diff options
Diffstat (limited to 'arch/um/os-Linux/start_up.c')
| -rw-r--r-- | arch/um/os-Linux/start_up.c | 359 |
1 files changed, 359 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..040cc1472bc7 --- /dev/null +++ b/arch/um/os-Linux/start_up.c @@ -0,0 +1,359 @@ +/* + * 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, 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); + + if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, + (void *) PTRACE_O_TRACESYSGOOD) < 0) + panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", + errno); + + 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|0x80))){ + 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; + } + else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) + count++; + else + panic("check_ptrace : expected SIGTRAP or " + "(SIGTRAP|0x80), got status = %d", status); + } + 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(); +} + +static int __init noprocmm_cmd_param(char *str, int* add) +{ + proc_mm = 0; + return 0; +} + +__uml_setup("noprocmm", noprocmm_cmd_param, +"noprocmm\n" +" Turns off usage of /proc/mm, even if host supports it.\n" +" To support /proc/mm, the host needs to be patched using\n" +" the current skas3 patch.\n\n"); + +static int __init noptracefaultinfo_cmd_param(char *str, int* add) +{ + ptrace_faultinfo = 0; + return 0; +} + +__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, +"noptracefaultinfo\n" +" Turns off usage of PTRACE_FAULTINFO, even if host supports\n" +" it. To support PTRACE_FAULTINFO, the host needs to be patched\n" +" using the current skas3 patch.\n\n"); + +#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 |