1*0Sstevel@tonic-gate /* 2*0Sstevel@tonic-gate * CDDL HEADER START 3*0Sstevel@tonic-gate * 4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the 5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only 6*0Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance 7*0Sstevel@tonic-gate * with the License. 8*0Sstevel@tonic-gate * 9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing. 11*0Sstevel@tonic-gate * See the License for the specific language governing permissions 12*0Sstevel@tonic-gate * and limitations under the License. 13*0Sstevel@tonic-gate * 14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each 15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the 17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying 18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner] 19*0Sstevel@tonic-gate * 20*0Sstevel@tonic-gate * CDDL HEADER END 21*0Sstevel@tonic-gate */ 22*0Sstevel@tonic-gate /* 23*0Sstevel@tonic-gate * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24*0Sstevel@tonic-gate * Use is subject to license terms. 25*0Sstevel@tonic-gate */ 26*0Sstevel@tonic-gate 27*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 28*0Sstevel@tonic-gate 29*0Sstevel@tonic-gate /* 30*0Sstevel@tonic-gate * Pstack.c 31*0Sstevel@tonic-gate * 32*0Sstevel@tonic-gate * Common helper functions for stack walking. The ISA-specific code is found in 33*0Sstevel@tonic-gate * Pstack_iter() in Pisadep.c. 34*0Sstevel@tonic-gate */ 35*0Sstevel@tonic-gate 36*0Sstevel@tonic-gate #include <stdlib.h> 37*0Sstevel@tonic-gate #include <unistd.h> 38*0Sstevel@tonic-gate #include <string.h> 39*0Sstevel@tonic-gate #include <errno.h> 40*0Sstevel@tonic-gate 41*0Sstevel@tonic-gate #include "libproc.h" 42*0Sstevel@tonic-gate #include "Pcontrol.h" 43*0Sstevel@tonic-gate #include "P32ton.h" 44*0Sstevel@tonic-gate #include "Pstack.h" 45*0Sstevel@tonic-gate 46*0Sstevel@tonic-gate /* 47*0Sstevel@tonic-gate * Utility function to prevent stack loops from running on forever by 48*0Sstevel@tonic-gate * detecting when there is a stack loop (the %fp has been seen before). 49*0Sstevel@tonic-gate */ 50*0Sstevel@tonic-gate int 51*0Sstevel@tonic-gate stack_loop(prgreg_t fp, prgreg_t **prevfpp, int *nfpp, uint_t *pfpsizep) 52*0Sstevel@tonic-gate { 53*0Sstevel@tonic-gate prgreg_t *prevfp = *prevfpp; 54*0Sstevel@tonic-gate uint_t pfpsize = *pfpsizep; 55*0Sstevel@tonic-gate int nfp = *nfpp; 56*0Sstevel@tonic-gate int i; 57*0Sstevel@tonic-gate 58*0Sstevel@tonic-gate for (i = 0; i < nfp; i++) { 59*0Sstevel@tonic-gate if (fp == prevfp[i]) 60*0Sstevel@tonic-gate return (1); /* stack loop detected */ 61*0Sstevel@tonic-gate } 62*0Sstevel@tonic-gate 63*0Sstevel@tonic-gate if (nfp == pfpsize) { 64*0Sstevel@tonic-gate pfpsize = pfpsize ? pfpsize * 2 : 16; 65*0Sstevel@tonic-gate prevfp = realloc(prevfp, pfpsize * sizeof (prgreg_t)); 66*0Sstevel@tonic-gate /* 67*0Sstevel@tonic-gate * Just assume there is no loop in the face of allocation 68*0Sstevel@tonic-gate * failure; the caller still has the original prevfp pointer. 69*0Sstevel@tonic-gate */ 70*0Sstevel@tonic-gate if (prevfp == NULL) 71*0Sstevel@tonic-gate return (0); 72*0Sstevel@tonic-gate } 73*0Sstevel@tonic-gate 74*0Sstevel@tonic-gate prevfp[nfp++] = fp; 75*0Sstevel@tonic-gate *prevfpp = prevfp; 76*0Sstevel@tonic-gate *pfpsizep = pfpsize; 77*0Sstevel@tonic-gate *nfpp = nfp; 78*0Sstevel@tonic-gate 79*0Sstevel@tonic-gate return (0); 80*0Sstevel@tonic-gate } 81*0Sstevel@tonic-gate 82*0Sstevel@tonic-gate /* 83*0Sstevel@tonic-gate * Signal Frame Detection 84*0Sstevel@tonic-gate * 85*0Sstevel@tonic-gate * In order to facilitate detection and processing of signal handler frames 86*0Sstevel@tonic-gate * during a stack backtrace, we define a set of utility routines to operate on 87*0Sstevel@tonic-gate * a uclist (ucontext address list), and then use these routines in the various 88*0Sstevel@tonic-gate * implementations of Pstack_iter below. Certain source-level debuggers and 89*0Sstevel@tonic-gate * virtual machines that shall remain nameless believe that in order to detect 90*0Sstevel@tonic-gate * signal handler frames, one must hard-code checks for symbol names defined 91*0Sstevel@tonic-gate * in libc and libthread and knowledge of their implementation. We make no 92*0Sstevel@tonic-gate * such assumptions, allowing us to operate on programs that manipulate their 93*0Sstevel@tonic-gate * underlying kernel signal handlers (i.e. use __sigaction) and to not require 94*0Sstevel@tonic-gate * changes in the face of future library modifications. 95*0Sstevel@tonic-gate * 96*0Sstevel@tonic-gate * A signal handler frame is essentially a set of data pushed on to the user 97*0Sstevel@tonic-gate * stack by the kernel prior to returning to the user program in one of the 98*0Sstevel@tonic-gate * pre-defined signal handlers. The signal handler itself receives the signal 99*0Sstevel@tonic-gate * number, an optional pointer to a siginfo_t, and a pointer to the interrupted 100*0Sstevel@tonic-gate * ucontext as arguments. When performing a stack backtrace, we would like to 101*0Sstevel@tonic-gate * detect these frames so that we can correctly return the interrupted program 102*0Sstevel@tonic-gate * counter and frame pointer as a separate frame. When a signal handler frame 103*0Sstevel@tonic-gate * is constructed on the stack by the kernel, the signalled LWP has its 104*0Sstevel@tonic-gate * lwp_oldcontext member (exported through /proc as lwpstatus.pr_oldcontext) 105*0Sstevel@tonic-gate * set to the user address at which the ucontext_t was placed on the LWP's 106*0Sstevel@tonic-gate * stack. The ucontext_t's uc_link member is set to the previous value of 107*0Sstevel@tonic-gate * lwp_oldcontext. Thus when signal handlers are active, pr_oldcontext will 108*0Sstevel@tonic-gate * point to the first element of a linked list of ucontext_t addresses. 109*0Sstevel@tonic-gate * 110*0Sstevel@tonic-gate * The stack layout for a signal handler frame is as follows: 111*0Sstevel@tonic-gate * 112*0Sstevel@tonic-gate * SPARC v7/v9: Intel ia32: 113*0Sstevel@tonic-gate * +--------------+ - high +--------------+ - 114*0Sstevel@tonic-gate * | struct fq | ^ addrs | siginfo_t | optional 115*0Sstevel@tonic-gate * +--------------+ | ^ +--------------+ - 116*0Sstevel@tonic-gate * | gwindows_t | | | ucontext_t | ^ 117*0Sstevel@tonic-gate * +--------------+ optional +--------------+ | 118*0Sstevel@tonic-gate * | siginfo_t | | ucontext_t * | | 119*0Sstevel@tonic-gate * +--------------+ | | +--------------+ 120*0Sstevel@tonic-gate * | xregs data | v v | siginfo_t * | mandatory 121*0Sstevel@tonic-gate * +--------------+ - low +--------------+ 122*0Sstevel@tonic-gate * | ucontext_t | ^ addrs | int (signo) | | 123*0Sstevel@tonic-gate * +--------------+ mandatory +--------------+ | 124*0Sstevel@tonic-gate * | struct frame | v | struct frame | v 125*0Sstevel@tonic-gate * +--------------+ - <- %sp on resume +--------------+ - <- %esp on resume 126*0Sstevel@tonic-gate * 127*0Sstevel@tonic-gate * amd64 (64-bit): 128*0Sstevel@tonic-gate * +--------------+ - 129*0Sstevel@tonic-gate * | siginfo_t | optional 130*0Sstevel@tonic-gate * +--------------+ - 131*0Sstevel@tonic-gate * | ucontext_t | ^ 132*0Sstevel@tonic-gate * +--------------+ | 133*0Sstevel@tonic-gate * | siginfo_t * | 134*0Sstevel@tonic-gate * +--------------+ mandatory 135*0Sstevel@tonic-gate * | int (signo) | 136*0Sstevel@tonic-gate * +--------------+ | 137*0Sstevel@tonic-gate * | struct frame | v 138*0Sstevel@tonic-gate * +--------------+ - <- %rsp on resume 139*0Sstevel@tonic-gate * 140*0Sstevel@tonic-gate * The bottom-most struct frame is actually constructed by the kernel by 141*0Sstevel@tonic-gate * copying the previous stack frame, allowing naive backtrace code to simply 142*0Sstevel@tonic-gate * skip over the interrupted frame. The copied frame is never really used, 143*0Sstevel@tonic-gate * since it is presumed the libc or libthread signal handler wrapper function 144*0Sstevel@tonic-gate * will explicitly setcontext(2) to the interrupted context if the user 145*0Sstevel@tonic-gate * program's handler returns. If we detect a signal handler frame, we simply 146*0Sstevel@tonic-gate * read the interrupted context structure from the stack, use its embedded 147*0Sstevel@tonic-gate * gregs to construct the register set for the interrupted frame, and then 148*0Sstevel@tonic-gate * continue our backtrace. Detecting the frame itself is easy according to 149*0Sstevel@tonic-gate * the diagram ("oldcontext" represents any element in the uc_link chain): 150*0Sstevel@tonic-gate * 151*0Sstevel@tonic-gate * On SPARC v7 or v9: 152*0Sstevel@tonic-gate * %fp + sizeof (struct frame) == oldcontext 153*0Sstevel@tonic-gate * 154*0Sstevel@tonic-gate * On Intel ia32: 155*0Sstevel@tonic-gate * %ebp + sizeof (struct frame) + (3 * regsize) == oldcontext 156*0Sstevel@tonic-gate * 157*0Sstevel@tonic-gate * On amd64: 158*0Sstevel@tonic-gate * %rbp + sizeof (struct frame) + (2 * regsize) == oldcontext 159*0Sstevel@tonic-gate * 160*0Sstevel@tonic-gate * A final complication is that we want libproc to support backtraces from 161*0Sstevel@tonic-gate * arbitrary addresses without the caller passing in an LWP id. To do this, 162*0Sstevel@tonic-gate * we must first determine all the known oldcontexts by iterating over all 163*0Sstevel@tonic-gate * LWPs and following their pr_oldcontext pointers. We optimize our search 164*0Sstevel@tonic-gate * by discarding NULL pointers and pointers whose value is less than that 165*0Sstevel@tonic-gate * of the initial stack pointer (since stacks grow down from high memory), 166*0Sstevel@tonic-gate * and then sort the resulting list by virtual address so we can binary search. 167*0Sstevel@tonic-gate */ 168*0Sstevel@tonic-gate 169*0Sstevel@tonic-gate int 170*0Sstevel@tonic-gate load_uclist(uclist_t *ucl, const lwpstatus_t *psp) 171*0Sstevel@tonic-gate { 172*0Sstevel@tonic-gate struct ps_prochandle *P = ucl->uc_proc; 173*0Sstevel@tonic-gate uintptr_t addr = psp->pr_oldcontext; 174*0Sstevel@tonic-gate 175*0Sstevel@tonic-gate uintptr_t *new_addrs; 176*0Sstevel@tonic-gate uint_t new_size, i; 177*0Sstevel@tonic-gate ucontext_t uc; 178*0Sstevel@tonic-gate 179*0Sstevel@tonic-gate if (addr == NULL) 180*0Sstevel@tonic-gate return (0); 181*0Sstevel@tonic-gate 182*0Sstevel@tonic-gate for (;;) { 183*0Sstevel@tonic-gate if (ucl->uc_nelems == ucl->uc_size) { 184*0Sstevel@tonic-gate new_size = ucl->uc_size ? ucl->uc_size * 2 : 16; 185*0Sstevel@tonic-gate new_addrs = realloc(ucl->uc_addrs, 186*0Sstevel@tonic-gate new_size * sizeof (uintptr_t)); 187*0Sstevel@tonic-gate 188*0Sstevel@tonic-gate if (new_addrs != NULL) { 189*0Sstevel@tonic-gate ucl->uc_addrs = new_addrs; 190*0Sstevel@tonic-gate ucl->uc_size = new_size; 191*0Sstevel@tonic-gate } else 192*0Sstevel@tonic-gate break; /* abort if allocation failure */ 193*0Sstevel@tonic-gate } 194*0Sstevel@tonic-gate #ifdef _LP64 195*0Sstevel@tonic-gate if (P->status.pr_dmodel == PR_MODEL_ILP32) { 196*0Sstevel@tonic-gate ucontext32_t u32; 197*0Sstevel@tonic-gate 198*0Sstevel@tonic-gate if (Pread(P, &u32, sizeof (u32), addr) != sizeof (u32)) 199*0Sstevel@tonic-gate break; /* abort if we fail to read ucontext */ 200*0Sstevel@tonic-gate uc.uc_link = (ucontext_t *)(uintptr_t)u32.uc_link; 201*0Sstevel@tonic-gate } else 202*0Sstevel@tonic-gate #endif 203*0Sstevel@tonic-gate if (Pread(P, &uc, sizeof (uc), addr) != sizeof (uc)) 204*0Sstevel@tonic-gate break; /* abort if we fail to read ucontext */ 205*0Sstevel@tonic-gate 206*0Sstevel@tonic-gate dprintf("detected lwp %d signal context at %p\n", 207*0Sstevel@tonic-gate (int)psp->pr_lwpid, (void *)addr); 208*0Sstevel@tonic-gate ucl->uc_addrs[ucl->uc_nelems++] = addr; 209*0Sstevel@tonic-gate 210*0Sstevel@tonic-gate addr = (uintptr_t)uc.uc_link; 211*0Sstevel@tonic-gate 212*0Sstevel@tonic-gate /* 213*0Sstevel@tonic-gate * Abort if we find a NULL uc_link pointer or a duplicate 214*0Sstevel@tonic-gate * entry which could indicate a cycle or a very peculiar 215*0Sstevel@tonic-gate * interference pattern between threads. 216*0Sstevel@tonic-gate */ 217*0Sstevel@tonic-gate if (addr == NULL) 218*0Sstevel@tonic-gate break; 219*0Sstevel@tonic-gate 220*0Sstevel@tonic-gate for (i = 0; i < ucl->uc_nelems - 1; i++) { 221*0Sstevel@tonic-gate if (ucl->uc_addrs[i] == addr) 222*0Sstevel@tonic-gate return (0); 223*0Sstevel@tonic-gate } 224*0Sstevel@tonic-gate } 225*0Sstevel@tonic-gate 226*0Sstevel@tonic-gate return (0); 227*0Sstevel@tonic-gate } 228*0Sstevel@tonic-gate 229*0Sstevel@tonic-gate int 230*0Sstevel@tonic-gate sort_uclist(const void *lhp, const void *rhp) 231*0Sstevel@tonic-gate { 232*0Sstevel@tonic-gate uintptr_t lhs = *((const uintptr_t *)lhp); 233*0Sstevel@tonic-gate uintptr_t rhs = *((const uintptr_t *)rhp); 234*0Sstevel@tonic-gate 235*0Sstevel@tonic-gate if (lhs < rhs) 236*0Sstevel@tonic-gate return (-1); 237*0Sstevel@tonic-gate if (lhs > rhs) 238*0Sstevel@tonic-gate return (+1); 239*0Sstevel@tonic-gate return (0); 240*0Sstevel@tonic-gate } 241*0Sstevel@tonic-gate 242*0Sstevel@tonic-gate void 243*0Sstevel@tonic-gate init_uclist(uclist_t *ucl, struct ps_prochandle *P) 244*0Sstevel@tonic-gate { 245*0Sstevel@tonic-gate if ((P->state == PS_STOP || P->state == PS_DEAD) && 246*0Sstevel@tonic-gate P->ucaddrs != NULL) { 247*0Sstevel@tonic-gate ucl->uc_proc = P; 248*0Sstevel@tonic-gate ucl->uc_addrs = P->ucaddrs; 249*0Sstevel@tonic-gate ucl->uc_nelems = P->ucnelems; 250*0Sstevel@tonic-gate ucl->uc_size = P->ucnelems; 251*0Sstevel@tonic-gate ucl->uc_cached = 1; 252*0Sstevel@tonic-gate return; 253*0Sstevel@tonic-gate } 254*0Sstevel@tonic-gate 255*0Sstevel@tonic-gate ucl->uc_proc = P; 256*0Sstevel@tonic-gate ucl->uc_addrs = NULL; 257*0Sstevel@tonic-gate ucl->uc_nelems = 0; 258*0Sstevel@tonic-gate ucl->uc_size = 0; 259*0Sstevel@tonic-gate 260*0Sstevel@tonic-gate (void) Plwp_iter(P, (proc_lwp_f *)load_uclist, ucl); 261*0Sstevel@tonic-gate qsort(ucl->uc_addrs, ucl->uc_nelems, sizeof (uintptr_t), sort_uclist); 262*0Sstevel@tonic-gate 263*0Sstevel@tonic-gate if (P->state == PS_STOP || P->state == PS_DEAD) { 264*0Sstevel@tonic-gate P->ucaddrs = ucl->uc_addrs; 265*0Sstevel@tonic-gate P->ucnelems = ucl->uc_nelems; 266*0Sstevel@tonic-gate ucl->uc_cached = 1; 267*0Sstevel@tonic-gate } else { 268*0Sstevel@tonic-gate ucl->uc_cached = 0; 269*0Sstevel@tonic-gate } 270*0Sstevel@tonic-gate } 271*0Sstevel@tonic-gate 272*0Sstevel@tonic-gate void 273*0Sstevel@tonic-gate free_uclist(uclist_t *ucl) 274*0Sstevel@tonic-gate { 275*0Sstevel@tonic-gate if (!ucl->uc_cached && ucl->uc_addrs != NULL) 276*0Sstevel@tonic-gate free(ucl->uc_addrs); 277*0Sstevel@tonic-gate } 278*0Sstevel@tonic-gate 279*0Sstevel@tonic-gate int 280*0Sstevel@tonic-gate find_uclink(uclist_t *ucl, uintptr_t addr) 281*0Sstevel@tonic-gate { 282*0Sstevel@tonic-gate if (ucl->uc_nelems != 0) { 283*0Sstevel@tonic-gate return (bsearch(&addr, ucl->uc_addrs, ucl->uc_nelems, 284*0Sstevel@tonic-gate sizeof (uintptr_t), sort_uclist) != NULL); 285*0Sstevel@tonic-gate } 286*0Sstevel@tonic-gate 287*0Sstevel@tonic-gate return (0); 288*0Sstevel@tonic-gate } 289