351f30528e
is a descriptor, not a code address), which prevents crashes when starting a context. This fixes QEMU on powerpc64. MFC after: 3 days
119 lines
3.3 KiB
C
119 lines
3.3 KiB
C
/*
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* Copyright (c) 2004 Suleiman Souhlal
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <ucontext.h>
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__weak_reference(__makecontext, makecontext);
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void _ctx_done(ucontext_t *ucp);
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void _ctx_start(void);
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void
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_ctx_done(ucontext_t *ucp)
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{
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if (ucp->uc_link == NULL)
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exit(0);
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else {
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/* invalidate context */
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ucp->uc_mcontext.mc_len = 0;
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setcontext((const ucontext_t *)ucp->uc_link);
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abort(); /* should never return from above call */
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}
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}
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void
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__makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...)
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{
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mcontext_t *mc;
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char *sp;
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va_list ap;
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int i, regargs, stackargs;
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/* Sanity checks */
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if ((ucp == NULL) || (argc < 0) || (argc > NCARGS)
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|| (ucp->uc_stack.ss_sp == NULL)
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|| (ucp->uc_stack.ss_size < MINSIGSTKSZ)) {
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/* invalidate context */
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ucp->uc_mcontext.mc_len = 0;
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return;
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}
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/*
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* The stack must have space for the frame pointer, saved
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* link register, overflow arguments, and be 16-byte
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* aligned.
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*/
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stackargs = (argc > 8) ? argc - 8 : 0;
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sp = (char *) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size
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- sizeof(uintptr_t)*(stackargs + 2);
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sp = (char *)((uintptr_t)sp & ~0x1f);
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mc = &ucp->uc_mcontext;
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/*
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* Up to 8 register args. Assumes all args are 64-bit and
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* integer only. Not sure how to cater for floating point.
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*/
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regargs = (argc > 8) ? 8 : argc;
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va_start(ap, argc);
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for (i = 0; i < regargs; i++)
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mc->mc_gpr[3 + i] = va_arg(ap, uint64_t);
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/*
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* Overflow args go onto the stack
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*/
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if (argc > 8) {
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uint64_t *argp;
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/* Skip past frame pointer and saved LR */
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argp = (uint64_t *)sp + 6;
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for (i = 0; i < stackargs; i++)
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*argp++ = va_arg(ap, uint64_t);
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}
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va_end(ap);
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/*
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* Use caller-saved regs 14/15 to hold params that _ctx_start
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* will use to invoke the user-supplied func
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*/
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mc->mc_srr0 = *(uintptr_t *)_ctx_start;
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mc->mc_gpr[1] = (uintptr_t) sp; /* new stack pointer */
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mc->mc_gpr[14] = (uintptr_t) start; /* r14 <- start */
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mc->mc_gpr[15] = (uintptr_t) ucp; /* r15 <- ucp */
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}
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