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02217ad447
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
162 lines
8.3 KiB
C
162 lines
8.3 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* SuperH specific definitions for NOLIBC
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* Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
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*/
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#ifndef _NOLIBC_ARCH_SH_H
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#define _NOLIBC_ARCH_SH_H
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#include "compiler.h"
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#include "crt.h"
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/*
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* Syscalls for SuperH:
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* - registers are 32bit wide
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* - syscall number is passed in r3
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* - arguments are in r4, r5, r6, r7, r0, r1, r2
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* - the system call is performed by calling trapa #31
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* - syscall return value is in r0
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*/
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#define my_syscall0(num) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall1(num, arg1) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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register long _arg1 __asm__ ("r4") = (long)(arg1); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num), "r"(_arg1) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall2(num, arg1, arg2) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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register long _arg1 __asm__ ("r4") = (long)(arg1); \
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register long _arg2 __asm__ ("r5") = (long)(arg2); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num), "r"(_arg1), "r"(_arg2) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall3(num, arg1, arg2, arg3) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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register long _arg1 __asm__ ("r4") = (long)(arg1); \
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register long _arg2 __asm__ ("r5") = (long)(arg2); \
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register long _arg3 __asm__ ("r6") = (long)(arg3); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall4(num, arg1, arg2, arg3, arg4) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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register long _arg1 __asm__ ("r4") = (long)(arg1); \
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register long _arg2 __asm__ ("r5") = (long)(arg2); \
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register long _arg3 __asm__ ("r6") = (long)(arg3); \
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register long _arg4 __asm__ ("r7") = (long)(arg4); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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register long _arg1 __asm__ ("r4") = (long)(arg1); \
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register long _arg2 __asm__ ("r5") = (long)(arg2); \
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register long _arg3 __asm__ ("r6") = (long)(arg3); \
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register long _arg4 __asm__ ("r7") = (long)(arg4); \
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register long _arg5 __asm__ ("r0") = (long)(arg5); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
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"r"(_arg5) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
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({ \
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register long _num __asm__ ("r3") = (num); \
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register long _ret __asm__ ("r0"); \
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register long _arg1 __asm__ ("r4") = (long)(arg1); \
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register long _arg2 __asm__ ("r5") = (long)(arg2); \
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register long _arg3 __asm__ ("r6") = (long)(arg3); \
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register long _arg4 __asm__ ("r7") = (long)(arg4); \
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register long _arg5 __asm__ ("r0") = (long)(arg5); \
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register long _arg6 __asm__ ("r1") = (long)(arg6); \
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\
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__asm__ volatile ( \
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"trapa #31" \
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: "=r"(_ret) \
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: "r"(_num), "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
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"r"(_arg5), "r"(_arg6) \
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: "memory", "cc" \
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); \
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_ret; \
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})
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/* startup code */
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void _start_wrapper(void);
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void __attribute__((weak,noreturn)) __nolibc_entrypoint __no_stack_protector _start_wrapper(void)
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{
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__asm__ volatile (
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".global _start\n" /* The C function will have a prologue, */
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".type _start, @function\n" /* corrupting "sp" */
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".weak _start\n"
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"_start:\n"
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"mov sp, r4\n" /* save argc pointer to r4, as arg1 of _start_c */
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"bsr _start_c\n" /* transfer to c runtime */
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"nop\n" /* delay slot */
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".size _start, .-_start\n"
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);
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__nolibc_entrypoint_epilogue();
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}
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#endif /* _NOLIBC_ARCH_SH_H */
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