| |
| /*--------------------------------------------------------------------*/ |
| /*--- Store and compare stack backtraces m_execontext.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, a dynamic binary instrumentation |
| framework. |
| |
| Copyright (C) 2000-2007 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_execontext.h" |
| #include "pub_core_libcassert.h" |
| #include "pub_core_libcprint.h" // For VG_(message)() |
| #include "pub_core_mallocfree.h" |
| #include "pub_core_options.h" |
| #include "pub_core_stacktrace.h" |
| |
| /*------------------------------------------------------------*/ |
| /*--- Low-level ExeContext storage. ---*/ |
| /*------------------------------------------------------------*/ |
| |
| /* The first 4 IP values are used in comparisons to remove duplicate errors, |
| and for comparing against suppression specifications. The rest are |
| purely informational (but often important). */ |
| |
| struct _ExeContext { |
| struct _ExeContext * next; |
| UInt n_ips; |
| /* Variable-length array. The size is 'n_ips'; at |
| least 1, at most VG_DEEPEST_BACKTRACE. [0] is the current IP, |
| [1] is its caller, [2] is the caller of [1], etc. */ |
| Addr ips[0]; |
| }; |
| |
| /* Number of lists in which we keep track of ExeContexts. Should be |
| prime. */ |
| #define N_EC_LISTS 30011 /*4999*/ /* a prime number */ |
| |
| /* The idea is only to ever store any one context once, so as to save |
| space and make exact comparisons faster. */ |
| |
| static ExeContext* ec_list[N_EC_LISTS]; |
| |
| /* Stats only: the number of times the system was searched to locate a |
| context. */ |
| static ULong ec_searchreqs; |
| |
| /* Stats only: the number of full context comparisons done. */ |
| static ULong ec_searchcmps; |
| |
| /* Stats only: total number of stored contexts. */ |
| static ULong ec_totstored; |
| |
| /* Number of 2, 4 and (fast) full cmps done. */ |
| static ULong ec_cmp2s; |
| static ULong ec_cmp4s; |
| static ULong ec_cmpAlls; |
| |
| |
| /*------------------------------------------------------------*/ |
| /*--- Exported functions. ---*/ |
| /*------------------------------------------------------------*/ |
| |
| |
| /* Initialise this subsystem. */ |
| static void init_ExeContext_storage ( void ) |
| { |
| Int i; |
| static Bool init_done = False; |
| if (init_done) |
| return; |
| ec_searchreqs = 0; |
| ec_searchcmps = 0; |
| ec_totstored = 0; |
| ec_cmp2s = 0; |
| ec_cmp4s = 0; |
| ec_cmpAlls = 0; |
| for (i = 0; i < N_EC_LISTS; i++) |
| ec_list[i] = NULL; |
| init_done = True; |
| } |
| |
| |
| /* Print stats. */ |
| void VG_(print_ExeContext_stats) ( void ) |
| { |
| init_ExeContext_storage(); |
| VG_(message)(Vg_DebugMsg, |
| " exectx: %,lu lists, %,llu contexts (avg %,llu per list)", |
| N_EC_LISTS, ec_totstored, ec_totstored / N_EC_LISTS |
| ); |
| VG_(message)(Vg_DebugMsg, |
| " exectx: %,llu searches, %,llu full compares (%,llu per 1000)", |
| ec_searchreqs, ec_searchcmps, |
| ec_searchreqs == 0 |
| ? 0L |
| : ( (ec_searchcmps * 1000) / ec_searchreqs ) |
| ); |
| VG_(message)(Vg_DebugMsg, |
| " exectx: %,llu cmp2, %,llu cmp4, %,llu cmpAll", |
| ec_cmp2s, ec_cmp4s, ec_cmpAlls |
| ); |
| } |
| |
| |
| /* Print an ExeContext. */ |
| void VG_(pp_ExeContext) ( ExeContext* ec ) |
| { |
| VG_(pp_StackTrace)( ec->ips, ec->n_ips ); |
| } |
| |
| |
| /* Compare two ExeContexts, comparing all callers. */ |
| Bool VG_(eq_ExeContext) ( VgRes res, ExeContext* e1, ExeContext* e2 ) |
| { |
| Int i; |
| |
| if (e1 == NULL || e2 == NULL) |
| return False; |
| |
| // Must be at least one address in each trace. |
| tl_assert(e1->n_ips >= 1 && e2->n_ips >= 1); |
| |
| switch (res) { |
| case Vg_LowRes: |
| /* Just compare the top two callers. */ |
| ec_cmp2s++; |
| for (i = 0; i < 2; i++) { |
| if ( (e1->n_ips <= i) && (e2->n_ips <= i)) return True; |
| if ( (e1->n_ips <= i) && !(e2->n_ips <= i)) return False; |
| if (!(e1->n_ips <= i) && (e2->n_ips <= i)) return False; |
| if (e1->ips[i] != e2->ips[i]) return False; |
| } |
| return True; |
| |
| case Vg_MedRes: |
| /* Just compare the top four callers. */ |
| ec_cmp4s++; |
| for (i = 0; i < 4; i++) { |
| if ( (e1->n_ips <= i) && (e2->n_ips <= i)) return True; |
| if ( (e1->n_ips <= i) && !(e2->n_ips <= i)) return False; |
| if (!(e1->n_ips <= i) && (e2->n_ips <= i)) return False; |
| if (e1->ips[i] != e2->ips[i]) return False; |
| } |
| return True; |
| |
| case Vg_HighRes: |
| ec_cmpAlls++; |
| /* Compare them all -- just do pointer comparison. */ |
| if (e1 != e2) return False; |
| return True; |
| |
| default: |
| VG_(core_panic)("VG_(eq_ExeContext): unrecognised VgRes"); |
| } |
| } |
| |
| /* 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. |
| */ |
| static inline UWord ROLW ( UWord w, Int n ) |
| { |
| Int bpw = 8 * sizeof(UWord); |
| w = (w << n) | (w >> (bpw-n)); |
| return w; |
| } |
| |
| ExeContext* VG_(record_ExeContext) ( ThreadId tid ) |
| { |
| Int i; |
| Addr ips[VG_DEEPEST_BACKTRACE]; |
| Bool same; |
| UWord hash; |
| ExeContext* new_ec; |
| ExeContext* list; |
| UInt n_ips; |
| ExeContext *prev2, *prev; |
| |
| static UInt ctr = 0; |
| |
| vg_assert(sizeof(void*) == sizeof(UWord)); |
| vg_assert(sizeof(void*) == sizeof(Addr)); |
| |
| init_ExeContext_storage(); |
| vg_assert(VG_(clo_backtrace_size) >= 1 && |
| VG_(clo_backtrace_size) <= VG_DEEPEST_BACKTRACE); |
| |
| n_ips = VG_(get_StackTrace)( tid, ips, VG_(clo_backtrace_size) ); |
| tl_assert(n_ips >= 1); |
| |
| /* 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 < n_ips; i++) { |
| hash ^= ips[i]; |
| hash = ROLW(hash, 19); |
| } |
| if (0) VG_(printf)("hash 0x%lx ", hash); |
| hash = hash % N_EC_LISTS; |
| if (0) VG_(printf)("%lu\n", hash); |
| |
| /* And (the expensive bit) look a matching entry in the list. */ |
| |
| ec_searchreqs++; |
| |
| prev2 = NULL; |
| prev = NULL; |
| list = ec_list[hash]; |
| |
| while (True) { |
| if (list == NULL) break; |
| ec_searchcmps++; |
| same = True; |
| for (i = 0; i < n_ips; i++) { |
| if (list->ips[i] != ips[i]) { |
| same = False; |
| break; |
| } |
| } |
| if (same) break; |
| prev2 = prev; |
| prev = list; |
| list = list->next; |
| } |
| |
| if (list != NULL) { |
| /* Yay! We found it. Once every 8 searches, move it one step |
| closer to the start of the list to make future searches |
| cheaper. */ |
| if (prev2 && prev && 0 == ((ctr++) & 7)) { |
| vg_assert(prev2->next == prev); |
| vg_assert(prev->next == list); |
| prev2->next = list; |
| prev->next = list->next; |
| list->next = prev; |
| } |
| return list; |
| } |
| |
| /* Bummer. We have to allocate a new context record. */ |
| ec_totstored++; |
| |
| new_ec = VG_(arena_malloc)( VG_AR_EXECTXT, |
| sizeof(struct _ExeContext) |
| + n_ips * sizeof(Addr) ); |
| |
| for (i = 0; i < n_ips; i++) |
| new_ec->ips[i] = ips[i]; |
| |
| new_ec->n_ips = n_ips; |
| new_ec->next = ec_list[hash]; |
| ec_list[hash] = new_ec; |
| |
| return new_ec; |
| } |
| |
| StackTrace VG_(extract_StackTrace) ( ExeContext* e ) |
| { |
| return e->ips; |
| } |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end m_execontext.c ---*/ |
| /*--------------------------------------------------------------------*/ |