1 files changed, 329 insertions, 0 deletions

diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
new file mode 100644
index 000000000000..a3eab25f3791
--- /dev/null
+++ b/arch/um/os-Linux/start_up.c
@@ -0,0 +1,329 @@
+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sched.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <setjmp.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <sys/mman.h>
+#include <asm/unistd.h>
+#include <asm/page.h>
+#include "user_util.h"
+#include "kern_util.h"
+#include "user.h"
+#include "signal_kern.h"
+#include "signal_user.h"
+#include "sysdep/ptrace.h"
+#include "sysdep/sigcontext.h"
+#include "irq_user.h"
+#include "ptrace_user.h"
+#include "time_user.h"
+#include "init.h"
+#include "os.h"
+#include "uml-config.h"
+#include "choose-mode.h"
+#include "mode.h"
+#include "tempfile.h"
+#ifdef UML_CONFIG_MODE_SKAS
+#include "skas.h"
+#include "skas_ptrace.h"
+#include "registers.h"
+#endif
+
+static int ptrace_child(void *arg)
+{
+        int ret;
+        int pid = os_getpid(), ppid = getppid();
+        int sc_result;
+
+        if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
+                perror("ptrace");
+                os_kill_process(pid, 0);
+        }
+        os_stop_process(pid);
+
+        /*This syscall will be intercepted by the parent. Don't call more than
+         * once, please.*/
+        sc_result = os_getpid();
+
+        if (sc_result == pid)
+                ret = 1; /*Nothing modified by the parent, we are running
+                           normally.*/
+        else if (sc_result == ppid)
+                ret = 0; /*Expected in check_ptrace and check_sysemu when they
+                           succeed in modifying the stack frame*/
+        else
+                ret = 2; /*Serious trouble! This could be caused by a bug in
+                           host 2.6 SKAS3/2.6 patch before release -V6, together
+                           with a bug in the UML code itself.*/
+        _exit(ret);
+}
+
+static int start_ptraced_child(void **stack_out)
+{
+        void *stack;
+        unsigned long sp;
+        int pid, n, status;
+
+        stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
+                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        if(stack == MAP_FAILED)
+                panic("check_ptrace : mmap failed, errno = %d", errno);
+        sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
+        pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
+        if(pid < 0)
+                panic("start_ptraced_child : clone failed, errno = %d", errno);
+        CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+        if(n < 0)
+                panic("check_ptrace : clone failed, errno = %d", errno);
+        if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
+                panic("check_ptrace : expected SIGSTOP, got status = %d",
+                      status);
+
+        *stack_out = stack;
+        return(pid);
+}
+
+/* When testing for SYSEMU support, if it is one of the broken versions, we
+ * must just avoid using sysemu, not panic, but only if SYSEMU features are
+ * broken.
+ * So only for SYSEMU features we test mustpanic, while normal host features
+ * must work anyway!
+ */
+static int stop_ptraced_child(int pid, void *stack, int exitcode,
+                              int mustpanic)
+{
+        int status, n, ret = 0;
+
+        if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
+                panic("check_ptrace : ptrace failed, errno = %d", errno);
+        CATCH_EINTR(n = waitpid(pid, &status, 0));
+        if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
+                int exit_with = WEXITSTATUS(status);
+                if (exit_with == 2)
+                        printk("check_ptrace : child exited with status 2. "
+                               "Serious trouble happening! Try updating your "
+                               "host skas patch!\nDisabling SYSEMU support.");
+                printk("check_ptrace : child exited with exitcode %d, while "
+                      "expecting %d; status 0x%x", exit_with,
+                      exitcode, status);
+                if (mustpanic)
+                        panic("\n");
+                else
+                        printk("\n");
+                ret = -1;
+        }
+
+        if(munmap(stack, PAGE_SIZE) < 0)
+                panic("check_ptrace : munmap failed, errno = %d", errno);
+        return ret;
+}
+
+int ptrace_faultinfo = 1;
+int proc_mm = 1;
+
+static int __init skas0_cmd_param(char *str, int* add)
+{
+        ptrace_faultinfo = proc_mm = 0;
+        return 0;
+}
+
+__uml_setup("skas0", skas0_cmd_param,
+                "skas0\n"
+                "    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
+                "    you specify mode=tt.\n\n");
+
+static int force_sysemu_disabled = 0;
+
+static int __init nosysemu_cmd_param(char *str, int* add)
+{
+        force_sysemu_disabled = 1;
+        return 0;
+}
+
+__uml_setup("nosysemu", nosysemu_cmd_param,
+"nosysemu\n"
+"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
+"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
+"    behaviour of ptrace() and helps reducing host context switch rate.\n"
+"    To make it working, you need a kernel patch for your host, too.\n"
+"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
+"    information.\n\n");
+
+static void __init check_sysemu(void)
+{
+        void *stack;
+        int pid, syscall, n, status, count=0;
+
+        printk("Checking syscall emulation patch for ptrace...");
+        sysemu_supported = 0;
+        pid = start_ptraced_child(&stack);
+
+        if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
+                goto fail;
+
+        CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+        if (n < 0)
+                panic("check_sysemu : wait failed, errno = %d", errno);
+        if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
+                panic("check_sysemu : expected SIGTRAP, "
+                      "got status = %d", status);
+
+        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
+                   os_getpid());
+        if(n < 0)
+                panic("check_sysemu : failed to modify system "
+                      "call return, errno = %d", errno);
+
+        if (stop_ptraced_child(pid, stack, 0, 0) < 0)
+                goto fail_stopped;
+
+        sysemu_supported = 1;
+        printk("OK\n");
+        set_using_sysemu(!force_sysemu_disabled);
+
+        printk("Checking advanced syscall emulation patch for ptrace...");
+        pid = start_ptraced_child(&stack);
+        while(1){
+                count++;
+                if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
+                        goto fail;
+                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+                if(n < 0)
+                        panic("check_ptrace : wait failed, errno = %d", errno);
+                if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
+                        panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), "
+                              "got status = %d", status);
+
+                syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
+                                 0);
+                if(syscall == __NR_getpid){
+                        if (!count)
+                                panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep");
+                        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
+                                   os_getpid());
+                        if(n < 0)
+                                panic("check_sysemu : failed to modify system "
+                                      "call return, errno = %d", errno);
+                        break;
+                }
+        }
+        if (stop_ptraced_child(pid, stack, 0, 0) < 0)
+                goto fail_stopped;
+
+        sysemu_supported = 2;
+        printk("OK\n");
+
+        if ( !force_sysemu_disabled )
+                set_using_sysemu(sysemu_supported);
+        return;
+
+fail:
+        stop_ptraced_child(pid, stack, 1, 0);
+fail_stopped:
+        printk("missing\n");
+}
+
+static void __init check_ptrace(void)
+{
+        void *stack;
+        int pid, syscall, n, status;
+
+        printk("Checking that ptrace can change system call numbers...");
+        pid = start_ptraced_child(&stack);
+
+        if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
+                panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno);
+
+        while(1){
+                if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
+                        panic("check_ptrace : ptrace failed, errno = %d",
+                              errno);
+                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+                if(n < 0)
+                        panic("check_ptrace : wait failed, errno = %d", errno);
+                if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80))
+                        panic("check_ptrace : expected SIGTRAP + 0x80, "
+                              "got status = %d", status);
+
+                syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
+                                 0);
+                if(syscall == __NR_getpid){
+                        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
+                                   __NR_getppid);
+                        if(n < 0)
+                                panic("check_ptrace : failed to modify system "
+                                      "call, errno = %d", errno);
+                        break;
+                }
+        }
+        stop_ptraced_child(pid, stack, 0, 1);
+        printk("OK\n");
+        check_sysemu();
+}
+
+void os_early_checks(void)
+{
+        check_ptrace();
+}
+
+#ifdef UML_CONFIG_MODE_SKAS
+static inline void check_skas3_ptrace_support(void)
+{
+        struct ptrace_faultinfo fi;
+        void *stack;
+        int pid, n;
+
+        printf("Checking for the skas3 patch in the host...");
+        pid = start_ptraced_child(&stack);
+
+        n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
+        if (n < 0) {
+                ptrace_faultinfo = 0;
+                if(errno == EIO)
+                        printf("not found\n");
+                else
+                        perror("not found");
+        }
+        else {
+                if (!ptrace_faultinfo)
+                        printf("found but disabled on command line\n");
+                else
+                        printf("found\n");
+        }
+
+        init_registers(pid);
+        stop_ptraced_child(pid, stack, 1, 1);
+}
+
+int can_do_skas(void)
+{
+        printf("Checking for /proc/mm...");
+        if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
+                proc_mm = 0;
+                printf("not found\n");
+        }
+        else {
+                if (!proc_mm)
+                        printf("found but disabled on command line\n");
+                else
+                        printf("found\n");
+        }
+
+        check_skas3_ptrace_support();
+        return 1;
+}
+#else
+int can_do_skas(void)
+{
+        return(0);
+}
+#endif