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872dbfa032
Silence the following warnings reported by the new -Wall -Wextra options
with pure assembly code.
In file included from sysroot/powerpc/include/stdio.h:13,
from nolibc-test.c:13:
sysroot/powerpc/include/arch.h: In function '_start':
sysroot/powerpc/include/arch.h:192:32: warning: unused variable 'r2' [-Wunused-variable]
192 | register volatile long r2 __asm__ ("r2") = (void *)&TOC - (void *)_start;
| ^~
sysroot/powerpc/include/arch.h:187:97: warning: optimization may eliminate reads and/or writes to register variables [-Wvolatile-register-var]
187 | void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
| ^~~~~~
Since only elfv2 ABI requires to save the TOC/GOT pointer to r2
register, when using elfv1 ABI, the old C code is simply ignored by the
compiler, but the compiler can not ignore the inline assembly code and
will introduce build failure or running segfaults. So, let's further
only add the new assembly code for elfv2 ABI with the checking of
_CALL_ELF == 2.
Link: https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.pdf
Link: https://www.llvm.org/devmtg/2014-04/PDFs/Talks/Euro-LLVM-2014-Weigand.pdf
Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
221 lines
11 KiB
C
221 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* PowerPC specific definitions for NOLIBC
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* Copyright (C) 2023 Zhangjin Wu <falcon@tinylab.org>
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*/
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#ifndef _NOLIBC_ARCH_POWERPC_H
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#define _NOLIBC_ARCH_POWERPC_H
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#include "compiler.h"
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#include "crt.h"
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/* Syscalls for PowerPC :
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* - stack is 16-byte aligned
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* - syscall number is passed in r0
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* - arguments are in r3, r4, r5, r6, r7, r8, r9
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* - the system call is performed by calling "sc"
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* - syscall return comes in r3, and the summary overflow bit is checked
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* to know if an error occurred, in which case errno is in r3.
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* - the arguments are cast to long and assigned into the target
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* registers which are then simply passed as registers to the asm code,
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* so that we don't have to experience issues with register constraints.
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*/
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#define _NOLIBC_SYSCALL_CLOBBERLIST \
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"memory", "cr0", "r12", "r11", "r10", "r9"
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#define my_syscall0(num) \
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({ \
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register long _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num) \
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: \
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: _NOLIBC_SYSCALL_CLOBBERLIST, "r8", "r7", "r6", "r5", "r4" \
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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 _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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register long _arg1 __asm__ ("r3") = (long)(arg1); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num) \
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: "0"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST, "r8", "r7", "r6", "r5", "r4" \
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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 _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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register long _arg1 __asm__ ("r3") = (long)(arg1); \
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register long _arg2 __asm__ ("r4") = (long)(arg2); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num), "+r"(_arg2) \
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: "0"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST, "r8", "r7", "r6", "r5" \
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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 _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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register long _arg1 __asm__ ("r3") = (long)(arg1); \
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register long _arg2 __asm__ ("r4") = (long)(arg2); \
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register long _arg3 __asm__ ("r5") = (long)(arg3); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num), "+r"(_arg2), "+r"(_arg3) \
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: "0"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST, "r8", "r7", "r6" \
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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 _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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register long _arg1 __asm__ ("r3") = (long)(arg1); \
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register long _arg2 __asm__ ("r4") = (long)(arg2); \
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register long _arg3 __asm__ ("r5") = (long)(arg3); \
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register long _arg4 __asm__ ("r6") = (long)(arg4); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num), "+r"(_arg2), "+r"(_arg3), \
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"+r"(_arg4) \
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: "0"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST, "r8", "r7" \
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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 _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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register long _arg1 __asm__ ("r3") = (long)(arg1); \
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register long _arg2 __asm__ ("r4") = (long)(arg2); \
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register long _arg3 __asm__ ("r5") = (long)(arg3); \
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register long _arg4 __asm__ ("r6") = (long)(arg4); \
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register long _arg5 __asm__ ("r7") = (long)(arg5); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num), "+r"(_arg2), "+r"(_arg3), \
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"+r"(_arg4), "+r"(_arg5) \
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: "0"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST, "r8" \
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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 _ret __asm__ ("r3"); \
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register long _num __asm__ ("r0") = (num); \
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register long _arg1 __asm__ ("r3") = (long)(arg1); \
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register long _arg2 __asm__ ("r4") = (long)(arg2); \
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register long _arg3 __asm__ ("r5") = (long)(arg3); \
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register long _arg4 __asm__ ("r6") = (long)(arg4); \
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register long _arg5 __asm__ ("r7") = (long)(arg5); \
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register long _arg6 __asm__ ("r8") = (long)(arg6); \
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\
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__asm__ volatile ( \
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" sc\n" \
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" bns+ 1f\n" \
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" neg %0, %0\n" \
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"1:\n" \
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: "=r"(_ret), "+r"(_num), "+r"(_arg2), "+r"(_arg3), \
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"+r"(_arg4), "+r"(_arg5), "+r"(_arg6) \
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: "0"(_arg1) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_ret; \
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})
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#ifndef __powerpc64__
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/* FIXME: For 32-bit PowerPC, with newer gcc compilers (e.g. gcc 13.1.0),
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* "omit-frame-pointer" fails with __attribute__((no_stack_protector)) but
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* works with __attribute__((__optimize__("-fno-stack-protector")))
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*/
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#ifdef __no_stack_protector
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#undef __no_stack_protector
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#define __no_stack_protector __attribute__((__optimize__("-fno-stack-protector")))
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#endif
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#endif /* !__powerpc64__ */
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/* startup code */
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void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
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{
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#ifdef __powerpc64__
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#if _CALL_ELF == 2
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/* with -mabi=elfv2, save TOC/GOT pointer to r2
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* r12 is global entry pointer, we use it to compute TOC from r12
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* https://www.llvm.org/devmtg/2014-04/PDFs/Talks/Euro-LLVM-2014-Weigand.pdf
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* https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.pdf
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*/
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__asm__ volatile (
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"addis 2, 12, .TOC. - _start@ha\n"
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"addi 2, 2, .TOC. - _start@l\n"
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);
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#endif /* _CALL_ELF == 2 */
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__asm__ volatile (
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"mr 3, 1\n" /* save stack pointer to r3, as arg1 of _start_c */
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"clrrdi 1, 1, 4\n" /* align the stack to 16 bytes */
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"li 0, 0\n" /* zero the frame pointer */
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"stdu 1, -32(1)\n" /* the initial stack frame */
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"bl _start_c\n" /* transfer to c runtime */
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);
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#else
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__asm__ volatile (
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"mr 3, 1\n" /* save stack pointer to r3, as arg1 of _start_c */
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"clrrwi 1, 1, 4\n" /* align the stack to 16 bytes */
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"li 0, 0\n" /* zero the frame pointer */
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"stwu 1, -16(1)\n" /* the initial stack frame */
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"bl _start_c\n" /* transfer to c runtime */
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);
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#endif
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__builtin_unreachable();
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}
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#endif /* _NOLIBC_ARCH_POWERPC_H */
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