391 lines
8.9 KiB
C
391 lines
8.9 KiB
C
/*
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* Copyright (C) 2000 - 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 <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sched.h>
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#include <signal.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <asm/unistd.h>
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#include <init.h>
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#include <os.h>
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#include <mem_user.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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static void ptrace_child(void)
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{
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int ret;
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/* Calling os_getpid because some libcs cached getpid incorrectly */
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int pid = os_getpid(), ppid = getppid();
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int sc_result;
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if (change_sig(SIGWINCH, 0) < 0 ||
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ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
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perror("ptrace");
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kill(pid, SIGKILL);
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}
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kill(pid, SIGSTOP);
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/*
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* This syscall will be intercepted by the parent. Don't call more than
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* once, please.
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*/
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sc_result = os_getpid();
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if (sc_result == pid)
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/* Nothing modified by the parent, we are running normally. */
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ret = 1;
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else if (sc_result == ppid)
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/*
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* Expected in check_ptrace and check_sysemu when they succeed
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* in modifying the stack frame
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*/
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ret = 0;
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else
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/* Serious trouble! This could be caused by a bug in host 2.6
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* SKAS3/2.6 patch before release -V6, together with a bug in
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* the UML code itself.
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*/
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ret = 2;
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exit(ret);
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}
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static void fatal_perror(const char *str)
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{
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perror(str);
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exit(1);
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}
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static void fatal(char *fmt, ...)
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{
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va_list list;
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va_start(list, fmt);
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vfprintf(stderr, fmt, list);
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va_end(list);
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exit(1);
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}
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static void non_fatal(char *fmt, ...)
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{
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va_list list;
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va_start(list, fmt);
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vfprintf(stderr, fmt, list);
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va_end(list);
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}
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static int start_ptraced_child(void)
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{
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int pid, n, status;
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fflush(stdout);
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pid = fork();
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if (pid == 0)
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ptrace_child();
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else if (pid < 0)
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fatal_perror("start_ptraced_child : fork failed");
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if (n < 0)
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fatal_perror("check_ptrace : waitpid failed");
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if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
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fatal("check_ptrace : expected SIGSTOP, got status = %d",
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status);
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return pid;
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}
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/* When testing for SYSEMU support, if it is one of the broken versions, we
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* must just avoid using sysemu, not panic, but only if SYSEMU features are
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* broken.
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* So only for SYSEMU features we test mustpanic, while normal host features
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* must work anyway!
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*/
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static int stop_ptraced_child(int pid, int exitcode, int mustexit)
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{
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int status, n, ret = 0;
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if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) {
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perror("stop_ptraced_child : ptrace failed");
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return -1;
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}
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CATCH_EINTR(n = waitpid(pid, &status, 0));
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if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
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int exit_with = WEXITSTATUS(status);
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if (exit_with == 2)
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non_fatal("check_ptrace : child exited with status 2. "
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"\nDisabling SYSEMU support.\n");
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non_fatal("check_ptrace : child exited with exitcode %d, while "
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"expecting %d; status 0x%x\n", exit_with,
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exitcode, status);
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if (mustexit)
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exit(1);
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ret = -1;
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}
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return ret;
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}
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/* Changed only during early boot */
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static int force_sysemu_disabled = 0;
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static int __init nosysemu_cmd_param(char *str, int* add)
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{
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force_sysemu_disabled = 1;
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return 0;
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}
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__uml_setup("nosysemu", nosysemu_cmd_param,
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"nosysemu\n"
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" Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
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" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
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" behaviour of ptrace() and helps reducing host context switch rate.\n"
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" To make it working, you need a kernel patch for your host, too.\n"
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" See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
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" information.\n\n");
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static void __init check_sysemu(void)
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{
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unsigned long regs[MAX_REG_NR];
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int pid, n, status, count=0;
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non_fatal("Checking syscall emulation patch for ptrace...");
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sysemu_supported = 0;
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pid = start_ptraced_child();
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if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
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goto fail;
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if (n < 0)
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fatal_perror("check_sysemu : wait failed");
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if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
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fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
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status);
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if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
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fatal_perror("check_sysemu : PTRACE_GETREGS failed");
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if (PT_SYSCALL_NR(regs) != __NR_getpid) {
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non_fatal("check_sysemu got system call number %d, "
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"expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
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goto fail;
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}
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n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
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if (n < 0) {
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non_fatal("check_sysemu : failed to modify system call "
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"return");
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goto fail;
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}
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if (stop_ptraced_child(pid, 0, 0) < 0)
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goto fail_stopped;
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sysemu_supported = 1;
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non_fatal("OK\n");
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set_using_sysemu(!force_sysemu_disabled);
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non_fatal("Checking advanced syscall emulation patch for ptrace...");
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pid = start_ptraced_child();
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if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
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(void *) PTRACE_O_TRACESYSGOOD) < 0))
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fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed");
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while (1) {
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count++;
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if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
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goto fail;
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if (n < 0)
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fatal_perror("check_sysemu: wait failed");
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if (WIFSTOPPED(status) &&
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(WSTOPSIG(status) == (SIGTRAP|0x80))) {
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if (!count) {
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non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
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"doesn't singlestep");
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goto fail;
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}
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n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
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os_getpid());
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if (n < 0)
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fatal_perror("check_sysemu : failed to modify "
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"system call return");
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break;
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}
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else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
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count++;
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else {
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non_fatal("check_sysemu: expected SIGTRAP or "
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"(SIGTRAP | 0x80), got status = %d\n",
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status);
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goto fail;
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}
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}
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if (stop_ptraced_child(pid, 0, 0) < 0)
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goto fail_stopped;
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sysemu_supported = 2;
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non_fatal("OK\n");
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if (!force_sysemu_disabled)
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set_using_sysemu(sysemu_supported);
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return;
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fail:
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stop_ptraced_child(pid, 1, 0);
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fail_stopped:
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non_fatal("missing\n");
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}
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static void __init check_ptrace(void)
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{
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int pid, syscall, n, status;
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non_fatal("Checking that ptrace can change system call numbers...");
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pid = start_ptraced_child();
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if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
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(void *) PTRACE_O_TRACESYSGOOD) < 0))
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fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
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while (1) {
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if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
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fatal_perror("check_ptrace : ptrace failed");
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if (n < 0)
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fatal_perror("check_ptrace : wait failed");
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if (!WIFSTOPPED(status) ||
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(WSTOPSIG(status) != (SIGTRAP | 0x80)))
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fatal("check_ptrace : expected (SIGTRAP|0x80), "
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"got status = %d", status);
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syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
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0);
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if (syscall == __NR_getpid) {
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n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
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__NR_getppid);
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if (n < 0)
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fatal_perror("check_ptrace : failed to modify "
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"system call");
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break;
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}
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}
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stop_ptraced_child(pid, 0, 1);
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non_fatal("OK\n");
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check_sysemu();
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}
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extern void check_tmpexec(void);
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static void __init check_coredump_limit(void)
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{
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struct rlimit lim;
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int err = getrlimit(RLIMIT_CORE, &lim);
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if (err) {
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perror("Getting core dump limit");
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return;
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}
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printf("Core dump limits :\n\tsoft - ");
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if (lim.rlim_cur == RLIM_INFINITY)
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printf("NONE\n");
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else printf("%lu\n", lim.rlim_cur);
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printf("\thard - ");
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if (lim.rlim_max == RLIM_INFINITY)
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printf("NONE\n");
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else printf("%lu\n", lim.rlim_max);
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}
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void __init os_early_checks(void)
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{
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int pid;
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/* Print out the core dump limits early */
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check_coredump_limit();
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check_ptrace();
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/* Need to check this early because mmapping happens before the
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* kernel is running.
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*/
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check_tmpexec();
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pid = start_ptraced_child();
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if (init_registers(pid))
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fatal("Failed to initialize default registers");
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stop_ptraced_child(pid, 1, 1);
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}
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int __init parse_iomem(char *str, int *add)
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{
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struct iomem_region *new;
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struct stat64 buf;
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char *file, *driver;
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int fd, size;
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driver = str;
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file = strchr(str,',');
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if (file == NULL) {
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fprintf(stderr, "parse_iomem : failed to parse iomem\n");
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goto out;
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}
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*file = '\0';
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file++;
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fd = open(file, O_RDWR, 0);
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if (fd < 0) {
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perror("parse_iomem - Couldn't open io file");
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goto out;
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}
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if (fstat64(fd, &buf) < 0) {
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perror("parse_iomem - cannot stat_fd file");
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goto out_close;
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}
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new = malloc(sizeof(*new));
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if (new == NULL) {
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perror("Couldn't allocate iomem_region struct");
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goto out_close;
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}
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size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
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*new = ((struct iomem_region) { .next = iomem_regions,
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.driver = driver,
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.fd = fd,
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.size = size,
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.phys = 0,
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.virt = 0 });
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iomem_regions = new;
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iomem_size += new->size + UM_KERN_PAGE_SIZE;
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return 0;
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out_close:
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close(fd);
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out:
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return 1;
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}
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