/*
* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sched.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/wait.h>
#include "user.h"
#include "sysdep/ptrace.h"
#include "sigcontext.h"
#include "sysdep/sigcontext.h"
#include "os.h"
#include "mem_user.h"
#include "process.h"
#include "kern_util.h"
#include "chan_user.h"
#include "ptrace_user.h"
#include "irq_user.h"
#include "mode.h"
#include "tt.h"
static int tracer_winch[2];
int is_tracer_winch(int pid, int fd, void *data)
{
if(pid != os_getpgrp())
return(0);
register_winch_irq(tracer_winch[0], fd, -1, data);
return(1);
}
static void tracer_winch_handler(int sig)
{
int n;
char c = 1;
n = os_write_file(tracer_winch[1], &c, sizeof(c));
if(n != sizeof(c))
printk("tracer_winch_handler - write failed, err = %d\n", -n);
}
/* Called only by the tracing thread during initialization */
static void setup_tracer_winch(void)
{
int err;
err = os_pipe(tracer_winch, 1, 1);
if(err < 0){
printk("setup_tracer_winch : os_pipe failed, err = %d\n", -err);
return;
}
signal(SIGWINCH, tracer_winch_handler);
}
void attach_process(int pid)
{
if((ptrace(PTRACE_ATTACH, pid, 0, 0) < 0) ||
(ptrace(PTRACE_CONT, pid, 0, 0) < 0))
tracer_panic("OP_FORK failed to attach pid");
wait_for_stop(pid, SIGSTOP, PTRACE_CONT, NULL);
if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
tracer_panic("OP_FORK: PTRACE_SETOPTIONS failed, errno = %d", errno);
if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
tracer_panic("OP_FORK failed to continue process");
}
void tracer_panic(char *format, ...)
{
va_list ap;
va_start(ap, format);
vprintf(format, ap);
va_end(ap);
printf("\n");
while(1) pause();
}
static void tracer_segv(int sig, struct sigcontext sc)
{
struct faultinfo fi;
GET_FAULTINFO_FROM_SC(fi, &sc);
printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
FAULT_ADDRESS(fi), SC_IP(&sc));
while(1)
pause();
}
/* Changed early in boot, and then only read */
int debug = 0;
int debug_stop = 1;
int debug_parent = 0;
int honeypot = 0;
static int signal_tramp(void *arg)
{
int (*proc)(void *);
if(honeypot && munmap((void *) (host_task_size - 0x10000000),
0x10000000))
panic("Unmapping stack failed");
if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
panic("ptrace PTRACE_TRACEME failed");
os_stop_process(os_getpid());
change_sig(SIGWINCH, 0);
signal(SIGUSR1, SIG_IGN);
change_sig(SIGCHLD, 0);
signal(SIGSEGV, (__sighandler_t) sig_handler);
set_cmdline("(idle thread)");
set_init_pid(os_getpid());
init_irq_signals(0);
proc = arg;
return((*proc)(NULL));
}
static void sleeping_process_signal(int pid, int sig)
{
switch(sig){
/* These two result from UML being ^Z-ed and bg-ed. PTRACE_CONT is
* right because the process must be in the kernel already.
*/
case SIGCONT:
case SIGTSTP:
if(ptrace(PTRACE_CONT, pid, 0, sig) < 0)
tracer_panic("sleeping_process_signal : Failed to "
"continue pid %d, signal = %d, "
"errno = %d\n", pid, sig, errno);
break;
/* This happens when the debugger (e.g. strace) is doing system call
* tracing on the kernel. During a context switch, the current task
* will be set to the incoming process and the outgoing process will
* hop into write and then read. Since it's not the current process
* any more, the trace of those will land here. So, we need to just
* PTRACE_SYSCALL it.
*/
case (SIGTRAP + 0x80):
if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
tracer_panic("sleeping_process_signal : Failed to "
"PTRACE_SYSCALL pid %d, errno = %d\n",
pid, errno);
break;
case SIGSTOP:
break;
default:
tracer_panic("sleeping process %d got unexpected "
"signal : %d\n", pid, sig);
break;
}
}
/* Accessed only by the tracing thread */
int debugger_pid = -1;
int debugger_parent = -1;
int debugger_fd = -1;
int gdb_pid = -1;
struct {
int pid;
int signal;
unsigned long addr;
struct timeval time;
} signal_record[1024][32];
int signal_index[32];
int nsignals = 0;
int debug_trace = 0;
extern void signal_usr1(int sig);
int tracing_pid = -1;
int tracer(int (*init_proc)(void *), void *sp)
{
void *task = NULL;
int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
int proc_id = 0, n, err, old_tracing = 0, strace = 0;
int local_using_sysemu = 0;
signal(SIGPIPE, SIG_IGN);
setup_tracer_winch();
tracing_pid = os_getpid();
printf("tracing thread pid = %d\n", tracing_pid);
pid = clone(signal_tramp, sp, CLONE_FILES | SIGCHLD, init_proc);
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0){
printf("waitpid on idle thread failed, errno = %d\n", errno);
exit(1);
}
if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) {
printf("Failed to PTRACE_SETOPTIONS for idle thread, errno = %d\n", errno);
exit(1);
}
if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
printf("Failed to continue idle thread, errno = %d\n", errno);
exit(1);
}
signal(SIGSEGV, (sighandler_t) tracer_segv);
signal(SIGUSR1, signal_usr1);
if(debug_trace){
printf("Tracing thread pausing to be attached\n");
stop();
}
if(debug){
if(gdb_pid != -1)
debugger_pid = attach_debugger(pid, gdb_pid, 1);
else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
if(debug_parent){
debugger_parent = os_process_parent(debugger_pid);
init_parent_proxy(debugger_parent);
err = attach(debugger_parent);
if(err){
printf("Failed to attach debugger parent %d, "
"errno = %d\n", debugger_parent, -err);
debugger_parent = -1;
}
else {
if(ptrace(PTRACE_SYSCALL, debugger_parent,
0, 0) < 0){
printf("Failed to continue debugger "
"parent, errno = %d\n", errno);
debugger_parent = -1;
}
}
}
}
set_cmdline("(tracing thread)");
while(1){
CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
if(pid <= 0){
if(errno != ECHILD){
printf("wait failed - errno = %d\n", errno);
}
continue;
}
if(pid == debugger_pid){
int cont = 0;
if(WIFEXITED(status) || WIFSIGNALED(status))
debugger_pid = -1;
/* XXX Figure out how to deal with gdb and SMP */
else cont = debugger_signal(status, cpu_tasks[0].pid);
if(cont == PTRACE_SYSCALL) strace = 1;
continue;
}
else if(pid == debugger_parent){
debugger_parent_signal(status, pid);
continue;
}
nsignals++;
if(WIFEXITED(status)) ;
#ifdef notdef
{
printf("Child %d exited with status %d\n", pid,
WEXITSTATUS(status));
}
#endif
else if(WIFSIGNALED(status)){
sig = WTERMSIG(status);
if(sig != 9){
printf("Child %d exited with signal %d\n", pid,
sig);
}
}
else if(WIFSTOPPED(status)){
proc_id = pid_to_processor_id(pid);
sig = WSTOPSIG(status);
if(proc_id == -1){
sleeping_process_signal(pid, sig);
continue;
}
task = cpu_tasks[proc_id].task;
tracing = is_tracing(task);
old_tracing = tracing;
/* Assume: no syscall, when coming from user */
if ( tracing )
do_sigtrap(task);
switch(sig){
case SIGUSR1:
sig = 0;
op = do_proc_op(task, proc_id);
switch(op){
/*
* This is called when entering user mode; after
* this, we start intercepting syscalls.
*
* In fact, a process is started in kernel mode,
* so with is_tracing() == 0 (and that is reset
* when executing syscalls, since UML kernel has
* the right to do syscalls);
*/
case OP_TRACE_ON:
arch_leave_kernel(task, pid);
tracing = 1;
break;
case OP_REBOOT:
case OP_HALT:
unmap_physmem();
kmalloc_ok = 0;
os_kill_ptraced_process(pid, 0);
/* Now let's reap remaining zombies */
errno = 0;
do {
waitpid(-1, &status,
WUNTRACED);
} while (errno != ECHILD);
return(op == OP_REBOOT);
case OP_NONE:
printf("Detaching pid %d\n", pid);
detach(pid, SIGSTOP);
continue;
default:
break;
}
/* OP_EXEC switches host processes on us,
* we want to continue the new one.
*/
pid = cpu_tasks[proc_id].pid;
break;
case (SIGTRAP + 0x80):
if(!tracing && (debugger_pid != -1)){
child_signal(pid, status & 0x7fff);
continue;
}
tracing = 0;
/* local_using_sysemu has been already set
* below, since if we are here, is_tracing() on
* the traced task was 1, i.e. the process had
* already run through one iteration of the
* loop which executed a OP_TRACE_ON request.*/
do_syscall(task, pid, local_using_sysemu);
sig = SIGUSR2;
break;
case SIGTRAP:
if(!tracing && (debugger_pid != -1)){
child_signal(pid, status);
continue;
}
tracing = 0;
break;
case SIGPROF:
if(tracing) sig = 0;
break;
case SIGCHLD:
case SIGHUP:
sig = 0;
break;
case SIGSEGV:
case SIGIO:
case SIGALRM:
case SIGVTALRM:
case SIGFPE:
case SIGBUS:
case SIGILL:
case SIGWINCH:
default:
tracing = 0;
break;
}
set_tracing(task, tracing);
if(!tracing && old_tracing)
arch_enter_kernel(task, pid);
if(!tracing && (debugger_pid != -1) && (sig != 0) &&
(sig != SIGALRM) && (sig != SIGVTALRM) &&
(sig != SIGSEGV) && (sig != SIGTRAP) &&
(sig != SIGUSR2) && (sig != SIGIO) &&
(sig != SIGFPE)){
child_signal(pid, status);
continue;
}
local_using_sysemu = get_using_sysemu();
if(tracing)
cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
singlestepping(task));
else if((debugger_pid != -1) && strace)
cont_type = PTRACE_SYSCALL;
else
cont_type = PTRACE_CONT;
if(ptrace(cont_type, pid, 0, sig) != 0){
tracer_panic("ptrace failed to continue "
"process - errno = %d\n",
errno);
}
}
}
return(0);
}
static int __init uml_debug_setup(char *line, int *add)
{
char *next;
debug = 1;
*add = 0;
if(*line != '=') return(0);
line++;
while(line != NULL){
next = strchr(line, ',');
if(next) *next++ = '\0';
if(!strcmp(line, "go")) debug_stop = 0;
else if(!strcmp(line, "parent")) debug_parent = 1;
else printf("Unknown debug option : '%s'\n", line);
line = next;
}
return(0);
}
__uml_setup("debug", uml_debug_setup,
"debug\n"
" Starts up the kernel under the control of gdb. See the \n"
" kernel debugging tutorial and the debugging session pages\n"
" at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
);
static int __init uml_debugtrace_setup(char *line, int *add)
{
debug_trace = 1;
return 0;
}
__uml_setup("debugtrace", uml_debugtrace_setup,
"debugtrace\n"
" Causes the tracing thread to pause until it is attached by a\n"
" debugger and continued. This is mostly for debugging crashes\n"
" early during boot, and should be pretty much obsoleted by\n"
" the debug switch.\n\n"
);
/*
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/
