f9dfefe423
cleanup and fix the check for advanced sysemu (PTRACE_SYSEMU_SINGLESTEP option) Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
360 lines
9.1 KiB
C
360 lines
9.1 KiB
C
/*
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* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.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 <unistd.h>
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#include <signal.h>
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#include <sched.h>
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#include <errno.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <setjmp.h>
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#include <sys/time.h>
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#include <sys/wait.h>
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#include <sys/mman.h>
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#include <asm/unistd.h>
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#include <asm/page.h>
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#include "user_util.h"
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#include "kern_util.h"
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#include "user.h"
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#include "signal_kern.h"
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#include "signal_user.h"
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#include "sysdep/ptrace.h"
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#include "sysdep/sigcontext.h"
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#include "irq_user.h"
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#include "ptrace_user.h"
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#include "time_user.h"
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#include "init.h"
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#include "os.h"
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#include "uml-config.h"
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#include "choose-mode.h"
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#include "mode.h"
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#include "tempfile.h"
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#ifdef UML_CONFIG_MODE_SKAS
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#include "skas.h"
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#include "skas_ptrace.h"
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#include "registers.h"
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#endif
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static int ptrace_child(void *arg)
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{
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int ret;
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int pid = os_getpid(), ppid = getppid();
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int sc_result;
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if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
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perror("ptrace");
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os_kill_process(pid, 0);
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}
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os_stop_process(pid);
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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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sc_result = os_getpid();
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if (sc_result == pid)
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ret = 1; /*Nothing modified by the parent, we are running
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normally.*/
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else if (sc_result == ppid)
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ret = 0; /*Expected in check_ptrace and check_sysemu when they
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succeed in modifying the stack frame*/
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else
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ret = 2; /*Serious trouble! This could be caused by a bug in
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host 2.6 SKAS3/2.6 patch before release -V6, together
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with a bug in the UML code itself.*/
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_exit(ret);
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}
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static int start_ptraced_child(void **stack_out)
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{
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void *stack;
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unsigned long sp;
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int pid, n, status;
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stack = mmap(NULL, PAGE_SIZE, 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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panic("check_ptrace : mmap failed, errno = %d", errno);
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sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
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pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
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if(pid < 0)
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panic("start_ptraced_child : clone failed, errno = %d", errno);
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if(n < 0)
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panic("check_ptrace : clone failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
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panic("check_ptrace : expected SIGSTOP, got status = %d",
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status);
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*stack_out = stack;
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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, void *stack, int exitcode,
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int mustpanic)
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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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panic("check_ptrace : ptrace failed, errno = %d", errno);
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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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printk("check_ptrace : child exited with status 2. "
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"Serious trouble happening! Try updating your "
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"host skas patch!\nDisabling SYSEMU support.");
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printk("check_ptrace : child exited with exitcode %d, while "
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"expecting %d; status 0x%x", exit_with,
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exitcode, status);
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if (mustpanic)
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panic("\n");
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else
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printk("\n");
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ret = -1;
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}
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if(munmap(stack, PAGE_SIZE) < 0)
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panic("check_ptrace : munmap failed, errno = %d", errno);
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return ret;
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}
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int ptrace_faultinfo = 1;
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int proc_mm = 1;
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static int __init skas0_cmd_param(char *str, int* add)
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{
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ptrace_faultinfo = proc_mm = 0;
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return 0;
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}
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__uml_setup("skas0", skas0_cmd_param,
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"skas0\n"
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" Disables SKAS3 usage, so that SKAS0 is used, unless \n"
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" you specify mode=tt.\n\n");
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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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void *stack;
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int pid, n, status, count=0;
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printk("Checking syscall emulation patch for ptrace...");
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sysemu_supported = 0;
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pid = start_ptraced_child(&stack);
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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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panic("check_sysemu : wait failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
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panic("check_sysemu : expected SIGTRAP, "
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"got status = %d", status);
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n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
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os_getpid());
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if(n < 0)
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panic("check_sysemu : failed to modify system "
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"call return, errno = %d", errno);
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if (stop_ptraced_child(pid, stack, 0, 0) < 0)
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goto fail_stopped;
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sysemu_supported = 1;
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printk("OK\n");
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set_using_sysemu(!force_sysemu_disabled);
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printk("Checking advanced syscall emulation patch for ptrace...");
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pid = start_ptraced_child(&stack);
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if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
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(void *) PTRACE_O_TRACESYSGOOD) < 0)
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panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d",
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errno);
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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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panic("check_ptrace : wait failed, errno = %d", errno);
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if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
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if (!count)
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panic("check_ptrace : SYSEMU_SINGLESTEP "
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"doesn't singlestep");
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n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
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os_getpid());
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if(n < 0)
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panic("check_sysemu : failed to modify system "
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"call return, errno = %d", errno);
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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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panic("check_ptrace : expected SIGTRAP or "
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"(SIGTRAP|0x80), got status = %d", status);
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}
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if (stop_ptraced_child(pid, stack, 0, 0) < 0)
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goto fail_stopped;
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sysemu_supported = 2;
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printk("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, stack, 1, 0);
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fail_stopped:
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printk("missing\n");
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}
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static void __init check_ptrace(void)
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{
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void *stack;
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int pid, syscall, n, status;
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printk("Checking that ptrace can change system call numbers...");
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pid = start_ptraced_child(&stack);
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if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
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panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno);
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while(1){
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if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
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panic("check_ptrace : ptrace failed, errno = %d",
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errno);
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if(n < 0)
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panic("check_ptrace : wait failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80)))
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panic("check_ptrace : expected (SIGTRAP|0x80), "
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"got status = %d", status);
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syscall = ptrace(PTRACE_PEEKUSR, 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_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
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__NR_getppid);
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if(n < 0)
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panic("check_ptrace : failed to modify system "
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"call, errno = %d", errno);
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break;
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}
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}
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stop_ptraced_child(pid, stack, 0, 1);
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printk("OK\n");
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check_sysemu();
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}
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void os_early_checks(void)
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{
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check_ptrace();
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}
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static int __init noprocmm_cmd_param(char *str, int* add)
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{
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proc_mm = 0;
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return 0;
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}
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__uml_setup("noprocmm", noprocmm_cmd_param,
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"noprocmm\n"
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" Turns off usage of /proc/mm, even if host supports it.\n"
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" To support /proc/mm, the host needs to be patched using\n"
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" the current skas3 patch.\n\n");
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static int __init noptracefaultinfo_cmd_param(char *str, int* add)
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{
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ptrace_faultinfo = 0;
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return 0;
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}
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__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
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"noptracefaultinfo\n"
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" Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
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" it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
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" using the current skas3 patch.\n\n");
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#ifdef UML_CONFIG_MODE_SKAS
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static inline void check_skas3_ptrace_support(void)
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{
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struct ptrace_faultinfo fi;
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void *stack;
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int pid, n;
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printf("Checking for the skas3 patch in the host...");
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pid = start_ptraced_child(&stack);
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n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
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if (n < 0) {
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ptrace_faultinfo = 0;
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if(errno == EIO)
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printf("not found\n");
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else
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perror("not found");
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}
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else {
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if (!ptrace_faultinfo)
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printf("found but disabled on command line\n");
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else
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printf("found\n");
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}
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init_registers(pid);
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stop_ptraced_child(pid, stack, 1, 1);
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}
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int can_do_skas(void)
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{
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printf("Checking for /proc/mm...");
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if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
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proc_mm = 0;
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printf("not found\n");
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}
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else {
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if (!proc_mm)
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printf("found but disabled on command line\n");
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else
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printf("found\n");
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}
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check_skas3_ptrace_support();
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return 1;
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}
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#else
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int can_do_skas(void)
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{
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return(0);
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}
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#endif
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