Merge tag 'linux_kselftest-nolibc-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull nolibc updates from Shuah Khan:
 "Highlights:

   - Clang support (including LTO)

  Other Changes:

   - stdbool.h support

   - argc/argv/envp arguments for constructors

   - Small #include ordering fix"

* tag 'linux_kselftest-nolibc-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (21 commits)
  tools/nolibc: x86_64: use local label in memcpy/memmove
  tools/nolibc: stackprotector: mark implicitly used symbols as used
  tools/nolibc: crt: mark _start_c() as used
  selftests/nolibc: run-tests.sh: allow building through LLVM
  selftests/nolibc: use correct clang target for s390/systemz
  selftests/nolibc: don't use libgcc when building with clang
  selftests/nolibc: run-tests.sh: avoid overwriting CFLAGS_EXTRA
  selftests/nolibc: add cc-option compatible with clang cross builds
  selftests/nolibc: add support for LLVM= parameter
  selftests/nolibc: determine $(srctree) first
  selftests/nolibc: avoid passing NULL to printf("%s")
  selftests/nolibc: report failure if no testcase passed
  tools/nolibc: compiler: use attribute((naked)) if available
  tools/nolibc: move entrypoint specifics to compiler.h
  tools/nolibc: compiler: introduce __nolibc_has_attribute()
  tools/nolibc: powerpc: limit stack-protector workaround to GCC
  tools/nolibc: mips: load current function to $t9
  tools/nolibc: arm: use clang-compatible asm syntax
  tools/nolibc: pass argc, argv and envp to constructors
  tools/nolibc: add stdbool.h header
  ...

19 files changed, 123 insertions, 67 deletions

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile
index e69c26abe1ea..a1f55fb24bb3 100644
--- a/tools/include/nolibc/Makefile
+++ b/tools/include/nolibc/Makefile
@@ -35,6 +35,7 @@ all_files := \
 		stackprotector.h \
 		std.h \
 		stdarg.h \
+		stdbool.h \
 		stdint.h \
 		stdlib.h \
 		string.h \
diff --git a/tools/include/nolibc/arch-aarch64.h b/tools/include/nolibc/arch-aarch64.h
index b23ac1f04035..06fdef7b291a 100644
--- a/tools/include/nolibc/arch-aarch64.h
+++ b/tools/include/nolibc/arch-aarch64.h
@@ -142,13 +142,13 @@
 })
 
 /* startup code */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
 		"mov x0, sp\n"          /* save stack pointer to x0, as arg1 of _start_c */
 		"and sp, x0, -16\n"     /* sp must be 16-byte aligned in the callee      */
 		"bl  _start_c\n"        /* transfer to c runtime                         */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 #endif /* _NOLIBC_ARCH_AARCH64_H */
diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h
index cae4afa7c1c7..6180ff99ab43 100644
--- a/tools/include/nolibc/arch-arm.h
+++ b/tools/include/nolibc/arch-arm.h
@@ -185,15 +185,15 @@
 })
 
 /* startup code */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
-		"mov %r0, sp\n"         /* save stack pointer to %r0, as arg1 of _start_c */
-		"and ip, %r0, #-8\n"    /* sp must be 8-byte aligned in the callee        */
+		"mov r0, sp\n"          /* save stack pointer to %r0, as arg1 of _start_c */
+		"and ip, r0, #-8\n"     /* sp must be 8-byte aligned in the callee        */
 		"mov sp, ip\n"
 		"bl  _start_c\n"        /* transfer to c runtime                          */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #endif /* _NOLIBC_ARCH_ARM_H */
diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h
index 28c26a00a762..ff5afc35bbd8 100644
--- a/tools/include/nolibc/arch-i386.h
+++ b/tools/include/nolibc/arch-i386.h
@@ -162,7 +162,7 @@
  * 2) The deepest stack frame should be set to zero
  *
  */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
 		"xor  %ebp, %ebp\n"       /* zero the stack frame                                */
@@ -174,7 +174,7 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 		"call _start_c\n"         /* transfer to c runtime                               */
 		"hlt\n"                   /* ensure it does not return                           */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #endif /* _NOLIBC_ARCH_I386_H */
diff --git a/tools/include/nolibc/arch-loongarch.h b/tools/include/nolibc/arch-loongarch.h
index 3f8ef8f86c0f..fb519545959e 100644
--- a/tools/include/nolibc/arch-loongarch.h
+++ b/tools/include/nolibc/arch-loongarch.h
@@ -149,14 +149,14 @@
 #endif
 
 /* startup code */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
 		"move          $a0, $sp\n"         /* save stack pointer to $a0, as arg1 of _start_c */
 		LONG_BSTRINS " $sp, $zero, 3, 0\n" /* $sp must be 16-byte aligned                    */
 		"bl            _start_c\n"         /* transfer to c runtime                          */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #endif /* _NOLIBC_ARCH_LOONGARCH_H */
diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h
index 62cc50ef3288..1791a8ce58da 100644
--- a/tools/include/nolibc/arch-mips.h
+++ b/tools/include/nolibc/arch-mips.h
@@ -179,7 +179,7 @@
 })
 
 /* startup code, note that it's called __start on MIPS */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector __start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector __start(void)
 {
 	__asm__ volatile (
 		".set push\n"
@@ -194,11 +194,13 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 		"li    $t0, -8\n"
 		"and   $sp, $sp, $t0\n"  /* $sp must be 8-byte aligned                     */
 		"addiu $sp, $sp, -16\n"  /* the callee expects to save a0..a3 there        */
-		"jal   _start_c\n"       /* transfer to c runtime                          */
+		"lui $t9, %hi(_start_c)\n" /* ABI requires current function address in $t9 */
+		"ori $t9, %lo(_start_c)\n"
+		"jalr $t9\n"             /* transfer to c runtime                          */
 		" nop\n"                 /* delayed slot                                   */
 		".set pop\n"
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #endif /* _NOLIBC_ARCH_MIPS_H */
diff --git a/tools/include/nolibc/arch-powerpc.h b/tools/include/nolibc/arch-powerpc.h
index ac212e6185b2..ee2fdb8d601d 100644
--- a/tools/include/nolibc/arch-powerpc.h
+++ b/tools/include/nolibc/arch-powerpc.h
@@ -172,7 +172,7 @@
 	_ret;                                                                \
 })
 
-#ifndef __powerpc64__
+#if !defined(__powerpc64__) && !defined(__clang__)
 /* FIXME: For 32-bit PowerPC, with newer gcc compilers (e.g. gcc 13.1.0),
  * "omit-frame-pointer" fails with __attribute__((no_stack_protector)) but
  * works with __attribute__((__optimize__("-fno-stack-protector")))
@@ -184,7 +184,7 @@
 #endif /* !__powerpc64__ */
 
 /* startup code */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 #ifdef __powerpc64__
 #if _CALL_ELF == 2
@@ -215,7 +215,7 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 		"bl     _start_c\n"     /* transfer to c runtime                         */
 	);
 #endif
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #endif /* _NOLIBC_ARCH_POWERPC_H */
diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h
index 1927c643c739..8827bf936212 100644
--- a/tools/include/nolibc/arch-riscv.h
+++ b/tools/include/nolibc/arch-riscv.h
@@ -140,7 +140,7 @@
 })
 
 /* startup code */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
 		".option push\n"
@@ -151,7 +151,7 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 		"andi sp, a0, -16\n"      /* sp must be 16-byte aligned                    */
 		"call _start_c\n"         /* transfer to c runtime                         */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #endif /* _NOLIBC_ARCH_RISCV_H */
diff --git a/tools/include/nolibc/arch-s390.h b/tools/include/nolibc/arch-s390.h
index 5d60fd43f883..2ec13d8b9a2d 100644
--- a/tools/include/nolibc/arch-s390.h
+++ b/tools/include/nolibc/arch-s390.h
@@ -139,7 +139,7 @@
 })
 
 /* startup code */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
 		"lgr	%r2, %r15\n"          /* save stack pointer to %r2, as arg1 of _start_c */
@@ -147,7 +147,7 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 		"xc	0(8,%r15), 0(%r15)\n" /* clear backchain                                */
 		"brasl	%r14, _start_c\n"     /* transfer to c runtime                          */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 struct s390_mmap_arg_struct {
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index 68609f421934..1e40620a2b33 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -161,7 +161,7 @@
  * 2) The deepest stack frame should be zero (the %rbp).
  *
  */
-void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector _start(void)
 {
 	__asm__ volatile (
 		"xor  %ebp, %ebp\n"       /* zero the stack frame                            */
@@ -170,7 +170,7 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
 		"call _start_c\n"         /* transfer to c runtime                           */
 		"hlt\n"                   /* ensure it does not return                       */
 	);
-	__builtin_unreachable();
+	__nolibc_entrypoint_epilogue();
 }
 
 #define NOLIBC_ARCH_HAS_MEMMOVE
@@ -193,10 +193,10 @@ __asm__ (
 	"movq %rdi, %rdx\n\t"
 	"subq %rsi, %rdx\n\t"
 	"cmpq %rcx, %rdx\n\t"
-	"jb   .Lbackward_copy\n\t"
+	"jb   1f\n\t"
 	"rep movsb\n\t"
 	"retq\n"
-".Lbackward_copy:"
+"1:" /* backward copy */
 	"leaq -1(%rdi, %rcx, 1), %rdi\n\t"
 	"leaq -1(%rsi, %rcx, 1), %rsi\n\t"
 	"std\n\t"
diff --git a/tools/include/nolibc/compiler.h b/tools/include/nolibc/compiler.h
index beddc3665d69..9bc6a706a332 100644
--- a/tools/include/nolibc/compiler.h
+++ b/tools/include/nolibc/compiler.h
@@ -6,20 +6,30 @@
 #ifndef _NOLIBC_COMPILER_H
 #define _NOLIBC_COMPILER_H
 
+#if defined(__has_attribute)
+#  define __nolibc_has_attribute(attr) __has_attribute(attr)
+#else
+#  define __nolibc_has_attribute(attr) 0
+#endif
+
+#if __nolibc_has_attribute(naked)
+#  define __nolibc_entrypoint __attribute__((naked))
+#  define __nolibc_entrypoint_epilogue()
+#else
+#  define __nolibc_entrypoint __attribute__((optimize("Os", "omit-frame-pointer")))
+#  define __nolibc_entrypoint_epilogue() __builtin_unreachable()
+#endif /* __nolibc_has_attribute(naked) */
+
 #if defined(__SSP__) || defined(__SSP_STRONG__) || defined(__SSP_ALL__) || defined(__SSP_EXPLICIT__)
 
 #define _NOLIBC_STACKPROTECTOR
 
 #endif /* defined(__SSP__) ... */
 
-#if defined(__has_attribute)
-#  if __has_attribute(no_stack_protector)
-#    define __no_stack_protector __attribute__((no_stack_protector))
-#  else
-#    define __no_stack_protector __attribute__((__optimize__("-fno-stack-protector")))
-#  endif
+#if __nolibc_has_attribute(no_stack_protector)
+#  define __no_stack_protector __attribute__((no_stack_protector))
 #else
 #  define __no_stack_protector __attribute__((__optimize__("-fno-stack-protector")))
-#endif /* defined(__has_attribute) */
+#endif /* __nolibc_has_attribute(no_stack_protector) */
 
 #endif /* _NOLIBC_COMPILER_H */
diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h
index 43b551468c2a..bbcd5fd09806 100644
--- a/tools/include/nolibc/crt.h
+++ b/tools/include/nolibc/crt.h
@@ -13,23 +13,24 @@ 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 __preinit_array_start[])(int, char **, char**) __attribute__((weak));
+extern void (*const __preinit_array_end[])(int, char **, char**) __attribute__((weak));
 
-extern void (*const __init_array_start[])(void) __attribute__((weak));
-extern void (*const __init_array_end[])(void) __attribute__((weak));
+extern void (*const __init_array_start[])(int, char **, char**) __attribute__((weak));
+extern void (*const __init_array_end[])(int, char **, char**) __attribute__((weak));
 
 extern void (*const __fini_array_start[])(void) __attribute__((weak));
 extern void (*const __fini_array_end[])(void) __attribute__((weak));
 
-__attribute__((weak))
+__attribute__((weak,used))
 void _start_c(long *sp)
 {
 	long argc;
 	char **argv;
 	char **envp;
 	int exitcode;
-	void (* const *func)(void);
+	void (* const *ctor_func)(int, char **, char **);
+	void (* const *dtor_func)(void);
 	const unsigned long *auxv;
 	/* silence potential warning: conflicting types for 'main' */
 	int _nolibc_main(int, char **, char **) __asm__ ("main");
@@ -66,16 +67,16 @@ 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)();
+	for (ctor_func = __preinit_array_start; ctor_func < __preinit_array_end; ctor_func++)
+		(*ctor_func)(argc, argv, envp);
+	for (ctor_func = __init_array_start; ctor_func < __init_array_end; ctor_func++)
+		(*ctor_func)(argc, argv, envp);
 
 	/* go to application */
 	exitcode = _nolibc_main(argc, argv, envp);
 
-	for (func = __fini_array_end; func > __fini_array_start;)
-		(*--func)();
+	for (dtor_func = __fini_array_end; dtor_func > __fini_array_start;)
+		(*--dtor_func)();
 
 	exit(exitcode);
 }
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 989e707263a4..92436b1e4441 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -74,7 +74,8 @@
  *            -I../nolibc -o hello hello.c -lgcc
  *
  * The available standard (but limited) include files are:
- *   ctype.h, errno.h, signal.h, stdarg.h, stdio.h, stdlib.h, string.h, time.h
+ *   ctype.h, errno.h, signal.h, stdarg.h, stdbool.h stdio.h, stdlib.h,
+ *   string.h, time.h
  *
  * In addition, the following ones are expected to be provided by the compiler:
  *   float.h, stddef.h
diff --git a/tools/include/nolibc/stackprotector.h b/tools/include/nolibc/stackprotector.h
index 13f1d0e60387..1d0d5259ec41 100644
--- a/tools/include/nolibc/stackprotector.h
+++ b/tools/include/nolibc/stackprotector.h
@@ -18,7 +18,7 @@
  * triggering stack protector errors themselves
  */
 
-__attribute__((weak,noreturn,section(".text.nolibc_stack_chk")))
+__attribute__((weak,used,noreturn,section(".text.nolibc_stack_chk")))
 void __stack_chk_fail(void)
 {
 	pid_t pid;
@@ -34,7 +34,7 @@ void __stack_chk_fail_local(void)
 	__stack_chk_fail();
 }
 
-__attribute__((weak,section(".data.nolibc_stack_chk")))
+__attribute__((weak,used,section(".data.nolibc_stack_chk")))
 uintptr_t __stack_chk_guard;
 
 static __no_stack_protector void __stack_chk_init(void)
diff --git a/tools/include/nolibc/stdbool.h b/tools/include/nolibc/stdbool.h
new file mode 100644
index 000000000000..60feece22f17
--- /dev/null
+++ b/tools/include/nolibc/stdbool.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * Boolean types support for NOLIBC
+ * Copyright (C) 2024 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+#ifndef _NOLIBC_STDBOOL_H
+#define _NOLIBC_STDBOOL_H
+
+#define bool _Bool
+#define true 1
+#define false 0
+
+#define __bool_true_false_are_defined 1
+
+#endif /* _NOLIBC_STDBOOL_H */
diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h
index f9ab28421e6d..9ec9c24f38c0 100644
--- a/tools/include/nolibc/string.h
+++ b/tools/include/nolibc/string.h
@@ -7,6 +7,7 @@
 #ifndef _NOLIBC_STRING_H
 #define _NOLIBC_STRING_H
 
+#include "arch.h"
 #include "std.h"
 
 static void *malloc(size_t len);
diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index 3fbabab46958..8de98ea7af80 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -1,19 +1,21 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for nolibc tests
-include ../../../scripts/Makefile.include
-include ../../../scripts/utilities.mak
-# We need this for the "cc-option" macro.
-include ../../../build/Build.include
+# we're in ".../tools/testing/selftests/nolibc"
+ifeq ($(srctree),)
+srctree := $(patsubst %/tools/testing/selftests/,%,$(dir $(CURDIR)))
+endif
+
+include $(srctree)/tools/scripts/utilities.mak
+# We need this for the "__cc-option" macro.
+include $(srctree)/scripts/Makefile.compiler
 
 ifneq ($(O),)
 ifneq ($(call is-absolute,$(O)),y)
 $(error Only absolute O= parameters are supported)
 endif
-endif
-
-# we're in ".../tools/testing/selftests/nolibc"
-ifeq ($(srctree),)
-srctree := $(patsubst %/tools/testing/selftests/,%,$(dir $(CURDIR)))
+objtree := $(O)
+else
+objtree ?= $(srctree)
 endif
 
 ifeq ($(ARCH),)
@@ -21,7 +23,7 @@ include $(srctree)/scripts/subarch.include
 ARCH = $(SUBARCH)
 endif
 
-objtree ?= $(srctree)
+cc-option = $(call __cc-option, $(CC),$(CLANG_CROSS_FLAGS),$(1),$(2))
 
 # XARCH extends the kernel's ARCH with a few variants of the same
 # architecture that only differ by the configuration, the toolchain
@@ -155,9 +157,22 @@ CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 -W -Wall -Wex
 		$(CFLAGS_$(XARCH)) $(CFLAGS_STACKPROTECTOR) $(CFLAGS_EXTRA)
 LDFLAGS :=
 
+LIBGCC := -lgcc
+
+ifneq ($(LLVM),)
+# Not needed for clang
+LIBGCC :=
+endif
+
+# Modify CFLAGS based on LLVM=
+include $(srctree)/tools/scripts/Makefile.include
+
+# GCC uses "s390", clang "systemz"
+CLANG_CROSS_FLAGS := $(subst --target=s390-linux,--target=systemz-linux,$(CLANG_CROSS_FLAGS))
+
 REPORT  ?= awk '/\[OK\][\r]*$$/{p++} /\[FAIL\][\r]*$$/{if (!f) printf("\n"); f++; print;} /\[SKIPPED\][\r]*$$/{s++} \
 		END{ printf("\n%3d test(s): %3d passed, %3d skipped, %3d failed => status: ", p+s+f, p, s, f); \
-		if (f) printf("failure\n"); else if (s) printf("warning\n"); else printf("success\n");; \
+		if (f || !p) printf("failure\n"); else if (s) printf("warning\n"); else printf("success\n");; \
 		printf("\nSee all results in %s\n", ARGV[1]); }'
 
 help:
@@ -204,11 +219,11 @@ sysroot/$(ARCH)/include:
 ifneq ($(NOLIBC_SYSROOT),0)
 nolibc-test: nolibc-test.c nolibc-test-linkage.c sysroot/$(ARCH)/include
 	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \
-	  -nostdlib -nostdinc -static -Isysroot/$(ARCH)/include nolibc-test.c nolibc-test-linkage.c -lgcc
+	  -nostdlib -nostdinc -static -Isysroot/$(ARCH)/include nolibc-test.c nolibc-test-linkage.c $(LIBGCC)
 else
 nolibc-test: nolibc-test.c nolibc-test-linkage.c
 	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \
-	  -nostdlib -static -include $(srctree)/tools/include/nolibc/nolibc.h nolibc-test.c nolibc-test-linkage.c -lgcc
+	  -nostdlib -static -include $(srctree)/tools/include/nolibc/nolibc.h nolibc-test.c nolibc-test-linkage.c $(LIBGCC)
 endif
 
 libc-test: nolibc-test.c nolibc-test-linkage.c
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 093d0512f4c5..6fba7025c5e3 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -542,7 +542,7 @@ int expect_strzr(const char *expr, int llen)
 {
 	int ret = 0;
 
-	llen += printf(" = <%s> ", expr);
+	llen += printf(" = <%s> ", expr ? expr : "(null)");
 	if (expr) {
 		ret = 1;
 		result(llen, FAIL);
@@ -561,7 +561,7 @@ int expect_strnz(const char *expr, int llen)
 {
 	int ret = 0;
 
-	llen += printf(" = <%s> ", expr);
+	llen += printf(" = <%s> ", expr ? expr : "(null)");
 	if (!expr) {
 		ret = 1;
 		result(llen, FAIL);
@@ -686,9 +686,10 @@ static void constructor1(void)
 }
 
 __attribute__((constructor))
-static void constructor2(void)
+static void constructor2(int argc, char **argv, char **envp)
 {
-	constructor_test_value *= 2;
+	if (argc && argv && envp)
+		constructor_test_value *= 2;
 }
 
 int run_startup(int min, int max)
diff --git a/tools/testing/selftests/nolibc/run-tests.sh b/tools/testing/selftests/nolibc/run-tests.sh
index 0446e6326a40..e7ecda4ae796 100755
--- a/tools/testing/selftests/nolibc/run-tests.sh
+++ b/tools/testing/selftests/nolibc/run-tests.sh
@@ -15,10 +15,11 @@ download_location="${cache_dir}/crosstools/"
 build_location="$(realpath "${cache_dir}"/nolibc-tests/)"
 perform_download=0
 test_mode=system
-CFLAGS_EXTRA="-Werror"
+werror=1
+llvm=
 archs="i386 x86_64 arm64 arm mips32le mips32be ppc ppc64 ppc64le riscv s390 loongarch"
 
-TEMP=$(getopt -o 'j:d:c:b:a:m:peh' -n "$0" -- "$@")
+TEMP=$(getopt -o 'j:d:c:b:a:m:pelh' -n "$0" -- "$@")
 
 eval set -- "$TEMP"
 unset TEMP
@@ -42,6 +43,7 @@ Options:
  -b [DIR]       Build location (default: ${build_location})
  -m [MODE]      Test mode user/system (default: ${test_mode})
  -e             Disable -Werror
+ -l             Build with LLVM/clang
 EOF
 }
 
@@ -69,7 +71,10 @@ while true; do
 			test_mode="$2"
 			shift 2; continue ;;
 		'-e')
-			CFLAGS_EXTRA=""
+			werror=0
+			shift; continue ;;
+		'-l')
+			llvm=1
 			shift; continue ;;
 		'-h')
 			print_usage
@@ -140,7 +145,10 @@ test_arch() {
 	ct_abi=$(crosstool_abi "$1")
 	cross_compile=$(realpath "${download_location}gcc-${crosstool_version}-nolibc/${ct_arch}-${ct_abi}/bin/${ct_arch}-${ct_abi}-")
 	build_dir="${build_location}/${arch}"
-	MAKE=(make -j"${nproc}" XARCH="${arch}" CROSS_COMPILE="${cross_compile}" O="${build_dir}")
+	if [ "$werror" -ne 0 ]; then
+		CFLAGS_EXTRA="$CFLAGS_EXTRA -Werror"
+	fi
+	MAKE=(make -j"${nproc}" XARCH="${arch}" CROSS_COMPILE="${cross_compile}" LLVM="${llvm}" O="${build_dir}")
 
 	mkdir -p "$build_dir"
 	if [ "$test_mode" = "system" ] && [ ! -f "${build_dir}/.config" ]; then