tools/nolibc: add support for OpenRISC / or1k

Add support for OpenRISC / or1k to nolibc.

_start() uses the same wrapper construct as in arch-sh.h.
libgcc is necessary as OpenRISC is missing 64-bit multiplication.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Stafford Horne <shorne@gmail.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260429-nolibc-openrisc-v2-1-8d7d7a2f3fec@weissschuh.net

3 files changed, 163 insertions, 1 deletions

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile
index 872c318f50d4..2cb4d610fe53 100644
--- a/tools/include/nolibc/Makefile
+++ b/tools/include/nolibc/Makefile
@@ -17,7 +17,7 @@ endif
 # it defaults to this nolibc directory.
 OUTPUT ?= $(CURDIR)/
 
-architectures := arm arm64 loongarch m68k mips powerpc riscv s390 sh sparc x86
+architectures := arm arm64 loongarch m68k mips openrisc powerpc riscv s390 sh sparc x86
 arch_files := arch.h $(addsuffix .h, $(addprefix arch-, $(architectures)))
 all_files := \
 		alloca.h \
diff --git a/tools/include/nolibc/arch-openrisc.h b/tools/include/nolibc/arch-openrisc.h
new file mode 100644
index 000000000000..5ef82fd9cc64
--- /dev/null
+++ b/tools/include/nolibc/arch-openrisc.h
@@ -0,0 +1,160 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * OpenRISC specific definitions for NOLIBC
+ * Copyright (C) 2026 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+#ifndef _NOLIBC_ARCH_OPENRISC_H
+#define _NOLIBC_ARCH_OPENRISC_H
+
+#include "compiler.h"
+#include "crt.h"
+
+/*
+ * Syscalls for OpenRISC:
+ *   - syscall number is passed in r11
+ *   - arguments are in r3, r4, r5, r6, r7, r8
+ *   - the system call is performed by calling l.sys 1
+ *   - syscall return value is in r11
+ */
+
+#define _NOLIBC_SYSCALL_CLOBBERLIST \
+	"r12", "r13", "r15", "r17", "r19", "r21", "r23", "r25", "r27", "r29", "r31", "memory"
+
+#define __nolibc_syscall0(num)                                                \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		:                                                             \
+		: "r3", "r4", "r5", "r6", "r7", "r8",                         \
+		  _NOLIBC_SYSCALL_CLOBBERLIST                                 \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#define __nolibc_syscall1(num, arg1)                                          \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+	register long _arg1 __asm__ ("r3") = (long)(arg1);                    \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		: "r"(_arg1)                                                  \
+		: "r4", "r5", "r6", "r7", "r8", _NOLIBC_SYSCALL_CLOBBERLIST   \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#define __nolibc_syscall2(num, arg1, arg2)                                    \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+	register long _arg1 __asm__ ("r3") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("r4") = (long)(arg2);                    \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		: "r"(_arg1), "r"(_arg2)                                      \
+		: "r5", "r6", "r7", "r8", _NOLIBC_SYSCALL_CLOBBERLIST         \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#define __nolibc_syscall3(num, arg1, arg2, arg3)                              \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+	register long _arg1 __asm__ ("r3") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("r4") = (long)(arg2);                    \
+	register long _arg3 __asm__ ("r5") = (long)(arg3);                    \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		: "r"(_arg1), "r"(_arg2), "r"(_arg3)                          \
+		: "r6", "r7", "r8", _NOLIBC_SYSCALL_CLOBBERLIST               \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#define __nolibc_syscall4(num, arg1, arg2, arg3, arg4)                        \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+	register long _arg1 __asm__ ("r3") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("r4") = (long)(arg2);                    \
+	register long _arg3 __asm__ ("r5") = (long)(arg3);                    \
+	register long _arg4 __asm__ ("r6") = (long)(arg4);                    \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4)              \
+		: "r7", "r8", _NOLIBC_SYSCALL_CLOBBERLIST                     \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5)                  \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+	register long _arg1 __asm__ ("r3") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("r4") = (long)(arg2);                    \
+	register long _arg3 __asm__ ("r5") = (long)(arg3);                    \
+	register long _arg4 __asm__ ("r6") = (long)(arg4);                    \
+	register long _arg5 __asm__ ("r7") = (long)(arg5);                    \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5)  \
+		: "r8", _NOLIBC_SYSCALL_CLOBBERLIST                           \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6)            \
+({                                                                            \
+	register long _num __asm__ ("r11") = (num);                           \
+	register long _arg1 __asm__ ("r3") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("r4") = (long)(arg2);                    \
+	register long _arg3 __asm__ ("r5") = (long)(arg3);                    \
+	register long _arg4 __asm__ ("r6") = (long)(arg4);                    \
+	register long _arg5 __asm__ ("r7") = (long)(arg5);                    \
+	register long _arg6 __asm__ ("r8") = (long)(arg6);                    \
+									      \
+	__asm__ volatile (                                                    \
+		"l.sys 1\n"                                                   \
+		: "+r"(_num)                                                  \
+		: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
+		  "r"(_arg6)                                                  \
+		: _NOLIBC_SYSCALL_CLOBBERLIST                                 \
+	);                                                                    \
+	_num;                                                                 \
+})
+
+#ifndef NOLIBC_NO_RUNTIME
+/* startup code */
+void _start_wrapper(void);
+void __attribute__((weak,noreturn))
+__nolibc_entrypoint __nolibc_no_stack_protector
+_start_wrapper(void)
+{
+	__asm__ volatile (
+		".global _start\n"           /* The C function will have a prologue,         */
+		".type _start, @function\n"  /* corrupting "sp/r1"                           */
+		".weak _start\n"
+		"_start:\n"
+
+		"l.jal _start_c\n"           /* transfer to c runtime                        */
+		"l.or r3,r1,r1\n"            /* save stack pointer to r3, as arg1 of _start_c */
+
+		".size _start, .-_start\n"
+	);
+	__nolibc_entrypoint_epilogue();
+}
+#endif /* NOLIBC_NO_RUNTIME */
+
+#endif /* _NOLIBC_ARCH_OPENRISC_H */
diff --git a/tools/include/nolibc/arch.h b/tools/include/nolibc/arch.h
index a3adaf433f2c..55009dcafe9e 100644
--- a/tools/include/nolibc/arch.h
+++ b/tools/include/nolibc/arch.h
@@ -28,6 +28,8 @@
 #include "arch-m68k.h"
 #elif defined(__sh__)
 #include "arch-sh.h"
+#elif defined(__or1k__)
+#include "arch-openrisc.h"
 #else
 #error Unsupported Architecture
 #endif