kernel-ark/arch/um/os-Linux/start_up.c
Jeff Dike 3a150e1da8 [PATCH] uml: fix error output during early boot
The startup code panics a lot if anything goes wrong early on.  This is wrong
for several reasons, like the kernel isn't running, so you can't really be
calling into it yet, but the harm comes from useful error messages being
trapped in the printk ring where no one will ever see them.

This patch changes these panics to perror and printf in wrappers which also
exit.  Normal, informational, prints are also wrapped so that fflush(stdout)
is called after each one.  This is so the output appears in the correct
sequence in the event of an error.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:24 -08:00

676 lines
15 KiB
C

/*
* 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);
}
kill(pid, SIGSTOP);
/*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 void fatal_perror(char *str)
{
perror(str);
exit(1);
}
static void fatal(char *fmt, ...)
{
va_list list;
va_start(list, fmt);
vprintf(fmt, list);
va_end(list);
fflush(stdout);
exit(1);
}
static void non_fatal(char *fmt, ...)
{
va_list list;
va_start(list, fmt);
vprintf(fmt, list);
va_end(list);
fflush(stdout);
}
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)
fatal_perror("check_ptrace : mmap failed");
sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
if(pid < 0)
fatal_perror("start_ptraced_child : clone failed");
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
fatal_perror("check_ptrace : clone failed");
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
fatal("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 mustexit)
{
int status, n, ret = 0;
if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
fatal_perror("stop_ptraced_child : ptrace failed");
CATCH_EINTR(n = waitpid(pid, &status, 0));
if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
int exit_with = WEXITSTATUS(status);
if (exit_with == 2)
non_fatal("check_ptrace : child exited with status 2. "
"Serious trouble happening! Try updating "
"your host skas patch!\nDisabling SYSEMU "
"support.");
non_fatal("check_ptrace : child exited with exitcode %d, while "
"expecting %d; status 0x%x\n", exit_with,
exitcode, status);
if (mustexit)
exit(1);
ret = -1;
}
if(munmap(stack, PAGE_SIZE) < 0)
fatal_perror("check_ptrace : munmap failed");
return ret;
}
/* Changed only during early boot */
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");
/* Changed only during early boot */
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;
non_fatal("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)
fatal_perror("check_sysemu : wait failed");
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
fatal("check_sysemu : expected SIGTRAP, got status = %d",
status);
n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if(n < 0)
fatal_perror("check_sysemu : failed to modify system call "
"return");
if (stop_ptraced_child(pid, stack, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 1;
non_fatal("OK\n");
set_using_sysemu(!force_sysemu_disabled);
non_fatal("Checking advanced syscall emulation patch for ptrace...");
pid = start_ptraced_child(&stack);
if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
while(1){
count++;
if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
fatal_perror("check_ptrace : wait failed");
if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
if (!count)
fatal("check_ptrace : SYSEMU_SINGLESTEP "
"doesn't singlestep");
n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if(n < 0)
fatal_perror("check_sysemu : failed to modify "
"system call return");
break;
}
else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
count++;
else
fatal("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;
non_fatal("OK\n");
if ( !force_sysemu_disabled )
set_using_sysemu(sysemu_supported);
return;
fail:
stop_ptraced_child(pid, stack, 1, 0);
fail_stopped:
non_fatal("missing\n");
}
static void __init check_ptrace(void)
{
void *stack;
int pid, syscall, n, status;
non_fatal("Checking that ptrace can change system call numbers...");
pid = start_ptraced_child(&stack);
if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
while(1){
if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
fatal_perror("check_ptrace : ptrace failed");
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
fatal_perror("check_ptrace : wait failed");
if(!WIFSTOPPED(status) ||
(WSTOPSIG(status) != (SIGTRAP | 0x80)))
fatal("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)
fatal_perror("check_ptrace : failed to modify "
"system call");
break;
}
}
stop_ptraced_child(pid, stack, 0, 1);
non_fatal("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;
non_fatal(" - PTRACE_FAULTINFO...");
pid = start_ptraced_child(&stack);
n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
if (n < 0) {
ptrace_faultinfo = 0;
if(errno == EIO)
non_fatal("not found\n");
else
perror("not found");
}
else {
if (!ptrace_faultinfo)
non_fatal("found but disabled on command line\n");
else
non_fatal("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)};
non_fatal(" - PTRACE_LDT...");
pid = start_ptraced_child(&stack);
n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
if (n < 0) {
if(errno == EIO)
non_fatal("not found\n");
else {
perror("not found");
}
ptrace_ldt = 0;
}
else {
if(ptrace_ldt)
non_fatal("found\n");
else
non_fatal("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)
{
non_fatal(" - /proc/mm...");
if (access("/proc/mm", W_OK) < 0) {
proc_mm = 0;
perror("not found");
}
else {
if (!proc_mm)
non_fatal("found but disabled on command line\n");
else
non_fatal("found\n");
}
}
int can_do_skas(void)
{
non_fatal("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 stat64 buf;
char *file, *driver;
int fd, size;
driver = str;
file = strchr(str,',');
if(file == NULL){
printf("parse_iomem : failed to parse iomem\n");
goto out;
}
*file = '\0';
file++;
fd = open(file, O_RDWR, 0);
if(fd < 0){
os_print_error(fd, "parse_iomem - Couldn't open io file");
goto out;
}
if(fstat64(fd, &buf) < 0){
perror("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.st_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:
close(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 int async_pty(int master, int slave)
{
int flags;
flags = fcntl(master, F_GETFL);
if(flags < 0)
return -errno;
if((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
(fcntl(master, F_SETOWN, os_getpid()) < 0))
return -errno;
if((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
return -errno;
return(0);
}
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 = async_pty(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();
}