e06173bde0
Kill a process that tries to branch into a stub and execute a system call. There are no security implications here - a system call in a stub is treated the same as a system call anywhere else. But if a process is trying to branch into a stub, either it is trying something nasty or it has gone haywire, so it's a good idea to get rid of it in either case. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
714 lines
18 KiB
C
714 lines
18 KiB
C
/*
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* Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <stdlib.h>
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#include <unistd.h>
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#include <sched.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/ptrace.h>
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#include <sys/wait.h>
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#include <asm/unistd.h>
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#include "as-layout.h"
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#include "chan_user.h"
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#include "kern_constants.h"
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#include "kern_util.h"
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#include "mem.h"
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#include "os.h"
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#include "process.h"
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#include "proc_mm.h"
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#include "ptrace_user.h"
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#include "registers.h"
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#include "skas.h"
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#include "skas_ptrace.h"
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#include "user.h"
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#include "sysdep/stub.h"
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int is_skas_winch(int pid, int fd, void *data)
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{
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if (pid != getpgrp())
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return 0;
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register_winch_irq(-1, fd, -1, data, 0);
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return 1;
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}
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static int ptrace_dump_regs(int pid)
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{
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unsigned long regs[MAX_REG_NR];
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int i;
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if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
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return -errno;
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printk(UM_KERN_ERR "Stub registers -\n");
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for (i = 0; i < ARRAY_SIZE(regs); i++)
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printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
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return 0;
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}
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/*
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* Signals that are OK to receive in the stub - we'll just continue it.
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* SIGWINCH will happen when UML is inside a detached screen.
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*/
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#define STUB_SIG_MASK (1 << SIGVTALRM)
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/* Signals that the stub will finish with - anything else is an error */
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#define STUB_DONE_MASK (1 << SIGTRAP)
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void wait_stub_done(int pid)
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{
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int n, status, err;
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while (1) {
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
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if ((n < 0) || !WIFSTOPPED(status))
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goto bad_wait;
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if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
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break;
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err = ptrace(PTRACE_CONT, pid, 0, 0);
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if (err) {
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printk(UM_KERN_ERR "wait_stub_done : continue failed, "
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"errno = %d\n", errno);
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fatal_sigsegv();
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}
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}
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if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
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return;
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bad_wait:
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err = ptrace_dump_regs(pid);
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if (err)
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printk(UM_KERN_ERR "Failed to get registers from stub, "
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"errno = %d\n", -err);
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printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
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"pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
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status);
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fatal_sigsegv();
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}
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extern unsigned long current_stub_stack(void);
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void get_skas_faultinfo(int pid, struct faultinfo * fi)
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{
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int err;
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if (ptrace_faultinfo) {
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err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
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if (err) {
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printk(UM_KERN_ERR "get_skas_faultinfo - "
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"PTRACE_FAULTINFO failed, errno = %d\n", errno);
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fatal_sigsegv();
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}
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/* Special handling for i386, which has different structs */
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if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
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memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
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sizeof(struct faultinfo) -
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sizeof(struct ptrace_faultinfo));
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}
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else {
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err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
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if (err) {
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printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
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"errno = %d\n", pid, errno);
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fatal_sigsegv();
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}
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wait_stub_done(pid);
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/*
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* faultinfo is prepared by the stub-segv-handler at start of
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* the stub stack page. We just have to copy it.
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*/
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memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
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}
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}
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static void handle_segv(int pid, struct uml_pt_regs * regs)
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{
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get_skas_faultinfo(pid, ®s->faultinfo);
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segv(regs->faultinfo, 0, 1, NULL);
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}
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/*
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* To use the same value of using_sysemu as the caller, ask it that value
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* (in local_using_sysemu
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*/
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static void handle_trap(int pid, struct uml_pt_regs *regs,
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int local_using_sysemu)
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{
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int err, status;
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if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
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fatal_sigsegv();
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/* Mark this as a syscall */
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UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
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if (!local_using_sysemu)
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{
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err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
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__NR_getpid);
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if (err < 0) {
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printk(UM_KERN_ERR "handle_trap - nullifying syscall "
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"failed, errno = %d\n", errno);
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fatal_sigsegv();
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}
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err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
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if (err < 0) {
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printk(UM_KERN_ERR "handle_trap - continuing to end of "
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"syscall failed, errno = %d\n", errno);
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fatal_sigsegv();
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}
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CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
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if ((err < 0) || !WIFSTOPPED(status) ||
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(WSTOPSIG(status) != SIGTRAP + 0x80)) {
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err = ptrace_dump_regs(pid);
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if (err)
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printk(UM_KERN_ERR "Failed to get registers "
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"from process, errno = %d\n", -err);
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printk(UM_KERN_ERR "handle_trap - failed to wait at "
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"end of syscall, errno = %d, status = %d\n",
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errno, status);
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fatal_sigsegv();
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}
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}
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handle_syscall(regs);
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}
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extern int __syscall_stub_start;
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static int userspace_tramp(void *stack)
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{
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void *addr;
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int err;
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ptrace(PTRACE_TRACEME, 0, 0, 0);
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signal(SIGTERM, SIG_DFL);
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signal(SIGWINCH, SIG_IGN);
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err = set_interval();
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if (err) {
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printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
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"errno = %d\n", err);
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exit(1);
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}
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if (!proc_mm) {
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/*
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* This has a pte, but it can't be mapped in with the usual
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* tlb_flush mechanism because this is part of that mechanism
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*/
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int fd;
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unsigned long long offset;
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fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
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addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
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PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
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if (addr == MAP_FAILED) {
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printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
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"errno = %d\n", STUB_CODE, errno);
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exit(1);
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}
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if (stack != NULL) {
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fd = phys_mapping(to_phys(stack), &offset);
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addr = mmap((void *) STUB_DATA,
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UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
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MAP_FIXED | MAP_SHARED, fd, offset);
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if (addr == MAP_FAILED) {
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printk(UM_KERN_ERR "mapping segfault stack "
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"at 0x%lx failed, errno = %d\n",
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STUB_DATA, errno);
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exit(1);
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}
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}
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}
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if (!ptrace_faultinfo && (stack != NULL)) {
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struct sigaction sa;
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unsigned long v = STUB_CODE +
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(unsigned long) stub_segv_handler -
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(unsigned long) &__syscall_stub_start;
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set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_ONSTACK | SA_NODEFER;
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sa.sa_handler = (void *) v;
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sa.sa_restorer = NULL;
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if (sigaction(SIGSEGV, &sa, NULL) < 0) {
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printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
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"handler failed - errno = %d\n", errno);
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exit(1);
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}
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}
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kill(os_getpid(), SIGSTOP);
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return 0;
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}
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/* Each element set once, and only accessed by a single processor anyway */
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#undef NR_CPUS
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#define NR_CPUS 1
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int userspace_pid[NR_CPUS];
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int start_userspace(unsigned long stub_stack)
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{
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void *stack;
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unsigned long sp;
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int pid, status, n, flags, err;
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stack = mmap(NULL, UM_KERN_PAGE_SIZE,
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PROT_READ | PROT_WRITE | PROT_EXEC,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if (stack == MAP_FAILED) {
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err = -errno;
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printk(UM_KERN_ERR "start_userspace : mmap failed, "
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"errno = %d", errno);
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return err;
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}
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sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
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flags = CLONE_FILES;
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if (proc_mm)
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flags |= CLONE_VM;
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else
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flags |= SIGCHLD;
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pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
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if (pid < 0) {
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err = -errno;
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printk(UM_KERN_ERR "start_userspace : clone failed, "
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"errno = %d", errno);
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return err;
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}
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do {
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
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if (n < 0) {
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err = -errno;
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printk(UM_KERN_ERR "start_userspace : wait failed, "
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"errno = %d", errno);
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goto out_kill;
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}
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} while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
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if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
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err = -EINVAL;
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printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
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"status = %d", status);
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goto out_kill;
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}
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if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
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(void *) PTRACE_O_TRACESYSGOOD) < 0) {
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err = -errno;
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printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
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"failed, errno = %d\n", errno);
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goto out_kill;
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}
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if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
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err = -errno;
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printk(UM_KERN_ERR "start_userspace : munmap failed, "
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"errno = %d\n", errno);
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goto out_kill;
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}
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return pid;
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out_kill:
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os_kill_ptraced_process(pid, 1);
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return err;
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}
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void userspace(struct uml_pt_regs *regs)
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{
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struct itimerval timer;
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unsigned long long nsecs, now;
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int err, status, op, pid = userspace_pid[0];
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/* To prevent races if using_sysemu changes under us.*/
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int local_using_sysemu;
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if (getitimer(ITIMER_VIRTUAL, &timer))
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printk("Failed to get itimer, errno = %d\n", errno);
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nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
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timer.it_value.tv_usec * UM_NSEC_PER_USEC;
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nsecs += os_nsecs();
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while (1) {
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/*
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* This can legitimately fail if the process loads a
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* bogus value into a segment register. It will
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* segfault and PTRACE_GETREGS will read that value
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* out of the process. However, PTRACE_SETREGS will
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* fail. In this case, there is nothing to do but
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* just kill the process.
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*/
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if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
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fatal_sigsegv();
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/* Now we set local_using_sysemu to be used for one loop */
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local_using_sysemu = get_using_sysemu();
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op = SELECT_PTRACE_OPERATION(local_using_sysemu,
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singlestepping(NULL));
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if (ptrace(op, pid, 0, 0)) {
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printk(UM_KERN_ERR "userspace - ptrace continue "
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"failed, op = %d, errno = %d\n", op, errno);
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fatal_sigsegv();
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}
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CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
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if (err < 0) {
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printk(UM_KERN_ERR "userspace - wait failed, "
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"errno = %d\n", errno);
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fatal_sigsegv();
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}
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regs->is_user = 1;
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if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
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printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
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"errno = %d\n", errno);
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fatal_sigsegv();
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}
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UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
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if (WIFSTOPPED(status)) {
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int sig = WSTOPSIG(status);
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switch(sig) {
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case SIGSEGV:
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if (PTRACE_FULL_FAULTINFO ||
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!ptrace_faultinfo) {
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get_skas_faultinfo(pid,
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®s->faultinfo);
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(*sig_info[SIGSEGV])(SIGSEGV, regs);
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}
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else handle_segv(pid, regs);
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break;
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case SIGTRAP + 0x80:
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handle_trap(pid, regs, local_using_sysemu);
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break;
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case SIGTRAP:
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relay_signal(SIGTRAP, regs);
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break;
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case SIGVTALRM:
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now = os_nsecs();
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if (now < nsecs)
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break;
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block_signals();
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(*sig_info[sig])(sig, regs);
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unblock_signals();
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nsecs = timer.it_value.tv_sec *
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UM_NSEC_PER_SEC +
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timer.it_value.tv_usec *
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UM_NSEC_PER_USEC;
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nsecs += os_nsecs();
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break;
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case SIGIO:
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case SIGILL:
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case SIGBUS:
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case SIGFPE:
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case SIGWINCH:
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block_signals();
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(*sig_info[sig])(sig, regs);
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unblock_signals();
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break;
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default:
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printk(UM_KERN_ERR "userspace - child stopped "
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"with signal %d\n", sig);
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fatal_sigsegv();
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}
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pid = userspace_pid[0];
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interrupt_end();
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/* Avoid -ERESTARTSYS handling in host */
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if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
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PT_SYSCALL_NR(regs->gp) = -1;
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}
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}
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}
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static unsigned long thread_regs[MAX_REG_NR];
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static int __init init_thread_regs(void)
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{
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get_safe_registers(thread_regs);
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/* Set parent's instruction pointer to start of clone-stub */
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thread_regs[REGS_IP_INDEX] = STUB_CODE +
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(unsigned long) stub_clone_handler -
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(unsigned long) &__syscall_stub_start;
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thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
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sizeof(void *);
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#ifdef __SIGNAL_FRAMESIZE
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thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
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#endif
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return 0;
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}
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__initcall(init_thread_regs);
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int copy_context_skas0(unsigned long new_stack, int pid)
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{
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struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
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int err;
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unsigned long current_stack = current_stub_stack();
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struct stub_data *data = (struct stub_data *) current_stack;
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struct stub_data *child_data = (struct stub_data *) new_stack;
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unsigned long long new_offset;
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int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
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/*
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* prepare offset and fd of child's stack as argument for parent's
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* and child's mmap2 calls
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*/
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*data = ((struct stub_data) { .offset = MMAP_OFFSET(new_offset),
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.fd = new_fd,
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.timer = ((struct itimerval)
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{ .it_value = tv,
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.it_interval = tv }) });
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err = ptrace_setregs(pid, thread_regs);
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if (err < 0) {
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err = -errno;
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printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
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"failed, pid = %d, errno = %d\n", pid, -err);
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return err;
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}
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/* set a well known return code for detection of child write failure */
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child_data->err = 12345678;
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/*
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* Wait, until parent has finished its work: read child's pid from
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* parent's stack, and check, if bad result.
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*/
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err = ptrace(PTRACE_CONT, pid, 0, 0);
|
|
if (err) {
|
|
err = -errno;
|
|
printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
|
|
"errno = %d\n", pid, errno);
|
|
return err;
|
|
}
|
|
|
|
wait_stub_done(pid);
|
|
|
|
pid = data->err;
|
|
if (pid < 0) {
|
|
printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
|
|
"error %d\n", -pid);
|
|
return pid;
|
|
}
|
|
|
|
/*
|
|
* Wait, until child has finished too: read child's result from
|
|
* child's stack and check it.
|
|
*/
|
|
wait_stub_done(pid);
|
|
if (child_data->err != STUB_DATA) {
|
|
printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
|
|
"error %ld\n", child_data->err);
|
|
err = child_data->err;
|
|
goto out_kill;
|
|
}
|
|
|
|
if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
|
|
(void *)PTRACE_O_TRACESYSGOOD) < 0) {
|
|
err = -errno;
|
|
printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
|
|
"failed, errno = %d\n", errno);
|
|
goto out_kill;
|
|
}
|
|
|
|
return pid;
|
|
|
|
out_kill:
|
|
os_kill_ptraced_process(pid, 1);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* This is used only, if stub pages are needed, while proc_mm is
|
|
* available. Opening /proc/mm creates a new mm_context, which lacks
|
|
* the stub-pages. Thus, we map them using /proc/mm-fd
|
|
*/
|
|
int map_stub_pages(int fd, unsigned long code, unsigned long data,
|
|
unsigned long stack)
|
|
{
|
|
struct proc_mm_op mmop;
|
|
int n;
|
|
unsigned long long code_offset;
|
|
int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
|
|
&code_offset);
|
|
|
|
mmop = ((struct proc_mm_op) { .op = MM_MMAP,
|
|
.u =
|
|
{ .mmap =
|
|
{ .addr = code,
|
|
.len = UM_KERN_PAGE_SIZE,
|
|
.prot = PROT_EXEC,
|
|
.flags = MAP_FIXED | MAP_PRIVATE,
|
|
.fd = code_fd,
|
|
.offset = code_offset
|
|
} } });
|
|
CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
|
|
if (n != sizeof(mmop)) {
|
|
n = errno;
|
|
printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
|
|
"offset = %llx\n", code, code_fd,
|
|
(unsigned long long) code_offset);
|
|
printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
|
|
"failed, err = %d\n", n);
|
|
return -n;
|
|
}
|
|
|
|
if (stack) {
|
|
unsigned long long map_offset;
|
|
int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
|
|
mmop = ((struct proc_mm_op)
|
|
{ .op = MM_MMAP,
|
|
.u =
|
|
{ .mmap =
|
|
{ .addr = data,
|
|
.len = UM_KERN_PAGE_SIZE,
|
|
.prot = PROT_READ | PROT_WRITE,
|
|
.flags = MAP_FIXED | MAP_SHARED,
|
|
.fd = map_fd,
|
|
.offset = map_offset
|
|
} } });
|
|
CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
|
|
if (n != sizeof(mmop)) {
|
|
n = errno;
|
|
printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
|
|
"data failed, err = %d\n", n);
|
|
return -n;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
|
|
{
|
|
(*buf)[0].JB_IP = (unsigned long) handler;
|
|
(*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
|
|
sizeof(void *);
|
|
}
|
|
|
|
#define INIT_JMP_NEW_THREAD 0
|
|
#define INIT_JMP_CALLBACK 1
|
|
#define INIT_JMP_HALT 2
|
|
#define INIT_JMP_REBOOT 3
|
|
|
|
void switch_threads(jmp_buf *me, jmp_buf *you)
|
|
{
|
|
if (UML_SETJMP(me) == 0)
|
|
UML_LONGJMP(you, 1);
|
|
}
|
|
|
|
static jmp_buf initial_jmpbuf;
|
|
|
|
/* XXX Make these percpu */
|
|
static void (*cb_proc)(void *arg);
|
|
static void *cb_arg;
|
|
static jmp_buf *cb_back;
|
|
|
|
int start_idle_thread(void *stack, jmp_buf *switch_buf)
|
|
{
|
|
int n;
|
|
|
|
set_handler(SIGWINCH, (__sighandler_t) sig_handler,
|
|
SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGVTALRM, -1);
|
|
|
|
/*
|
|
* Can't use UML_SETJMP or UML_LONGJMP here because they save
|
|
* and restore signals, with the possible side-effect of
|
|
* trying to handle any signals which came when they were
|
|
* blocked, which can't be done on this stack.
|
|
* Signals must be blocked when jumping back here and restored
|
|
* after returning to the jumper.
|
|
*/
|
|
n = setjmp(initial_jmpbuf);
|
|
switch(n) {
|
|
case INIT_JMP_NEW_THREAD:
|
|
(*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
|
|
(*switch_buf)[0].JB_SP = (unsigned long) stack +
|
|
UM_THREAD_SIZE - sizeof(void *);
|
|
break;
|
|
case INIT_JMP_CALLBACK:
|
|
(*cb_proc)(cb_arg);
|
|
longjmp(*cb_back, 1);
|
|
break;
|
|
case INIT_JMP_HALT:
|
|
kmalloc_ok = 0;
|
|
return 0;
|
|
case INIT_JMP_REBOOT:
|
|
kmalloc_ok = 0;
|
|
return 1;
|
|
default:
|
|
printk(UM_KERN_ERR "Bad sigsetjmp return in "
|
|
"start_idle_thread - %d\n", n);
|
|
fatal_sigsegv();
|
|
}
|
|
longjmp(*switch_buf, 1);
|
|
}
|
|
|
|
void initial_thread_cb_skas(void (*proc)(void *), void *arg)
|
|
{
|
|
jmp_buf here;
|
|
|
|
cb_proc = proc;
|
|
cb_arg = arg;
|
|
cb_back = &here;
|
|
|
|
block_signals();
|
|
if (UML_SETJMP(&here) == 0)
|
|
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
|
|
unblock_signals();
|
|
|
|
cb_proc = NULL;
|
|
cb_arg = NULL;
|
|
cb_back = NULL;
|
|
}
|
|
|
|
void halt_skas(void)
|
|
{
|
|
block_signals();
|
|
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
|
|
}
|
|
|
|
void reboot_skas(void)
|
|
{
|
|
block_signals();
|
|
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
|
|
}
|
|
|
|
void __switch_mm(struct mm_id *mm_idp)
|
|
{
|
|
int err;
|
|
|
|
/* FIXME: need cpu pid in __switch_mm */
|
|
if (proc_mm) {
|
|
err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
|
|
mm_idp->u.mm_fd);
|
|
if (err) {
|
|
printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
|
|
"failed, errno = %d\n", errno);
|
|
fatal_sigsegv();
|
|
}
|
|
}
|
|
else userspace_pid[0] = mm_idp->u.pid;
|
|
}
|