| |
| /*--------------------------------------------------------------------*/ |
| /*--- Storage, and equality on, execution contexts (backtraces). ---*/ |
| /*--- vg_execontext.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, an x86 protected-mode emulator |
| designed for debugging and profiling binaries on x86-Unixes. |
| |
| Copyright (C) 2000-2002 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 LICENSE. |
| */ |
| |
| #include "vg_include.h" |
| #include "vg_constants.h" |
| |
| |
| /*------------------------------------------------------------*/ |
| /*--- Low-level ExeContext storage. ---*/ |
| /*------------------------------------------------------------*/ |
| |
| /* The idea is only to ever store any one context once, so as to save |
| space and make exact comparisons faster. */ |
| |
| static ExeContext* vg_ec_list[VG_N_EC_LISTS]; |
| |
| /* Stats only: the number of times the system was searched to locate a |
| context. */ |
| static UInt vg_ec_searchreqs; |
| |
| /* Stats only: the number of full context comparisons done. */ |
| static UInt vg_ec_searchcmps; |
| |
| /* Stats only: total number of stored contexts. */ |
| static UInt vg_ec_totstored; |
| |
| /* Number of 2, 4 and (fast) full cmps done. */ |
| static UInt vg_ec_cmp2s; |
| static UInt vg_ec_cmp4s; |
| static UInt vg_ec_cmpAlls; |
| |
| |
| /*------------------------------------------------------------*/ |
| /*--- Exported functions. ---*/ |
| /*------------------------------------------------------------*/ |
| |
| |
| /* Initialise this subsystem. */ |
| void VG_(init_ExeContext_storage) ( void ) |
| { |
| Int i; |
| vg_ec_searchreqs = 0; |
| vg_ec_searchcmps = 0; |
| vg_ec_totstored = 0; |
| vg_ec_cmp2s = 0; |
| vg_ec_cmp4s = 0; |
| vg_ec_cmpAlls = 0; |
| for (i = 0; i < VG_N_EC_LISTS; i++) |
| vg_ec_list[i] = NULL; |
| } |
| |
| |
| /* Show stats. */ |
| void VG_(show_ExeContext_stats) ( void ) |
| { |
| VG_(message)(Vg_DebugMsg, |
| "exectx: %d lists, %d contexts (avg %d per list)", |
| VG_N_EC_LISTS, vg_ec_totstored, |
| vg_ec_totstored / VG_N_EC_LISTS |
| ); |
| VG_(message)(Vg_DebugMsg, |
| "exectx: %d searches, %d full compares (%d per 1000)", |
| vg_ec_searchreqs, vg_ec_searchcmps, |
| vg_ec_searchreqs == 0 |
| ? 0 |
| : (UInt)( (((ULong)vg_ec_searchcmps) * 1000) |
| / ((ULong)vg_ec_searchreqs )) |
| ); |
| VG_(message)(Vg_DebugMsg, |
| "exectx: %d cmp2, %d cmp4, %d cmpAll", |
| vg_ec_cmp2s, vg_ec_cmp4s, vg_ec_cmpAlls |
| ); |
| } |
| |
| |
| /* Print an ExeContext. */ |
| void VG_(pp_ExeContext) ( ExeContext* e ) |
| { |
| VG_(mini_stack_dump) ( e ); |
| } |
| |
| |
| /* Compare two ExeContexts, comparing all callers. */ |
| Bool VG_(eq_ExeContext_all) ( ExeContext* e1, ExeContext* e2 ) |
| { |
| vg_ec_cmpAlls++; |
| /* Just do pointer comparison. */ |
| if (e1 != e2) return False; |
| return True; |
| } |
| |
| |
| /* Compare two ExeContexts, just comparing the top two callers. */ |
| Bool VG_(eq_ExeContext_top2) ( ExeContext* e1, ExeContext* e2 ) |
| { |
| vg_ec_cmp2s++; |
| if (e1->eips[0] != e2->eips[0] |
| || e1->eips[1] != e2->eips[1]) return False; |
| return True; |
| } |
| |
| |
| /* Compare two ExeContexts, just comparing the top four callers. */ |
| Bool VG_(eq_ExeContext_top4) ( ExeContext* e1, ExeContext* e2 ) |
| { |
| vg_ec_cmp4s++; |
| if (e1->eips[0] != e2->eips[0] |
| || e1->eips[1] != e2->eips[1]) return False; |
| |
| if (VG_(clo_backtrace_size) < 3) return True; |
| if (e1->eips[2] != e2->eips[2]) return False; |
| |
| if (VG_(clo_backtrace_size) < 4) return True; |
| if (e1->eips[3] != e2->eips[3]) return False; |
| |
| return True; |
| } |
| |
| |
| /* This guy is the head honcho here. Take a snapshot of the client's |
| stack. Search our collection of ExeContexts to see if we already |
| have it, and if not, allocate a new one. Either way, return a |
| pointer to the context. If there is a matching context we |
| guarantee to not allocate a new one. Thus we never store |
| duplicates, and so exact equality can be quickly done as equality |
| on the returned ExeContext* values themselves. Inspired by Hugs's |
| Text type. |
| |
| In order to be thread-safe, we pass in the thread's %EIP and %EBP. |
| */ |
| ExeContext* VG_(get_ExeContext) ( Bool skip_top_frame, |
| Addr eip, Addr ebp ) |
| { |
| Int i; |
| Addr eips[VG_DEEPEST_BACKTRACE]; |
| Bool same; |
| UInt hash; |
| ExeContext* new_ec; |
| ExeContext* list; |
| |
| VGP_PUSHCC(VgpExeContext); |
| |
| vg_assert(VG_(clo_backtrace_size) >= 2 |
| && VG_(clo_backtrace_size) <= VG_DEEPEST_BACKTRACE); |
| |
| /* First snaffle %EIPs from the client's stack into eips[0 |
| .. VG_(clo_backtrace_size)-1], putting zeroes in when the trail |
| goes cold. */ |
| |
| for (i = 0; i < VG_(clo_backtrace_size); i++) |
| eips[i] = 0; |
| |
| # define GET_CALLER(lval) \ |
| if (ebp != 0 && VGM_(check_readable)(ebp, 8, NULL)) { \ |
| lval = ((UInt*)ebp)[1]; /* ret addr */ \ |
| ebp = ((UInt*)ebp)[0]; /* old ebp */ \ |
| } else { \ |
| lval = ebp = 0; \ |
| } |
| |
| if (skip_top_frame) { |
| for (i = 0; i < VG_(clo_backtrace_size); i++) |
| GET_CALLER(eips[i]); |
| } else { |
| eips[0] = eip; |
| for (i = 1; i < VG_(clo_backtrace_size); i++) |
| GET_CALLER(eips[i]); |
| } |
| # undef GET_CALLER |
| |
| /* Now figure out if we've seen this one before. First hash it so |
| as to determine the list number. */ |
| |
| hash = 0; |
| for (i = 0; i < VG_(clo_backtrace_size); i++) { |
| hash ^= (UInt)eips[i]; |
| hash = (hash << 29) | (hash >> 3); |
| } |
| hash = hash % VG_N_EC_LISTS; |
| |
| /* And (the expensive bit) look a matching entry in the list. */ |
| |
| vg_ec_searchreqs++; |
| |
| list = vg_ec_list[hash]; |
| |
| while (True) { |
| if (list == NULL) break; |
| vg_ec_searchcmps++; |
| same = True; |
| for (i = 0; i < VG_(clo_backtrace_size); i++) { |
| if (list->eips[i] != eips[i]) { |
| same = False; |
| break; |
| } |
| } |
| if (same) break; |
| list = list->next; |
| } |
| |
| if (list != NULL) { |
| /* Yay! We found it. */ |
| VGP_POPCC; |
| return list; |
| } |
| |
| /* Bummer. We have to allocate a new context record. */ |
| vg_ec_totstored++; |
| |
| new_ec |
| = VG_(malloc)( |
| VG_AR_EXECTXT, |
| sizeof(struct _ExeContextRec *) |
| + VG_(clo_backtrace_size) * sizeof(Addr) |
| ); |
| |
| for (i = 0; i < VG_(clo_backtrace_size); i++) |
| new_ec->eips[i] = eips[i]; |
| |
| new_ec->next = vg_ec_list[hash]; |
| vg_ec_list[hash] = new_ec; |
| |
| VGP_POPCC; |
| return new_ec; |
| } |
| |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end vg_execontext.c ---*/ |
| /*--------------------------------------------------------------------*/ |