tools/nolibc: add support for SuperH

Add support for SuperH/"sh" to nolibc.
Only sh4 is tested for now.

The startup code is special:

__nolibc_entrypoint_epilogue() calls __builtin_unreachable() which emits
a call to abort(). To make this work a function prologue is generated to
set up a GOT pointer which corrupts "sp".
__builtin_unreachable() is necessary for __attribute__((noreturn)).
Also depending on compiler flags (for example -fPIC) even more prologue
is generated.

Work around this by defining a nested function in asm.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70216
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Acked-by: Rob Landley <rob@landley.net>
Acked-by: D. Jeff Dionne <jeff@coresemi.io>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20250623-nolibc-sh-v2-3-0f5b4b303025@weissschuh.net
This commit is contained in:
Thomas Weißschuh 2025-06-23 23:15:54 +02:00
parent 358b2511d7
commit 02217ad447
4 changed files with 173 additions and 1 deletions

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@ -0,0 +1,162 @@
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
* SuperH specific definitions for NOLIBC
* Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
*/
#ifndef _NOLIBC_ARCH_SH_H
#define _NOLIBC_ARCH_SH_H
#include "compiler.h"
#include "crt.h"
/*
* Syscalls for SuperH:
* - registers are 32bit wide
* - syscall number is passed in r3
* - arguments are in r4, r5, r6, r7, r0, r1, r2
* - the system call is performed by calling trapa #31
* - syscall return value is in r0
*/
#define my_syscall0(num) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num) \
: "memory", "cc" \
); \
_ret; \
})
#define my_syscall1(num, arg1) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
register long _arg1 __asm__ ("r4") = (long)(arg1); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num), "r"(_arg1) \
: "memory", "cc" \
); \
_ret; \
})
#define my_syscall2(num, arg1, arg2) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
register long _arg1 __asm__ ("r4") = (long)(arg1); \
register long _arg2 __asm__ ("r5") = (long)(arg2); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num), "r"(_arg1), "r"(_arg2) \
: "memory", "cc" \
); \
_ret; \
})
#define my_syscall3(num, arg1, arg2, arg3) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
register long _arg1 __asm__ ("r4") = (long)(arg1); \
register long _arg2 __asm__ ("r5") = (long)(arg2); \
register long _arg3 __asm__ ("r6") = (long)(arg3); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3) \
: "memory", "cc" \
); \
_ret; \
})
#define my_syscall4(num, arg1, arg2, arg3, arg4) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
register long _arg1 __asm__ ("r4") = (long)(arg1); \
register long _arg2 __asm__ ("r5") = (long)(arg2); \
register long _arg3 __asm__ ("r6") = (long)(arg3); \
register long _arg4 __asm__ ("r7") = (long)(arg4); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \
: "memory", "cc" \
); \
_ret; \
})
#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
register long _arg1 __asm__ ("r4") = (long)(arg1); \
register long _arg2 __asm__ ("r5") = (long)(arg2); \
register long _arg3 __asm__ ("r6") = (long)(arg3); \
register long _arg4 __asm__ ("r7") = (long)(arg4); \
register long _arg5 __asm__ ("r0") = (long)(arg5); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
"r"(_arg5) \
: "memory", "cc" \
); \
_ret; \
})
#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
({ \
register long _num __asm__ ("r3") = (num); \
register long _ret __asm__ ("r0"); \
register long _arg1 __asm__ ("r4") = (long)(arg1); \
register long _arg2 __asm__ ("r5") = (long)(arg2); \
register long _arg3 __asm__ ("r6") = (long)(arg3); \
register long _arg4 __asm__ ("r7") = (long)(arg4); \
register long _arg5 __asm__ ("r0") = (long)(arg5); \
register long _arg6 __asm__ ("r1") = (long)(arg6); \
\
__asm__ volatile ( \
"trapa #31" \
: "=r"(_ret) \
: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
"r"(_arg5), "r"(_arg6) \
: "memory", "cc" \
); \
_ret; \
})
/* startup code */
void _start_wrapper(void);
void __attribute__((weak,noreturn)) __nolibc_entrypoint __no_stack_protector _start_wrapper(void)
{
__asm__ volatile (
".global _start\n" /* The C function will have a prologue, */
".type _start, @function\n" /* corrupting "sp" */
".weak _start\n"
"_start:\n"
"mov sp, r4\n" /* save argc pointer to r4, as arg1 of _start_c */
"bsr _start_c\n" /* transfer to c runtime */
"nop\n" /* delay slot */
".size _start, .-_start\n"
);
__nolibc_entrypoint_epilogue();
}
#endif /* _NOLIBC_ARCH_SH_H */

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@ -35,6 +35,8 @@
#include "arch-sparc.h"
#elif defined(__m68k__)
#include "arch-m68k.h"
#elif defined(__sh__)
#include "arch-sh.h"
#else
#error Unsupported Architecture
#endif

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@ -62,6 +62,7 @@ ARCH_riscv64 = riscv
ARCH_s390x = s390
ARCH_sparc32 = sparc
ARCH_sparc64 = sparc
ARCH_sh4 = sh
ARCH := $(or $(ARCH_$(XARCH)),$(XARCH))
# kernel image names by architecture
@ -89,6 +90,7 @@ IMAGE_loongarch = arch/loongarch/boot/vmlinuz.efi
IMAGE_sparc32 = arch/sparc/boot/image
IMAGE_sparc64 = arch/sparc/boot/image
IMAGE_m68k = vmlinux
IMAGE_sh4 = arch/sh/boot/zImage
IMAGE = $(objtree)/$(IMAGE_$(XARCH))
IMAGE_NAME = $(notdir $(IMAGE))
@ -117,11 +119,13 @@ DEFCONFIG_loongarch = defconfig
DEFCONFIG_sparc32 = sparc32_defconfig
DEFCONFIG_sparc64 = sparc64_defconfig
DEFCONFIG_m68k = virt_defconfig
DEFCONFIG_sh4 = rts7751r2dplus_defconfig
DEFCONFIG = $(DEFCONFIG_$(XARCH))
EXTRACONFIG_arm = -e CONFIG_NAMESPACES
EXTRACONFIG_armthumb = -e CONFIG_NAMESPACES
EXTRACONFIG_m68k = -e CONFIG_BLK_DEV_INITRD
EXTRACONFIG_sh4 = -e CONFIG_BLK_DEV_INITRD -e CONFIG_CMDLINE_FROM_BOOTLOADER
EXTRACONFIG = $(EXTRACONFIG_$(XARCH))
# optional tests to run (default = all)
@ -152,6 +156,7 @@ QEMU_ARCH_loongarch = loongarch64
QEMU_ARCH_sparc32 = sparc
QEMU_ARCH_sparc64 = sparc64
QEMU_ARCH_m68k = m68k
QEMU_ARCH_sh4 = sh4
QEMU_ARCH = $(QEMU_ARCH_$(XARCH))
QEMU_ARCH_USER_ppc64le = ppc64le
@ -191,6 +196,7 @@ QEMU_ARGS_loongarch = -M virt -append "console=ttyS0,115200 panic=-1 $(TEST:%=N
QEMU_ARGS_sparc32 = -M SS-5 -m 256M -append "console=ttyS0,115200 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
QEMU_ARGS_sparc64 = -M sun4u -append "console=ttyS0,115200 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
QEMU_ARGS_m68k = -M virt -append "console=ttyGF0,115200 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
QEMU_ARGS_sh4 = -M r2d -serial file:/dev/stdout -append "console=ttySC1,115200 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
QEMU_ARGS = -m 1G $(QEMU_ARGS_$(XARCH)) $(QEMU_ARGS_BIOS) $(QEMU_ARGS_EXTRA)
# OUTPUT is only set when run from the main makefile, otherwise
@ -218,6 +224,7 @@ CFLAGS_mipsn32be = -EB -mabi=n32 -march=mips64r6
CFLAGS_mips64le = -EL -mabi=64 -march=mips64r6
CFLAGS_mips64be = -EB -mabi=64 -march=mips64r2
CFLAGS_sparc32 = $(call cc-option,-m32)
CFLAGS_sh4 = -ml -m4
ifeq ($(origin XARCH),command line)
CFLAGS_XARCH = $(CFLAGS_$(XARCH))
endif

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@ -27,6 +27,7 @@ all_archs=(
loongarch
sparc32 sparc64
m68k
sh4
)
archs="${all_archs[@]}"
@ -187,7 +188,7 @@ test_arch() {
echo "Unsupported configuration"
return
fi
if [ "$arch" = "m68k" ] && [ "$llvm" = "1" ]; then
if [ "$arch" = "m68k" -o "$arch" = "sh4" ] && [ "$llvm" = "1" ]; then
echo "Unsupported configuration"
return
fi