/*--------------------------------------------------------------------*/ /*--- Take snapshots of client stacks. m_stacktrace.c ---*/ /*--------------------------------------------------------------------*/ /* This file is part of Valgrind, a dynamic binary instrumentation framework. Copyright (C) 2000-2009 Julian Seward jseward@acm.org This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. The GNU General Public License is contained in the file COPYING. */ #include "pub_core_basics.h" #include "pub_core_vki.h" #include "pub_core_threadstate.h" #include "pub_core_debuginfo.h" // XXX: circular dependency #include "pub_core_aspacemgr.h" // For VG_(is_addressable)() #include "pub_core_libcbase.h" #include "pub_core_libcassert.h" #include "pub_core_libcprint.h" #include "pub_core_machine.h" #include "pub_core_options.h" #include "pub_core_stacks.h" // VG_(stack_limits) #include "pub_core_stacktrace.h" #include "pub_core_xarray.h" #include "pub_core_clientstate.h" // VG_(client__dl_sysinfo_int80) #include "pub_core_trampoline.h" /*------------------------------------------------------------*/ /*--- Exported functions. ---*/ /*------------------------------------------------------------*/ /* Take a snapshot of the client's stack, putting up to 'max_n_ips' IPs into 'ips'. In order to be thread-safe, we pass in the thread's IP SP, FP if that's meaningful, and LR if that's meaningful. Returns number of IPs put in 'ips'. If you know what the thread ID for this stack is, send that as the first parameter, else send zero. This helps generate better stack traces on ppc64-linux and has no effect on other platforms. */ UInt VG_(get_StackTrace_wrk) ( ThreadId tid_if_known, /*OUT*/Addr* ips, UInt max_n_ips, /*OUT*/Addr* sps, /*OUT*/Addr* fps, Addr ip, Addr sp, Addr fp, Addr lr, Addr fp_min, Addr fp_max_orig ) { # if defined(VGP_ppc32_linux) || defined(VGP_ppc64_linux) \ || defined(VGP_ppc32_aix5) \ || defined(VGP_ppc64_aix5) Bool lr_is_first_RA = False; # endif # if defined(VGP_ppc64_linux) || defined(VGP_ppc64_aix5) \ || defined(VGP_ppc32_aix5) Word redir_stack_size = 0; Word redirs_used = 0; # endif Bool debug = False; Int i; Addr fp_max; UInt n_found = 0; vg_assert(sizeof(Addr) == sizeof(UWord)); vg_assert(sizeof(Addr) == sizeof(void*)); /* Snaffle IPs from the client's stack into ips[0 .. max_n_ips-1], stopping when the trail goes cold, which we guess to be when FP is not a reasonable stack location. */ // JRS 2002-sep-17: hack, to round up fp_max to the end of the // current page, at least. Dunno if it helps. // NJN 2002-sep-17: seems to -- stack traces look like 1.0.X again fp_max = VG_PGROUNDUP(fp_max_orig); if (fp_max >= sizeof(Addr)) fp_max -= sizeof(Addr); if (debug) VG_(printf)("max_n_ips=%d fp_min=0x%lx fp_max_orig=0x%lx, " "fp_max=0x%lx ip=0x%lx fp=0x%lx\n", max_n_ips, fp_min, fp_max_orig, fp_max, ip, fp); /* Assertion broken before main() is reached in pthreaded programs; the * offending stack traces only have one item. --njn, 2002-aug-16 */ /* vg_assert(fp_min <= fp_max);*/ // On Darwin, this kicks in for pthread-related stack traces, so they're // only 1 entry long which is wrong. #if !defined(VGO_darwin) if (fp_min + 512 >= fp_max) { /* If the stack limits look bogus, don't poke around ... but don't bomb out either. */ if (sps) sps[0] = sp; if (fps) fps[0] = fp; ips[0] = ip; return 1; } #endif /* Otherwise unwind the stack in a platform-specific way. Trying to merge the x86, amd64, ppc32 and ppc64 logic into a single piece of code is just too confusing and difficult to performance-tune. */ # if defined(VGP_x86_linux) || defined(VGP_x86_darwin) /*--------------------- x86 ---------------------*/ /* fp is %ebp. sp is %esp. ip is %eip. */ if (sps) sps[0] = sp; if (fps) fps[0] = fp; ips[0] = ip; i = 1; /* Loop unwinding the stack. Note that the IP value we get on * each pass (whether from CFI info or a stack frame) is a * return address so is actually after the calling instruction * in the calling function. * * Because of this we subtract one from the IP after each pass * of the loop so that we find the right CFI block on the next * pass - otherwise we can find the wrong CFI info if it happens * to change after the calling instruction and that will mean * that we will fail to unwind the next step. * * This most frequently happens at the end of a function when * a tail call occurs and we wind up using the CFI info for the * next function which is completely wrong. */ while (True) { if (i >= max_n_ips) break; /* Try to derive a new (ip,sp,fp) triple from the current set. */ /* On x86, first try the old-fashioned method of following the %ebp-chain. Code which doesn't use this (that is, compiled with -fomit-frame-pointer) is not ABI compliant and so relatively rare. Besides, trying the CFI first almost always fails, and is expensive. */ /* Deal with frames resulting from functions which begin "pushl% ebp ; movl %esp, %ebp" which is the ABI-mandated preamble. */ if (fp_min <= fp && fp <= fp_max - 1 * sizeof(UWord)/*see comment below*/) { /* fp looks sane, so use it. */ ip = (((UWord*)fp)[1]); // We stop if we hit a zero (the traditional end-of-stack // marker) or a one -- these correspond to recorded IPs of 0 or -1. // The latter because r8818 (in this file) changes the meaning of // entries [1] and above in a stack trace, by subtracting 1 from // them. Hence stacks that used to end with a zero value now end in // -1 and so we must detect that too. if (0 == ip || 1 == ip) break; sp = fp + sizeof(Addr) /*saved %ebp*/ + sizeof(Addr) /*ra*/; fp = (((UWord*)fp)[0]); if (sps) sps[i] = sp; if (fps) fps[i] = fp; ips[i++] = ip - 1; /* -1: refer to calling insn, not the RA */ if (debug) VG_(printf)(" ipsF[%d]=0x%08lx\n", i-1, ips[i-1]); ip = ip - 1; /* as per comment at the head of this loop */ continue; } /* That didn't work out, so see if there is any CF info to hand which can be used. */ if ( VG_(use_CF_info)( &ip, &sp, &fp, fp_min, fp_max ) ) { if (0 == ip || 1 == ip) break; if (sps) sps[i] = sp; if (fps) fps[i] = fp; ips[i++] = ip - 1; /* -1: refer to calling insn, not the RA */ if (debug) VG_(printf)(" ipsC[%d]=0x%08lx\n", i-1, ips[i-1]); ip = ip - 1; /* as per comment at the head of this loop */ continue; } /* And, similarly, try for MSVC FPO unwind info. */ if ( VG_(use_FPO_info)( &ip, &sp, &fp, fp_min, fp_max ) ) { if (0 == ip || 1 == ip) break; if (sps) sps[i] = sp; if (fps) fps[i] = fp; ips[i++] = ip; if (debug) VG_(printf)(" ipsC[%d]=0x%08lx\n", i-1, ips[i-1]); ip = ip - 1; continue; } /* No luck. We have to give up. */ break; } # elif defined(VGP_amd64_linux) || defined(VGP_amd64_darwin) /*--------------------- amd64 ---------------------*/ /* fp is %rbp. sp is %rsp. ip is %rip. */ ips[0] = ip; if (sps) sps[0] = sp; if (fps) fps[0] = fp; i = 1; /* Loop unwinding the stack. Note that the IP value we get on * each pass (whether from CFI info or a stack frame) is a * return address so is actually after the calling instruction * in the calling function. * * Because of this we subtract one from the IP after each pass * of the loop so that we find the right CFI block on the next * pass - otherwise we can find the wrong CFI info if it happens * to change after the calling instruction and that will mean * that we will fail to unwind the next step. * * This most frequently happens at the end of a function when * a tail call occurs and we wind up using the CFI info for the * next function which is completely wrong. */ while (True) { if (i >= max_n_ips) break; /* Try to derive a new (ip,sp,fp) triple from the current set. */ /* First off, see if there is any CFI info to hand which can be used. */ if ( VG_(use_CF_info)( &ip, &sp, &fp, fp_min, fp_max ) ) { if (0 == ip || 1 == ip) break; if (sps) sps[i] = sp; if (fps) fps[i] = fp; ips[i++] = ip - 1; /* -1: refer to calling insn, not the RA */ if (debug) VG_(printf)(" ipsC[%d]=%#08lx\n", i-1, ips[i-1]); ip = ip - 1; /* as per comment at the head of this loop */ continue; } /* If VG_(use_CF_info) fails, it won't modify ip/sp/fp, so we can safely try the old-fashioned method. */ /* This bit is supposed to deal with frames resulting from functions which begin "pushq %rbp ; movq %rsp, %rbp". Unfortunately, since we can't (easily) look at the insns at the start of the fn, like GDB does, there's no reliable way to tell. Hence the hack of first trying out CFI, and if that fails, then use this as a fallback. */ /* Note: re "- 1 * sizeof(UWord)", need to take account of the fact that we are prodding at & ((UWord*)fp)[1] and so need to adjust the limit check accordingly. Omitting this has been observed to cause segfaults on rare occasions. */ if (fp_min <= fp && fp <= fp_max - 1 * sizeof(UWord)) { /* fp looks sane, so use it. */ ip = (((UWord*)fp)[1]); if (0 == ip || 1 == ip) break; sp = fp + sizeof(Addr) /*saved %rbp*/ + sizeof(Addr) /*ra*/; fp = (((UWord*)fp)[0]); if (sps) sps[i] = sp; if (fps) fps[i] = fp; ips[i++] = ip - 1; /* -1: refer to calling insn, not the RA */ if (debug) VG_(printf)(" ipsF[%d]=%#08lx\n", i-1, ips[i-1]); ip = ip - 1; /* as per comment at the head of this loop */ continue; } /* Last-ditch hack (evidently GDB does something similar). We are in the middle of nowhere and we have a nonsense value for the frame pointer. If the stack pointer is still valid, assume that what it points at is a return address. Yes, desperate measures. Could do better here: - check that the supposed return address is in an executable page - check that the supposed return address is just after a call insn - given those two checks, don't just consider *sp as the return address; instead scan a likely section of stack (eg sp .. sp+256) and use suitable values found there. */ if (fp_min <= sp && sp < fp_max) { ip = ((UWord*)sp)[0]; if (0 == ip || 1 == ip) break; if (sps) sps[i] = sp; if (fps) fps[i] = fp; ips[i++] = ip == 0 ? 0 /* sp[0] == 0 ==> stuck at the bottom of a thread stack */ : ip - 1; /* -1: refer to calling insn, not the RA */ if (debug) VG_(printf)(" ipsH[%d]=%#08lx\n", i-1, ips[i-1]); ip = ip - 1; /* as per comment at the head of this loop */ sp += 8; continue; } /* No luck at all. We have to give up. */ break; } # elif defined(VGP_ppc32_linux) || defined(VGP_ppc64_linux) \ || defined(VGP_ppc32_aix5) || defined(VGP_ppc64_aix5) /*--------------------- ppc32/64 ---------------------*/ /* fp is %r1. ip is %cia. Note, ppc uses r1 as both the stack and frame pointers. */ # if defined(VGP_ppc64_linux) || defined(VGP_ppc64_aix5) redir_stack_size = VEX_GUEST_PPC64_REDIR_STACK_SIZE; redirs_used = 0; # elif defined(VGP_ppc32_aix5) redir_stack_size = VEX_GUEST_PPC32_REDIR_STACK_SIZE; redirs_used = 0; # endif # if defined(VG_PLAT_USES_PPCTOC) /* Deal with bogus LR values caused by function interception/wrapping on ppc-TOC platforms; see comment on similar code a few lines further down. */ if (ULong_to_Ptr(lr) == (void*)&VG_(ppctoc_magic_redirect_return_stub) && VG_(is_valid_tid)(tid_if_known)) { Word hsp = VG_(threads)[tid_if_known].arch.vex.guest_REDIR_SP; redirs_used++; if (hsp >= 1 && hsp < redir_stack_size) lr = VG_(threads)[tid_if_known] .arch.vex.guest_REDIR_STACK[hsp-1]; } # endif /* We have to determine whether or not LR currently holds this fn (call it F)'s return address. It might not if F has previously called some other function, hence overwriting LR with a pointer to some part of F. Hence if LR and IP point to the same function then we conclude LR does not hold this function's return address; instead the LR at entry must have been saved in the stack by F's prologue and so we must get it from there instead. Note all this guff only applies to the innermost frame. */ lr_is_first_RA = False; { # define M_VG_ERRTXT 1000 UChar buf_lr[M_VG_ERRTXT], buf_ip[M_VG_ERRTXT]; /* The following conditional looks grossly inefficient and surely could be majorly improved, with not much effort. */ if (VG_(get_fnname_raw) (lr, buf_lr, M_VG_ERRTXT)) if (VG_(get_fnname_raw) (ip, buf_ip, M_VG_ERRTXT)) if (VG_(strncmp)(buf_lr, buf_ip, M_VG_ERRTXT)) lr_is_first_RA = True; # undef M_VG_ERRTXT } if (sps) sps[0] = fp; /* NB. not sp */ if (fps) fps[0] = fp; ips[0] = ip; i = 1; if (fp_min <= fp && fp < fp_max-VG_WORDSIZE+1) { /* initial FP is sane; keep going */ fp = (((UWord*)fp)[0]); while (True) { /* On ppc64-linux (ppc64-elf, really), and on AIX, the lr save slot is 2 words back from sp, whereas on ppc32-elf(?) it's only one word back. */ # if defined(VGP_ppc64_linux) \ || defined(VGP_ppc32_aix5) || defined(VGP_ppc64_aix5) const Int lr_offset = 2; # else const Int lr_offset = 1; # endif if (i >= max_n_ips) break; /* Try to derive a new (ip,fp) pair from the current set. */ if (fp_min <= fp && fp <= fp_max - lr_offset * sizeof(UWord)) { /* fp looks sane, so use it. */ if (i == 1 && lr_is_first_RA) ip = lr; else ip = (((UWord*)fp)[lr_offset]); # if defined(VG_PLAT_USES_PPCTOC) /* Nasty hack to do with function replacement/wrapping on ppc64-linux/ppc64-aix/ppc32-aix. If LR points to our magic return stub, then we are in a wrapped or intercepted function, in which LR has been messed with. The original LR will have been pushed onto the thread's hidden REDIR stack one down from the top (top element is the saved R2) and so we should restore the value from there instead. Since nested redirections can and do happen, we keep track of the number of nested LRs used by the unwinding so far with 'redirs_used'. */ if (ip == (Addr)&VG_(ppctoc_magic_redirect_return_stub) && VG_(is_valid_tid)(tid_if_known)) { Word hsp = VG_(threads)[tid_if_known] .arch.vex.guest_REDIR_SP; hsp -= 2 * redirs_used; redirs_used ++; if (hsp >= 1 && hsp < redir_stack_size) ip = VG_(threads)[tid_if_known] .arch.vex.guest_REDIR_STACK[hsp-1]; } # endif if (0 == ip || 1 == ip) break; fp = (((UWord*)fp)[0]); if (sps) sps[i] = fp; /* NB. not sp */ if (fps) fps[i] = fp; ips[i++] = ip - 1; /* -1: refer to calling insn, not the RA */ if (debug) VG_(printf)(" ipsF[%d]=%#08lx\n", i-1, ips[i-1]); ip = ip - 1; /* ip is probably dead at this point, but play safe, a la x86/amd64 above. See extensive comments above. */ continue; } /* No luck there. We have to give up. */ break; } } # else # error "Unknown platform" # endif n_found = i; return n_found; } UInt VG_(get_StackTrace) ( ThreadId tid, /*OUT*/StackTrace ips, UInt max_n_ips, /*OUT*/StackTrace sps, /*OUT*/StackTrace fps, Word first_ip_delta ) { /* thread in thread table */ Addr ip = VG_(get_IP)(tid); Addr fp = VG_(get_FP)(tid); Addr sp = VG_(get_SP)(tid); Addr lr = VG_(get_LR)(tid); Addr stack_highest_word = VG_(threads)[tid].client_stack_highest_word; Addr stack_lowest_word = 0; # if defined(VGP_x86_linux) /* Nasty little hack to deal with syscalls - if libc is using its _dl_sysinfo_int80 function for syscalls (the TLS version does), then ip will always appear to be in that function when doing a syscall, not the actual libc function doing the syscall. This check sees if IP is within that function, and pops the return address off the stack so that ip is placed within the library function calling the syscall. This makes stack backtraces much more useful. The function is assumed to look like this (from glibc-2.3.6 sources): _dl_sysinfo_int80: int $0x80 ret That is 3 (2+1) bytes long. We could be more thorough and check the 3 bytes of the function are as expected, but I can't be bothered. */ if (VG_(client__dl_sysinfo_int80) != 0 /* we know its address */ && ip >= VG_(client__dl_sysinfo_int80) && ip < VG_(client__dl_sysinfo_int80)+3 && VG_(am_is_valid_for_client)(sp, sizeof(Addr), VKI_PROT_READ)) { ip = *(Addr *)sp; sp += sizeof(Addr); } # endif /* See if we can get a better idea of the stack limits */ VG_(stack_limits)(sp, &stack_lowest_word, &stack_highest_word); /* Take into account the first_ip_delta. */ vg_assert( sizeof(Addr) == sizeof(Word) ); ip += first_ip_delta; if (0) VG_(printf)("tid %d: stack_highest=0x%08lx ip=0x%08lx " "sp=0x%08lx fp=0x%08lx\n", tid, stack_highest_word, ip, sp, fp); return VG_(get_StackTrace_wrk)(tid, ips, max_n_ips, sps, fps, ip, sp, fp, lr, sp, stack_highest_word); } static void printIpDesc(UInt n, Addr ip) { #define BUF_LEN 4096 static UChar buf[BUF_LEN]; VG_(describe_IP)(ip, buf, BUF_LEN); if (VG_(clo_xml)) { VG_(message)(Vg_UserMsg, " %s", buf); } else { VG_(message)(Vg_UserMsg, " %s %s", ( n == 0 ? "at" : "by" ), buf); } } /* Print a StackTrace. */ void VG_(pp_StackTrace) ( StackTrace ips, UInt n_ips ) { vg_assert( n_ips > 0 ); if (VG_(clo_xml)) VG_(message)(Vg_UserMsg, " "); VG_(apply_StackTrace)( printIpDesc, ips, n_ips ); if (VG_(clo_xml)) VG_(message)(Vg_UserMsg, " "); } /* Get and immediately print a StackTrace. */ void VG_(get_and_pp_StackTrace) ( ThreadId tid, UInt max_n_ips ) { Addr ips[max_n_ips]; UInt n_ips = VG_(get_StackTrace)(tid, ips, max_n_ips, NULL/*array to dump SP values in*/, NULL/*array to dump FP values in*/, 0/*first_ip_delta*/); VG_(pp_StackTrace)(ips, n_ips); } void VG_(apply_StackTrace)( void(*action)(UInt n, Addr ip), StackTrace ips, UInt n_ips ) { Bool main_done = False; Int i = 0; vg_assert(n_ips > 0); do { Addr ip = ips[i]; // Stop after the first appearance of "main" or one of the other names // (the appearance of which is a pretty good sign that we've gone past // main without seeing it, for whatever reason) if ( ! VG_(clo_show_below_main) ) { Vg_FnNameKind kind = VG_(get_fnname_kind_from_IP)(ip); if (Vg_FnNameMain == kind || Vg_FnNameBelowMain == kind) { main_done = True; } } // Act on the ip action(i, ip); i++; } while (i < n_ips && !main_done); #undef MYBUF_LEN } /*--------------------------------------------------------------------*/ /*--- end ---*/ /*--------------------------------------------------------------------*/