Merge tag 'nolibc.2023.10.23a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull nolibc updates from Paul McKenney:

 - Add stdarg.h header and a few additional system-call upgrades

 - Add support for constructors and destructors

 - Add tests to verify the ability to link multiple .o files against
   nolibc

 - Numerous string-function optimizations and improvements

 - Prevent redundant kernel relinks by avoiding embedding of initramfs
   into the kernel image

 - Allow building i386 with multiarch compiler and make ppc64le use
   qemu-system-ppc64

 - Miscellaneous fixups, including addition of -nostdinc for
   nolibc-test, avoiding -Wstringop-overflow warnings, and avoiding
   unused parameter warnings for ENOSYS fallbacks

* tag 'nolibc.2023.10.23a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  selftests/nolibc: add tests for multi-object linkage
  selftests/nolibc: use qemu-system-ppc64 for ppc64le
  tools/nolibc: add support for constructors and destructors
  tools/nolibc: drop test for getauxval(AT_PAGESZ)
  tools/nolibc: automatically detect necessity to use pselect6
  tools/nolibc: don't define new syscall number
  tools/nolibc: avoid unused parameter warnings for ENOSYS fallbacks
  selftests/nolibc: allow building i386 with multiarch compiler
  selftests/nolibc: don't embed initramfs into kernel image
  selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings
  tools/nolibc: string: Remove the `_nolibc_memcpy_up()` function
  tools/nolibc: string: Remove the `_nolibc_memcpy_down()` function
  tools/nolibc: x86-64: Use `rep stosb` for `memset()`
  tools/nolibc: x86-64: Use `rep movsb` for `memcpy()` and `memmove()`
  selftests/nolibc: use -nostdinc for nolibc-test
  tools/nolibc: add stdarg.h header

11 files changed, 131 insertions, 61 deletions

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile
index 909b6eb500fe..e69c26abe1ea 100644
--- a/tools/include/nolibc/Makefile
+++ b/tools/include/nolibc/Makefile
@@ -34,6 +34,7 @@ all_files := \
 		signal.h \
 		stackprotector.h \
 		std.h \
+		stdarg.h \
 		stdint.h \
 		stdlib.h \
 		string.h \
diff --git a/tools/include/nolibc/arch-aarch64.h b/tools/include/nolibc/arch-aarch64.h
index 6c33c46848e3..b23ac1f04035 100644
--- a/tools/include/nolibc/arch-aarch64.h
+++ b/tools/include/nolibc/arch-aarch64.h
@@ -20,10 +20,7 @@
  *   - the arguments are cast to long and assigned into the target registers
  *     which are then simply passed as registers to the asm code, so that we
  *     don't have to experience issues with register constraints.
- *
- * On aarch64, select() is not implemented so we have to use pselect6().
  */
-#define __ARCH_WANT_SYS_PSELECT6
 
 #define my_syscall0(num)                                                      \
 ({                                                                            \
diff --git a/tools/include/nolibc/arch-loongarch.h b/tools/include/nolibc/arch-loongarch.h
index bf98f6220195..3f8ef8f86c0f 100644
--- a/tools/include/nolibc/arch-loongarch.h
+++ b/tools/include/nolibc/arch-loongarch.h
@@ -19,10 +19,8 @@
  *   - the arguments are cast to long and assigned into the target
  *     registers which are then simply passed as registers to the asm code,
  *     so that we don't have to experience issues with register constraints.
- *
- * On LoongArch, select() is not implemented so we have to use pselect6().
  */
-#define __ARCH_WANT_SYS_PSELECT6
+
 #define _NOLIBC_SYSCALL_CLOBBERLIST \
 	"memory", "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$t8"
 
diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h
index 950cc2283fd7..1927c643c739 100644
--- a/tools/include/nolibc/arch-riscv.h
+++ b/tools/include/nolibc/arch-riscv.h
@@ -19,10 +19,7 @@
  *   - the arguments are cast to long and assigned into the target
  *     registers which are then simply passed as registers to the asm code,
  *     so that we don't have to experience issues with register constraints.
- *
- * On riscv, select() is not implemented so we have to use pselect6().
  */
-#define __ARCH_WANT_SYS_PSELECT6
 
 #define my_syscall0(num)                                                      \
 ({                                                                            \
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index e5ccb926c903..68609f421934 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -173,4 +173,46 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 	__builtin_unreachable();
 }
 
+#define NOLIBC_ARCH_HAS_MEMMOVE
+void *memmove(void *dst, const void *src, size_t len);
+
+#define NOLIBC_ARCH_HAS_MEMCPY
+void *memcpy(void *dst, const void *src, size_t len);
+
+#define NOLIBC_ARCH_HAS_MEMSET
+void *memset(void *dst, int c, size_t len);
+
+__asm__ (
+".section .text.nolibc_memmove_memcpy\n"
+".weak memmove\n"
+".weak memcpy\n"
+"memmove:\n"
+"memcpy:\n"
+	"movq %rdx, %rcx\n\t"
+	"movq %rdi, %rax\n\t"
+	"movq %rdi, %rdx\n\t"
+	"subq %rsi, %rdx\n\t"
+	"cmpq %rcx, %rdx\n\t"
+	"jb   .Lbackward_copy\n\t"
+	"rep movsb\n\t"
+	"retq\n"
+".Lbackward_copy:"
+	"leaq -1(%rdi, %rcx, 1), %rdi\n\t"
+	"leaq -1(%rsi, %rcx, 1), %rsi\n\t"
+	"std\n\t"
+	"rep movsb\n\t"
+	"cld\n\t"
+	"retq\n"
+
+".section .text.nolibc_memset\n"
+".weak memset\n"
+"memset:\n"
+	"xchgl %eax, %esi\n\t"
+	"movq  %rdx, %rcx\n\t"
+	"pushq %rdi\n\t"
+	"rep stosb\n\t"
+	"popq  %rax\n\t"
+	"retq\n"
+);
+
 #endif /* _NOLIBC_ARCH_X86_64_H */
diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h
index a05655b4ce1d..43b551468c2a 100644
--- a/tools/include/nolibc/crt.h
+++ b/tools/include/nolibc/crt.h
@@ -13,12 +13,23 @@ const unsigned long *_auxv __attribute__((weak));
 static void __stack_chk_init(void);
 static void exit(int);
 
+extern void (*const __preinit_array_start[])(void) __attribute__((weak));
+extern void (*const __preinit_array_end[])(void) __attribute__((weak));
+
+extern void (*const __init_array_start[])(void) __attribute__((weak));
+extern void (*const __init_array_end[])(void) __attribute__((weak));
+
+extern void (*const __fini_array_start[])(void) __attribute__((weak));
+extern void (*const __fini_array_end[])(void) __attribute__((weak));
+
 __attribute__((weak))
 void _start_c(long *sp)
 {
 	long argc;
 	char **argv;
 	char **envp;
+	int exitcode;
+	void (* const *func)(void);
 	const unsigned long *auxv;
 	/* silence potential warning: conflicting types for 'main' */
 	int _nolibc_main(int, char **, char **) __asm__ ("main");
@@ -55,8 +66,18 @@ void _start_c(long *sp)
 		;
 	_auxv = auxv;
 
+	for (func = __preinit_array_start; func < __preinit_array_end; func++)
+		(*func)();
+	for (func = __init_array_start; func < __init_array_end; func++)
+		(*func)();
+
 	/* go to application */
-	exit(_nolibc_main(argc, argv, envp));
+	exitcode = _nolibc_main(argc, argv, envp);
+
+	for (func = __fini_array_end; func > __fini_array_start;)
+		(*--func)();
+
+	exit(exitcode);
 }
 
 #endif /* _NOLIBC_CRT_H */
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 1f8d821000ac..989e707263a4 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -74,10 +74,10 @@
  *            -I../nolibc -o hello hello.c -lgcc
  *
  * The available standard (but limited) include files are:
- *   ctype.h, errno.h, signal.h, stdio.h, stdlib.h, string.h, time.h
+ *   ctype.h, errno.h, signal.h, stdarg.h, stdio.h, stdlib.h, string.h, time.h
  *
  * In addition, the following ones are expected to be provided by the compiler:
- *   float.h, stdarg.h, stddef.h
+ *   float.h, stddef.h
  *
  * The following ones which are part to the C standard are not provided:
  *   assert.h, locale.h, math.h, setjmp.h, limits.h
diff --git a/tools/include/nolibc/stdarg.h b/tools/include/nolibc/stdarg.h
new file mode 100644
index 000000000000..c628b5783da6
--- /dev/null
+++ b/tools/include/nolibc/stdarg.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * Variadic argument support for NOLIBC
+ * Copyright (C) 2005-2020 Rich Felker, et al.
+ */
+
+#ifndef _NOLIBC_STDARG_H
+#define _NOLIBC_STDARG_H
+
+typedef __builtin_va_list va_list;
+#define va_start(v, l)   __builtin_va_start(v, l)
+#define va_end(v)        __builtin_va_end(v)
+#define va_arg(v, l)     __builtin_va_arg(v, l)
+#define va_copy(d, s)    __builtin_va_copy(d, s)
+
+#endif /* _NOLIBC_STDARG_H */
diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index cae402c11e57..d7ef43973916 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -7,13 +7,12 @@
 #ifndef _NOLIBC_STDIO_H
 #define _NOLIBC_STDIO_H
 
-#include <stdarg.h>
-
 #include "std.h"
 #include "arch.h"
 #include "errno.h"
 #include "types.h"
 #include "sys.h"
+#include "stdarg.h"
 #include "stdlib.h"
 #include "string.h"
 
diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h
index 0c2e06c7c477..a01c69dd495f 100644
--- a/tools/include/nolibc/string.h
+++ b/tools/include/nolibc/string.h
@@ -27,28 +27,7 @@ int memcmp(const void *s1, const void *s2, size_t n)
 	return c1;
 }
 
-static __attribute__((unused))
-void *_nolibc_memcpy_up(void *dst, const void *src, size_t len)
-{
-	size_t pos = 0;
-
-	while (pos < len) {
-		((char *)dst)[pos] = ((const char *)src)[pos];
-		pos++;
-	}
-	return dst;
-}
-
-static __attribute__((unused))
-void *_nolibc_memcpy_down(void *dst, const void *src, size_t len)
-{
-	while (len) {
-		len--;
-		((char *)dst)[len] = ((const char *)src)[len];
-	}
-	return dst;
-}
-
+#ifndef NOLIBC_ARCH_HAS_MEMMOVE
 /* might be ignored by the compiler without -ffreestanding, then found as
  * missing.
  */
@@ -72,14 +51,24 @@ void *memmove(void *dst, const void *src, size_t len)
 	}
 	return dst;
 }
+#endif /* #ifndef NOLIBC_ARCH_HAS_MEMMOVE */
 
+#ifndef NOLIBC_ARCH_HAS_MEMCPY
 /* must be exported, as it's used by libgcc on ARM */
 __attribute__((weak,unused,section(".text.nolibc_memcpy")))
 void *memcpy(void *dst, const void *src, size_t len)
 {
-	return _nolibc_memcpy_up(dst, src, len);
+	size_t pos = 0;
+
+	while (pos < len) {
+		((char *)dst)[pos] = ((const char *)src)[pos];
+		pos++;
+	}
+	return dst;
 }
+#endif /* #ifndef NOLIBC_ARCH_HAS_MEMCPY */
 
+#ifndef NOLIBC_ARCH_HAS_MEMSET
 /* might be ignored by the compiler without -ffreestanding, then found as
  * missing.
  */
@@ -95,6 +84,7 @@ void *memset(void *dst, int b, size_t len)
 	}
 	return dst;
 }
+#endif /* #ifndef NOLIBC_ARCH_HAS_MEMSET */
 
 static __attribute__((unused))
 char *strchr(const char *s, int c)
diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index fdb6bd6c0e2f..2f359cb03d10 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -7,7 +7,6 @@
 #ifndef _NOLIBC_SYS_H
 #define _NOLIBC_SYS_H
 
-#include <stdarg.h>
 #include "std.h"
 
 /* system includes */
@@ -25,6 +24,7 @@
 
 #include "arch.h"
 #include "errno.h"
+#include "stdarg.h"
 #include "types.h"
 
 
@@ -43,6 +43,16 @@
 		: __sysret_arg;                         /* return original value */ \
 })
 
+/* Syscall ENOSYS helper: Avoids unused-parameter warnings and provides a
+ * debugging hook.
+ */
+
+static __inline__ int __nolibc_enosys(const char *syscall, ...)
+{
+	(void)syscall;
+	return -ENOSYS;
+}
+
 
 /* Functions in this file only describe syscalls. They're declared static so
  * that the compiler usually decides to inline them while still being allowed
@@ -133,7 +143,7 @@ int sys_chmod(const char *path, mode_t mode)
 #elif defined(__NR_chmod)
 	return my_syscall2(__NR_chmod, path, mode);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path, mode);
 #endif
 }
 
@@ -156,7 +166,7 @@ int sys_chown(const char *path, uid_t owner, gid_t group)
 #elif defined(__NR_chown)
 	return my_syscall3(__NR_chown, path, owner, group);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path, owner, group);
 #endif
 }
 
@@ -230,7 +240,7 @@ int sys_dup2(int old, int new)
 #elif defined(__NR_dup2)
 	return my_syscall2(__NR_dup2, old, new);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, old, new);
 #endif
 }
 
@@ -312,7 +322,7 @@ pid_t sys_fork(void)
 #elif defined(__NR_fork)
 	return my_syscall0(__NR_fork);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__);
 #endif
 }
 #endif
@@ -486,7 +496,7 @@ int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
 #ifdef __NR_gettimeofday
 	return my_syscall2(__NR_gettimeofday, tv, tz);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, tv, tz);
 #endif
 }
 
@@ -563,7 +573,7 @@ int sys_link(const char *old, const char *new)
 #elif defined(__NR_link)
 	return my_syscall2(__NR_link, old, new);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, old, new);
 #endif
 }
 
@@ -584,7 +594,7 @@ off_t sys_lseek(int fd, off_t offset, int whence)
 #ifdef __NR_lseek
 	return my_syscall3(__NR_lseek, fd, offset, whence);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, fd, offset, whence);
 #endif
 }
 
@@ -607,7 +617,7 @@ int sys_mkdir(const char *path, mode_t mode)
 #elif defined(__NR_mkdir)
 	return my_syscall2(__NR_mkdir, path, mode);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path, mode);
 #endif
 }
 
@@ -629,7 +639,7 @@ int sys_rmdir(const char *path)
 #elif defined(__NR_unlinkat)
 	return my_syscall3(__NR_unlinkat, AT_FDCWD, path, AT_REMOVEDIR);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path);
 #endif
 }
 
@@ -652,7 +662,7 @@ long sys_mknod(const char *path, mode_t mode, dev_t dev)
 #elif defined(__NR_mknod)
 	return my_syscall3(__NR_mknod, path, mode, dev);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path, mode, dev);
 #endif
 }
 
@@ -742,7 +752,7 @@ int sys_open(const char *path, int flags, mode_t mode)
 #elif defined(__NR_open)
 	return my_syscall3(__NR_open, path, flags, mode);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path, flags, mode);
 #endif
 }
 
@@ -842,7 +852,7 @@ int sys_poll(struct pollfd *fds, int nfds, int timeout)
 #elif defined(__NR_poll)
 	return my_syscall3(__NR_poll, fds, nfds, timeout);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, fds, nfds, timeout);
 #endif
 }
 
@@ -920,7 +930,11 @@ int sys_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeva
 		struct timeval *t;
 	} arg = { .n = nfds, .r = rfds, .w = wfds, .e = efds, .t = timeout };
 	return my_syscall1(__NR_select, &arg);
-#elif defined(__ARCH_WANT_SYS_PSELECT6) && defined(__NR_pselect6)
+#elif defined(__NR__newselect)
+	return my_syscall5(__NR__newselect, nfds, rfds, wfds, efds, timeout);
+#elif defined(__NR_select)
+	return my_syscall5(__NR_select, nfds, rfds, wfds, efds, timeout);
+#elif defined(__NR_pselect6)
 	struct timespec t;
 
 	if (timeout) {
@@ -928,13 +942,8 @@ int sys_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeva
 		t.tv_nsec = timeout->tv_usec * 1000;
 	}
 	return my_syscall6(__NR_pselect6, nfds, rfds, wfds, efds, timeout ? &t : NULL, NULL);
-#elif defined(__NR__newselect) || defined(__NR_select)
-#ifndef __NR__newselect
-#define __NR__newselect __NR_select
-#endif
-	return my_syscall5(__NR__newselect, nfds, rfds, wfds, efds, timeout);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, nfds, rfds, wfds, efds, timeout);
 #endif
 }
 
@@ -989,7 +998,7 @@ int sys_statx(int fd, const char *path, int flags, unsigned int mask, struct sta
 #ifdef __NR_statx
 	return my_syscall5(__NR_statx, fd, path, flags, mask, buf);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, fd, path, flags, mask, buf);
 #endif
 }
 
@@ -1047,7 +1056,7 @@ int sys_symlink(const char *old, const char *new)
 #elif defined(__NR_symlink)
 	return my_syscall2(__NR_symlink, old, new);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, old, new);
 #endif
 }
 
@@ -1104,7 +1113,7 @@ int sys_unlink(const char *path)
 #elif defined(__NR_unlink)
 	return my_syscall1(__NR_unlink, path);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, path);
 #endif
 }
 
@@ -1127,7 +1136,7 @@ pid_t sys_wait4(pid_t pid, int *status, int options, struct rusage *rusage)
 #ifdef __NR_wait4
 	return my_syscall4(__NR_wait4, pid, status, options, rusage);
 #else
-	return -ENOSYS;
+	return __nolibc_enosys(__func__, pid, status, options, rusage);
 #endif
 }