kevin/linux
1
Fork 0
Code
469b1d8741
linux/arch/um/os-Linux/start_up.c
Jeff Dike 75e29b18d9 [PATCH] uml: stack usage reduction 
The KSTK_* macros used an inordinate amount of stack.  In order to overcome
an impedance mismatch between their interface, which just returns a single
register value, and the interface of get_thread_regs, which took a full
pt_regs, the implementation created an on-stack pt_regs, filled it in, and
returned one field.  do_task_stat calls KSTK_* twice, resulting in two
local pt_regs, blowing out the stack.

This patch changes the interface (and name) of get_thread_regs to just
return a single register from a jmp_buf.

The include of archsetjmp.h" in registers.h to get the definition of
jmp_buf exposed a bogus include of <setjmp.h> in start_up.c.  <setjmp.h>
shouldn't be used anywhere any more since UML uses the klibc
setjmp/longjmp.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26 08:49:09 -07:00

627 lines
15 KiB
C
Raw Blame History

/*
* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <pty.h>
#include <stdio.h>
#include <stddef.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sched.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <asm/unistd.h>
#include <asm/page.h>
#include <sys/types.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "signal_kern.h"
#include "sysdep/ptrace.h"
#include "sysdep/sigcontext.h"
#include "irq_user.h"
#include "ptrace_user.h"
#include "mem_user.h"
#include "init.h"
#include "os.h"
#include "uml-config.h"
#include "choose-mode.h"
#include "mode.h"
#include "tempfile.h"
#include "kern_constants.h"
#ifdef UML_CONFIG_MODE_SKAS
#include "skas.h"
#include "skas_ptrace.h"
#include "registers.h"
#endif
static int ptrace_child(void *arg)
{
int ret;
int pid = os_getpid(), ppid = getppid();
int sc_result;
change_sig(SIGWINCH, 0);
if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
perror("ptrace");
os_kill_process(pid, 0);
}
os_stop_process(pid);
/*This syscall will be intercepted by the parent. Don't call more than
* once, please.*/
sc_result = os_getpid();
if (sc_result == pid)
ret = 1; /*Nothing modified by the parent, we are running
normally.*/
else if (sc_result == ppid)
ret = 0; /*Expected in check_ptrace and check_sysemu when they
succeed in modifying the stack frame*/
else
ret = 2; /*Serious trouble! This could be caused by a bug in
host 2.6 SKAS3/2.6 patch before release -V6, together
with a bug in the UML code itself.*/
_exit(ret);
}
static int start_ptraced_child(void **stack_out)
{
void *stack;
unsigned long sp;
int pid, n, status;
stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if(stack == MAP_FAILED)
panic("check_ptrace : mmap failed, errno = %d", errno);
sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
if(pid < 0)
panic("start_ptraced_child : clone failed, errno = %d", errno);
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
panic("check_ptrace : clone failed, errno = %d", errno);
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
panic("check_ptrace : expected SIGSTOP, got status = %d",
status);
*stack_out = stack;
return(pid);
}
/* When testing for SYSEMU support, if it is one of the broken versions, we
* must just avoid using sysemu, not panic, but only if SYSEMU features are
* broken.
* So only for SYSEMU features we test mustpanic, while normal host features
* must work anyway!
*/
static int stop_ptraced_child(int pid, void *stack, int exitcode,
int mustpanic)
{
int status, n, ret = 0;
if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
panic("check_ptrace : ptrace failed, errno = %d", errno);
CATCH_EINTR(n = waitpid(pid, &status, 0));
if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
int exit_with = WEXITSTATUS(status);
if (exit_with == 2)
printf("check_ptrace : child exited with status 2. "
"Serious trouble happening! Try updating your "
"host skas patch!\nDisabling SYSEMU support.");
printf("check_ptrace : child exited with exitcode %d, while "
"expecting %d; status 0x%x", exit_with,
exitcode, status);
if (mustpanic)
panic("\n");
else
printf("\n");
ret = -1;
}
if(munmap(stack, PAGE_SIZE) < 0)
panic("check_ptrace : munmap failed, errno = %d", errno);
return ret;
}
int ptrace_faultinfo = 1;
int ptrace_ldt = 1;
int proc_mm = 1;
int skas_needs_stub = 0;
static int __init skas0_cmd_param(char *str, int* add)
{
ptrace_faultinfo = proc_mm = 0;
return 0;
}
/* The two __uml_setup would conflict, without this stupid alias. */
static int __init mode_skas0_cmd_param(char *str, int* add)
__attribute__((alias("skas0_cmd_param")));
__uml_setup("skas0", skas0_cmd_param,
"skas0\n"
" Disables SKAS3 usage, so that SKAS0 is used, unless \n"
" you specify mode=tt.\n\n");
__uml_setup("mode=skas0", mode_skas0_cmd_param,
"mode=skas0\n"
" Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
" specify mode=tt. Note that this was recently added - on \n"
" older kernels you must use simply \"skas0\".\n\n");
static int force_sysemu_disabled = 0;
static int __init nosysemu_cmd_param(char *str, int* add)
{
force_sysemu_disabled = 1;
return 0;
}
__uml_setup("nosysemu", nosysemu_cmd_param,
"nosysemu\n"
" Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
" behaviour of ptrace() and helps reducing host context switch rate.\n"
" To make it working, you need a kernel patch for your host, too.\n"
" See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
" information.\n\n");
static void __init check_sysemu(void)
{
void *stack;
int pid, n, status, count=0;
printf("Checking syscall emulation patch for ptrace...");
sysemu_supported = 0;
pid = start_ptraced_child(&stack);
if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
panic("check_sysemu : wait failed, errno = %d", errno);
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
panic("check_sysemu : expected SIGTRAP, "
"got status = %d", status);
n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if(n < 0)
panic("check_sysemu : failed to modify system "
"call return, errno = %d", errno);
if (stop_ptraced_child(pid, stack, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 1;
printf("OK\n");
set_using_sysemu(!force_sysemu_disabled);
printf("Checking advanced syscall emulation patch for ptrace...");
pid = start_ptraced_child(&stack);
if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0)
panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d",
errno);
while(1){
count++;
if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
panic("check_ptrace : wait failed, errno = %d", errno);
if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
if (!count)
panic("check_ptrace : SYSEMU_SINGLESTEP "
"doesn't singlestep");
n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if(n < 0)
panic("check_sysemu : failed to modify system "
"call return, errno = %d", errno);
break;
}
else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
count++;
else
panic("check_ptrace : expected SIGTRAP or "
"(SIGTRAP|0x80), got status = %d", status);
}
if (stop_ptraced_child(pid, stack, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 2;
printf("OK\n");
if ( !force_sysemu_disabled )
set_using_sysemu(sysemu_supported);
return;
fail:
stop_ptraced_child(pid, stack, 1, 0);
fail_stopped:
printf("missing\n");
}
static void __init check_ptrace(void)
{
void *stack;
int pid, syscall, n, status;
printf("Checking that ptrace can change system call numbers...");
pid = start_ptraced_child(&stack);
if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno);
while(1){
if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
panic("check_ptrace : ptrace failed, errno = %d",
errno);
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
panic("check_ptrace : wait failed, errno = %d", errno);
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80)))
panic("check_ptrace : expected (SIGTRAP|0x80), "
"got status = %d", status);
syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
0);
if(syscall == __NR_getpid){
n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
__NR_getppid);
if(n < 0)
panic("check_ptrace : failed to modify system "
"call, errno = %d", errno);
break;
}
}
stop_ptraced_child(pid, stack, 0, 1);
printf("OK\n");
check_sysemu();
}
extern void check_tmpexec(void);
void os_early_checks(void)
{
check_ptrace();
/* Need to check this early because mmapping happens before the
* kernel is running.
*/
check_tmpexec();
}
static int __init noprocmm_cmd_param(char *str, int* add)
{
proc_mm = 0;
return 0;
}
__uml_setup("noprocmm", noprocmm_cmd_param,
"noprocmm\n"
" Turns off usage of /proc/mm, even if host supports it.\n"
" To support /proc/mm, the host needs to be patched using\n"
" the current skas3 patch.\n\n");
static int __init noptracefaultinfo_cmd_param(char *str, int* add)
{
ptrace_faultinfo = 0;
return 0;
}
__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
"noptracefaultinfo\n"
" Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
" it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
" using the current skas3 patch.\n\n");
static int __init noptraceldt_cmd_param(char *str, int* add)
{
ptrace_ldt = 0;
return 0;
}
__uml_setup("noptraceldt", noptraceldt_cmd_param,
"noptraceldt\n"
" Turns off usage of PTRACE_LDT, even if host supports it.\n"
" To support PTRACE_LDT, the host needs to be patched using\n"
" the current skas3 patch.\n\n");
#ifdef UML_CONFIG_MODE_SKAS
static inline void check_skas3_ptrace_faultinfo(void)
{
struct ptrace_faultinfo fi;
void *stack;
int pid, n;
printf(" - PTRACE_FAULTINFO...");
pid = start_ptraced_child(&stack);
n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
if (n < 0) {
ptrace_faultinfo = 0;
if(errno == EIO)
printf("not found\n");
else
perror("not found");
}
else {
if (!ptrace_faultinfo)
printf("found but disabled on command line\n");
else
printf("found\n");
}
init_registers(pid);
stop_ptraced_child(pid, stack, 1, 1);
}
static inline void check_skas3_ptrace_ldt(void)
{
#ifdef PTRACE_LDT
void *stack;
int pid, n;
unsigned char ldtbuf[40];
struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
.func = 2, /* read default ldt */
.ptr = ldtbuf,
.bytecount = sizeof(ldtbuf)};
printf(" - PTRACE_LDT...");
pid = start_ptraced_child(&stack);
n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
if (n < 0) {
if(errno == EIO)
printf("not found\n");
else {
perror("not found");
}
ptrace_ldt = 0;
}
else {
if(ptrace_ldt)
printf("found\n");
else
printf("found, but use is disabled\n");
}
stop_ptraced_child(pid, stack, 1, 1);
#else
/* PTRACE_LDT might be disabled via cmdline option.
* We want to override this, else we might use the stub
* without real need
*/
ptrace_ldt = 1;
#endif
}
static inline void check_skas3_proc_mm(void)
{
printf(" - /proc/mm...");
if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
proc_mm = 0;
printf("not found\n");
}
else {
if (!proc_mm)
printf("found but disabled on command line\n");
else
printf("found\n");
}
}
int can_do_skas(void)
{
printf("Checking for the skas3 patch in the host:\n");
check_skas3_proc_mm();
check_skas3_ptrace_faultinfo();
check_skas3_ptrace_ldt();
if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
skas_needs_stub = 1;
return 1;
}
#else
int can_do_skas(void)
{
return(0);
}
#endif
int __init parse_iomem(char *str, int *add)
{
struct iomem_region *new;
struct uml_stat buf;
char *file, *driver;
int fd, err, size;
driver = str;
file = strchr(str,',');
if(file == NULL){
printf("parse_iomem : failed to parse iomem\n");
goto out;
}
*file = '\0';
file++;
fd = os_open_file(file, of_rdwr(OPENFLAGS()), 0);
if(fd < 0){
os_print_error(fd, "parse_iomem - Couldn't open io file");
goto out;
}
err = os_stat_fd(fd, &buf);
if(err < 0){
os_print_error(err, "parse_iomem - cannot stat_fd file");
goto out_close;
}
new = malloc(sizeof(*new));
if(new == NULL){
perror("Couldn't allocate iomem_region struct");
goto out_close;
}
size = (buf.ust_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
*new = ((struct iomem_region) { .next = iomem_regions,
.driver = driver,
.fd = fd,
.size = size,
.phys = 0,
.virt = 0 });
iomem_regions = new;
iomem_size += new->size + UM_KERN_PAGE_SIZE;
return(0);
out_close:
os_close_file(fd);
out:
return(1);
}
/* Changed during early boot */
int pty_output_sigio = 0;
int pty_close_sigio = 0;
/* Used as a flag during SIGIO testing early in boot */
static volatile int got_sigio = 0;
static void __init handler(int sig)
{
got_sigio = 1;
}
struct openpty_arg {
int master;
int slave;
int err;
};
static void openpty_cb(void *arg)
{
struct openpty_arg *info = arg;
info->err = 0;
if(openpty(&info->master, &info->slave, NULL, NULL, NULL))
info->err = -errno;
}
static void __init check_one_sigio(void (*proc)(int, int))
{
struct sigaction old, new;
struct openpty_arg pty = { .master = -1, .slave = -1 };
int master, slave, err;
initial_thread_cb(openpty_cb, &pty);
if(pty.err){
printk("openpty failed, errno = %d\n", -pty.err);
return;
}
master = pty.master;
slave = pty.slave;
if((master == -1) || (slave == -1)){
printk("openpty failed to allocate a pty\n");
return;
}
/* Not now, but complain so we now where we failed. */
err = raw(master);
if (err < 0)
panic("check_sigio : __raw failed, errno = %d\n", -err);
err = os_sigio_async(master, slave);
if(err < 0)
panic("tty_fds : sigio_async failed, err = %d\n", -err);
if(sigaction(SIGIO, NULL, &old) < 0)
panic("check_sigio : sigaction 1 failed, errno = %d\n", errno);
new = old;
new.sa_handler = handler;
if(sigaction(SIGIO, &new, NULL) < 0)
panic("check_sigio : sigaction 2 failed, errno = %d\n", errno);
got_sigio = 0;
(*proc)(master, slave);
close(master);
close(slave);
if(sigaction(SIGIO, &old, NULL) < 0)
panic("check_sigio : sigaction 3 failed, errno = %d\n", errno);
}
static void tty_output(int master, int slave)
{
int n;
char buf[512];
printk("Checking that host ptys support output SIGIO...");
memset(buf, 0, sizeof(buf));
while(os_write_file(master, buf, sizeof(buf)) > 0) ;
if(errno != EAGAIN)
panic("check_sigio : write failed, errno = %d\n", errno);
while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ;
if(got_sigio){
printk("Yes\n");
pty_output_sigio = 1;
}
else if(n == -EAGAIN) printk("No, enabling workaround\n");
else panic("check_sigio : read failed, err = %d\n", n);
}
static void tty_close(int master, int slave)
{
printk("Checking that host ptys support SIGIO on close...");
close(slave);
if(got_sigio){
printk("Yes\n");
pty_close_sigio = 1;
}
else printk("No, enabling workaround\n");
}
void __init check_sigio(void)
{
if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) &&
(os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){
printk("No pseudo-terminals available - skipping pty SIGIO "
"check\n");
return;
}
check_one_sigio(tty_output);
check_one_sigio(tty_close);
}
void os_check_bugs(void)
{
check_ptrace();
check_sigio();
}
View Git Blame Copy Permalink