| Current Path : /sys/dev/ksyms/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/dev/ksyms/ksyms.c |
/*-
* Copyright (c) 2008-2009, Stacey Son <sson@freebsd.org>
* 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.
* 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*
* $FreeBSD: release/9.1.0/sys/dev/ksyms/ksyms.c 220100 2011-03-28 12:48:33Z kib $
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/elf.h>
#include <sys/ksyms.h>
#include <sys/linker.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <machine/elf.h>
#include <vm/pmap.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include "linker_if.h"
#define SHDR_NULL 0
#define SHDR_SYMTAB 1
#define SHDR_STRTAB 2
#define SHDR_SHSTRTAB 3
#define SHDR_NUM 4
#define STR_SYMTAB ".symtab"
#define STR_STRTAB ".strtab"
#define STR_SHSTRTAB ".shstrtab"
#define KSYMS_DNAME "ksyms"
static d_open_t ksyms_open;
static d_read_t ksyms_read;
static d_close_t ksyms_close;
static d_ioctl_t ksyms_ioctl;
static d_mmap_t ksyms_mmap;
static struct cdevsw ksyms_cdevsw = {
.d_version = D_VERSION,
.d_flags = D_PSEUDO | D_TRACKCLOSE,
.d_open = ksyms_open,
.d_close = ksyms_close,
.d_read = ksyms_read,
.d_ioctl = ksyms_ioctl,
.d_mmap = ksyms_mmap,
.d_name = KSYMS_DNAME
};
struct ksyms_softc {
LIST_ENTRY(ksyms_softc) sc_list;
vm_offset_t sc_uaddr;
size_t sc_usize;
pmap_t sc_pmap;
struct proc *sc_proc;
};
static struct mtx ksyms_mtx;
static struct cdev *ksyms_dev;
static LIST_HEAD(, ksyms_softc) ksyms_list =
LIST_HEAD_INITIALIZER(ksyms_list);
static const char ksyms_shstrtab[] =
"\0" STR_SYMTAB "\0" STR_STRTAB "\0" STR_SHSTRTAB "\0";
struct ksyms_hdr {
Elf_Ehdr kh_ehdr;
Elf_Phdr kh_txtphdr;
Elf_Phdr kh_datphdr;
Elf_Shdr kh_shdr[SHDR_NUM];
char kh_shstrtab[sizeof(ksyms_shstrtab)];
};
struct tsizes {
size_t ts_symsz;
size_t ts_strsz;
};
struct toffsets {
vm_offset_t to_symoff;
vm_offset_t to_stroff;
unsigned to_stridx;
size_t to_resid;
};
static MALLOC_DEFINE(M_KSYMS, "KSYMS", "Kernel Symbol Table");
/*
* Get the symbol and string table sizes for a kernel module. Add it to the
* running total.
*/
static int
ksyms_size_permod(linker_file_t lf, void *arg)
{
struct tsizes *ts;
const Elf_Sym *symtab;
caddr_t strtab;
long syms;
ts = arg;
syms = LINKER_SYMTAB_GET(lf, &symtab);
ts->ts_symsz += syms * sizeof(Elf_Sym);
ts->ts_strsz += LINKER_STRTAB_GET(lf, &strtab);
return (0);
}
/*
* For kernel module get the symbol and string table sizes, returning the
* totals in *ts.
*/
static void
ksyms_size_calc(struct tsizes *ts)
{
ts->ts_symsz = 0;
ts->ts_strsz = 0;
(void) linker_file_foreach(ksyms_size_permod, ts);
}
#define KSYMS_EMIT(src, des, sz) do { \
copyout(src, (void *)des, sz); \
des += sz; \
} while (0)
#define SYMBLKSZ 256 * sizeof (Elf_Sym)
/*
* For a kernel module, add the symbol and string tables into the
* snapshot buffer. Fix up the offsets in the tables.
*/
static int
ksyms_add(linker_file_t lf, void *arg)
{
struct toffsets *to;
const Elf_Sym *symtab;
Elf_Sym *symp;
caddr_t strtab;
long symsz;
size_t strsz, numsyms;
linker_symval_t symval;
char *buf;
int i, nsyms, len;
to = arg;
MOD_SLOCK;
numsyms = LINKER_SYMTAB_GET(lf, &symtab);
strsz = LINKER_STRTAB_GET(lf, &strtab);
symsz = numsyms * sizeof(Elf_Sym);
buf = malloc(SYMBLKSZ, M_KSYMS, M_WAITOK);
while (symsz > 0) {
len = min(SYMBLKSZ, symsz);
bcopy(symtab, buf, len);
/*
* Fix up symbol table for kernel modules:
* string offsets need adjusted
* symbol values made absolute
*/
symp = (Elf_Sym *) buf;
nsyms = len / sizeof (Elf_Sym);
for (i = 0; i < nsyms; i++) {
symp[i].st_name += to->to_stridx;
if (lf->id > 1 && LINKER_SYMBOL_VALUES(lf,
(c_linker_sym_t) &symtab[i], &symval) == 0) {
symp[i].st_value = (uintptr_t) symval.value;
}
}
if (len > to->to_resid) {
MOD_SUNLOCK;
free(buf, M_KSYMS);
return (ENXIO);
} else
to->to_resid -= len;
KSYMS_EMIT(buf, to->to_symoff, len);
symtab += nsyms;
symsz -= len;
}
free(buf, M_KSYMS);
MOD_SUNLOCK;
if (strsz > to->to_resid)
return (ENXIO);
else
to->to_resid -= strsz;
KSYMS_EMIT(strtab, to->to_stroff, strsz);
to->to_stridx += strsz;
return (0);
}
/*
* Create a single ELF symbol table for the kernel and kernel modules loaded
* at this time. Write this snapshot out in the process address space. Return
* 0 on success, otherwise error.
*/
static int
ksyms_snapshot(struct tsizes *ts, vm_offset_t uaddr, size_t resid)
{
struct ksyms_hdr *hdr;
struct toffsets to;
int error = 0;
/* Be kernel stack friendly */
hdr = malloc(sizeof (*hdr), M_KSYMS, M_WAITOK|M_ZERO);
/*
* Create the ELF header.
*/
hdr->kh_ehdr.e_ident[EI_PAD] = 0;
hdr->kh_ehdr.e_ident[EI_MAG0] = ELFMAG0;
hdr->kh_ehdr.e_ident[EI_MAG1] = ELFMAG1;
hdr->kh_ehdr.e_ident[EI_MAG2] = ELFMAG2;
hdr->kh_ehdr.e_ident[EI_MAG3] = ELFMAG3;
hdr->kh_ehdr.e_ident[EI_DATA] = ELF_DATA;
hdr->kh_ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
hdr->kh_ehdr.e_ident[EI_CLASS] = ELF_CLASS;
hdr->kh_ehdr.e_ident[EI_VERSION] = EV_CURRENT;
hdr->kh_ehdr.e_ident[EI_ABIVERSION] = 0;
hdr->kh_ehdr.e_type = ET_EXEC;
hdr->kh_ehdr.e_machine = ELF_ARCH;
hdr->kh_ehdr.e_version = EV_CURRENT;
hdr->kh_ehdr.e_entry = 0;
hdr->kh_ehdr.e_phoff = offsetof(struct ksyms_hdr, kh_txtphdr);
hdr->kh_ehdr.e_shoff = offsetof(struct ksyms_hdr, kh_shdr);
hdr->kh_ehdr.e_flags = 0;
hdr->kh_ehdr.e_ehsize = sizeof(Elf_Ehdr);
hdr->kh_ehdr.e_phentsize = sizeof(Elf_Phdr);
hdr->kh_ehdr.e_phnum = 2; /* Text and Data */
hdr->kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
hdr->kh_ehdr.e_shnum = SHDR_NUM;
hdr->kh_ehdr.e_shstrndx = SHDR_SHSTRTAB;
/*
* Add both the text and data Program headers.
*/
hdr->kh_txtphdr.p_type = PT_LOAD;
/* XXX - is there a way to put the actual .text addr/size here? */
hdr->kh_txtphdr.p_vaddr = 0;
hdr->kh_txtphdr.p_memsz = 0;
hdr->kh_txtphdr.p_flags = PF_R | PF_X;
hdr->kh_datphdr.p_type = PT_LOAD;
/* XXX - is there a way to put the actual .data addr/size here? */
hdr->kh_datphdr.p_vaddr = 0;
hdr->kh_datphdr.p_memsz = 0;
hdr->kh_datphdr.p_flags = PF_R | PF_W | PF_X;
/*
* Add the Section headers: null, symtab, strtab, shstrtab,
*/
/* First section header - null */
/* Second section header - symtab */
hdr->kh_shdr[SHDR_SYMTAB].sh_name = 1; /* String offset (skip null) */
hdr->kh_shdr[SHDR_SYMTAB].sh_type = SHT_SYMTAB;
hdr->kh_shdr[SHDR_SYMTAB].sh_flags = 0;
hdr->kh_shdr[SHDR_SYMTAB].sh_addr = 0;
hdr->kh_shdr[SHDR_SYMTAB].sh_offset = sizeof(*hdr);
hdr->kh_shdr[SHDR_SYMTAB].sh_size = ts->ts_symsz;
hdr->kh_shdr[SHDR_SYMTAB].sh_link = SHDR_STRTAB;
hdr->kh_shdr[SHDR_SYMTAB].sh_info = ts->ts_symsz / sizeof(Elf_Sym);
hdr->kh_shdr[SHDR_SYMTAB].sh_addralign = sizeof(long);
hdr->kh_shdr[SHDR_SYMTAB].sh_entsize = sizeof(Elf_Sym);
/* Third section header - strtab */
hdr->kh_shdr[SHDR_STRTAB].sh_name = 1 + sizeof(STR_SYMTAB);
hdr->kh_shdr[SHDR_STRTAB].sh_type = SHT_STRTAB;
hdr->kh_shdr[SHDR_STRTAB].sh_flags = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_addr = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_offset =
hdr->kh_shdr[SHDR_SYMTAB].sh_offset + ts->ts_symsz;
hdr->kh_shdr[SHDR_STRTAB].sh_size = ts->ts_strsz;
hdr->kh_shdr[SHDR_STRTAB].sh_link = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_info = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_addralign = sizeof(char);
hdr->kh_shdr[SHDR_STRTAB].sh_entsize = 0;
/* Fourth section - shstrtab */
hdr->kh_shdr[SHDR_SHSTRTAB].sh_name = 1 + sizeof(STR_SYMTAB) +
sizeof(STR_STRTAB);
hdr->kh_shdr[SHDR_SHSTRTAB].sh_type = SHT_STRTAB;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_flags = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_addr = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_offset =
offsetof(struct ksyms_hdr, kh_shstrtab);
hdr->kh_shdr[SHDR_SHSTRTAB].sh_size = sizeof(ksyms_shstrtab);
hdr->kh_shdr[SHDR_SHSTRTAB].sh_link = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_info = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_addralign = 0 /* sizeof(char) */;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_entsize = 0;
/* Copy shstrtab into the header */
bcopy(ksyms_shstrtab, hdr->kh_shstrtab, sizeof(ksyms_shstrtab));
to.to_symoff = uaddr + hdr->kh_shdr[SHDR_SYMTAB].sh_offset;
to.to_stroff = uaddr + hdr->kh_shdr[SHDR_STRTAB].sh_offset;
to.to_stridx = 0;
if (sizeof(struct ksyms_hdr) > resid) {
free(hdr, M_KSYMS);
return (ENXIO);
}
to.to_resid = resid - sizeof(struct ksyms_hdr);
/* Emit Header */
copyout(hdr, (void *)uaddr, sizeof(struct ksyms_hdr));
free(hdr, M_KSYMS);
/* Add symbol and string tables for each kernelmodule */
error = linker_file_foreach(ksyms_add, &to);
if (to.to_resid != 0)
return (ENXIO);
return (error);
}
static void
ksyms_cdevpriv_dtr(void *data)
{
struct ksyms_softc *sc;
sc = (struct ksyms_softc *)data;
mtx_lock(&ksyms_mtx);
LIST_REMOVE(sc, sc_list);
mtx_unlock(&ksyms_mtx);
free(sc, M_KSYMS);
}
/* ARGSUSED */
static int
ksyms_open(struct cdev *dev, int flags, int fmt __unused, struct thread *td)
{
struct tsizes ts;
size_t total_elf_sz;
int error, try;
struct ksyms_softc *sc;
/*
* Limit one open() per process. The process must close()
* before open()'ing again.
*/
mtx_lock(&ksyms_mtx);
LIST_FOREACH(sc, &ksyms_list, sc_list) {
if (sc->sc_proc == td->td_proc) {
mtx_unlock(&ksyms_mtx);
return (EBUSY);
}
}
sc = (struct ksyms_softc *) malloc(sizeof (*sc), M_KSYMS,
M_NOWAIT|M_ZERO);
if (sc == NULL) {
mtx_unlock(&ksyms_mtx);
return (ENOMEM);
}
sc->sc_proc = td->td_proc;
sc->sc_pmap = &td->td_proc->p_vmspace->vm_pmap;
LIST_INSERT_HEAD(&ksyms_list, sc, sc_list);
mtx_unlock(&ksyms_mtx);
error = devfs_set_cdevpriv(sc, ksyms_cdevpriv_dtr);
if (error)
goto failed;
/*
* MOD_SLOCK doesn't work here (because of a lock reversal with
* KLD_SLOCK). Therefore, simply try upto 3 times to get a "clean"
* snapshot of the kernel symbol table. This should work fine in the
* rare case of a kernel module being loaded/unloaded at the same
* time.
*/
for(try = 0; try < 3; try++) {
/*
* Map a buffer in the calling process memory space and
* create a snapshot of the kernel symbol table in it.
*/
/* Compute the size of buffer needed. */
ksyms_size_calc(&ts);
total_elf_sz = sizeof(struct ksyms_hdr) + ts.ts_symsz +
ts.ts_strsz;
error = copyout_map(td, &(sc->sc_uaddr),
(vm_size_t) total_elf_sz);
if (error)
break;
sc->sc_usize = total_elf_sz;
error = ksyms_snapshot(&ts, sc->sc_uaddr, total_elf_sz);
if (!error) {
/* Successful Snapshot */
return (0);
}
/* Snapshot failed, unmap the memory and try again */
(void) copyout_unmap(td, sc->sc_uaddr, sc->sc_usize);
}
failed:
ksyms_cdevpriv_dtr(sc);
return (error);
}
/* ARGSUSED */
static int
ksyms_read(struct cdev *dev, struct uio *uio, int flags __unused)
{
int error;
size_t len, sz;
struct ksyms_softc *sc;
off_t off;
char *buf;
vm_size_t ubase;
error = devfs_get_cdevpriv((void **)&sc);
if (error)
return (error);
off = uio->uio_offset;
len = uio->uio_resid;
if (off < 0 || off > sc->sc_usize)
return (EFAULT);
if (len > (sc->sc_usize - off))
len = sc->sc_usize - off;
if (len == 0)
return (0);
/*
* Since the snapshot buffer is in the user space we have to copy it
* in to the kernel and then back out. The extra copy saves valuable
* kernel memory.
*/
buf = malloc(PAGE_SIZE, M_KSYMS, M_WAITOK);
ubase = sc->sc_uaddr + off;
while (len) {
sz = min(PAGE_SIZE, len);
if (copyin((void *)ubase, buf, sz))
error = EFAULT;
else
error = uiomove(buf, sz, uio);
if (error)
break;
len -= sz;
ubase += sz;
}
free(buf, M_KSYMS);
return (error);
}
/* ARGSUSED */
static int
ksyms_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int32_t flag __unused,
struct thread *td __unused)
{
int error = 0;
struct ksyms_softc *sc;
error = devfs_get_cdevpriv((void **)&sc);
if (error)
return (error);
switch (cmd) {
case KIOCGSIZE:
/*
* Return the size (in bytes) of the symbol table
* snapshot.
*/
*(size_t *)data = sc->sc_usize;
break;
case KIOCGADDR:
/*
* Return the address of the symbol table snapshot.
* XXX - compat32 version of this?
*/
*(void **)data = (void *)sc->sc_uaddr;
break;
default:
error = ENOTTY;
break;
}
return (error);
}
/* ARGUSED */
static int
ksyms_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
int prot __unused, vm_memattr_t *memattr __unused)
{
struct ksyms_softc *sc;
int error;
error = devfs_get_cdevpriv((void **)&sc);
if (error)
return (error);
/*
* XXX mmap() will actually map the symbol table into the process
* address space again.
*/
if (offset > round_page(sc->sc_usize) ||
(*paddr = pmap_extract(sc->sc_pmap,
(vm_offset_t)sc->sc_uaddr + offset)) == 0)
return (-1);
return (0);
}
/* ARGUSED */
static int
ksyms_close(struct cdev *dev, int flags __unused, int fmt __unused,
struct thread *td)
{
int error = 0;
struct ksyms_softc *sc;
error = devfs_get_cdevpriv((void **)&sc);
if (error)
return (error);
/* Unmap the buffer from the process address space. */
error = copyout_unmap(td, sc->sc_uaddr, sc->sc_usize);
devfs_clear_cdevpriv();
return (error);
}
/* ARGSUSED */
static int
ksyms_modevent(module_t mod __unused, int type, void *data __unused)
{
int error = 0;
switch (type) {
case MOD_LOAD:
mtx_init(&ksyms_mtx, "KSyms mtx", NULL, MTX_DEF);
ksyms_dev = make_dev(&ksyms_cdevsw, 0, UID_ROOT, GID_WHEEL,
0444, KSYMS_DNAME);
break;
case MOD_UNLOAD:
if (!LIST_EMPTY(&ksyms_list))
return (EBUSY);
destroy_dev(ksyms_dev);
mtx_destroy(&ksyms_mtx);
break;
case MOD_SHUTDOWN:
break;
default:
error = EOPNOTSUPP;
break;
}
return (error);
}
DEV_MODULE(ksyms, ksyms_modevent, NULL);
MODULE_VERSION(ksyms, 1);