| |
| /*--------------------------------------------------------------------*/ |
| /*--- 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_debuglog.h" |
| #include "pub_core_execontext.h" // self |
| #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). |
| |
| The contexts are stored in a traditional chained hash table, so as |
| to allow quick determination of whether a new context already |
| exists. The hash table starts small and expands dynamically, so as |
| to keep the load factor below 1.0. |
| |
| The idea is only to ever store any one context once, so as to save |
| space and make exact comparisons faster. */ |
| |
| |
| /* Primes for the hash table */ |
| |
| #define N_EC_PRIMES 18 |
| |
| static SizeT ec_primes[N_EC_PRIMES] = { |
| 769UL, 1543UL, 3079UL, 6151UL, |
| 12289UL, 24593UL, 49157UL, 98317UL, |
| 196613UL, 393241UL, 786433UL, 1572869UL, |
| 3145739UL, 6291469UL, 12582917UL, 25165843UL, |
| 50331653UL, 100663319UL |
| }; |
| |
| |
| /* Each element is present in a hash chain, and also contains a |
| variable length array of guest code addresses (the useful part). */ |
| |
| struct _ExeContext { |
| struct _ExeContext* chain; |
| 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]; |
| }; |
| |
| |
| /* This is the dynamically expanding hash table. */ |
| static ExeContext** ec_htab; /* array [ec_htab_size] of ExeContext* */ |
| static SizeT ec_htab_size; /* one of the values in ec_primes */ |
| static SizeT ec_htab_size_idx; /* 0 .. N_EC_PRIMES-1 */ |
| |
| |
| /* 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; |
| |
| ec_htab_size_idx = 0; |
| ec_htab_size = ec_primes[ec_htab_size_idx]; |
| ec_htab = VG_(arena_malloc)(VG_AR_EXECTXT, |
| sizeof(ExeContext*) * ec_htab_size); |
| for (i = 0; i < ec_htab_size; i++) |
| ec_htab[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)", |
| ec_htab_size, ec_totstored, ec_totstored / ec_htab_size |
| ); |
| 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"); |
| } |
| } |
| |
| /* VG_(record_ExeContext) 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. |
| |
| Also checks whether the hash table needs expanding, and expands it |
| if so. */ |
| |
| static inline UWord ROLW ( UWord w, Int n ) |
| { |
| Int bpw = 8 * sizeof(UWord); |
| w = (w << n) | (w >> (bpw-n)); |
| return w; |
| } |
| |
| static UWord calc_hash ( Addr* ips, UInt n_ips, UWord htab_sz ) |
| { |
| UInt i; |
| UWord hash = 0; |
| vg_assert(htab_sz > 0); |
| for (i = 0; i < n_ips; i++) { |
| hash ^= ips[i]; |
| hash = ROLW(hash, 19); |
| } |
| return hash % htab_sz; |
| } |
| |
| static void resize_ec_htab ( void ) |
| { |
| SizeT i; |
| SizeT new_size; |
| ExeContext** new_ec_htab; |
| |
| vg_assert(ec_htab_size_idx >= 0 && ec_htab_size_idx < N_EC_PRIMES); |
| if (ec_htab_size_idx == N_EC_PRIMES-1) |
| return; /* out of primes - can't resize further */ |
| |
| new_size = ec_primes[ec_htab_size_idx + 1]; |
| new_ec_htab = VG_(arena_malloc)(VG_AR_EXECTXT, |
| sizeof(ExeContext*) * new_size); |
| |
| VG_(debugLog)( |
| 1, "execontext", |
| "resizing htab from size %lu to %lu (idx %lu) Total#ECs=%llu\n", |
| ec_htab_size, new_size, ec_htab_size_idx + 1, ec_totstored); |
| |
| for (i = 0; i < new_size; i++) |
| new_ec_htab[i] = NULL; |
| |
| for (i = 0; i < ec_htab_size; i++) { |
| ExeContext* cur = ec_htab[i]; |
| while (cur) { |
| ExeContext* next = cur->chain; |
| UWord hash = calc_hash(cur->ips, cur->n_ips, new_size); |
| vg_assert(hash < new_size); |
| cur->chain = new_ec_htab[hash]; |
| new_ec_htab[hash] = cur; |
| cur = next; |
| } |
| } |
| |
| VG_(arena_free)(VG_AR_EXECTXT, ec_htab); |
| ec_htab = new_ec_htab; |
| ec_htab_size = new_size; |
| ec_htab_size_idx++; |
| } |
| |
| ExeContext* VG_(record_ExeContext) ( ThreadId tid, Word first_ip_delta ) |
| { |
| 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), |
| first_ip_delta ); |
| tl_assert(n_ips >= 1 && n_ips <= VG_(clo_backtrace_size)); |
| |
| /* Now figure out if we've seen this one before. First hash it so |
| as to determine the list number. */ |
| hash = calc_hash( ips, n_ips, ec_htab_size ); |
| |
| /* And (the expensive bit) look a for matching entry in the list. */ |
| |
| ec_searchreqs++; |
| |
| prev2 = NULL; |
| prev = NULL; |
| list = ec_htab[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->chain; |
| } |
| |
| 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 (0 == ((ctr++) & 7)) { |
| if (prev2 != NULL && prev != NULL) { |
| /* Found at 3rd or later position in the chain. */ |
| vg_assert(prev2->chain == prev); |
| vg_assert(prev->chain == list); |
| prev2->chain = list; |
| prev->chain = list->chain; |
| list->chain = prev; |
| } |
| else if (prev2 == NULL && prev != NULL) { |
| /* Found at 2nd position in the chain. */ |
| vg_assert(ec_htab[hash] == prev); |
| vg_assert(prev->chain == list); |
| prev->chain = list->chain; |
| list->chain = prev; |
| ec_htab[hash] = list; |
| } |
| } |
| 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->chain = ec_htab[hash]; |
| ec_htab[hash] = new_ec; |
| |
| /* Resize the hash table, maybe? */ |
| if ( ((ULong)ec_totstored) > ((ULong)ec_htab_size) ) { |
| vg_assert(ec_htab_size_idx >= 0 && ec_htab_size_idx < N_EC_PRIMES); |
| if (ec_htab_size_idx < N_EC_PRIMES-1) |
| resize_ec_htab(); |
| } |
| |
| return new_ec; |
| } |
| |
| StackTrace VG_(extract_StackTrace) ( ExeContext* e ) |
| { |
| return e->ips; |
| } |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end m_execontext.c ---*/ |
| /*--------------------------------------------------------------------*/ |