diff options
Diffstat (limited to 'arch/um/os-Linux/start_up.c')
| -rw-r--r-- | arch/um/os-Linux/start_up.c | 424 |
1 files changed, 424 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 0000000000..e3ee4db58b --- /dev/null +++ b/arch/um/os-Linux/start_up.c @@ -0,0 +1,424 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include <stdio.h> +#include <stdlib.h> +#include <stdarg.h> +#include <unistd.h> +#include <errno.h> +#include <fcntl.h> +#include <sched.h> +#include <signal.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/wait.h> +#include <sys/time.h> +#include <sys/resource.h> +#include <asm/unistd.h> +#include <init.h> +#include <os.h> +#include <mem_user.h> +#include <ptrace_user.h> +#include <registers.h> +#include <skas.h> + +static void ptrace_child(void) +{ + int ret; + /* Calling os_getpid because some libcs cached getpid incorrectly */ + int pid = os_getpid(), ppid = getppid(); + int sc_result; + + if (change_sig(SIGWINCH, 0) < 0 || + ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) { + perror("ptrace"); + kill(pid, SIGKILL); + } + kill(pid, SIGSTOP); + + /* + * This syscall will be intercepted by the parent. Don't call more than + * once, please. + */ + sc_result = os_getpid(); + + if (sc_result == pid) + /* Nothing modified by the parent, we are running normally. */ + ret = 1; + else if (sc_result == ppid) + /* + * Expected in check_ptrace and check_sysemu when they succeed + * in modifying the stack frame + */ + ret = 0; + else + /* 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. + */ + ret = 2; + + exit(ret); +} + +static void fatal_perror(const char *str) +{ + perror(str); + exit(1); +} + +static void fatal(char *fmt, ...) +{ + va_list list; + + va_start(list, fmt); + vfprintf(stderr, fmt, list); + va_end(list); + + exit(1); +} + +static void non_fatal(char *fmt, ...) +{ + va_list list; + + va_start(list, fmt); + vfprintf(stderr, fmt, list); + va_end(list); +} + +static int start_ptraced_child(void) +{ + int pid, n, status; + + fflush(stdout); + + pid = fork(); + if (pid == 0) + ptrace_child(); + else if (pid < 0) + fatal_perror("start_ptraced_child : fork failed"); + + CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); + if (n < 0) + fatal_perror("check_ptrace : waitpid failed"); + if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) + fatal("check_ptrace : expected SIGSTOP, got status = %d", + status); + + 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, int exitcode, int mustexit) +{ + int status, n, ret = 0; + + if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) { + perror("stop_ptraced_child : ptrace failed"); + return -1; + } + CATCH_EINTR(n = waitpid(pid, &status, 0)); + if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { + int exit_with = WEXITSTATUS(status); + if (exit_with == 2) + non_fatal("check_ptrace : child exited with status 2. " + "\nDisabling SYSEMU support.\n"); + non_fatal("check_ptrace : child exited with exitcode %d, while " + "expecting %d; status 0x%x\n", exit_with, + exitcode, status); + if (mustexit) + exit(1); + ret = -1; + } + + 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..."); + pid = start_ptraced_child(); + + if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, + (void *) PTRACE_O_TRACESYSGOOD) < 0)) + fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed"); + + while (1) { + count++; + if (ptrace(PTRACE_SYSEMU_SINGLESTEP, 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|0x80))) { + if (!count) { + non_fatal("check_sysemu: SYSEMU_SINGLESTEP " + "doesn't singlestep"); + goto fail; + } + n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, + os_getpid()); + if (n < 0) + fatal_perror("check_sysemu : failed to modify " + "system call return"); + break; + } + else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) + count++; + else { + non_fatal("check_sysemu: expected SIGTRAP or " + "(SIGTRAP | 0x80), got status = %d\n", + status); + goto fail; + } + } + 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"); +} + +static void __init check_ptrace(void) +{ + int pid, syscall, n, status; + + os_info("Checking that ptrace can change system call numbers..."); + pid = start_ptraced_child(); + + if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, + (void *) PTRACE_O_TRACESYSGOOD) < 0)) + fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); + + while (1) { + if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) + fatal_perror("check_ptrace : ptrace failed"); + + CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); + if (n < 0) + fatal_perror("check_ptrace : wait failed"); + + if (!WIFSTOPPED(status) || + (WSTOPSIG(status) != (SIGTRAP | 0x80))) + fatal("check_ptrace : expected (SIGTRAP|0x80), " + "got status = %d", status); + + syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET, + 0); + if (syscall == __NR_getpid) { + n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, + __NR_getppid); + if (n < 0) + fatal_perror("check_ptrace : failed to modify " + "system call"); + break; + } + } + stop_ptraced_child(pid, 0, 1); + os_info("OK\n"); + check_sysemu(); +} + +extern void check_tmpexec(void); + +static void __init check_coredump_limit(void) +{ + struct rlimit lim; + int err = getrlimit(RLIMIT_CORE, &lim); + + if (err) { + perror("Getting core dump limit"); + return; + } + + os_info("Core dump limits :\n\tsoft - "); + if (lim.rlim_cur == RLIM_INFINITY) + os_info("NONE\n"); + else + os_info("%llu\n", (unsigned long long)lim.rlim_cur); + + os_info("\thard - "); + if (lim.rlim_max == RLIM_INFINITY) + os_info("NONE\n"); + else + os_info("%llu\n", (unsigned long long)lim.rlim_max); +} + +void __init get_host_cpu_features( + void (*flags_helper_func)(char *line), + void (*cache_helper_func)(char *line)) +{ + FILE *cpuinfo; + char *line = NULL; + size_t len = 0; + int done_parsing = 0; + + cpuinfo = fopen("/proc/cpuinfo", "r"); + if (cpuinfo == NULL) { + os_info("Failed to get host CPU features\n"); + } else { + while ((getline(&line, &len, cpuinfo)) != -1) { + if (strstr(line, "flags")) { + flags_helper_func(line); + done_parsing++; + } + if (strstr(line, "cache_alignment")) { + cache_helper_func(line); + done_parsing++; + } + free(line); + line = NULL; + if (done_parsing > 1) + break; + } + fclose(cpuinfo); + } +} + + +void __init os_early_checks(void) +{ + int pid; + + /* Print out the core dump limits early */ + check_coredump_limit(); + + check_ptrace(); + + /* Need to check this early because mmapping happens before the + * kernel is running. + */ + check_tmpexec(); + + pid = start_ptraced_child(); + if (init_pid_registers(pid)) + fatal("Failed to initialize default registers"); + stop_ptraced_child(pid, 1, 1); +} + +int __init parse_iomem(char *str, int *add) +{ + struct iomem_region *new; + struct stat64 buf; + char *file, *driver; + int fd, size; + + driver = str; + file = strchr(str,','); + if (file == NULL) { + os_warn("parse_iomem : failed to parse iomem\n"); + goto out; + } + *file = '\0'; + file++; + fd = open(file, O_RDWR, 0); + if (fd < 0) { + perror("parse_iomem - Couldn't open io file"); + goto out; + } + + if (fstat64(fd, &buf) < 0) { + perror("parse_iomem - cannot stat_fd file"); + goto out_close; + } + + new = malloc(sizeof(*new)); + if (new == NULL) { + perror("Couldn't allocate iomem_region struct"); + goto out_close; + } + + size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); + + *new = ((struct iomem_region) { .next = iomem_regions, + .driver = driver, + .fd = fd, + .size = size, + .phys = 0, + .virt = 0 }); + iomem_regions = new; + iomem_size += new->size + UM_KERN_PAGE_SIZE; + + return 0; + out_close: + close(fd); + out: + return 1; +} |