/*--------------------------------------------------------------------*/ /*--- Take snapshots of client stacks. m_stacktrace.c ---*/ /*--------------------------------------------------------------------*/ /* This file is part of Valgrind, a dynamic binary instrumentation framework. Copyright (C) 2000-2005 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_threadstate.h" #include "pub_core_debuginfo.h" #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_stacktrace.h" #include "pub_core_trampoline.h" /*------------------------------------------------------------*/ /*--- Exported functions. ---*/ /*------------------------------------------------------------*/ /* Take a snapshot of the client's stack, putting the up to '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_StackTrace2) ( ThreadId tid_if_known, Addr* ips, UInt n_ips, Addr ip, Addr sp, Addr fp, Addr lr, Addr fp_min, Addr fp_max_orig ) { #if defined(VGP_ppc32_linux) || defined(VGP_ppc64_linux) Bool lr_is_first_RA = False; /* ppc only */ #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 .. 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); fp_max -= sizeof(Addr); if (debug) VG_(printf)("n_ips=%d fp_min=%p fp_max_orig=%p, fp_max=%p ip=%p fp=%p\n", 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);*/ if (fp_min + VG_(clo_max_stackframe) <= fp_max) { /* If the stack is ridiculously big, don't poke around ... but don't bomb out either. Needed to make John Regehr's user-space threads package work. JRS 20021001 */ ips[0] = ip; return 1; } /* 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) /*--------------------- x86 ---------------------*/ /* fp is %ebp. sp is %esp. ip is %eip. */ 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 >= 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) { /* fp looks sane, so use it. */ ip = (((UWord*)fp)[1]); sp = fp + sizeof(Addr) /*saved %ebp*/ + sizeof(Addr) /*ra*/; fp = (((UWord*)fp)[0]); ips[i++] = ip; if (debug) VG_(printf)(" ipsF[%d]=%08p\n", i-1, ips[i-1]); ip = ip - 1; continue; } /* That didn't work out, so see if there is any CFI info to hand which can be used. */ if ( VG_(use_CFI_info)( &ip, &sp, &fp, fp_min, fp_max ) ) { ips[i++] = ip; if (debug) VG_(printf)(" ipsC[%d]=%08p\n", i-1, ips[i-1]); ip = ip - 1; continue; } /* No luck. We have to give up. */ break; } # elif defined(VGP_amd64_linux) /*--------------------- amd64 ---------------------*/ /* fp is %rbp. sp is %rsp. ip is %rip. */ 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 >= 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_CFI_info)( &ip, &sp, &fp, fp_min, fp_max ) ) { ips[i++] = ip; if (debug) VG_(printf)(" ipsC[%d]=%08p\n", i-1, ips[i-1]); ip = ip - 1; continue; } /* If VG_(use_CFI_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. */ if (fp_min <= fp && fp <= fp_max) { /* fp looks sane, so use it. */ ip = (((UWord*)fp)[1]); sp = fp + sizeof(Addr) /*saved %rbp*/ + sizeof(Addr) /*ra*/; fp = (((UWord*)fp)[0]); ips[i++] = ip; if (debug) VG_(printf)(" ipsF[%d]=%08p\n", i-1, ips[i-1]); ip = ip - 1; continue; } /* No luck there. We have to give up. */ break; } # elif defined(VGP_ppc32_linux) || defined(VGP_ppc64_linux) /*--------------------- ppc32/64 ---------------------*/ /* fp is %r1. ip is %cia. Note, ppc uses r1 as both the stack and frame pointers. */ lr_is_first_RA = False; { # define M_VG_ERRTXT 1000 UChar buf_lr[M_VG_ERRTXT], buf_ip[M_VG_ERRTXT]; if (VG_(get_fnname_nodemangle) (lr, buf_lr, M_VG_ERRTXT)) if (VG_(get_fnname_nodemangle) (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 } 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), 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) const Int lr_offset = 2; # else const Int lr_offset = 1; # endif if (i >= n_ips) break; /* Try to derive a new (ip,fp) pair from the current set. */ if (fp_min <= fp && fp <= fp_max) { /* fp looks sane, so use it. */ if (i == 1 && lr_is_first_RA) ip = lr; else ip = (((UWord*)fp)[lr_offset]); # if defined(VGP_ppc64_linux) /* Nasty hack to do with function replacement/wrapping on ppc64-linux. 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. */ if (i == 1 && ip == (Addr)&VG_(ppc64_linux_magic_redirect_return_stub) && VG_(is_valid_tid)(tid_if_known)) { Long hsp = VG_(threads)[tid_if_known].arch.vex.guest_REDIR_SP; if (hsp >= 1 && hsp < VEX_GUEST_PPC64_REDIR_STACK_SIZE) ip = VG_(threads)[tid_if_known] .arch.vex.guest_REDIR_STACK[hsp-1]; } # endif fp = (((UWord*)fp)[0]); ips[i++] = ip; if (debug) VG_(printf)(" ipsF[%d]=%08p\n", i-1, ips[i-1]); 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, StackTrace ips, UInt n_ips ) { /* 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; # if defined(VGP_x86_linux) /* Nasty little hack to deal with sysinfo syscalls - if libc is using the sysinfo page for syscalls (the TLS version does), then ip will always appear to be in that page when doing a syscall, not the actual libc function doing the syscall. This check sees if IP is within the syscall code, 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. */ if (ip >= (Addr)&VG_(trampoline_stuff_start) && ip < (Addr)&VG_(trampoline_stuff_end) && VG_(am_is_valid_for_client)(sp, sizeof(Addr), VKI_PROT_READ)) { ip = *(Addr *)sp; sp += sizeof(Addr); } # endif if (0) VG_(printf)("tid %d: stack_highest=%p ip=%p sp=%p fp=%p\n", tid, stack_highest_word, ip, sp, fp); return VG_(get_StackTrace2)(tid, ips, n_ips, 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 n_ips ) { Addr ips[n_ips]; VG_(get_StackTrace)(tid, ips, n_ips); VG_(pp_StackTrace) ( ips, n_ips); } void VG_(apply_StackTrace)( void(*action)(UInt n, Addr ip), StackTrace ips, UInt n_ips ) { #define MYBUF_LEN 50 // only needs to be long enough for // the names specially tested for Bool main_done = False; Char mybuf[MYBUF_LEN]; // ok to stack allocate mybuf[] -- it's tiny Int i = 0; vg_assert(n_ips > 0); do { Addr ip = ips[i]; if (i > 0) ip -= VG_MIN_INSTR_SZB; // point to calling line // 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_(get_fnname_nodemangle)( ip, mybuf, MYBUF_LEN ); mybuf[MYBUF_LEN-1] = 0; // paranoia if ( VG_STREQ("main", mybuf) # if defined(VGO_linux) || VG_STREQ("__libc_start_main", mybuf) // glibc glibness || VG_STREQ("generic_start_main", mybuf) // Yellow Dog doggedness # endif ) main_done = True; } // Act on the ip action(i, ip); i++; } while (i < n_ips && ips[i] != 0 && !main_done); #undef MYBUF_LEN } /*--------------------------------------------------------------------*/ /*--- end ---*/ /*--------------------------------------------------------------------*/