Merge tag 'nolibc.2022.09.30a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull nolibc updates from Paul McKenney:
 "Most notably greatly improved testing. These tests are located in
  tools/testing/selftests/nolibc. The output of "make help" is as
  follows:

    Supported targets under selftests/nolibc:
      all          call the "run" target below
      help         this help
      sysroot      create the nolibc sysroot here (uses $ARCH)
      nolibc-test  build the executable (uses $CC and $CROSS_COMPILE)
      initramfs    prepare the initramfs with nolibc-test
      defconfig    create a fresh new default config (uses $ARCH)
      kernel       (re)build the kernel with the initramfs (uses $ARCH)
      run          runs the kernel in QEMU after building it (uses $ARCH, $TEST)
      rerun        runs a previously prebuilt kernel in QEMU (uses $ARCH, $TEST)
      clean        clean the sysroot, initramfs, build and output files

    The output file is "run.out". Test ranges may be passed using $TEST.

    Currently using the following variables:
      ARCH          = x86
      CROSS_COMPILE =
      CC            = gcc
      OUTPUT        = /home/git/linux-rcu/tools/testing/selftests/nolibc/
      TEST          =
      QEMU_ARCH     = x86_64 [determined from $ARCH]
      IMAGE_NAME    = bzImage [determined from $ARCH]

  The output of a successful x86 "make run" is currently as follows,
  with kernel build output omitted:

    $ make run
    71 test(s) passed."

* tag 'nolibc.2022.09.30a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  selftests/nolibc: Avoid generated files being committed
  selftests/nolibc: add a "help" target
  selftests/nolibc: "sysroot" target installs a local copy of the sysroot
  selftests/nolibc: add a "run" target to start the kernel in QEMU
  selftests/nolibc: add a "defconfig" target
  selftests/nolibc: add a "kernel" target to build the kernel with the initramfs
  selftests/nolibc: support glibc as well
  selftests/nolibc: condition some tests on /proc existence
  selftests/nolibc: recreate and populate /dev and /proc if missing
  selftests/nolibc: on x86, support exiting with isa-debug-exit
  selftests/nolibc: exit with poweroff on success when getpid() == 1
  selftests/nolibc: add a few tests for some libc functions
  selftests/nolibc: implement a few tests for various syscalls
  selftests/nolibc: support a test definition format
  selftests/nolibc: add basic infrastructure to ease creation of nolibc tests
  tools/nolibc: make sys_mmap() automatically use the right __NR_mmap definition
  tools/nolibc: fix build warning in sys_mmap() when my_syscall6 is not defined
  tools/nolibc: make argc 32-bit in riscv startup code

5 files changed, 899 insertions, 3 deletions

diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h
index 95e2b7924925..ba04771cb3a3 100644
--- a/tools/include/nolibc/arch-riscv.h
+++ b/tools/include/nolibc/arch-riscv.h
@@ -190,7 +190,7 @@ __asm__ (".section .text\n"
     ".option norelax\n"
     "lla   gp, __global_pointer$\n"
     ".option pop\n"
-    "ld    a0, 0(sp)\n"          // argc (a0) was in the stack
+    "lw    a0, 0(sp)\n"          // argc (a0) was in the stack
     "add   a1, sp, "SZREG"\n"    // argv (a1) = sp
     "slli  a2, a0, "PTRLOG"\n"   // envp (a2) = SZREG*argc ...
     "add   a2, a2, "SZREG"\n"    //             + SZREG (skip null)
diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 08491070387b..ce3ee03aa679 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -692,12 +692,12 @@ void *sys_mmap(void *addr, size_t length, int prot, int flags, int fd,
 {
 #ifndef my_syscall6
 	/* Function not implemented. */
-	return -ENOSYS;
+	return (void *)-ENOSYS;
 #else
 
 	int n;
 
-#if defined(__i386__)
+#if defined(__NR_mmap2)
 	n = __NR_mmap2;
 	offset >>= 12;
 #else
diff --git a/tools/testing/selftests/nolibc/.gitignore b/tools/testing/selftests/nolibc/.gitignore
new file mode 100644
index 000000000000..4696df589d68
--- /dev/null
+++ b/tools/testing/selftests/nolibc/.gitignore
@@ -0,0 +1,4 @@
+/initramfs/
+/nolibc-test
+/run.out
+/sysroot/
diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
new file mode 100644
index 000000000000..69ea659caca9
--- /dev/null
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -0,0 +1,135 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for nolibc tests
+include ../../../scripts/Makefile.include
+
+# we're in ".../tools/testing/selftests/nolibc"
+ifeq ($(srctree),)
+srctree := $(patsubst %/tools/testing/selftests/,%,$(dir $(CURDIR)))
+endif
+
+ifeq ($(ARCH),)
+include $(srctree)/scripts/subarch.include
+ARCH = $(SUBARCH)
+endif
+
+# kernel image names by architecture
+IMAGE_i386    = arch/x86/boot/bzImage
+IMAGE_x86     = arch/x86/boot/bzImage
+IMAGE_arm64   = arch/arm64/boot/Image
+IMAGE_arm     = arch/arm/boot/zImage
+IMAGE_mips    = vmlinuz
+IMAGE_riscv   = arch/riscv/boot/Image
+IMAGE         = $(IMAGE_$(ARCH))
+IMAGE_NAME    = $(notdir $(IMAGE))
+
+# default kernel configurations that appear to be usable
+DEFCONFIG_i386    = defconfig
+DEFCONFIG_x86     = defconfig
+DEFCONFIG_arm64   = defconfig
+DEFCONFIG_arm     = multi_v7_defconfig
+DEFCONFIG_mips    = malta_defconfig
+DEFCONFIG_riscv   = defconfig
+DEFCONFIG         = $(DEFCONFIG_$(ARCH))
+
+# optional tests to run (default = all)
+TEST =
+
+# QEMU_ARCH: arch names used by qemu
+QEMU_ARCH_i386    = i386
+QEMU_ARCH_x86     = x86_64
+QEMU_ARCH_arm64   = aarch64
+QEMU_ARCH_arm     = arm
+QEMU_ARCH_mips    = mipsel  # works with malta_defconfig
+QEMU_ARCH_riscv   = riscv64
+QEMU_ARCH         = $(QEMU_ARCH_$(ARCH))
+
+# QEMU_ARGS : some arch-specific args to pass to qemu
+QEMU_ARGS_i386    = -M pc -append "console=ttyS0,9600 i8042.noaux panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_x86     = -M pc -append "console=ttyS0,9600 i8042.noaux panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_arm64   = -M virt -cpu cortex-a53 -append "panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_arm     = -M virt -append "panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_mips    = -M malta -append "panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_riscv   = -M virt -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS         = $(QEMU_ARGS_$(ARCH))
+
+# OUTPUT is only set when run from the main makefile, otherwise
+# it defaults to this nolibc directory.
+OUTPUT ?= $(CURDIR)/
+
+ifeq ($(V),1)
+Q=
+else
+Q=@
+endif
+
+CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables
+LDFLAGS := -s
+
+help:
+	@echo "Supported targets under selftests/nolibc:"
+	@echo "  all          call the \"run\" target below"
+	@echo "  help         this help"
+	@echo "  sysroot      create the nolibc sysroot here (uses \$$ARCH)"
+	@echo "  nolibc-test  build the executable (uses \$$CC and \$$CROSS_COMPILE)"
+	@echo "  initramfs    prepare the initramfs with nolibc-test"
+	@echo "  defconfig    create a fresh new default config (uses \$$ARCH)"
+	@echo "  kernel       (re)build the kernel with the initramfs (uses \$$ARCH)"
+	@echo "  run          runs the kernel in QEMU after building it (uses \$$ARCH, \$$TEST)"
+	@echo "  rerun        runs a previously prebuilt kernel in QEMU (uses \$$ARCH, \$$TEST)"
+	@echo "  clean        clean the sysroot, initramfs, build and output files"
+	@echo ""
+	@echo "The output file is \"run.out\". Test ranges may be passed using \$$TEST."
+	@echo ""
+	@echo "Currently using the following variables:"
+	@echo "  ARCH          = $(ARCH)"
+	@echo "  CROSS_COMPILE = $(CROSS_COMPILE)"
+	@echo "  CC            = $(CC)"
+	@echo "  OUTPUT        = $(OUTPUT)"
+	@echo "  TEST          = $(TEST)"
+	@echo "  QEMU_ARCH     = $(if $(QEMU_ARCH),$(QEMU_ARCH),UNKNOWN_ARCH) [determined from \$$ARCH]"
+	@echo "  IMAGE_NAME    = $(if $(IMAGE_NAME),$(IMAGE_NAME),UNKNOWN_ARCH) [determined from \$$ARCH]"
+	@echo ""
+
+all: run
+
+sysroot: sysroot/$(ARCH)/include
+
+sysroot/$(ARCH)/include:
+	$(QUIET_MKDIR)mkdir -p sysroot
+	$(Q)$(MAKE) -C ../../../include/nolibc ARCH=$(ARCH) OUTPUT=$(CURDIR)/sysroot/ headers_standalone
+	$(Q)mv sysroot/sysroot sysroot/$(ARCH)
+
+nolibc-test: nolibc-test.c sysroot/$(ARCH)/include
+	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \
+	  -nostdlib -static -Isysroot/$(ARCH)/include $< -lgcc
+
+initramfs: nolibc-test
+	$(QUIET_MKDIR)mkdir -p initramfs
+	$(call QUIET_INSTALL, initramfs/init)
+	$(Q)cp nolibc-test initramfs/init
+
+defconfig:
+	$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) mrproper $(DEFCONFIG) prepare
+
+kernel: initramfs
+	$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) $(IMAGE_NAME) CONFIG_INITRAMFS_SOURCE=$(CURDIR)/initramfs
+
+# run the tests after building the kernel
+run: kernel
+	$(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
+	$(Q)grep -w FAIL "$(CURDIR)/run.out" && echo "See all results in $(CURDIR)/run.out" || echo "$$(grep -c ^[0-9].*OK $(CURDIR)/run.out) test(s) passed."
+
+# re-run the tests from an existing kernel
+rerun:
+	$(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
+	$(Q)grep -w FAIL "$(CURDIR)/run.out" && echo "See all results in $(CURDIR)/run.out" || echo "$$(grep -c ^[0-9].*OK $(CURDIR)/run.out) test(s) passed."
+
+clean:
+	$(call QUIET_CLEAN, sysroot)
+	$(Q)rm -rf sysroot
+	$(call QUIET_CLEAN, nolibc-test)
+	$(Q)rm -f nolibc-test
+	$(call QUIET_CLEAN, initramfs)
+	$(Q)rm -rf initramfs
+	$(call QUIET_CLEAN, run.out)
+	$(Q)rm -rf run.out
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
new file mode 100644
index 000000000000..78bced95ac63
--- /dev/null
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -0,0 +1,757 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+
+/* platform-specific include files coming from the compiler */
+#include <limits.h>
+
+/* libc-specific include files
+ * The program may be built in 3 ways:
+ *   $(CC) -nostdlib -include /path/to/nolibc.h => NOLIBC already defined
+ *   $(CC) -nostdlib -I/path/to/nolibc/sysroot  => _NOLIBC_* guards are present
+ *   $(CC) with default libc                    => NOLIBC* never defined
+ */
+#ifndef NOLIBC
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifndef _NOLIBC_STDIO_H
+/* standard libcs need more includes */
+#include <linux/reboot.h>
+#include <sys/io.h>
+#include <sys/ioctl.h>
+#include <sys/mount.h>
+#include <sys/reboot.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/sysmacros.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <unistd.h>
+#endif
+#endif
+
+/* will be used by nolibc by getenv() */
+char **environ;
+
+/* definition of a series of tests */
+struct test {
+	const char *name;              // test name
+	int (*func)(int min, int max); // handler
+};
+
+#ifndef _NOLIBC_STDLIB_H
+char *itoa(int i)
+{
+	static char buf[12];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf), "%d", i);
+	return (ret >= 0 && ret < sizeof(buf)) ? buf : "#err";
+}
+#endif
+
+#define CASE_ERR(err) \
+	case err: return #err
+
+/* returns the error name (e.g. "ENOENT") for common errors, "SUCCESS" for 0,
+ * or the decimal value for less common ones.
+ */
+const char *errorname(int err)
+{
+	switch (err) {
+	case 0: return "SUCCESS";
+	CASE_ERR(EPERM);
+	CASE_ERR(ENOENT);
+	CASE_ERR(ESRCH);
+	CASE_ERR(EINTR);
+	CASE_ERR(EIO);
+	CASE_ERR(ENXIO);
+	CASE_ERR(E2BIG);
+	CASE_ERR(ENOEXEC);
+	CASE_ERR(EBADF);
+	CASE_ERR(ECHILD);
+	CASE_ERR(EAGAIN);
+	CASE_ERR(ENOMEM);
+	CASE_ERR(EACCES);
+	CASE_ERR(EFAULT);
+	CASE_ERR(ENOTBLK);
+	CASE_ERR(EBUSY);
+	CASE_ERR(EEXIST);
+	CASE_ERR(EXDEV);
+	CASE_ERR(ENODEV);
+	CASE_ERR(ENOTDIR);
+	CASE_ERR(EISDIR);
+	CASE_ERR(EINVAL);
+	CASE_ERR(ENFILE);
+	CASE_ERR(EMFILE);
+	CASE_ERR(ENOTTY);
+	CASE_ERR(ETXTBSY);
+	CASE_ERR(EFBIG);
+	CASE_ERR(ENOSPC);
+	CASE_ERR(ESPIPE);
+	CASE_ERR(EROFS);
+	CASE_ERR(EMLINK);
+	CASE_ERR(EPIPE);
+	CASE_ERR(EDOM);
+	CASE_ERR(ERANGE);
+	CASE_ERR(ENOSYS);
+	default:
+		return itoa(err);
+	}
+}
+
+static int pad_spc(int llen, int cnt, const char *fmt, ...)
+{
+	va_list args;
+	int len;
+	int ret;
+
+	for (len = 0; len < cnt - llen; len++)
+		putchar(' ');
+
+	va_start(args, fmt);
+	ret = vfprintf(stdout, fmt, args);
+	va_end(args);
+	return ret < 0 ? ret : ret + len;
+}
+
+/* The tests below are intended to be used by the macroes, which evaluate
+ * expression <expr>, print the status to stdout, and update the "ret"
+ * variable to count failures. The functions themselves return the number
+ * of failures, thus either 0 or 1.
+ */
+
+#define EXPECT_ZR(cond, expr)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_zr(expr, llen); } while (0)
+
+static int expect_zr(int expr, int llen)
+{
+	int ret = !(expr == 0);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_NZ(cond, expr, val)			\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_nz(expr, llen; } while (0)
+
+static int expect_nz(int expr, int llen)
+{
+	int ret = !(expr != 0);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_EQ(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_eq(expr, llen, val); } while (0)
+
+static int expect_eq(int expr, int llen, int val)
+{
+	int ret = !(expr == val);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_NE(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_ne(expr, llen, val); } while (0)
+
+static int expect_ne(int expr, int llen, int val)
+{
+	int ret = !(expr != val);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_GE(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_ge(expr, llen, val); } while (0)
+
+static int expect_ge(int expr, int llen, int val)
+{
+	int ret = !(expr >= val);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_GT(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_gt(expr, llen, val); } while (0)
+
+static int expect_gt(int expr, int llen, int val)
+{
+	int ret = !(expr > val);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_LE(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_le(expr, llen, val); } while (0)
+
+static int expect_le(int expr, int llen, int val)
+{
+	int ret = !(expr <= val);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_LT(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_lt(expr, llen, val); } while (0)
+
+static int expect_lt(int expr, int llen, int val)
+{
+	int ret = !(expr < val);
+
+	llen += printf(" = %d ", expr);
+	pad_spc(llen, 40, ret ? "[FAIL]\n" : " [OK]\n");
+	return ret;
+}
+
+
+#define EXPECT_SYSZR(cond, expr)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_syszr(expr, llen); } while (0)
+
+static int expect_syszr(int expr, int llen)
+{
+	int ret = 0;
+
+	if (expr) {
+		ret = 1;
+		llen += printf(" = %d %s ", expr, errorname(errno));
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += printf(" = %d ", expr);
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_SYSEQ(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_syseq(expr, llen, val); } while (0)
+
+static int expect_syseq(int expr, int llen, int val)
+{
+	int ret = 0;
+
+	if (expr != val) {
+		ret = 1;
+		llen += printf(" = %d %s ", expr, errorname(errno));
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += printf(" = %d ", expr);
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_SYSNE(cond, expr, val)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_sysne(expr, llen, val); } while (0)
+
+static int expect_sysne(int expr, int llen, int val)
+{
+	int ret = 0;
+
+	if (expr == val) {
+		ret = 1;
+		llen += printf(" = %d %s ", expr, errorname(errno));
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += printf(" = %d ", expr);
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_SYSER(cond, expr, expret, experr)			\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_syserr(expr, expret, experr, llen); } while (0)
+
+static int expect_syserr(int expr, int expret, int experr, int llen)
+{
+	int ret = 0;
+	int _errno = errno;
+
+	llen += printf(" = %d %s ", expr, errorname(_errno));
+	if (expr != expret || _errno != experr) {
+		ret = 1;
+		llen += printf(" != (%d %s) ", expret, errorname(experr));
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_PTRZR(cond, expr)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_ptrzr(expr, llen); } while (0)
+
+static int expect_ptrzr(const void *expr, int llen)
+{
+	int ret = 0;
+
+	llen += printf(" = <%p> ", expr);
+	if (expr) {
+		ret = 1;
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_PTRNZ(cond, expr)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_ptrnz(expr, llen); } while (0)
+
+static int expect_ptrnz(const void *expr, int llen)
+{
+	int ret = 0;
+
+	llen += printf(" = <%p> ", expr);
+	if (!expr) {
+		ret = 1;
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_STRZR(cond, expr)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_strzr(expr, llen); } while (0)
+
+static int expect_strzr(const char *expr, int llen)
+{
+	int ret = 0;
+
+	llen += printf(" = <%s> ", expr);
+	if (expr) {
+		ret = 1;
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_STRNZ(cond, expr)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_strnz(expr, llen); } while (0)
+
+static int expect_strnz(const char *expr, int llen)
+{
+	int ret = 0;
+
+	llen += printf(" = <%s> ", expr);
+	if (!expr) {
+		ret = 1;
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_STREQ(cond, expr, cmp)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_streq(expr, llen, cmp); } while (0)
+
+static int expect_streq(const char *expr, int llen, const char *cmp)
+{
+	int ret = 0;
+
+	llen += printf(" = <%s> ", expr);
+	if (strcmp(expr, cmp) != 0) {
+		ret = 1;
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+#define EXPECT_STRNE(cond, expr, cmp)				\
+	do { if (!cond) pad_spc(llen, 40, "[SKIPPED]\n"); else ret += expect_strne(expr, llen, cmp); } while (0)
+
+static int expect_strne(const char *expr, int llen, const char *cmp)
+{
+	int ret = 0;
+
+	llen += printf(" = <%s> ", expr);
+	if (strcmp(expr, cmp) == 0) {
+		ret = 1;
+		llen += pad_spc(llen, 40, "[FAIL]\n");
+	} else {
+		llen += pad_spc(llen, 40, " [OK]\n");
+	}
+	return ret;
+}
+
+
+/* declare tests based on line numbers. There must be exactly one test per line. */
+#define CASE_TEST(name) \
+	case __LINE__: llen += printf("%d %s", test, #name);
+
+
+/* used by some syscall tests below */
+int test_getdents64(const char *dir)
+{
+	char buffer[4096];
+	int fd, ret;
+	int err;
+
+	ret = fd = open(dir, O_RDONLY | O_DIRECTORY, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = getdents64(fd, (void *)buffer, sizeof(buffer));
+	err = errno;
+	close(fd);
+
+	errno = err;
+	return ret;
+}
+
+/* Run syscall tests between IDs <min> and <max>.
+ * Return 0 on success, non-zero on failure.
+ */
+int run_syscall(int min, int max)
+{
+	struct stat stat_buf;
+	int proc;
+	int test;
+	int tmp;
+	int ret = 0;
+	void *p1, *p2;
+
+	/* <proc> indicates whether or not /proc is mounted */
+	proc = stat("/proc", &stat_buf) == 0;
+
+	for (test = min; test >= 0 && test <= max; test++) {
+		int llen = 0; // line length
+
+		/* avoid leaving empty lines below, this will insert holes into
+		 * test numbers.
+		 */
+		switch (test + __LINE__ + 1) {
+		CASE_TEST(getpid);            EXPECT_SYSNE(1, getpid(), -1); break;
+		CASE_TEST(getppid);           EXPECT_SYSNE(1, getppid(), -1); break;
+#ifdef NOLIBC
+		CASE_TEST(gettid);            EXPECT_SYSNE(1, gettid(), -1); break;
+#endif
+		CASE_TEST(getpgid_self);      EXPECT_SYSNE(1, getpgid(0), -1); break;
+		CASE_TEST(getpgid_bad);       EXPECT_SYSER(1, getpgid(-1), -1, ESRCH); break;
+		CASE_TEST(kill_0);            EXPECT_SYSZR(1, kill(getpid(), 0)); break;
+		CASE_TEST(kill_CONT);         EXPECT_SYSZR(1, kill(getpid(), 0)); break;
+		CASE_TEST(kill_BADPID);       EXPECT_SYSER(1, kill(INT_MAX, 0), -1, ESRCH); break;
+		CASE_TEST(sbrk);              if ((p1 = p2 = sbrk(4096)) != (void *)-1) p2 = sbrk(-4096); EXPECT_SYSZR(1, (p2 == (void *)-1) || p2 == p1); break;
+		CASE_TEST(brk);               EXPECT_SYSZR(1, brk(sbrk(0))); break;
+		CASE_TEST(chdir_root);        EXPECT_SYSZR(1, chdir("/")); break;
+		CASE_TEST(chdir_dot);         EXPECT_SYSZR(1, chdir(".")); break;
+		CASE_TEST(chdir_blah);        EXPECT_SYSER(1, chdir("/blah"), -1, ENOENT); break;
+		CASE_TEST(chmod_net);         EXPECT_SYSZR(proc, chmod("/proc/self/net", 0555)); break;
+		CASE_TEST(chmod_self);        EXPECT_SYSER(proc, chmod("/proc/self", 0555), -1, EPERM); break;
+		CASE_TEST(chown_self);        EXPECT_SYSER(proc, chown("/proc/self", 0, 0), -1, EPERM); break;
+		CASE_TEST(chroot_root);       EXPECT_SYSZR(1, chroot("/")); break;
+		CASE_TEST(chroot_blah);       EXPECT_SYSER(1, chroot("/proc/self/blah"), -1, ENOENT); break;
+		CASE_TEST(chroot_exe);        EXPECT_SYSER(proc, chroot("/proc/self/exe"), -1, ENOTDIR); break;
+		CASE_TEST(close_m1);          EXPECT_SYSER(1, close(-1), -1, EBADF); break;
+		CASE_TEST(close_dup);         EXPECT_SYSZR(1, close(dup(0))); break;
+		CASE_TEST(dup_0);             tmp = dup(0);  EXPECT_SYSNE(1, tmp, -1); close(tmp); break;
+		CASE_TEST(dup_m1);            tmp = dup(-1); EXPECT_SYSER(1, tmp, -1, EBADF); if (tmp != -1) close(tmp); break;
+		CASE_TEST(dup2_0);            tmp = dup2(0, 100);  EXPECT_SYSNE(1, tmp, -1); close(tmp); break;
+		CASE_TEST(dup2_m1);           tmp = dup2(-1, 100); EXPECT_SYSER(1, tmp, -1, EBADF); if (tmp != -1) close(tmp); break;
+		CASE_TEST(dup3_0);            tmp = dup3(0, 100, 0);  EXPECT_SYSNE(1, tmp, -1); close(tmp); break;
+		CASE_TEST(dup3_m1);           tmp = dup3(-1, 100, 0); EXPECT_SYSER(1, tmp, -1, EBADF); if (tmp != -1) close(tmp); break;
+		CASE_TEST(execve_root);       EXPECT_SYSER(1, execve("/", (char*[]){ [0] = "/", [1] = NULL }, NULL), -1, EACCES); break;
+		CASE_TEST(getdents64_root);   EXPECT_SYSNE(1, test_getdents64("/"), -1); break;
+		CASE_TEST(getdents64_null);   EXPECT_SYSER(1, test_getdents64("/dev/null"), -1, ENOTDIR); break;
+		CASE_TEST(gettimeofday_null); EXPECT_SYSZR(1, gettimeofday(NULL, NULL)); break;
+#ifdef NOLIBC
+		CASE_TEST(gettimeofday_bad1); EXPECT_SYSER(1, gettimeofday((void *)1, NULL), -1, EFAULT); break;
+		CASE_TEST(gettimeofday_bad2); EXPECT_SYSER(1, gettimeofday(NULL, (void *)1), -1, EFAULT); break;
+		CASE_TEST(gettimeofday_bad2); EXPECT_SYSER(1, gettimeofday(NULL, (void *)1), -1, EFAULT); break;
+#endif
+		CASE_TEST(ioctl_tiocinq);     EXPECT_SYSZR(1, ioctl(0, TIOCINQ, &tmp)); break;
+		CASE_TEST(ioctl_tiocinq);     EXPECT_SYSZR(1, ioctl(0, TIOCINQ, &tmp)); break;
+		CASE_TEST(link_root1);        EXPECT_SYSER(1, link("/", "/"), -1, EEXIST); break;
+		CASE_TEST(link_blah);         EXPECT_SYSER(1, link("/proc/self/blah", "/blah"), -1, ENOENT); break;
+		CASE_TEST(link_dir);          EXPECT_SYSER(1, link("/", "/blah"), -1, EPERM); break;
+		CASE_TEST(link_cross);        EXPECT_SYSER(proc, link("/proc/self/net", "/blah"), -1, EXDEV); break;
+		CASE_TEST(lseek_m1);          EXPECT_SYSER(1, lseek(-1, 0, SEEK_SET), -1, EBADF); break;
+		CASE_TEST(lseek_0);           EXPECT_SYSER(1, lseek(0, 0, SEEK_SET), -1, ESPIPE); break;
+		CASE_TEST(mkdir_root);        EXPECT_SYSER(1, mkdir("/", 0755), -1, EEXIST); break;
+		CASE_TEST(open_tty);          EXPECT_SYSNE(1, tmp = open("/dev/null", 0), -1); if (tmp != -1) close(tmp); break;
+		CASE_TEST(open_blah);         EXPECT_SYSER(1, tmp = open("/proc/self/blah", 0), -1, ENOENT); if (tmp != -1) close(tmp); break;
+		CASE_TEST(poll_null);         EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
+		CASE_TEST(poll_stdout);       EXPECT_SYSNE(1, ({ struct pollfd fds = { 1, POLLOUT, 0}; poll(&fds, 1, 0); }), -1); break;
+		CASE_TEST(poll_fault);        EXPECT_SYSER(1, poll((void *)1, 1, 0), -1, EFAULT); break;
+		CASE_TEST(read_badf);         EXPECT_SYSER(1, read(-1, &tmp, 1), -1, EBADF); break;
+		CASE_TEST(sched_yield);       EXPECT_SYSZR(1, sched_yield()); break;
+		CASE_TEST(select_null);       EXPECT_SYSZR(1, ({ struct timeval tv = { 0 }; select(0, NULL, NULL, NULL, &tv); })); break;
+		CASE_TEST(select_stdout);     EXPECT_SYSNE(1, ({ fd_set fds; FD_ZERO(&fds); FD_SET(1, &fds); select(2, NULL, &fds, NULL, NULL); }), -1); break;
+		CASE_TEST(select_fault);      EXPECT_SYSER(1, select(1, (void *)1, NULL, NULL, 0), -1, EFAULT); break;
+		CASE_TEST(stat_blah);         EXPECT_SYSER(1, stat("/proc/self/blah", &stat_buf), -1, ENOENT); break;
+		CASE_TEST(stat_fault);        EXPECT_SYSER(1, stat(NULL, &stat_buf), -1, EFAULT); break;
+		CASE_TEST(symlink_root);      EXPECT_SYSER(1, symlink("/", "/"), -1, EEXIST); break;
+		CASE_TEST(unlink_root);       EXPECT_SYSER(1, unlink("/"), -1, EISDIR); break;
+		CASE_TEST(unlink_blah);       EXPECT_SYSER(1, unlink("/proc/self/blah"), -1, ENOENT); break;
+		CASE_TEST(wait_child);        EXPECT_SYSER(1, wait(&tmp), -1, ECHILD); break;
+		CASE_TEST(waitpid_min);       EXPECT_SYSER(1, waitpid(INT_MIN, &tmp, WNOHANG), -1, ESRCH); break;
+		CASE_TEST(waitpid_child);     EXPECT_SYSER(1, waitpid(getpid(), &tmp, WNOHANG), -1, ECHILD); break;
+		CASE_TEST(write_badf);        EXPECT_SYSER(1, write(-1, &tmp, 1), -1, EBADF); break;
+		CASE_TEST(write_zero);        EXPECT_SYSZR(1, write(1, &tmp, 0)); break;
+		case __LINE__:
+			return ret; /* must be last */
+		/* note: do not set any defaults so as to permit holes above */
+		}
+	}
+	return ret;
+}
+
+int run_stdlib(int min, int max)
+{
+	int test;
+	int tmp;
+	int ret = 0;
+	void *p1, *p2;
+
+	for (test = min; test >= 0 && test <= max; test++) {
+		int llen = 0; // line length
+
+		/* avoid leaving empty lines below, this will insert holes into
+		 * test numbers.
+		 */
+		switch (test + __LINE__ + 1) {
+		CASE_TEST(getenv_TERM);        EXPECT_STRNZ(1, getenv("TERM")); break;
+		CASE_TEST(getenv_blah);        EXPECT_STRZR(1, getenv("blah")); break;
+		CASE_TEST(setcmp_blah_blah);   EXPECT_EQ(1, strcmp("blah", "blah"), 0); break;
+		CASE_TEST(setcmp_blah_blah2);  EXPECT_NE(1, strcmp("blah", "blah2"), 0); break;
+		CASE_TEST(setncmp_blah_blah);  EXPECT_EQ(1, strncmp("blah", "blah", 10), 0); break;
+		CASE_TEST(setncmp_blah_blah4); EXPECT_EQ(1, strncmp("blah", "blah4", 4), 0); break;
+		CASE_TEST(setncmp_blah_blah5); EXPECT_NE(1, strncmp("blah", "blah5", 5), 0); break;
+		CASE_TEST(setncmp_blah_blah6); EXPECT_NE(1, strncmp("blah", "blah6", 6), 0); break;
+		CASE_TEST(strchr_foobar_o);    EXPECT_STREQ(1, strchr("foobar", 'o'), "oobar"); break;
+		CASE_TEST(strchr_foobar_z);    EXPECT_STRZR(1, strchr("foobar", 'z')); break;
+		CASE_TEST(strrchr_foobar_o);   EXPECT_STREQ(1, strrchr("foobar", 'o'), "obar"); break;
+		CASE_TEST(strrchr_foobar_z);   EXPECT_STRZR(1, strrchr("foobar", 'z')); break;
+		case __LINE__:
+			return ret; /* must be last */
+		/* note: do not set any defaults so as to permit holes above */
+		}
+	}
+	return ret;
+}
+
+/* prepare what needs to be prepared for pid 1 (stdio, /dev, /proc, etc) */
+int prepare(void)
+{
+	struct stat stat_buf;
+
+	/* It's possible that /dev doesn't even exist or was not mounted, so
+	 * we'll try to create it, mount it, or create minimal entries into it.
+	 * We want at least /dev/null and /dev/console.
+	 */
+	if (stat("/dev/.", &stat_buf) == 0 || mkdir("/dev", 0755) == 0) {
+		if (stat("/dev/console", &stat_buf) != 0 ||
+		    stat("/dev/null", &stat_buf) != 0) {
+			/* try devtmpfs first, otherwise fall back to manual creation */
+			if (mount("/dev", "/dev", "devtmpfs", 0, 0) != 0) {
+				mknod("/dev/console", 0600 | S_IFCHR, makedev(5, 1));
+				mknod("/dev/null",    0666 | S_IFCHR, makedev(1, 3));
+			}
+		}
+	}
+
+	/* If no /dev/console was found before calling init, stdio is closed so
+	 * we need to reopen it from /dev/console. If it failed above, it will
+	 * still fail here and we cannot emit a message anyway.
+	 */
+	if (close(dup(1)) == -1) {
+		int fd = open("/dev/console", O_RDWR);
+
+		if (fd >= 0) {
+			if (fd != 0)
+				dup2(fd, 0);
+			if (fd != 1)
+				dup2(fd, 1);
+			if (fd != 2)
+				dup2(fd, 2);
+			if (fd > 2)
+				close(fd);
+			puts("\nSuccessfully reopened /dev/console.");
+		}
+	}
+
+	/* try to mount /proc if not mounted. Silently fail otherwise */
+	if (stat("/proc/.", &stat_buf) == 0 || mkdir("/proc", 0755) == 0) {
+		if (stat("/proc/self", &stat_buf) != 0)
+			mount("/proc", "/proc", "proc", 0, 0);
+	}
+
+	return 0;
+}
+
+/* This is the definition of known test names, with their functions */
+static struct test test_names[] = {
+	/* add new tests here */
+	{ .name = "syscall",   .func = run_syscall  },
+	{ .name = "stdlib",    .func = run_stdlib   },
+	{ 0 }
+};
+
+int main(int argc, char **argv, char **envp)
+{
+	int min = 0;
+	int max = __INT_MAX__;
+	int ret = 0;
+	int err;
+	int idx;
+	char *test;
+
+	environ = envp;
+
+	/* when called as init, it's possible that no console was opened, for
+	 * example if no /dev file system was provided. We'll check that fd#1
+	 * was opened, and if not we'll attempt to create and open /dev/console
+	 * and /dev/null that we'll use for later tests.
+	 */
+	if (getpid() == 1)
+		prepare();
+
+	/* the definition of a series of tests comes from either argv[1] or the
+	 * "NOLIBC_TEST" environment variable. It's made of a comma-delimited
+	 * series of test names and optional ranges:
+	 *    syscall:5-15[:.*],stdlib:8-10
+	 */
+	test = argv[1];
+	if (!test)
+		test = getenv("NOLIBC_TEST");
+
+	if (test) {
+		char *comma, *colon, *dash, *value;
+
+		do {
+			comma = strchr(test, ',');
+			if (comma)
+				*(comma++) = '\0';
+
+			colon = strchr(test, ':');
+			if (colon)
+				*(colon++) = '\0';
+
+			for (idx = 0; test_names[idx].name; idx++) {
+				if (strcmp(test, test_names[idx].name) == 0)
+					break;
+			}
+
+			if (test_names[idx].name) {
+				/* The test was named, it will be called at least
+				 * once. We may have an optional range at <colon>
+				 * here, which defaults to the full range.
+				 */
+				do {
+					min = 0; max = __INT_MAX__;
+					value = colon;
+					if (value && *value) {
+						colon = strchr(value, ':');
+						if (colon)
+							*(colon++) = '\0';
+
+						dash = strchr(value, '-');
+						if (dash)
+							*(dash++) = '\0';
+
+						/* support :val: :min-max: :min-: :-max: */
+						if (*value)
+							min = atoi(value);
+						if (!dash)
+							max = min;
+						else if (*dash)
+							max = atoi(dash);
+
+						value = colon;
+					}
+
+					/* now's time to call the test */
+					printf("Running test '%s'\n", test_names[idx].name);
+					err = test_names[idx].func(min, max);
+					ret += err;
+					printf("Errors during this test: %d\n\n", err);
+				} while (colon && *colon);
+			} else
+				printf("Ignoring unknown test name '%s'\n", test);
+
+			test = comma;
+		} while (test && *test);
+	} else {
+		/* no test mentioned, run everything */
+		for (idx = 0; test_names[idx].name; idx++) {
+			printf("Running test '%s'\n", test_names[idx].name);
+			err = test_names[idx].func(min, max);
+			ret += err;
+			printf("Errors during this test: %d\n\n", err);
+		}
+	}
+
+	printf("Total number of errors: %d\n", ret);
+
+	if (getpid() == 1) {
+		/* we're running as init, there's no other process on the
+		 * system, thus likely started from a VM for a quick check.
+		 * Exiting will provoke a kernel panic that may be reported
+		 * as an error by Qemu or the hypervisor, while stopping
+		 * cleanly will often be reported as a success. This allows
+		 * to use the output of this program for bisecting kernels.
+		 */
+		printf("Leaving init with final status: %d\n", !!ret);
+		if (ret == 0)
+			reboot(LINUX_REBOOT_CMD_POWER_OFF);
+#if defined(__x86_64__)
+		/* QEMU started with "-device isa-debug-exit -no-reboot" will
+		 * exit with status code 2N+1 when N is written to 0x501. We
+		 * hard-code the syscall here as it's arch-dependent.
+		 */
+#if defined(_NOLIBC_SYS_H)
+		else if (my_syscall3(__NR_ioperm, 0x501, 1, 1) == 0)
+#else
+		else if (ioperm(0x501, 1, 1) == 0)
+#endif
+			asm volatile ("outb %%al, %%dx" :: "d"(0x501), "a"(0));
+		/* if it does nothing, fall back to the regular panic */
+#endif
+	}
+
+	printf("Exiting with status %d\n", !!ret);
+	return !!ret;
+}