mirror of git://sourceware.org/git/glibc.git
83 lines
2.4 KiB
C
83 lines
2.4 KiB
C
/* Swap to new context.
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Copyright (C) 2008-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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#include <ucontext.h>
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#include "ucontext_i.h"
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extern int __getcontext (ucontext_t *ucp);
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extern int __setcontext (const ucontext_t *ucp);
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int
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__swapcontext (ucontext_t *oucp, const ucontext_t *ucp)
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{
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/* Save rp for debugger. */
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asm ("stw %rp,-20(%sp)");
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asm (".cfi_offset 2, -20");
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/* Copy rp to ret0 (r28). */
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asm ("copy %rp,%ret0");
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/* Create a frame. */
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asm ("ldo 64(%sp),%sp");
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asm (".cfi_def_cfa_offset -64");
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/* Save the current machine context to oucp. */
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asm ("bl __getcontext,%rp");
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/* Copy oucp to register ret1 (r29). __getcontext saves and restores it
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on a normal return. It is restored from oR29 on reactivation. */
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asm ("copy %r26,%ret1");
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/* Pop frame. */
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asm ("ldo -64(%sp),%sp");
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asm (".cfi_def_cfa_offset 0");
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/* Load return pointer from oR28. */
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asm ("ldw %0(%%ret1),%%rp" : : "i" (oR28));
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/* Return if error. */
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asm ("or,= %r0,%ret0,%r0");
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asm ("bv,n %r0(%rp)");
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/* Load sc_sar flag. */
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asm ("ldb %0(%%ret1),%%r20" : : "i" (oSAR));
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/* Return if oucp context has been reactivated. */
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asm ("or,= %r0,%r20,%r0");
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asm ("bv,n %r0(%rp)");
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/* Mark sc_sar flag. */
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asm ("1: ldi 1,%r20");
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asm ("stb %%r20,%0(%%ret1)" : : "i" (oSAR));
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/* Activate the machine context in ucp. */
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asm ("bl __setcontext,%rp");
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asm ("ldw %0(%%ret1),%%r26" : : "i" (oR25));
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/* Load return pointer. */
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asm ("ldw %0(%%ret1),%%rp" : : "i" (oR28));
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/* A successful call to setcontext does not return. */
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asm ("bv,n %r0(%rp)");
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/* Make gcc happy. */
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return 0;
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}
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weak_alias (__swapcontext, swapcontext)
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