v4.19.13 snapshot.
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
new file mode 100644
index 0000000..82bf5f8
--- /dev/null
+++ b/arch/um/os-Linux/start_up.c
@@ -0,0 +1,392 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#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 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_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;
+}