAB_KERNEL
);
229 memset(vma
, 0, sizeof(*vma
));
232 * pick a base address for the vDSO in process space. We try to put it
233 * at vdso_base which is the "natural" base for it, but we might fail
234 * and end up putting it elsewhere.
236 vdso_base
= get_unmapped_area(NULL
, vdso_base
,
237 vdso_pages
<< PAGE_SHIFT
, 0, 0);
238 if (vdso_base
& ~PAGE_MASK
) {
239 kmem_cache_free(vm_area_cachep
, vma
);
240 return (int)vdso_base
;
243 current
->thread
.vdso_base
= vdso_base
;
246 vma
->vm_start
= current
->thread
.vdso_base
;
249 * the VMA size is one page more than the vDSO since systemcfg
250 * is mapped in the last one
252 vma
->vm_end
= vma
->vm_start
+ ((vdso_pages
+ 1) << PAGE_SHIFT
);
255 * our vma flags don't have VM_WRITE so by default, the process isn't allowed
256 * to write those pages.
257 * gdb can break that with ptrace interface, and thus trigger COW on those
258 * pages but it's then your responsibility to never do that on the "data" page
259 * of the vDSO or you'll stop getting kernel updates and your nice userland
260 * gettimeofday will be totally dead. It's fine to use that for setting
261 * breakpoints in the vDSO code pages though
263 vma
->vm_flags
= VM_READ
| VM_EXEC
| VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
| VM_RESERVED
;
264 vma
->vm_flags
|= mm
->def_flags
;
265 vma
->vm_page_prot
= protection_map
[vma
->vm_flags
& 0x7];
266 vma
->vm_ops
= &vdso_vmops
;
268 down_write(&mm
->mmap_sem
);
269 if (insert_vm_struct(mm
, vma
)) {
270 up_write(&mm
->mmap_sem
);
271 kmem_cache_free(vm_area_cachep
, vma
);
274 mm
->total_vm
+= (vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
;
275 up_write(&mm
->mmap_sem
);
280 static void * __init
find_section32(Elf32_Ehdr
*ehdr
, const char *secname
,
287 /* Grab section headers and strings so we can tell who is who */
288 sechdrs
= (void *)ehdr
+ ehdr
->e_shoff
;
289 secnames
= (void *)ehdr
+ sechdrs
[ehdr
->e_shstrndx
].sh_offset
;
291 /* Find the section they want */
292 for (i
= 1; i
< ehdr
->e_shnum
; i
++) {
293 if (strcmp(secnames
+sechdrs
[i
].sh_name
, secname
) == 0) {
295 *size
= sechdrs
[i
].sh_size
;
296 return (void *)ehdr
+ sechdrs
[i
].sh_offset
;
303 static void * __init
find_section64(Elf64_Ehdr
*ehdr
, const char *secname
,
310 /* Grab section headers and strings so we can tell who is who */
311 sechdrs
= (void *)ehdr
+ ehdr
->e_shoff
;
312 secnames
= (void *)ehdr
+ sechdrs
[ehdr
->e_shstrndx
].sh_offset
;
314 /* Find the section they want */
315 for (i
= 1; i
< ehdr
->e_shnum
; i
++) {
316 if (strcmp(secnames
+sechdrs
[i
].sh_name
, secname
) == 0) {
318 *size
= sechdrs
[i
].sh_size
;
319 return (void *)ehdr
+ sechdrs
[i
].sh_offset
;
327 static Elf32_Sym
* __init
find_symbol32(struct lib32_elfinfo
*lib
, const char *symname
)
332 for (i
= 0; i
< (lib
->dynsymsize
/ sizeof(Elf32_Sym
)); i
++) {
333 if (lib
->dynsym
[i
].st_name
== 0)
335 strlcpy(name
, lib
->dynstr
+ lib
->dynsym
[i
].st_name
, 32);
336 c
= strchr(name
, '@');
339 if (strcmp(symname
, name
) == 0)
340 return &lib
->dynsym
[i
];
345 static Elf64_Sym
* __init
find_symbol64(struct lib64_elfinfo
*lib
, const char *symname
)
350 for (i
= 0; i
< (lib
->dynsymsize
/ sizeof(Elf64_Sym
)); i
++) {
351 if (lib
->dynsym
[i
].st_name
== 0)
353 strlcpy(name
, lib
->dynstr
+ lib
->dynsym
[i
].st_name
, 32);
354 c
= strchr(name
, '@');
357 if (strcmp(symname
, name
) == 0)
358 return &lib
->dynsym
[i
];
363 /* Note that we assume the section is .text and the symbol is relative to
366 static unsigned long __init
find_function32(struct lib32_elfinfo
*lib
, const char *symname
)
368 Elf32_Sym
*sym
= find_symbol32(lib
, symname
);
371 printk(KERN_WARNING
"vDSO32: function %s not found !\n", symname
);
374 return sym
->st_value
- VDSO32_LBASE
;
377 /* Note that we assume the section is .text and the symbol is relative to
380 static unsigned long __init
find_function64(struct lib64_elfinfo
*lib
, const char *symname
)
382 Elf64_Sym
*sym
= find_symbol64(lib
, symname
);
385 printk(KERN_WARNING
"vDSO64: function %s not found !\n", symname
);
388 #ifdef VDS64_HAS_DESCRIPTORS
389 return *((u64
*)(vdso64_kbase
+ sym
->st_value
- VDSO64_LBASE
)) - VDSO64_LBASE
;
391 return sym
->st_value
- VDSO64_LBASE
;
396 static __init
int vdso_do_find_sections(struct lib32_elfinfo
*v32
,
397 struct lib64_elfinfo
*v64
)
402 * Locate symbol tables & text section
405 v32
->dynsym
= find_section32(v32
->hdr
, ".dynsym", &v32
->dynsymsize
);
406 v32
->dynstr
= find_section32(v32
->hdr
, ".dynstr", NULL
);
407 if (v32
->dynsym
== NULL
|| v32
->dynstr
== NULL
) {
408 printk(KERN_ERR
"vDSO32: a required symbol section was not found\n");
411 sect
= find_section32(v32
->hdr
, ".text", NULL
);
413 printk(KERN_ERR
"vDSO32: the .text section was not found\n");
416 v32
->text
= sect
- vdso32_kbase
;
418 v64
->dynsym
= find_section64(v64
->hdr
, ".dynsym", &v64
->dynsymsize
);
419 v64
->dynstr
= find_section64(v64
->hdr
, ".dynstr", NULL
);
420 if (v64
->dynsym
== NULL
|| v64
->dynstr
== NULL
) {
421 printk(KERN_ERR
"vDSO64: a required symbol section was not found\n");
424 sect
= find_section64(v64
->hdr
, ".text", NULL
);
426 printk(KERN_ERR
"vDSO64: the .text section was not found\n");
429 v64
->text
= sect
- vdso64_kbase
;
434 static __init
void vdso_setup_trampolines(struct lib32_elfinfo
*v32
,
435 struct lib64_elfinfo
*v64
)
438 * Find signal trampolines
441 vdso64_rt_sigtramp
= find_function64(v64
, "__kernel_sigtramp_rt64");
442 vdso32_sigtramp
= find_function32(v32
, "__kernel_sigtramp32");
443 vdso32_rt_sigtramp
= find_function32(v32
, "__kernel_sigtramp_rt32");
446 static __init
int vdso_fixup_datapage(struct lib32_elfinfo
*v32
,
447 struct lib64_elfinfo
*v64
)
452 sym32
= find_symbol32(v32
, "__kernel_datapage_offset");
454 printk(KERN_ERR
"vDSO32: Can't find symbol __kernel_datapage_offset !\n");
457 *((int *)(vdso32_kbase
+ (sym32
->st_value
- VDSO32_LBASE
))) =
458 (vdso32_pages
<< PAGE_SHIFT
) - (sym32
->st_value
- VDSO32_LBASE
);
460 sym64
= find_symbol64(v64
, "__kernel_datapage_offset");
462 printk(KERN_ERR
"vDSO64: Can't find symbol __kernel_datapage_offset !\n");
465 *((int *)(vdso64_kbase
+ sym64
->st_value
- VDSO64_LBASE
)) =
466 (vdso64_pages
<< PAGE_SHIFT
) - (sym64
->st_value
- VDSO64_LBASE
);
471 static int vdso_do_func_patch32(struct lib32_elfinfo
*v32
,
472 struct lib64_elfinfo
*v64
,
473 const char *orig
, const char *fix
)
475 Elf32_Sym
*sym32_gen
, *sym32_fix
;
477 sym32_gen
= find_symbol32(v32
, orig
);
478 if (sym32_gen
== NULL
) {
479 printk(KERN_ERR
"vDSO32: Can't find symbol %s !\n", orig
);
482 sym32_fix
= find_symbol32(v32
, fix
);
483 if (sym32_fix
== NULL
) {
484 printk(KERN_ERR
"vDSO32: Can't find symbol %s !\n", fix
);
487 sym32_gen
->st_value
= sym32_fix
->st_value
;
488 sym32_gen
->st_size
= sym32_fix
->st_size
;
489 sym32_gen
->st_info
= sym32_fix
->st_info
;
490 sym32_gen
->st_other
= sym32_fix
->st_other
;
491 sym32_gen
->st_shndx
= sym32_fix
->st_shndx
;
496 static int vdso_do_func_patch64(struct lib32_elfinfo
*v32
,
497 struct lib64_elfinfo
*v64
,
498 const char *orig
, const char *fix
)
500 Elf64_Sym
*sym64_gen
, *sym64_fix
;
502 sym64_gen
= find_symbol64(v64
, orig
);
503 if (sym64_gen
== NULL
) {
504 printk(KERN_ERR
"vDSO64: Can't find symbol %s !\n", orig
);
507 sym64_fix
= find_symbol64(v64
, fix
);
508 if (sym64_fix
== NULL
) {
509 printk(KERN_ERR
"vDSO64: Can't find symbol %s !\n", fix
);
512 sym64_gen
->st_value
= sym64_fix
->st_value
;
513 sym64_gen
->st_size
= sym64_fix
->st_size
;
514 sym64_gen
->st_info
= sym64_fix
->st_info
;
515 sym64_gen
->st_other
= sym64_fix
->st_other
;
516 sym64_gen
->st_shndx
= sym64_fix
->st_shndx
;
521 static __init
int vdso_fixup_alt_funcs(struct lib32_elfinfo
*v32
,
522 struct lib64_elfinfo
*v64
)
527 pvr
= mfspr(SPRN_PVR
);
528 for (i
= 0; i
< ARRAY_SIZE(vdso_patches
); i
++) {
529 struct vdso_patch_def
*patch
= &vdso_patches
[i
];
530 int match
= (pvr
& patch
->pvr_mask
) == patch
->pvr_value
;
532 DBG("patch %d (mask: %x, pvr: %x) : %s\n",
533 i
, patch
->pvr_mask
, patch
->pvr_value
, match
? "match" : "skip");
538 DBG("replacing %s with %s...\n", patch
->gen_name
, patch
->fix_name
);
541 * Patch the 32 bits and 64 bits symbols. Note that we do not patch
542 * the "." symbol on 64 bits. It would be easy to do, but doesn't
543 * seem to be necessary, patching the OPD symbol is enough.
545 vdso_do_func_patch32(v32
, v64
, patch
->gen_name
, patch
->fix_name
);
546 vdso_do_func_patch64(v32
, v64
, patch
->gen_name
, patch
->fix_name
);
553 static __init
int vdso_setup(void)
555 struct lib32_elfinfo v32
;
556 struct lib64_elfinfo v64
;
558 v32
.hdr
= vdso32_kbase
;
559 v64
.hdr
= vdso64_kbase
;
561 if (vdso_do_find_sections(&v32
, &v64
))
564 if (vdso_fixup_datapage(&v32
, &v64
))
567 if (vdso_fixup_alt_funcs(&v32
, &v64
))
570 vdso_setup_trampolines(&v32
, &v64
);
575 void __init
vdso_init(void)
579 vdso64_pages
= (&vdso64_end
- &vdso64_start
) >> PAGE_SHIFT
;
580 vdso32_pages
= (&vdso32_end
- &vdso32_start
) >> PAGE_SHIFT
;
582 DBG("vdso64_kbase: %p, 0x%x pages, vdso32_kbase: %p, 0x%x pages\n",
583 vdso64_kbase
, vdso64_pages
, vdso32_kbase
, vdso32_pages
);
586 * Initialize the vDSO images in memory, that is do necessary
587 * fixups of vDSO symbols, locate trampolines, etc...
590 printk(KERN_ERR
"vDSO setup failure, not enabled !\n");
591 /* XXX should free pages here ? */
592 vdso64_pages
= vdso32_pages
= 0;
596 /* Make sure pages are in the correct state */
597 for (i
= 0; i
< vdso64_pages
; i
++) {
598 struct page
*pg
= virt_to_page(vdso64_kbase
+ i
*PAGE_SIZE
);
599 ClearPageReserved(pg
);
602 for (i
= 0; i
< vdso32_pages
; i
++) {
603 struct page
*pg
= virt_to_page(vdso32_kbase
+ i
*PAGE_SIZE
);
604 ClearPageReserved(pg
);
608 get_page(virt_to_page(_systemcfg
));
611 int in_gate_area_no_task(unsigned long addr
)
616 int in_gate_area(struct task_struct
*task
, unsigned long addr
)
621 struct vm_area_struct
*get_gate_vma(struct task_struct
*tsk
)