diff options
Diffstat (limited to 'arch/um/os-Linux/start_up.c')
-rw-r--r-- | arch/um/os-Linux/start_up.c | 70 |
1 files changed, 6 insertions, 64 deletions
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index e3ee4db58b40..561c08e0cc9c 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -143,71 +143,16 @@ static int stop_ptraced_child(int pid, int exitcode, int mustexit) return ret; } -/* Changed only during early boot */ -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).\n" -" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" -" behaviour of ptrace() and helps reduce host context switch rates.\n" -" To make it work, 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) { - unsigned long regs[MAX_REG_NR]; int pid, n, status, count=0; - os_info("Checking syscall emulation patch for ptrace..."); - sysemu_supported = 0; - pid = start_ptraced_child(); - - if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) - goto fail; - - CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); - if (n < 0) - fatal_perror("check_sysemu : wait failed"); - if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) - fatal("check_sysemu : expected SIGTRAP, got status = %d\n", - status); - - if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0) - fatal_perror("check_sysemu : PTRACE_GETREGS failed"); - if (PT_SYSCALL_NR(regs) != __NR_getpid) { - non_fatal("check_sysemu got system call number %d, " - "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid); - goto fail; - } - - n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid()); - if (n < 0) { - non_fatal("check_sysemu : failed to modify system call " - "return"); - goto fail; - } - - if (stop_ptraced_child(pid, 0, 0) < 0) - goto fail_stopped; - - sysemu_supported = 1; - os_info("OK\n"); - set_using_sysemu(!force_sysemu_disabled); - - os_info("Checking advanced syscall emulation patch for ptrace..."); + os_info("Checking syscall emulation for ptrace..."); pid = start_ptraced_child(); - if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, + if ((ptrace(PTRACE_SETOPTIONS, pid, 0, (void *) PTRACE_O_TRACESYSGOOD) < 0)) - fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed"); + fatal_perror("check_sysemu: PTRACE_SETOPTIONS failed"); while (1) { count++; @@ -243,17 +188,14 @@ static void __init check_sysemu(void) if (stop_ptraced_child(pid, 0, 0) < 0) goto fail_stopped; - sysemu_supported = 2; os_info("OK\n"); - if (!force_sysemu_disabled) - set_using_sysemu(sysemu_supported); return; fail: stop_ptraced_child(pid, 1, 0); fail_stopped: - non_fatal("missing\n"); + fatal("missing\n"); } static void __init check_ptrace(void) @@ -263,9 +205,9 @@ static void __init check_ptrace(void) os_info("Checking that ptrace can change system call numbers..."); pid = start_ptraced_child(); - if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, + if ((ptrace(PTRACE_SETOPTIONS, pid, 0, (void *) PTRACE_O_TRACESYSGOOD) < 0)) - fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); + fatal_perror("check_ptrace: PTRACE_SETOPTIONS failed"); while (1) { if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) |