1 files changed, 392 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 000000000..b28373a2b
--- /dev/null
+++ b/arch/um/os-Linux/start_up.c
@@ -0,0 +1,392 @@
+// 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 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;
+}