/*
* 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.
*/
if ((vma->vm_end - address) <= PAGE_SIZE)
pg = virt_to_page(systemcfg);
else
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 | VM_RESERVED;
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);
}
get_page(virt_to_page(systemcfg));
}
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;
}
