freebsd-dev/sys/compat/linux/linux_vdso.c

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/*-
* Copyright (c) 2013 Dmitry Chagin
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
#define __ELF_WORD_SIZE 32
#else
#define __ELF_WORD_SIZE 64
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/elf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/queue.h>
#include <sys/sysent.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <compat/linux/linux_vdso.h>
SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
static int __elfN(symtabindex);
static int __elfN(symstrindex);
static void
__elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *);
void
__elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s)
{
SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym);
}
vm_object_t
__elfN(linux_shared_page_init)(char **mapping)
{
vm_page_t m;
vm_object_t obj;
vm_offset_t addr;
obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
VM_PROT_DEFAULT, 0, NULL);
VM_OBJECT_WLOCK(obj);
m = vm_page_grab(obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
m->valid = VM_PAGE_BITS_ALL;
VM_OBJECT_WUNLOCK(obj);
addr = kva_alloc(PAGE_SIZE);
pmap_qenter(addr, &m, 1);
*mapping = (char *)addr;
return (obj);
}
void
__elfN(linux_shared_page_fini)(vm_object_t obj)
{
vm_object_deallocate(obj);
}
void
__elfN(linux_vdso_fixup)(struct sysentvec *sv)
{
Elf_Ehdr *ehdr;
Elf_Shdr *shdr;
int i;
ehdr = (Elf_Ehdr *) sv->sv_sigcode;
if (!IS_ELF(*ehdr) ||
ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
ehdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
ehdr->e_shoff == 0 ||
ehdr->e_shentsize != sizeof(Elf_Shdr))
panic("Linux invalid vdso header.\n");
if (ehdr->e_type != ET_DYN)
panic("Linux invalid vdso header.\n");
shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff);
__elfN(symtabindex) = -1;
__elfN(symstrindex) = -1;
for (i = 0; i < ehdr->e_shnum; i++) {
if (shdr[i].sh_size == 0)
continue;
if (shdr[i].sh_type == SHT_DYNSYM) {
__elfN(symtabindex) = i;
__elfN(symstrindex) = shdr[i].sh_link;
}
}
if (__elfN(symtabindex) == -1 || __elfN(symstrindex) == -1)
panic("Linux invalid vdso header.\n");
ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX;
}
void
__elfN(linux_vdso_reloc)(struct sysentvec *sv, long vdso_adjust)
{
struct linux_vdso_sym *lsym;
Elf_Ehdr *ehdr;
Elf_Phdr *phdr;
Elf_Shdr *shdr;
Elf_Dyn *dyn;
Elf_Sym *sym;
int i, symcnt;
ehdr = (Elf_Ehdr *) sv->sv_sigcode;
/* Adjust our so relative to the sigcode_base */
if (vdso_adjust != 0) {
ehdr->e_entry += vdso_adjust;
phdr = (Elf_Phdr *)((caddr_t)ehdr + ehdr->e_phoff);
/* phdrs */
for (i = 0; i < ehdr->e_phnum; i++) {
phdr[i].p_vaddr += vdso_adjust;
if (phdr[i].p_type != PT_DYNAMIC)
continue;
dyn = (Elf_Dyn *)((caddr_t)ehdr + phdr[i].p_offset);
for(; dyn->d_tag != DT_NULL; dyn++) {
switch (dyn->d_tag) {
case DT_PLTGOT:
case DT_HASH:
case DT_STRTAB:
case DT_SYMTAB:
case DT_RELA:
case DT_INIT:
case DT_FINI:
case DT_REL:
case DT_DEBUG:
case DT_JMPREL:
case DT_VERSYM:
case DT_VERDEF:
case DT_VERNEED:
case DT_ADDRRNGLO ... DT_ADDRRNGHI:
dyn->d_un.d_ptr += vdso_adjust;
break;
case DT_ENCODING ... DT_LOOS-1:
case DT_LOOS ... DT_HIOS:
if (dyn->d_tag >= DT_ENCODING &&
(dyn->d_tag & 1) == 0)
dyn->d_un.d_ptr += vdso_adjust;
break;
default:
break;
}
}
}
/* sections */
shdr = (Elf_Shdr *)((caddr_t)ehdr + ehdr->e_shoff);
for(i = 0; i < ehdr->e_shnum; i++) {
if (!(shdr[i].sh_flags & SHF_ALLOC))
continue;
shdr[i].sh_addr += vdso_adjust;
if (shdr[i].sh_type != SHT_SYMTAB &&
shdr[i].sh_type != SHT_DYNSYM)
continue;
sym = (Elf_Sym *)((caddr_t)ehdr + shdr[i].sh_offset);
symcnt = shdr[i].sh_size / sizeof(*sym);
for(i = 0; i < symcnt; i++, sym++) {
if (sym->st_shndx == SHN_UNDEF ||
sym->st_shndx == SHN_ABS)
continue;
sym->st_value += vdso_adjust;
}
}
}
SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym)
__elfN(linux_vdso_lookup)(ehdr, lsym);
}
static void
__elfN(linux_vdso_lookup)(Elf_Ehdr *ehdr, struct linux_vdso_sym *vsym)
{
vm_offset_t strtab, symname;
uint32_t symcnt;
Elf_Shdr *shdr;
int i;
shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff);
strtab = (vm_offset_t)((caddr_t)ehdr +
shdr[__elfN(symstrindex)].sh_offset);
Elf_Sym *sym = (Elf_Sym *)((caddr_t)ehdr +
shdr[__elfN(symtabindex)].sh_offset);
symcnt = shdr[__elfN(symtabindex)].sh_size / sizeof(*sym);
for (i = 0; i < symcnt; ++i, ++sym) {
symname = strtab + sym->st_name;
if (strncmp(vsym->symname, (char *)symname, vsym->size) == 0) {
*vsym->ptr = (uintptr_t)sym->st_value;
break;
}
}
}