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Add the ksyms(4) pseudo driver. The ksyms driver allows a process to

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get a quick snapshot of the kernel's symbol table including the symbols
from any loaded modules (the symbols are all merged into one symbol
table).  Unlike like other implementations, this ksyms driver maps
memory in the process memory space to store the snapshot at the time
/dev/ksyms is opened.  It also checks to see if the process has already
a snapshot open and won't allow it to open /dev/ksyms it again until it
closes first.  This prevents kernel and process memory from being
exhausted.  Note that /dev/ksyms is used by the lockstat(1) command.

Reviewed by:	gallatin kib (freebsd-arch)
Approved by:	gnn (mentor)
This commit is contained in:
Stacey Son 2009-05-26 21:39:09 +00:00
parent 3e8739762f
commit 00a5db46de
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=192859
11 changed files with 967 additions and 0 deletions
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1
share/man/man4/Makefile
View File

@ -160,6 +160,7 @@ MAN= aac.4 \
kbdmux.4 \
keyboard.4 \
kld.4 \
ksyms.4 \
ktr.4 \
kue.4 \
lagg.4 \

158
share/man/man4/ksyms.4 Normal file
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@ -0,0 +1,158 @@
.\" Copyright (c) 2008-2009 Stacey Son <sson@freebsd.org>
.\" The Regents of the University of California. 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.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
.\"
.\" $FreeBSD$
.\"
.Dd April 5, 2009
.Dt KSYMS 4
.Os
.Sh NAME
.Nm ksyms
.Nd kernel symbol table interface
.Sh SYNOPSIS
.Cd "device ksyms"
.Sh DESCRIPTION
The
.Pa /dev/ksyms
character device provides a read-only interface to a snapshot of the kernel
symbol table. The in-kernel symbol manager is designed to be able to handle
many types of symbols tables, however, only
.Xr elf 5
symbol tables are supported by this device. The ELF format image contains two
sections: a symbol table and a corresponding string table.
.Bl -tag -width indent -offset indent
.It Dv Symbol Table
The SYMTAB section contains the symbol table entries present in the current
running kernel, including the symbol table entries of any loaded modules. The
symbols are ordered by the kernel module load time starting with kernel file
symbols first, followed by the first loaded module's symbols and so on.
.It Dv String Table
The STRTAB section contains the symbol name strings from the kernel and any
loaded modules that the symbol table entries reference.
.El
.Pp
Elf formated symbol table data read from the
.Pa /dev/ksyms
file represents the state of the kernel at the time when the device is opened.
Since
.Pa /dev/ksyms
has no text or data, most of the fields are initialized to NULL.
The
.Nm
driver does not block the loading or unloading of modules into the kernel
while the
.Pa /dev/ksyms
file is open but may contain stale data.
.Sh IOCTLS
The
.Xr ioctl 2
command codes below are defined in
.Aq Pa sys/ksyms.h .
.Pp
The (third) argument to the
.Xr ioctl 2
should be a pointer to the type indicated.
.Bl -tag -width indent -offset indent
.It Dv KIOCGSIZE (size_t)
Returns the total size of the current symbol table.
This can be used when allocating a buffer to make a copy of
the kernel symbol table.
.It Dv KIOCGADDR (void *)
Returns the address of the kernel symbol table mapped in
the process memory.
.El
.Sh FILES
.Bl -tag -width /dev/ksymsX
.It Pa /dev/ksyms
.El
.Sh ERRORS
An
.Xr open 2
of
.Pa /dev/ksyms
will fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
The device is already open. A process must close
.Pa /dev/ksyms
before it can be opened again.
.It Bq Er ENOMEM
There is a resource shortage in the kernel.
.It Bq Er ENXIO
The driver was unsuccessful in creating a snapshot of the kernel symbol
table. This may occur if the kernel was in the process of loading or
unloading a module.
.El
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr nlist 3 ,
.Xr elf 5 ,
.Xr kldload 8
.Sh HISTORY
A
.Nm
device exists in many different operating systems.
This implementation is similar in function to the Solaris and NetBSD
.Nm
driver.
.Pp
The
.Nm
driver first appeared in
.Fx 8.0
to support
.Xr lockstat 1 .
.Sh BUGS
Because files can be dynamically linked into the kernel at any time the symbol
information can vary. When you open the
.Pa /dev/ksyms
file, you have access to an ELF image which represents a snapshot of the state of the kernel symbol information at that instant in time. Keeping the device open does not block the loading or unloading of kernel modules. To get a new snapshot you must close and re-open the device.
.Pp
A process is only allowed to open the
.Pa /dev/ksyms
file once at a time. The process must close the
.Pa /dev/ksyms
before it is allowed to open it again.
.Pp
The
.Nm
driver uses the calling process' memory address space to store the snapshot.
.Xr ioctl 2
can be used to get the memory address where the symbol table is stored to
save kernel memory.
.Xr mmap 2
may also be used but it will map it to another address.
.Sh AUTHORS
The
.Nm
driver was written by
.An Stacey Son
.Aq sson@freebsd.org .

3
sys/conf/NOTES
View File

@ -1080,6 +1080,9 @@ device random
# The system memory devices; /dev/mem, /dev/kmem
device mem
# The kernel symbol table device; /dev/ksyms
device ksyms
# Optional character code conversion support with LIBICONV.
# Each option requires their base file system and LIBICONV.
options CD9660_ICONV

1
sys/conf/files
View File

@ -1085,6 +1085,7 @@ dev/joy/joy.c optional joy
dev/joy/joy_isa.c optional joy isa
dev/joy/joy_pccard.c optional joy pccard
dev/kbdmux/kbdmux.c optional kbdmux
dev/ksyms/ksyms.c optional ksyms
dev/le/am7990.c optional le
dev/le/am79900.c optional le
dev/le/if_le_pci.c optional le pci

678
sys/dev/ksyms/ksyms.c Normal file
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@ -0,0 +1,678 @@
/*-
* 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.
*
* $FreeBSD$
*/
#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;
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;
Elf_Sym *symtab, *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);
}
/*
* Map some anonymous memory in user space of size sz, rounded up to the page
* boundary.
*/
static int
ksyms_map(struct thread *td, vm_offset_t *addr, size_t sz)
{
struct vmspace *vms = td->td_proc->p_vmspace;
int error;
vm_size_t size;
/*
* Map somewhere after heap in process memory.
*/
PROC_LOCK(td->td_proc);
*addr = round_page((vm_offset_t)vms->vm_daddr +
lim_max(td->td_proc, RLIMIT_DATA));
PROC_UNLOCK(td->td_proc);
/* round size up to page boundry */
size = (vm_size_t) round_page(sz);
error = vm_mmap(&vms->vm_map, addr, size, PROT_READ | PROT_WRITE,
VM_PROT_ALL, MAP_PRIVATE | MAP_ANON, OBJT_DEFAULT, NULL, 0);
return (error);
}
/*
* Unmap memory in user space.
*/
static int
ksyms_unmap(struct thread *td, vm_offset_t addr, size_t sz)
{
vm_map_t map;
int error;
vm_size_t size;
map = &td->td_proc->p_vmspace->vm_map;
size = (vm_size_t) round_page(sz);
/* check for address wrap-around */
if (addr + size < addr || addr < vm_map_min(map) ||
addr + size > vm_map_max(map))
return (EINVAL);
vm_map_lock(map);
/* make sure the pages are mapped */
if (!vm_map_check_protection(map, addr, addr + size, VM_PROT_NONE)) {
vm_map_unlock(map);
return (EINVAL);
}
error = vm_map_delete(map, addr, addr + size);
vm_map_unlock(map);
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 = ksyms_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) ksyms_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,
d_thread_t *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_offset_t offset, vm_paddr_t *paddr,
int prot __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 = ksyms_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);

30
sys/kern/link_elf.c
View File

@ -137,6 +137,8 @@ static int link_elf_each_function_nameval(linker_file_t,
linker_function_nameval_callback_t,
void *);
static void link_elf_reloc_local(linker_file_t);
static long link_elf_symtab_get(linker_file_t, const Elf_Sym **);
static long link_elf_strtab_get(linker_file_t, caddr_t *);
static Elf_Addr elf_lookup(linker_file_t lf, Elf_Size symidx, int deps);
static kobj_method_t link_elf_methods[] = {
@ -151,6 +153,8 @@ static kobj_method_t link_elf_methods[] = {
KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
KOBJMETHOD(linker_ctf_get, link_elf_ctf_get),
KOBJMETHOD(linker_symtab_get, link_elf_symtab_get),
KOBJMETHOD(linker_strtab_get, link_elf_strtab_get),
{ 0, 0 }
};
@ -1390,3 +1394,29 @@ link_elf_reloc_local(linker_file_t lf)
}
}
}
static long
link_elf_symtab_get(linker_file_t lf, const Elf_Sym **symtab)
{
elf_file_t ef = (elf_file_t)lf;
*symtab = ef->ddbsymtab;
if (*symtab == NULL)
return (0);
return (ef->ddbsymcnt);
}
static long
link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
{
elf_file_t ef = (elf_file_t)lf;
*strtab = ef->ddbstrtab;
if (*strtab == NULL)
return (0);
return (ef->ddbstrcnt);
}

30
sys/kern/link_elf_obj.c
View File

@ -140,6 +140,8 @@ static int link_elf_each_function_nameval(linker_file_t,
linker_function_nameval_callback_t,
void *);
static void link_elf_reloc_local(linker_file_t);
static long link_elf_symtab_get(linker_file_t, Elf_Sym **);
static long link_elf_strtab_get(linker_file_t, caddr_t *);
static Elf_Addr elf_obj_lookup(linker_file_t lf, Elf_Size symidx, int deps);
@ -155,6 +157,8 @@ static kobj_method_t link_elf_methods[] = {
KOBJMETHOD(linker_each_function_name, link_elf_each_function_name),
KOBJMETHOD(linker_each_function_nameval, link_elf_each_function_nameval),
KOBJMETHOD(linker_ctf_get, link_elf_ctf_get),
KOBJMETHOD(linker_symtab_get, link_elf_symtab_get),
KOBJMETHOD(linker_strtab_get, link_elf_strtab_get),
{ 0, 0 }
};
@ -1286,3 +1290,29 @@ link_elf_reloc_local(linker_file_t lf)
}
}
}
static long
link_elf_symtab_get(linker_file_t lf, Elf_Sym **symtab)
{
elf_file_t ef = (elf_file_t)lf;
*symtab = ef->ddbsymtab;
if (*symtab == NULL)
return (0);
return (ef->ddbsymcnt);
}
static long
link_elf_strtab_get(linker_file_t lf, caddr_t *strtab)
{
elf_file_t ef = (elf_file_t)lf;
*strtab = ef->ddbstrtab;
if (*strtab == NULL)
return (0);
return (ef->ddbstrcnt);
}

18
sys/kern/linker_if.m
View File

@ -104,6 +104,24 @@ METHOD int ctf_get {
linker_ctf_t *lc;
};
#
# Get the symbol table, returning it in **symtab. Return the
# number of symbols, otherwise zero.
#
METHOD long symtab_get {
linker_file_t file;
Elf_Sym **symtab;
};
#
# Get the string table, returning it in *strtab. Return the
# size (in bytes) of the string table, otherwise zero.
#
METHOD long strtab_get {
linker_file_t file;
caddr_t *strtab;
};
#
# Load a file, returning the new linker_file_t in *result. If
# the class does not recognise the file type, zero should be

1
sys/modules/Makefile
View File

@ -139,6 +139,7 @@ SUBDIR= ${_3dfx} \
joy \
kbdmux \
krpc \
ksyms \
le \
lge \
libalias \

10
sys/modules/ksyms/Makefile Normal file
View File

@ -0,0 +1,10 @@
# $FreeBSD$
.PATH: ${.CURDIR}/../../dev/ksyms
KMOD= ksyms
SRCS= ksyms.c linker_if.h
MFILES= kern/linker_if.m
.include <bsd.kmod.mk>

37
sys/sys/ksyms.h Normal file
View File

@ -0,0 +1,37 @@
/*-
* 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.
*
* $FreeBSD$
*/
#ifndef _SYS_KSYMS_H_
#define _SYS_KSYMS_H_
#include <sys/ioccom.h>
#define KIOCGSIZE _IOR('l', 1, size_t)
#define KIOCGADDR _IOR('l', 2, void *)
#endif /* _SYS_KSYMS_H_ */