[deliverable/linux.git] / arch / um / kernel / process.c

/* 
 * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sched.h>
#include <errno.h>
#include <stdarg.h>
#include <stdlib.h>
#include <setjmp.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <asm/unistd.h>
#include <asm/page.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "process.h"
#include "signal_kern.h"
#include "signal_user.h"
#include "sysdep/ptrace.h"
#include "sysdep/sigcontext.h"
#include "irq_user.h"
#include "ptrace_user.h"
#include "time_user.h"
#include "init.h"
#include "os.h"
#include "uml-config.h"
#include "choose-mode.h"
#include "mode.h"
#include "tempfile.h"
#ifdef UML_CONFIG_MODE_SKAS
#include "skas.h"
#include "skas_ptrace.h"
#include "registers.h"
#endif

void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
{
	int flags = 0, pages;

	if(sig_stack != NULL){
		pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);
		set_sigstack(sig_stack, pages * page_size());
		flags = SA_ONSTACK;
	}
	if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
}

void init_new_thread_signals(int altstack)
{
	int flags = altstack ? SA_ONSTACK : 0;

	set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags, 
		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	set_handler(SIGFPE, (__sighandler_t) sig_handler, flags, 
		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	set_handler(SIGILL, (__sighandler_t) sig_handler, flags, 
		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags, 
		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	set_handler(SIGUSR2, (__sighandler_t) sig_handler, 
		    flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	signal(SIGHUP, SIG_IGN);

	init_irq_signals(altstack);
}

struct tramp {
	int (*tramp)(void *);
	void *tramp_data;
	unsigned long temp_stack;
	int flags;
	int pid;
};

/* See above for why sigkill is here */

int sigkill = SIGKILL;

int outer_tramp(void *arg)
{
	struct tramp *t;
	int sig = sigkill;

	t = arg;
	t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,
		       t->flags, t->tramp_data);
	if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);
	kill(os_getpid(), sig);
	_exit(0);
}

int start_fork_tramp(void *thread_arg, unsigned long temp_stack, 
		     int clone_flags, int (*tramp)(void *))
{
	struct tramp arg;
	unsigned long sp;
	int new_pid, status, err;

	/* The trampoline will run on the temporary stack */
	sp = stack_sp(temp_stack);

	clone_flags |= CLONE_FILES | SIGCHLD;

	arg.tramp = tramp;
	arg.tramp_data = thread_arg;
	arg.temp_stack = temp_stack;
	arg.flags = clone_flags;

	/* Start the process and wait for it to kill itself */
	new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);
	if(new_pid < 0)
		return(new_pid);

	CATCH_EINTR(err = waitpid(new_pid, &status, 0));
	if(err < 0)
		panic("Waiting for outer trampoline failed - errno = %d",
		      errno);

	if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL))
		panic("outer trampoline didn't exit with SIGKILL, "
		      "status = %d", status);

	return(arg.pid);
}

static int ptrace_child(void)
{
	int ret;
	int pid = os_getpid(), ppid = getppid();
	int sc_result;

	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)
{
	int pid, n, status;
	
	pid = fork();
	if(pid == 0)
		ptrace_child();

	if(pid < 0)
		panic("check_ptrace : fork 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) != SIGSTOP))
		panic("check_ptrace : expected SIGSTOP, got status = %d",
		      status);

	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, int exitcode, int mustexit)
{
	int status, n, ret = 0;

	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
		panic("stop_ptraced_child : 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)
			printk("check_ptrace : child exited with status 2. "
			       "Serious trouble happening! Try updating your "
			       "host skas patch!\nDisabling SYSEMU support.");
		printk("check_ptrace : child exited with exitcode %d, while "
		      "expecting %d; status 0x%x", exit_with,
		      exitcode, status);
		if (mustexit)
			panic("\n");
		else
			printk("\n");
		ret = -1;
	}

	return ret;
}

static int force_sysemu_disabled = 0;

int ptrace_faultinfo = 1;
int proc_mm = 1;

static int __init skas0_cmd_param(char *str, int* add)
{
	ptrace_faultinfo = proc_mm = 0;
	return 0;
}

static int __init nosysemu_cmd_param(char *str, int* add)
{
	force_sysemu_disabled = 1;
	return 0;
}

__uml_setup("skas0", skas0_cmd_param,
		"skas0\n"
		"    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
		"    specify mode=tt.\n\n");

__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 information.\n\n");

static void __init check_sysemu(void)
{
	int pid, syscall, n, status, count=0;

	printk("Checking syscall emulation patch for ptrace...");
	sysemu_supported = 0;
	pid = start_ptraced_child();

	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, 0, 0) < 0)
		goto fail_stopped;

	sysemu_supported = 1;
	printk("OK\n");
	set_using_sysemu(!force_sysemu_disabled);

	printk("Checking advanced syscall emulation patch for ptrace...");
	pid = start_ptraced_child();
	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))
			panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), "
			      "got status = %d", status);

		syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
				 0);
		if(syscall == __NR_getpid){
			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;
		}
	}
	if (stop_ptraced_child(pid, 0, 0) < 0)
		goto fail_stopped;

	sysemu_supported = 2;
	printk("OK\n");

	if ( !force_sysemu_disabled )
		set_using_sysemu(sysemu_supported);
	return;

fail:
	stop_ptraced_child(pid, 1, 0);
fail_stopped:
	printk("missing\n");
}

void __init check_ptrace(void)
{
	int pid, syscall, n, status;

	printk("Checking that ptrace can change system call numbers...");
	pid = start_ptraced_child();

	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
		panic("check_ptrace: PTRACE_SETOPTIONS 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, 0, 1);
	printk("OK\n");
	check_sysemu();
}

int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
{
	sigjmp_buf buf;
	int n;

	*jmp_ptr = &buf;
	n = sigsetjmp(buf, 1);
	if(n != 0)
		return(n);
	(*fn)(arg);
	return(0);
}

void forward_pending_sigio(int target)
{
	sigset_t sigs;

	if(sigpending(&sigs)) 
		panic("forward_pending_sigio : sigpending failed");
	if(sigismember(&sigs, SIGIO))
		kill(target, SIGIO);
}

extern void *__syscall_stub_start, __syscall_stub_end;

#ifdef UML_CONFIG_MODE_SKAS

static inline void check_skas3_ptrace_support(void)
{
	struct ptrace_faultinfo fi;
	int pid, n;

	printf("Checking for the skas3 patch in the host...");
	pid = start_ptraced_child();

	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, 1, 1);
}

int can_do_skas(void)
{
	printf("Checking for /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");
	}

	check_skas3_ptrace_support();
	return 1;
}
#else
int can_do_skas(void)
{
	return(0);
}
#endif
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
	3	* Licensed under the GPL
	4	*/
	5
	6	#include <stdio.h>
	7	#include <unistd.h>
	8	#include <signal.h>
	9	#include <sched.h>
	10	#include <errno.h>
	11	#include <stdarg.h>
	12	#include <stdlib.h>
	13	#include <setjmp.h>
	14	#include <sys/time.h>
	15	#include <sys/wait.h>
	16	#include <sys/mman.h>
	17	#include <asm/unistd.h>
	18	#include <asm/page.h>
	19	#include "user_util.h"
	20	#include "kern_util.h"
	21	#include "user.h"
	22	#include "process.h"
	23	#include "signal_kern.h"
	24	#include "signal_user.h"
	25	#include "sysdep/ptrace.h"
	26	#include "sysdep/sigcontext.h"
	27	#include "irq_user.h"
	28	#include "ptrace_user.h"
	29	#include "time_user.h"
	30	#include "init.h"
	31	#include "os.h"
	32	#include "uml-config.h"
1da177e4 LT	33	#include "choose-mode.h"
1da177e4 LT	34	#include "mode.h"
d67b569f	35	#include "tempfile.h"
1da177e4 LT	36	#ifdef UML_CONFIG_MODE_SKAS
	37	#include "skas.h"
	38	#include "skas_ptrace.h"
	39	#include "registers.h"
	40	#endif
	41
	42	void init_new_thread_stack(void sig_stack, void (usr1_handler)(int))
	43	{
	44	int flags = 0, pages;
	45
	46	if(sig_stack != NULL){
	47	pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);
	48	set_sigstack(sig_stack, pages * page_size());
	49	flags = SA_ONSTACK;
	50	}
	51	if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
	52	}
	53
	54	void init_new_thread_signals(int altstack)
	55	{
	56	int flags = altstack ? SA_ONSTACK : 0;
	57
	58	set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
	59	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	60	set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags,
	61	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	62	set_handler(SIGFPE, (__sighandler_t) sig_handler, flags,
	63	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	64	set_handler(SIGILL, (__sighandler_t) sig_handler, flags,
	65	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	66	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags,
	67	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
1da177e4 LT	68	set_handler(SIGUSR2, (__sighandler_t) sig_handler,
	69	flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
	70	signal(SIGHUP, SIG_IGN);
	71
	72	init_irq_signals(altstack);
	73	}
	74
	75	struct tramp {
	76	int (tramp)(void );
	77	void *tramp_data;
	78	unsigned long temp_stack;
	79	int flags;
	80	int pid;
	81	};
	82
	83	/* See above for why sigkill is here */
	84
	85	int sigkill = SIGKILL;
	86
	87	int outer_tramp(void *arg)
	88	{
	89	struct tramp *t;
	90	int sig = sigkill;
	91
	92	t = arg;
	93	t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,
	94	t->flags, t->tramp_data);
	95	if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);
	96	kill(os_getpid(), sig);
	97	_exit(0);
	98	}
	99
	100	int start_fork_tramp(void *thread_arg, unsigned long temp_stack,
	101	int clone_flags, int (tramp)(void ))
	102	{
	103	struct tramp arg;
	104	unsigned long sp;
	105	int new_pid, status, err;
	106
	107	/* The trampoline will run on the temporary stack */
	108	sp = stack_sp(temp_stack);
	109
	110	clone_flags \|= CLONE_FILES \| SIGCHLD;
	111
	112	arg.tramp = tramp;
	113	arg.tramp_data = thread_arg;
	114	arg.temp_stack = temp_stack;
	115	arg.flags = clone_flags;
	116
	117	/* Start the process and wait for it to kill itself */
	118	new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);
	119	if(new_pid < 0)
	120	return(new_pid);
	121
	122	CATCH_EINTR(err = waitpid(new_pid, &status, 0));
	123	if(err < 0)
	124	panic("Waiting for outer trampoline failed - errno = %d",
	125	errno);
	126
	127	if(!WIFSIGNALED(status) \|\| (WTERMSIG(status) != SIGKILL))
	128	panic("outer trampoline didn't exit with SIGKILL, "
	129	"status = %d", status);
	130
	131	return(arg.pid);
132	}
133
98fdffcc	134	static int ptrace_child(void)
1da177e4 LT	135	{
	136	int ret;
	137	int pid = os_getpid(), ppid = getppid();
	138	int sc_result;
	139
	140	if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
	141	perror("ptrace");
	142	os_kill_process(pid, 0);
	143	}
	144	os_stop_process(pid);
	145
	146	/*This syscall will be intercepted by the parent. Don't call more than
	147	* once, please.*/
	148	sc_result = os_getpid();
	149
	150	if (sc_result == pid)
	151	ret = 1; /*Nothing modified by the parent, we are running
	152	normally.*/
	153	else if (sc_result == ppid)
	154	ret = 0; /*Expected in check_ptrace and check_sysemu when they
	155	succeed in modifying the stack frame*/
	156	else
	157	ret = 2; /*Serious trouble! This could be caused by a bug in
	158	host 2.6 SKAS3/2.6 patch before release -V6, together
	159	with a bug in the UML code itself.*/
	160	_exit(ret);
	161	}
	162
98fdffcc	163	static int start_ptraced_child(void)
1da177e4	164	{
1da177e4 LT	165	int pid, n, status;
1da177e4 LT	166
98fdffcc JD	167	pid = fork();
	168	if(pid == 0)
	169	ptrace_child();
	170
1da177e4	171	if(pid < 0)
98fdffcc	172	panic("check_ptrace : fork failed, errno = %d", errno);
1da177e4 LT	173	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	174	if(n < 0)
	175	panic("check_ptrace : wait failed, errno = %d", errno);
	176	if(!WIFSTOPPED(status) \|\| (WSTOPSIG(status) != SIGSTOP))
	177	panic("check_ptrace : expected SIGSTOP, got status = %d",
	178	status);
	179
1da177e4 LT	180	return(pid);
	181	}
	182
	183	/* When testing for SYSEMU support, if it is one of the broken versions, we must
	184	* just avoid using sysemu, not panic, but only if SYSEMU features are broken.
	185	* So only for SYSEMU features we test mustpanic, while normal host features
	186	* must work anyway!*/
98fdffcc	187	static int stop_ptraced_child(int pid, int exitcode, int mustexit)
1da177e4 LT	188	{
	189	int status, n, ret = 0;
	190
	191	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
98fdffcc	192	panic("stop_ptraced_child : ptrace failed, errno = %d", errno);
1da177e4 LT	193	CATCH_EINTR(n = waitpid(pid, &status, 0));
	194	if(!WIFEXITED(status) \|\| (WEXITSTATUS(status) != exitcode)) {
	195	int exit_with = WEXITSTATUS(status);
	196	if (exit_with == 2)
	197	printk("check_ptrace : child exited with status 2. "
	198	"Serious trouble happening! Try updating your "
	199	"host skas patch!\nDisabling SYSEMU support.");
	200	printk("check_ptrace : child exited with exitcode %d, while "
	201	"expecting %d; status 0x%x", exit_with,
	202	exitcode, status);
98fdffcc	203	if (mustexit)
1da177e4 LT	204	panic("\n");
	205	else
	206	printk("\n");
	207	ret = -1;
	208	}
	209
1da177e4 LT	210	return ret;
	211	}
	212
	213	static int force_sysemu_disabled = 0;
	214
cb66504d PBG	215	int ptrace_faultinfo = 1;
	216	int proc_mm = 1;
	217
	218	static int __init skas0_cmd_param(char str, int add)
	219	{
	220	ptrace_faultinfo = proc_mm = 0;
	221	return 0;
	222	}
	223
1da177e4 LT	224	static int __init nosysemu_cmd_param(char str, int add)
	225	{
	226	force_sysemu_disabled = 1;
	227	return 0;
	228	}
	229
cb66504d PBG	230	__uml_setup("skas0", skas0_cmd_param,
	231	"skas0\n"
	232	" Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
	233	" specify mode=tt.\n\n");
	234
1da177e4 LT	235	__uml_setup("nosysemu", nosysemu_cmd_param,
	236	"nosysemu\n"
	237	" Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
	238	" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
	239	" behaviour of ptrace() and helps reducing host context switch rate.\n"
	240	" To make it working, you need a kernel patch for your host, too.\n"
	241	" See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n");
	242
	243	static void __init check_sysemu(void)
	244	{
1da177e4 LT	245	int pid, syscall, n, status, count=0;
	246
	247	printk("Checking syscall emulation patch for ptrace...");
	248	sysemu_supported = 0;
98fdffcc	249	pid = start_ptraced_child();
1da177e4 LT	250
	251	if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
	252	goto fail;
	253
	254	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	255	if (n < 0)
	256	panic("check_sysemu : wait failed, errno = %d", errno);
	257	if(!WIFSTOPPED(status) \|\| (WSTOPSIG(status) != SIGTRAP))
	258	panic("check_sysemu : expected SIGTRAP, "
	259	"got status = %d", status);
	260
	261	n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
	262	os_getpid());
	263	if(n < 0)
	264	panic("check_sysemu : failed to modify system "
	265	"call return, errno = %d", errno);
	266
98fdffcc	267	if (stop_ptraced_child(pid, 0, 0) < 0)
1da177e4 LT	268	goto fail_stopped;
	269
	270	sysemu_supported = 1;
	271	printk("OK\n");
	272	set_using_sysemu(!force_sysemu_disabled);
	273
	274	printk("Checking advanced syscall emulation patch for ptrace...");
98fdffcc	275	pid = start_ptraced_child();
1da177e4 LT	276	while(1){
	277	count++;
	278	if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
	279	goto fail;
	280	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	281	if(n < 0)
	282	panic("check_ptrace : wait failed, errno = %d", errno);
	283	if(!WIFSTOPPED(status) \|\| (WSTOPSIG(status) != SIGTRAP))
	284	panic("check_ptrace : expected (SIGTRAP\|SYSCALL_TRAP), "
	285	"got status = %d", status);
	286
	287	syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
	288	0);
	289	if(syscall == __NR_getpid){
	290	if (!count)
	291	panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep");
	292	n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
	293	os_getpid());
	294	if(n < 0)
	295	panic("check_sysemu : failed to modify system "
	296	"call return, errno = %d", errno);
	297	break;
	298	}
	299	}
98fdffcc	300	if (stop_ptraced_child(pid, 0, 0) < 0)
1da177e4 LT	301	goto fail_stopped;
	302
	303	sysemu_supported = 2;
	304	printk("OK\n");
	305
	306	if ( !force_sysemu_disabled )
	307	set_using_sysemu(sysemu_supported);
	308	return;
	309
	310	fail:
98fdffcc	311	stop_ptraced_child(pid, 1, 0);
1da177e4 LT	312	fail_stopped:
	313	printk("missing\n");
	314	}
	315
	316	void __init check_ptrace(void)
	317	{
1da177e4 LT	318	int pid, syscall, n, status;
	319
	320	printk("Checking that ptrace can change system call numbers...");
98fdffcc	321	pid = start_ptraced_child();
1da177e4 LT	322
	323	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
	324	panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno);
	325
	326	while(1){
	327	if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
	328	panic("check_ptrace : ptrace failed, errno = %d",
	329	errno);
	330	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	331	if(n < 0)
	332	panic("check_ptrace : wait failed, errno = %d", errno);
	333	if(!WIFSTOPPED(status) \|\| (WSTOPSIG(status) != SIGTRAP + 0x80))
	334	panic("check_ptrace : expected SIGTRAP + 0x80, "
	335	"got status = %d", status);
	336
	337	syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
	338	0);
	339	if(syscall == __NR_getpid){
	340	n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
	341	__NR_getppid);
	342	if(n < 0)
	343	panic("check_ptrace : failed to modify system "
	344	"call, errno = %d", errno);
	345	break;
	346	}
	347	}
98fdffcc	348	stop_ptraced_child(pid, 0, 1);
1da177e4 LT	349	printk("OK\n");
	350	check_sysemu();
	351	}
	352
	353	int run_kernel_thread(int (fn)(void ), void arg, void *jmp_ptr)
	354	{
	355	sigjmp_buf buf;
	356	int n;
	357
	358	*jmp_ptr = &buf;
	359	n = sigsetjmp(buf, 1);
	360	if(n != 0)
	361	return(n);
	362	(*fn)(arg);
	363	return(0);
	364	}
	365
	366	void forward_pending_sigio(int target)
	367	{
	368	sigset_t sigs;
	369
	370	if(sigpending(&sigs))
	371	panic("forward_pending_sigio : sigpending failed");
	372	if(sigismember(&sigs, SIGIO))
	373	kill(target, SIGIO);
	374	}
	375
d67b569f JD	376	extern void *__syscall_stub_start, __syscall_stub_end;
d67b569f JD	377
1da177e4	378	#ifdef UML_CONFIG_MODE_SKAS
cb66504d	379
d67b569f	380	static inline void check_skas3_ptrace_support(void)
1da177e4 LT	381	{
1da177e4 LT	382	struct ptrace_faultinfo fi;
d67b569f	383	int pid, n;
1da177e4 LT	384
1da177e4 LT	385	printf("Checking for the skas3 patch in the host...");
98fdffcc	386	pid = start_ptraced_child();
1da177e4 LT	387
	388	n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
	389	if (n < 0) {
cb66504d	390	ptrace_faultinfo = 0;
1da177e4 LT	391	if(errno == EIO)
	392	printf("not found\n");
	393	else {
	394	perror("not found");
	395	}
d67b569f JD	396	}
d67b569f JD	397	else {
cb66504d PBG	398	if (!ptrace_faultinfo)
	399	printf("found but disabled on command line\n");
	400	else
	401	printf("found\n");
1da177e4 LT	402	}
	403
	404	init_registers(pid);
98fdffcc	405	stop_ptraced_child(pid, 1, 1);
1da177e4 LT	406	}
	407
	408	int can_do_skas(void)
	409	{
1da177e4 LT	410	printf("Checking for /proc/mm...");
1da177e4 LT	411	if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
d67b569f	412	proc_mm = 0;
1da177e4	413	printf("not found\n");
cb66504d PBG	414	} else {
	415	if (!proc_mm)
	416	printf("found but disabled on command line\n");
	417	else
	418	printf("found\n");
1da177e4 LT	419	}
1da177e4 LT	420
d67b569f JD	421	check_skas3_ptrace_support();
d67b569f JD	422	return 1;
1da177e4 LT	423	}
	424	#else
	425	int can_do_skas(void)
	426	{
	427	return(0);
	428	}
	429	#endif