arch/um/kernel/skas/process.c

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

#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <setjmp.h>
#include <sched.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <asm/unistd.h>
#include "user.h"
#include "ptrace_user.h"
#include "time_user.h"
#include "sysdep/ptrace.h"
#include "user_util.h"
#include "kern_util.h"
#include "skas.h"
#include "sysdep/sigcontext.h"
#include "os.h"
#include "proc_mm.h"
#include "skas_ptrace.h"
#include "chan_user.h"
#include "signal_user.h"
#include "registers.h"

int is_skas_winch(int pid, int fd, void *data)
{
	if(pid != os_getpid())
		return(0);

	register_winch_irq(-1, fd, -1, data);
	return(1);
}

static void handle_segv(int pid)
{
	struct ptrace_faultinfo fault;
	int err;

	err = ptrace(PTRACE_FAULTINFO, pid, 0, &fault);
	if(err)
		panic("handle_segv - PTRACE_FAULTINFO failed, errno = %d\n",
		      errno);

	segv(fault.addr, 0, FAULT_WRITE(fault.is_write), 1, NULL);
}

/*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
{
	int err, status;

	/* Mark this as a syscall */
	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);

	if (!local_using_sysemu)
	{
		err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
		if(err < 0)
			panic("handle_trap - nullifying syscall failed errno = %d\n",
			      errno);

		err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
		if(err < 0)
			panic("handle_trap - continuing to end of syscall failed, "
			      "errno = %d\n", errno);

		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
		if((err < 0) || !WIFSTOPPED(status) ||
		   (WSTOPSIG(status) != SIGTRAP + 0x80))
			panic("handle_trap - failed to wait at end of syscall, "
			      "errno = %d, status = %d\n", errno, status);
	}

	handle_syscall(regs);
}

static int userspace_tramp(void *arg)
{
	init_new_thread_signals(0);
	enable_timer();
	ptrace(PTRACE_TRACEME, 0, 0, 0);
	os_stop_process(os_getpid());
	return(0);
}

/* Each element set once, and only accessed by a single processor anyway */
#undef NR_CPUS
#define NR_CPUS 1
int userspace_pid[NR_CPUS];

void start_userspace(int cpu)
{
	void *stack;
	unsigned long sp;
	int pid, status, n;

	stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
	if(stack == MAP_FAILED)
		panic("start_userspace : mmap failed, errno = %d", errno);
	sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);

	pid = clone(userspace_tramp, (void *) sp, 
		    CLONE_FILES | CLONE_VM | SIGCHLD, NULL);
	if(pid < 0)
		panic("start_userspace : clone failed, errno = %d", errno);

	do {
		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
		if(n < 0)
			panic("start_userspace : wait failed, errno = %d", 
			      errno);
	} while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));

	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
		panic("start_userspace : expected SIGSTOP, got status = %d",
		      status);

	if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
		panic("start_userspace : PTRACE_SETOPTIONS failed, errno=%d\n",
		      errno);

	if(munmap(stack, PAGE_SIZE) < 0)
		panic("start_userspace : munmap failed, errno = %d\n", errno);

	userspace_pid[cpu] = pid;
}

void userspace(union uml_pt_regs *regs)
{
	int err, status, op, pid = userspace_pid[0];
	int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/

	while(1){
		restore_registers(pid, regs);

		/* Now we set local_using_sysemu to be used for one loop */
		local_using_sysemu = get_using_sysemu();

		op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));

		err = ptrace(op, pid, 0, 0);
		if(err)
			panic("userspace - could not resume userspace process, "
			      "pid=%d, ptrace operation = %d, errno = %d\n",
			      op, errno);

		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
		if(err < 0)
			panic("userspace - waitpid failed, errno = %d\n", 
			      errno);

		regs->skas.is_user = 1;
		save_registers(pid, regs);
		UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */

		if(WIFSTOPPED(status)){
		  	switch(WSTOPSIG(status)){
			case SIGSEGV:
				handle_segv(pid);
				break;
			case SIGTRAP + 0x80:
			        handle_trap(pid, regs, local_using_sysemu);
				break;
			case SIGTRAP:
				relay_signal(SIGTRAP, regs);
				break;
			case SIGIO:
			case SIGVTALRM:
			case SIGILL:
			case SIGBUS:
			case SIGFPE:
			case SIGWINCH:
				user_signal(WSTOPSIG(status), regs);
				break;
			default:
			        printk("userspace - child stopped with signal "
				       "%d\n", WSTOPSIG(status));
			}
			interrupt_end();

			/* Avoid -ERESTARTSYS handling in host */
			PT_SYSCALL_NR(regs->skas.regs) = -1;
		}
	}
}

void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
		void (*handler)(int))
{
	unsigned long flags;
	sigjmp_buf switch_buf, fork_buf;

	*switch_buf_ptr = &switch_buf;
	*fork_buf_ptr = &fork_buf;

	/* Somewhat subtle - siglongjmp restores the signal mask before doing
	 * the longjmp.  This means that when jumping from one stack to another
	 * when the target stack has interrupts enabled, an interrupt may occur
	 * on the source stack.  This is bad when starting up a process because
	 * it's not supposed to get timer ticks until it has been scheduled.
	 * So, we disable interrupts around the sigsetjmp to ensure that
	 * they can't happen until we get back here where they are safe.
	 */
	flags = get_signals();
	block_signals();
	if(sigsetjmp(fork_buf, 1) == 0)
		new_thread_proc(stack, handler);

	remove_sigstack();

	set_signals(flags);
}

void thread_wait(void *sw, void *fb)
{
	sigjmp_buf buf, **switch_buf = sw, *fork_buf;

	*switch_buf = &buf;
	fork_buf = fb;
	if(sigsetjmp(buf, 1) == 0)
		siglongjmp(*fork_buf, 1);
}

void switch_threads(void *me, void *next)
{
	sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
	
	*me_ptr = &my_buf;
	if(sigsetjmp(my_buf, 1) == 0)
		siglongjmp(*next_buf, 1);
}

static sigjmp_buf initial_jmpbuf;

/* XXX Make these percpu */
static void (*cb_proc)(void *arg);
static void *cb_arg;
static sigjmp_buf *cb_back;

int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
{
	sigjmp_buf **switch_buf = switch_buf_ptr;
	int n;

	*fork_buf_ptr = &initial_jmpbuf;
	n = sigsetjmp(initial_jmpbuf, 1);
	if(n == 0)
		new_thread_proc((void *) stack, new_thread_handler);
	else if(n == 1)
		remove_sigstack();
	else if(n == 2){
		(*cb_proc)(cb_arg);
		siglongjmp(*cb_back, 1);
	}
	else if(n == 3){
		kmalloc_ok = 0;
		return(0);
	}
	else if(n == 4){
		kmalloc_ok = 0;
		return(1);
	}
	siglongjmp(**switch_buf, 1);
}

void remove_sigstack(void)
{
	stack_t stack = ((stack_t) { .ss_flags	= SS_DISABLE,
				     .ss_sp	= NULL,
				     .ss_size	= 0 });

	if(sigaltstack(&stack, NULL) != 0)
		panic("disabling signal stack failed, errno = %d\n", errno);
}

void initial_thread_cb_skas(void (*proc)(void *), void *arg)
{
	sigjmp_buf here;

	cb_proc = proc;
	cb_arg = arg;
	cb_back = &here;

	block_signals();
	if(sigsetjmp(here, 1) == 0)
		siglongjmp(initial_jmpbuf, 2);
	unblock_signals();

	cb_proc = NULL;
	cb_arg = NULL;
	cb_back = NULL;
}

void halt_skas(void)
{
	block_signals();
	siglongjmp(initial_jmpbuf, 3);
}

void reboot_skas(void)
{
	block_signals();
	siglongjmp(initial_jmpbuf, 4);
}

void switch_mm_skas(int mm_fd)
{
	int err;

#warning need cpu pid in switch_mm_skas
	err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0, mm_fd);
	if(err)
		panic("switch_mm_skas - PTRACE_SWITCH_MM failed, errno = %d\n",
		      errno);
}

void kill_off_processes_skas(void)
{
#warning need to loop over userspace_pids in kill_off_processes_skas
	os_kill_ptraced_process(userspace_pid[0], 1);
}

/*
 * 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:
 */