usr/src/lib/libc/port/gen/stack.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include "thr_uberdata.h"
  30 #include <sys/stack.h>
  31
  32 /*
  33  * Initialization of the main stack is performed in libc_init().
  34  * Initialization of thread stacks is performed in _thrp_setup().
  35  */
  36
  37 #pragma weak _stack_getbounds = stack_getbounds
  38 int
  39 stack_getbounds(stack_t *sp)
  40 {
  41         *sp = curthread->ul_ustack;
  42         return (0);
  43 }
  44
  45 #pragma weak _stack_setbounds = stack_setbounds
  46 int
  47 stack_setbounds(const stack_t *sp)
  48 {
  49         ulwp_t *self = curthread;
  50
  51         if (sp == NULL || sp->ss_sp == NULL ||
  52             (uintptr_t)sp->ss_sp != SA((uintptr_t)sp->ss_sp) ||
  53             sp->ss_flags != 0 || sp->ss_size < MINSIGSTKSZ ||
  54             (uintptr_t)sp->ss_size != SA((uintptr_t)sp->ss_size)) {
  55                 errno = EINVAL;
  56                 return (-1);
  57         }
  58
  59         sigoff(self);
  60         self->ul_ustack = *sp;
  61         sigon(self);
  62
  63         return (0);
  64 }
  65
  66 /*
  67  * Returns a boolean value:
  68  *      1 addr is within the bounds of the current stack
  69  *      0 addr is outside of the bounds of the current stack
  70  * Note that addr is an unbiased value.
  71  */
  72 #pragma weak _stack_inbounds = stack_inbounds
  73 int
  74 stack_inbounds(void *addr)
  75 {
  76         stack_t *ustackp = &curthread->ul_ustack;
  77         uintptr_t base = (uintptr_t)ustackp->ss_sp;
  78         size_t size = ustackp->ss_size;
  79
  80         return ((uintptr_t)addr >= base && (uintptr_t)addr < base + size);
  81 }
  82
  83 #pragma weak _stack_violation = stack_violation
  84 int
  85 stack_violation(int sig, const siginfo_t *sip, const ucontext_t *ucp)
  86 {
  87         uintptr_t addr;
  88         uintptr_t base;
  89         size_t size;
  90
  91         if ((sig != SIGSEGV && sig != SIGBUS) ||
  92             sip == NULL || ucp == NULL || SI_FROMUSER(sip))
  93                 return (0);
  94
  95         /*
  96          * ucp has the correct view of the stack when the signal was raised.
  97          */
  98         base = (uintptr_t)ucp->uc_stack.ss_sp;
  99         size = ucp->uc_stack.ss_size;
 100 #if defined(__sparc)
 101         addr = ucp->uc_mcontext.gregs[REG_SP] + STACK_BIAS;
 102 #elif defined(__amd64) || defined(__i386)
 103         addr = ucp->uc_mcontext.gregs[REG_SP];
 104         /*
 105          * If the faulted address is just below the stack pointer we
 106          * might be looking at a push instruction that caused the fault
 107          * (the largest amount a push instruction can decrement the
 108          * stack pointer by is 32).  In that case, use the faulted
 109          * address in our computation rather than the stack pointer.
 110          */
 111         if (addr - (uintptr_t)sip->si_addr < 32)
 112                 addr = (uintptr_t)sip->si_addr;
 113 #else
 114 #error "none of __sparc, __amd64, __i386 is defined"
 115 #endif
 116         return (!(addr >= base && addr < base + size));
 117 }