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ftmemsim-valgrind/memcheck/mc_leakcheck.c
Bart Van Assche 8122b2aaef Added new memcheck command-line option --show-possibly-lost. Closes #201170. 
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11292
2010-08-26 10:56:27 +00:00

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/*--------------------------------------------------------------------*/
/*--- The leak checker. mc_leakcheck.c ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of MemCheck, a heavyweight Valgrind tool for
detecting memory errors.
Copyright (C) 2000-2010 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_tool_basics.h"
#include "pub_tool_vki.h"
#include "pub_tool_aspacehl.h"
#include "pub_tool_aspacemgr.h"
#include "pub_tool_execontext.h"
#include "pub_tool_hashtable.h"
#include "pub_tool_libcbase.h"
#include "pub_tool_libcassert.h"
#include "pub_tool_libcprint.h"
#include "pub_tool_libcsignal.h"
#include "pub_tool_machine.h"
#include "pub_tool_mallocfree.h"
#include "pub_tool_options.h"
#include "pub_tool_oset.h"
#include "pub_tool_signals.h"
#include "pub_tool_tooliface.h" // Needed for mc_include.h
#include "mc_include.h"
#include <setjmp.h> // For jmp_buf
/*------------------------------------------------------------*/
/*--- An overview of leak checking. ---*/
/*------------------------------------------------------------*/
// Leak-checking is a directed-graph traversal problem. The graph has
// two kinds of nodes:
// - root-set nodes:
// - GP registers of all threads;
// - valid, aligned, pointer-sized data words in valid client memory,
// including stacks, but excluding words within client heap-allocated
// blocks (they are excluded so that later on we can differentiate
// between heap blocks that are indirectly leaked vs. directly leaked).
// - heap-allocated blocks. A block is a mempool chunk or a malloc chunk
// that doesn't contain a mempool chunk. Nb: the terms "blocks" and
// "chunks" are used interchangeably below.
//
// There are two kinds of edges:
// - start-pointers, i.e. pointers to the start of a block;
// - interior-pointers, i.e. pointers to the interior of a block.
//
// We use "pointers" rather than "edges" below.
//
// Root set nodes only point to blocks. Blocks only point to blocks;
// a block can point to itself.
//
// The aim is to traverse the graph and determine the status of each block.
//
// There are 9 distinct cases. See memcheck/docs/mc-manual.xml for details.
// Presenting all nine categories to the user is probably too much.
// Currently we do this:
// - definitely lost: case 3
// - indirectly lost: case 4, 9
// - possibly lost: cases 5..8
// - still reachable: cases 1, 2
//
// It's far from clear that this is the best possible categorisation; it's
// accreted over time without any central guiding principle.
/*------------------------------------------------------------*/
/*--- XXX: Thoughts for improvement. ---*/
/*------------------------------------------------------------*/
// From the user's point of view:
// - If they aren't using interior-pointers, they just have to fix the
// directly lost blocks, and the indirectly lost ones will be fixed as
// part of that. Any possibly lost blocks will just be due to random
// pointer garbage and can be ignored.
//
// - If they are using interior-pointers, the fact that they currently are not
// being told which ones might be directly lost vs. indirectly lost makes
// it hard to know where to begin.
//
// All this makes me wonder if new option is warranted:
// --follow-interior-pointers. By default it would be off, the leak checker
// wouldn't follow interior-pointers and there would only be 3 categories:
// R, DL, IL.
//
// If turned on, then it would show 7 categories (R, DL, IL, DR/DL, IR/IL,
// IR/IL/DL, IL/DL). That output is harder to understand but it's your own
// damn fault for using interior-pointers...
//
// ----
//
// Also, why are two blank lines printed between each loss record?
// [bug 197930]
//
// ----
//
// Also, --show-reachable is a bad name because it also turns on the showing
// of indirectly leaked blocks(!) It would be better named --show-all or
// --show-all-heap-blocks, because that's the end result.
//
// ----
//
// Also, the VALGRIND_LEAK_CHECK and VALGRIND_QUICK_LEAK_CHECK aren't great
// names. VALGRIND_FULL_LEAK_CHECK and VALGRIND_SUMMARY_LEAK_CHECK would be
// better.
//
// ----
//
// Also, VALGRIND_COUNT_LEAKS and VALGRIND_COUNT_LEAK_BLOCKS aren't great as
// they combine direct leaks and indirect leaks into one. New, more precise
// ones (they'll need new names) would be good. If more categories are
// used, as per the --follow-interior-pointers option, they should be
// updated accordingly. And they should use a struct to return the values.
//
// ----
//
// Also, for this case:
//
// (4) p4 BBB ---> AAA
//
// BBB is definitely directly lost. AAA is definitely indirectly lost.
// Here's the relevant loss records printed for a full check (each block is
// 16 bytes):
//
// ==20397== 16 bytes in 1 blocks are indirectly lost in loss record 9 of 15
// ==20397== at 0x4C2694E: malloc (vg_replace_malloc.c:177)
// ==20397== by 0x400521: mk (leak-cases.c:49)
// ==20397== by 0x400578: main (leak-cases.c:72)
//
// ==20397== 32 (16 direct, 16 indirect) bytes in 1 blocks are definitely
// lost in loss record 14 of 15
// ==20397== at 0x4C2694E: malloc (vg_replace_malloc.c:177)
// ==20397== by 0x400521: mk (leak-cases.c:49)
// ==20397== by 0x400580: main (leak-cases.c:72)
//
// The first one is fine -- it describes AAA.
//
// The second one is for BBB. It's correct in that 16 bytes in 1 block are
// directly lost. It's also correct that 16 are indirectly lost as a result,
// but it means that AAA is being counted twice in the loss records. (It's
// not, thankfully, counted twice in the summary counts). Argh.
//
// This would be less confusing for the second one:
//
// ==20397== 16 bytes in 1 blocks are definitely lost in loss record 14
// of 15 (and 16 bytes in 1 block are indirectly lost as a result; they
// are mentioned elsewhere (if --show-reachable=yes is given!))
// ==20397== at 0x4C2694E: malloc (vg_replace_malloc.c:177)
// ==20397== by 0x400521: mk (leak-cases.c:49)
// ==20397== by 0x400580: main (leak-cases.c:72)
//
// But ideally we'd present the loss record for the directly lost block and
// then the resultant indirectly lost blocks and make it clear the
// dependence. Double argh.
/*------------------------------------------------------------*/
/*--- The actual algorithm. ---*/
/*------------------------------------------------------------*/
// - Find all the blocks (a.k.a. chunks) to check. Mempool chunks require
// some special treatment because they can be within malloc'd blocks.
// - Scan every word in the root set (GP registers and valid
// non-heap memory words).
// - First, we skip if it doesn't point to valid memory.
// - Then, we see if it points to the start or interior of a block. If
// so, we push the block onto the mark stack and mark it as having been
// reached.
// - Then, we process the mark stack, repeating the scanning for each block;
// this can push more blocks onto the mark stack. We repeat until the
// mark stack is empty. Each block is marked as definitely or possibly
// reachable, depending on whether interior-pointers were required to
// reach it.
// - At this point we know for every block if it's reachable or not.
// - We then push each unreached block onto the mark stack, using the block
// number as the "clique" number.
// - We process the mark stack again, this time grouping blocks into cliques
// in order to facilitate the directly/indirectly lost categorisation.
// - We group blocks by their ExeContexts and categorisation, and print them
// if --leak-check=full. We also print summary numbers.
//
// A note on "cliques":
// - A directly lost block is one with no pointers to it. An indirectly
// lost block is one that is pointed to by a directly or indirectly lost
// block.
// - Each directly lost block has zero or more indirectly lost blocks
// hanging off it. All these blocks together form a "clique". The
// directly lost block is called the "clique leader". The clique number
// is the number (in lc_chunks[]) of the clique leader.
// - Actually, a directly lost block may be pointed to if it's part of a
// cycle. In that case, there may be more than one choice for the clique
// leader, and the choice is arbitrary. Eg. if you have A-->B and B-->A
// either A or B could be the clique leader.
// - Cliques cannot overlap, and will be truncated to avoid this. Eg. if we
// have A-->C and B-->C, the two cliques will be {A,C} and {B}, or {A} and
// {B,C} (again the choice is arbitrary). This is because we don't want
// to count a block as indirectly lost more than once.
//
// A note on 'is_prior_definite':
// - This is a boolean used in various places that indicates if the chain
// up to the prior node (prior to the one being considered) is definite.
// - In the clique == -1 case:
// - if True it means that the prior node is a root-set node, or that the
// prior node is a block which is reachable from the root-set via
// start-pointers.
// - if False it means that the prior node is a block that is only
// reachable from the root-set via a path including at least one
// interior-pointer.
// - In the clique != -1 case, currently it's always True because we treat
// start-pointers and interior-pointers the same for direct/indirect leak
// checking. If we added a PossibleIndirectLeak state then this would
// change.
// Define to debug the memory-leak-detector.
#define VG_DEBUG_LEAKCHECK 0
#define VG_DEBUG_CLIQUE 0
/*------------------------------------------------------------*/
/*--- Getting the initial chunks, and searching them. ---*/
/*------------------------------------------------------------*/
// Compare the MC_Chunks by 'data' (i.e. the address of the block).
static Int compare_MC_Chunks(void* n1, void* n2)
{
MC_Chunk* mc1 = *(MC_Chunk**)n1;
MC_Chunk* mc2 = *(MC_Chunk**)n2;
if (mc1->data < mc2->data) return -1;
if (mc1->data > mc2->data) return 1;
return 0;
}
#if VG_DEBUG_LEAKCHECK
// Used to sanity-check the fast binary-search mechanism.
static
Int find_chunk_for_OLD ( Addr ptr,
MC_Chunk** chunks,
Int n_chunks )
{
Int i;
Addr a_lo, a_hi;
PROF_EVENT(70, "find_chunk_for_OLD");
for (i = 0; i < n_chunks; i++) {
PROF_EVENT(71, "find_chunk_for_OLD(loop)");
a_lo = chunks[i]->data;
a_hi = ((Addr)chunks[i]->data) + chunks[i]->szB;
if (a_lo <= ptr && ptr < a_hi)
return i;
}
return -1;
}
#endif
// Find the i such that ptr points at or inside the block described by
// chunks[i]. Return -1 if none found. This assumes that chunks[]
// has been sorted on the 'data' field.
static
Int find_chunk_for ( Addr ptr,
MC_Chunk** chunks,
Int n_chunks )
{
Addr a_mid_lo, a_mid_hi;
Int lo, mid, hi, retVal;
// VG_(printf)("find chunk for %p = ", ptr);
retVal = -1;
lo = 0;
hi = n_chunks-1;
while (True) {
// Invariant: current unsearched space is from lo to hi, inclusive.
if (lo > hi) break; // not found
mid = (lo + hi) / 2;
a_mid_lo = chunks[mid]->data;
a_mid_hi = chunks[mid]->data + chunks[mid]->szB;
// Extent of block 'mid' is [a_mid_lo .. a_mid_hi).
// Special-case zero-sized blocks - treat them as if they had
// size 1. Not doing so causes them to not cover any address
// range at all and so will never be identified as the target of
// any pointer, which causes them to be incorrectly reported as
// definitely leaked.
if (chunks[mid]->szB == 0)
a_mid_hi++;
if (ptr < a_mid_lo) {
hi = mid-1;
continue;
}
if (ptr >= a_mid_hi) {
lo = mid+1;
continue;
}
tl_assert(ptr >= a_mid_lo && ptr < a_mid_hi);
retVal = mid;
break;
}
# if VG_DEBUG_LEAKCHECK
tl_assert(retVal == find_chunk_for_OLD ( ptr, chunks, n_chunks ));
# endif
// VG_(printf)("%d\n", retVal);
return retVal;
}
static MC_Chunk**
find_active_chunks(UInt* pn_chunks)
{
// Our goal is to construct a set of chunks that includes every
// mempool chunk, and every malloc region that *doesn't* contain a
// mempool chunk.
MC_Mempool *mp;
MC_Chunk **mallocs, **chunks, *mc;
UInt n_mallocs, n_chunks, m, s;
Bool *malloc_chunk_holds_a_pool_chunk;
// First we collect all the malloc chunks into an array and sort it.
// We do this because we want to query the chunks by interior
// pointers, requiring binary search.
mallocs = (MC_Chunk**) VG_(HT_to_array)( MC_(malloc_list), &n_mallocs );
if (n_mallocs == 0) {
tl_assert(mallocs == NULL);
*pn_chunks = 0;
return NULL;
}
VG_(ssort)(mallocs, n_mallocs, sizeof(VgHashNode*), compare_MC_Chunks);
// Then we build an array containing a Bool for each malloc chunk,
// indicating whether it contains any mempools.
malloc_chunk_holds_a_pool_chunk = VG_(calloc)( "mc.fas.1",
n_mallocs, sizeof(Bool) );
n_chunks = n_mallocs;
// Then we loop over the mempool tables. For each chunk in each
// pool, we set the entry in the Bool array corresponding to the
// malloc chunk containing the mempool chunk.
VG_(HT_ResetIter)(MC_(mempool_list));
while ( (mp = VG_(HT_Next)(MC_(mempool_list))) ) {
VG_(HT_ResetIter)(mp->chunks);
while ( (mc = VG_(HT_Next)(mp->chunks)) ) {
// We'll need to record this chunk.
n_chunks++;
// Possibly invalidate the malloc holding the beginning of this chunk.
m = find_chunk_for(mc->data, mallocs, n_mallocs);
if (m != -1 && malloc_chunk_holds_a_pool_chunk[m] == False) {
tl_assert(n_chunks > 0);
n_chunks--;
malloc_chunk_holds_a_pool_chunk[m] = True;
}
// Possibly invalidate the malloc holding the end of this chunk.
if (mc->szB > 1) {
m = find_chunk_for(mc->data + (mc->szB - 1), mallocs, n_mallocs);
if (m != -1 && malloc_chunk_holds_a_pool_chunk[m] == False) {
tl_assert(n_chunks > 0);
n_chunks--;
malloc_chunk_holds_a_pool_chunk[m] = True;
}
}
}
}
tl_assert(n_chunks > 0);
// Create final chunk array.
chunks = VG_(malloc)("mc.fas.2", sizeof(VgHashNode*) * (n_chunks));
s = 0;
// Copy the mempool chunks and the non-marked malloc chunks into a
// combined array of chunks.
VG_(HT_ResetIter)(MC_(mempool_list));
while ( (mp = VG_(HT_Next)(MC_(mempool_list))) ) {
VG_(HT_ResetIter)(mp->chunks);
while ( (mc = VG_(HT_Next)(mp->chunks)) ) {
tl_assert(s < n_chunks);
chunks[s++] = mc;
}
}
for (m = 0; m < n_mallocs; ++m) {
if (!malloc_chunk_holds_a_pool_chunk[m]) {
tl_assert(s < n_chunks);
chunks[s++] = mallocs[m];
}
}
tl_assert(s == n_chunks);
// Free temporaries.
VG_(free)(mallocs);
VG_(free)(malloc_chunk_holds_a_pool_chunk);
*pn_chunks = n_chunks;
return chunks;
}
/*------------------------------------------------------------*/
/*--- The leak detector proper. ---*/
/*------------------------------------------------------------*/
// Holds extra info about each block during leak checking.
typedef
struct {
UInt state:2; // Reachedness.
SizeT indirect_szB : (sizeof(SizeT)*8)-2; // If Unreached, how many bytes
// are unreachable from here.
}
LC_Extra;
// An array holding pointers to every chunk we're checking. Sorted by address.
static MC_Chunk** lc_chunks;
// How many chunks we're dealing with.
static Int lc_n_chunks;
// This has the same number of entries as lc_chunks, and each entry
// in lc_chunks corresponds with the entry here (ie. lc_chunks[i] and
// lc_extras[i] describe the same block).
static LC_Extra* lc_extras;
// Records chunks that are currently being processed. Each element in the
// stack is an index into lc_chunks and lc_extras. Its size is
// 'lc_n_chunks' because in the worst case that's how many chunks could be
// pushed onto it (actually I think the maximum is lc_n_chunks-1 but let's
// be conservative).
static Int* lc_markstack;
// The index of the top element of the stack; -1 if the stack is empty, 0 if
// the stack has one element, 1 if it has two, etc.
static Int lc_markstack_top;
// Keeps track of how many bytes of memory we've scanned, for printing.
// (Nb: We don't keep track of how many register bytes we've scanned.)
static SizeT lc_scanned_szB;
SizeT MC_(bytes_leaked) = 0;
SizeT MC_(bytes_indirect) = 0;
SizeT MC_(bytes_dubious) = 0;
SizeT MC_(bytes_reachable) = 0;
SizeT MC_(bytes_suppressed) = 0;
SizeT MC_(blocks_leaked) = 0;
SizeT MC_(blocks_indirect) = 0;
SizeT MC_(blocks_dubious) = 0;
SizeT MC_(blocks_reachable) = 0;
SizeT MC_(blocks_suppressed) = 0;
// Determines if a pointer is to a chunk. Returns the chunk number et al
// via call-by-reference.
static Bool
lc_is_a_chunk_ptr(Addr ptr, Int* pch_no, MC_Chunk** pch, LC_Extra** pex)
{
Int ch_no;
MC_Chunk* ch;
LC_Extra* ex;
// Quick filter.
if (!VG_(am_is_valid_for_client)(ptr, 1, VKI_PROT_READ)) {
return False;
} else {
ch_no = find_chunk_for(ptr, lc_chunks, lc_n_chunks);
tl_assert(ch_no >= -1 && ch_no < lc_n_chunks);
if (ch_no == -1) {
return False;
} else {
// Ok, we've found a pointer to a chunk. Get the MC_Chunk and its
// LC_Extra.
ch = lc_chunks[ch_no];
ex = &(lc_extras[ch_no]);
tl_assert(ptr >= ch->data);
tl_assert(ptr < ch->data + ch->szB + (ch->szB==0 ? 1 : 0));
if (VG_DEBUG_LEAKCHECK)
VG_(printf)("ptr=%#lx -> block %d\n", ptr, ch_no);
*pch_no = ch_no;
*pch = ch;
*pex = ex;
return True;
}
}
}
// Push a chunk (well, just its index) onto the mark stack.
static void lc_push(Int ch_no, MC_Chunk* ch)
{
if (0) {
VG_(printf)("pushing %#lx-%#lx\n", ch->data, ch->data + ch->szB);
}
lc_markstack_top++;
tl_assert(lc_markstack_top < lc_n_chunks);
lc_markstack[lc_markstack_top] = ch_no;
}
// Return the index of the chunk on the top of the mark stack, or -1 if
// there isn't one.
static Bool lc_pop(Int* ret)
{
if (-1 == lc_markstack_top) {
return False;
} else {
tl_assert(0 <= lc_markstack_top && lc_markstack_top < lc_n_chunks);
*ret = lc_markstack[lc_markstack_top];
lc_markstack_top--;
return True;
}
}
// If 'ptr' is pointing to a heap-allocated block which hasn't been seen
// before, push it onto the mark stack.
static void
lc_push_without_clique_if_a_chunk_ptr(Addr ptr, Bool is_prior_definite)
{
Int ch_no;
MC_Chunk* ch;
LC_Extra* ex;
if ( ! lc_is_a_chunk_ptr(ptr, &ch_no, &ch, &ex) )
return;
// Only push it if it hasn't been seen previously.
if (ex->state == Unreached) {
lc_push(ch_no, ch);
}
// Possibly upgrade the state, ie. one of:
// - Unreached --> Possible
// - Unreached --> Reachable
// - Possible --> Reachable
if (ptr == ch->data && is_prior_definite) {
// 'ptr' points to the start of the block, and the prior node is
// definite, which means that this block is definitely reachable.
ex->state = Reachable;
} else if (ex->state == Unreached) {
// Either 'ptr' is a interior-pointer, or the prior node isn't definite,
// which means that we can only mark this block as possibly reachable.
ex->state = Possible;
}
}
static void
lc_push_if_a_chunk_ptr_register(Addr ptr)
{
lc_push_without_clique_if_a_chunk_ptr(ptr, /*is_prior_definite*/True);
}
// If ptr is pointing to a heap-allocated block which hasn't been seen
// before, push it onto the mark stack. Clique is the index of the
// clique leader.
static void
lc_push_with_clique_if_a_chunk_ptr(Addr ptr, Int clique)
{
Int ch_no;
MC_Chunk* ch;
LC_Extra* ex;
tl_assert(0 <= clique && clique < lc_n_chunks);
if ( ! lc_is_a_chunk_ptr(ptr, &ch_no, &ch, &ex) )
return;
// If it's not Unreached, it's already been handled so ignore it.
// If ch_no==clique, it's the clique leader, which means this is a cyclic
// structure; again ignore it because it's already been handled.
if (ex->state == Unreached && ch_no != clique) {
// Note that, unlike reachable blocks, we currently don't distinguish
// between start-pointers and interior-pointers here. We probably
// should, though.
ex->state = IndirectLeak;
lc_push(ch_no, ch);
// Add the block to the clique, and add its size to the
// clique-leader's indirect size. Also, if the new block was
// itself a clique leader, it isn't any more, so add its
// indirect_szB to the new clique leader.
if (VG_DEBUG_CLIQUE) {
if (ex->indirect_szB > 0)
VG_(printf)(" clique %d joining clique %d adding %lu+%lu\n",
ch_no, clique, (SizeT)ch->szB, (SizeT)ex->indirect_szB);
else
VG_(printf)(" block %d joining clique %d adding %lu\n",
ch_no, clique, (SizeT)ch->szB);
}
lc_extras[clique].indirect_szB += ch->szB;
lc_extras[clique].indirect_szB += ex->indirect_szB;
ex->indirect_szB = 0; // Shouldn't matter.
}
}
static void
lc_push_if_a_chunk_ptr(Addr ptr, Int clique, Bool is_prior_definite)
{
if (-1 == clique)
lc_push_without_clique_if_a_chunk_ptr(ptr, is_prior_definite);
else
lc_push_with_clique_if_a_chunk_ptr(ptr, clique);
}
static jmp_buf memscan_jmpbuf;
static
void scan_all_valid_memory_catcher ( Int sigNo, Addr addr )
{
if (0)
VG_(printf)("OUCH! sig=%d addr=%#lx\n", sigNo, addr);
if (sigNo == VKI_SIGSEGV || sigNo == VKI_SIGBUS)
__builtin_longjmp(memscan_jmpbuf, 1);
}
// Scan a block of memory between [start, start+len). This range may
// be bogus, inaccessable, or otherwise strange; we deal with it. For each
// valid aligned word we assume it's a pointer to a chunk a push the chunk
// onto the mark stack if so.
static void
lc_scan_memory(Addr start, SizeT len, Bool is_prior_definite, Int clique)
{
Addr ptr = VG_ROUNDUP(start, sizeof(Addr));
Addr end = VG_ROUNDDN(start+len, sizeof(Addr));
vki_sigset_t sigmask;
if (VG_DEBUG_LEAKCHECK)
VG_(printf)("scan %#lx-%#lx (%lu)\n", start, end, len);
VG_(sigprocmask)(VKI_SIG_SETMASK, NULL, &sigmask);
VG_(set_fault_catcher)(scan_all_valid_memory_catcher);
// We might be in the middle of a page. Do a cheap check to see if
// it's valid; if not, skip onto the next page.
if (!VG_(am_is_valid_for_client)(ptr, sizeof(Addr), VKI_PROT_READ))
ptr = VG_PGROUNDUP(ptr+1); // First page is bad - skip it.
while (ptr < end) {
Addr addr;
// Skip invalid chunks.
if ( ! MC_(is_within_valid_secondary)(ptr) ) {
ptr = VG_ROUNDUP(ptr+1, SM_SIZE);
continue;
}
// Look to see if this page seems reasonable.
if ((ptr % VKI_PAGE_SIZE) == 0) {
if (!VG_(am_is_valid_for_client)(ptr, sizeof(Addr), VKI_PROT_READ)) {
ptr += VKI_PAGE_SIZE; // Bad page - skip it.
continue;
}
}
if (__builtin_setjmp(memscan_jmpbuf) == 0) {
if ( MC_(is_valid_aligned_word)(ptr) ) {
lc_scanned_szB += sizeof(Addr);
addr = *(Addr *)ptr;
// If we get here, the scanned word is in valid memory. Now
// let's see if its contents point to a chunk.
lc_push_if_a_chunk_ptr(addr, clique, is_prior_definite);
} else if (0 && VG_DEBUG_LEAKCHECK) {
VG_(printf)("%#lx not valid\n", ptr);
}
ptr += sizeof(Addr);
} else {
// We need to restore the signal mask, because we were
// longjmped out of a signal handler.
VG_(sigprocmask)(VKI_SIG_SETMASK, &sigmask, NULL);
ptr = VG_PGROUNDUP(ptr+1); // Bad page - skip it.
}
}
VG_(sigprocmask)(VKI_SIG_SETMASK, &sigmask, NULL);
VG_(set_fault_catcher)(NULL);
}
// Process the mark stack until empty.
static void lc_process_markstack(Int clique)
{
Int top = -1; // shut gcc up
Bool is_prior_definite;
while (lc_pop(&top)) {
tl_assert(top >= 0 && top < lc_n_chunks);
// See comment about 'is_prior_definite' at the top to understand this.
is_prior_definite = ( Possible != lc_extras[top].state );
lc_scan_memory(lc_chunks[top]->data, lc_chunks[top]->szB,
is_prior_definite, clique);
}
}
static Word cmp_LossRecordKey_LossRecord(const void* key, const void* elem)
{
LossRecordKey* a = (LossRecordKey*)key;
LossRecordKey* b = &(((LossRecord*)elem)->key);
// Compare on states first because that's fast.
if (a->state < b->state) return -1;
if (a->state > b->state) return 1;
// Ok, the states are equal. Now compare the locations, which is slower.
if (VG_(eq_ExeContext)(
MC_(clo_leak_resolution), a->allocated_at, b->allocated_at))
return 0;
// Different locations. Ordering is arbitrary, just use the ec pointer.
if (a->allocated_at < b->allocated_at) return -1;
if (a->allocated_at > b->allocated_at) return 1;
VG_(tool_panic)("bad LossRecord comparison");
}
static Int cmp_LossRecords(void* va, void* vb)
{
LossRecord* lr_a = *(LossRecord**)va;
LossRecord* lr_b = *(LossRecord**)vb;
SizeT total_szB_a = lr_a->szB + lr_a->indirect_szB;
SizeT total_szB_b = lr_b->szB + lr_b->indirect_szB;
// First compare by sizes.
if (total_szB_a < total_szB_b) return -1;
if (total_szB_a > total_szB_b) return 1;
// If size are equal, compare by states.
if (lr_a->key.state < lr_b->key.state) return -1;
if (lr_a->key.state > lr_b->key.state) return 1;
// If they're still equal here, it doesn't matter that much, but we keep
// comparing other things so that regtests are as deterministic as
// possible. So: compare num_blocks.
if (lr_a->num_blocks < lr_b->num_blocks) return -1;
if (lr_a->num_blocks > lr_b->num_blocks) return 1;
// Finally, compare ExeContext addresses... older ones are likely to have
// lower addresses.
if (lr_a->key.allocated_at < lr_b->key.allocated_at) return -1;
if (lr_a->key.allocated_at > lr_b->key.allocated_at) return 1;
return 0;
}
static void print_results(ThreadId tid, Bool is_full_check)
{
Int i, n_lossrecords;
OSet* lr_table;
LossRecord** lr_array;
LossRecord* lr;
Bool is_suppressed;
// Create the lr_table, which holds the loss records.
lr_table =
VG_(OSetGen_Create)(offsetof(LossRecord, key),
cmp_LossRecordKey_LossRecord,
VG_(malloc), "mc.pr.1",
VG_(free));
// Convert the chunks into loss records, merging them where appropriate.
for (i = 0; i < lc_n_chunks; i++) {
MC_Chunk* ch = lc_chunks[i];
LC_Extra* ex = &(lc_extras)[i];
LossRecord* old_lr;
LossRecordKey lrkey;
lrkey.state = ex->state;
lrkey.allocated_at = ch->where;
old_lr = VG_(OSetGen_Lookup)(lr_table, &lrkey);
if (old_lr) {
// We found an existing loss record matching this chunk. Update the
// loss record's details in-situ. This is safe because we don't
// change the elements used as the OSet key.
old_lr->szB += ch->szB;
old_lr->indirect_szB += ex->indirect_szB;
old_lr->num_blocks++;
} else {
// No existing loss record matches this chunk. Create a new loss
// record, initialise it from the chunk, and insert it into lr_table.
lr = VG_(OSetGen_AllocNode)(lr_table, sizeof(LossRecord));
lr->key = lrkey;
lr->szB = ch->szB;
lr->indirect_szB = ex->indirect_szB;
lr->num_blocks = 1;
VG_(OSetGen_Insert)(lr_table, lr);
}
}
n_lossrecords = VG_(OSetGen_Size)(lr_table);
// Create an array of pointers to the loss records.
lr_array = VG_(malloc)("mc.pr.2", n_lossrecords * sizeof(LossRecord*));
i = 0;
VG_(OSetGen_ResetIter)(lr_table);
while ( (lr = VG_(OSetGen_Next)(lr_table)) ) {
lr_array[i++] = lr;
}
tl_assert(i == n_lossrecords);
// Sort the array by loss record sizes.
VG_(ssort)(lr_array, n_lossrecords, sizeof(LossRecord*),
cmp_LossRecords);
// Zero totals.
MC_(blocks_leaked) = MC_(bytes_leaked) = 0;
MC_(blocks_indirect) = MC_(bytes_indirect) = 0;
MC_(blocks_dubious) = MC_(bytes_dubious) = 0;
MC_(blocks_reachable) = MC_(bytes_reachable) = 0;
MC_(blocks_suppressed) = MC_(bytes_suppressed) = 0;
// Print the loss records (in size order) and collect summary stats.
for (i = 0; i < n_lossrecords; i++) {
Bool count_as_error, print_record;
// Rules for printing:
// - We don't show suppressed loss records ever (and that's controlled
// within the error manager).
// - We show non-suppressed loss records that are not "reachable" if
// --leak-check=yes.
// - We show all non-suppressed loss records if --leak-check=yes and
// --show-reachable=yes.
//
// Nb: here "reachable" means Reachable *or* IndirectLeak; note that
// this is different to "still reachable" used elsewhere because it
// includes indirectly lost blocks!
//
lr = lr_array[i];
print_record = is_full_check &&
( MC_(clo_show_reachable) ||
Unreached == lr->key.state ||
( MC_(clo_show_possibly_lost) &&
Possible == lr->key.state ) );
// We don't count a leaks as errors with --leak-check=summary.
// Otherwise you can get high error counts with few or no error
// messages, which can be confusing. Also, you could argue that
// indirect leaks should be counted as errors, but it seems better to
// make the counting criteria similar to the printing criteria. So we
// don't count them.
count_as_error = is_full_check &&
( Unreached == lr->key.state ||
Possible == lr->key.state );
is_suppressed =
MC_(record_leak_error) ( tid, i+1, n_lossrecords, lr, print_record,
count_as_error );
if (is_suppressed) {
MC_(blocks_suppressed) += lr->num_blocks;
MC_(bytes_suppressed) += lr->szB;
} else if (Unreached == lr->key.state) {
MC_(blocks_leaked) += lr->num_blocks;
MC_(bytes_leaked) += lr->szB;
} else if (IndirectLeak == lr->key.state) {
MC_(blocks_indirect) += lr->num_blocks;
MC_(bytes_indirect) += lr->szB;
} else if (Possible == lr->key.state) {
MC_(blocks_dubious) += lr->num_blocks;
MC_(bytes_dubious) += lr->szB;
} else if (Reachable == lr->key.state) {
MC_(blocks_reachable) += lr->num_blocks;
MC_(bytes_reachable) += lr->szB;
} else {
VG_(tool_panic)("unknown loss mode");
}
}
if (VG_(clo_verbosity) > 0 && !VG_(clo_xml)) {
VG_(umsg)("LEAK SUMMARY:\n");
VG_(umsg)(" definitely lost: %'lu bytes in %'lu blocks\n",
MC_(bytes_leaked), MC_(blocks_leaked) );
VG_(umsg)(" indirectly lost: %'lu bytes in %'lu blocks\n",
MC_(bytes_indirect), MC_(blocks_indirect) );
VG_(umsg)(" possibly lost: %'lu bytes in %'lu blocks\n",
MC_(bytes_dubious), MC_(blocks_dubious) );
VG_(umsg)(" still reachable: %'lu bytes in %'lu blocks\n",
MC_(bytes_reachable), MC_(blocks_reachable) );
VG_(umsg)(" suppressed: %'lu bytes in %'lu blocks\n",
MC_(bytes_suppressed), MC_(blocks_suppressed) );
if (!is_full_check &&
(MC_(blocks_leaked) + MC_(blocks_indirect) +
MC_(blocks_dubious) + MC_(blocks_reachable)) > 0) {
VG_(umsg)("Rerun with --leak-check=full to see details "
"of leaked memory\n");
}
if (is_full_check &&
MC_(blocks_reachable) > 0 && !MC_(clo_show_reachable))
{
VG_(umsg)("Reachable blocks (those to which a pointer "
"was found) are not shown.\n");
VG_(umsg)("To see them, rerun with: --leak-check=full "
"--show-reachable=yes\n");
}
VG_(umsg)("\n");
}
}
/*------------------------------------------------------------*/
/*--- Top-level entry point. ---*/
/*------------------------------------------------------------*/
void MC_(detect_memory_leaks) ( ThreadId tid, LeakCheckMode mode )
{
Int i, j;
tl_assert(mode != LC_Off);
// Get the chunks, stop if there were none.
lc_chunks = find_active_chunks(&lc_n_chunks);
if (lc_n_chunks == 0) {
tl_assert(lc_chunks == NULL);
if (VG_(clo_verbosity) >= 1 && !VG_(clo_xml)) {
VG_(umsg)("All heap blocks were freed -- no leaks are possible\n");
VG_(umsg)("\n");
}
return;
}
// Sort the array so blocks are in ascending order in memory.
VG_(ssort)(lc_chunks, lc_n_chunks, sizeof(VgHashNode*), compare_MC_Chunks);
// Sanity check -- make sure they're in order.
for (i = 0; i < lc_n_chunks-1; i++) {
tl_assert( lc_chunks[i]->data <= lc_chunks[i+1]->data);
}
// Sanity check -- make sure they don't overlap. The one exception is that
// we allow a MALLOCLIKE block to sit entirely within a malloc() block.
// This is for bug 100628. If this occurs, we ignore the malloc() block
// for leak-checking purposes. This is a hack and probably should be done
// better, but at least it's consistent with mempools (which are treated
// like this in find_active_chunks). Mempools have a separate VgHashTable
// for mempool chunks, but if custom-allocated blocks are put in a separate
// table from normal heap blocks it makes free-mismatch checking more
// difficult.
//
// If this check fails, it probably means that the application
// has done something stupid with VALGRIND_MALLOCLIKE_BLOCK client
// requests, eg. has made overlapping requests (which are
// nonsensical), or used VALGRIND_MALLOCLIKE_BLOCK for stack locations;
// again nonsensical.
//
for (i = 0; i < lc_n_chunks-1; i++) {
MC_Chunk* ch1 = lc_chunks[i];
MC_Chunk* ch2 = lc_chunks[i+1];
Addr start1 = ch1->data;
Addr start2 = ch2->data;
Addr end1 = ch1->data + ch1->szB - 1;
Addr end2 = ch2->data + ch2->szB - 1;
Bool isCustom1 = ch1->allockind == MC_AllocCustom;
Bool isCustom2 = ch2->allockind == MC_AllocCustom;
if (end1 < start2) {
// Normal case - no overlap.
// We used to allow exact duplicates, I'm not sure why. --njn
//} else if (start1 == start2 && end1 == end2) {
// Degenerate case: exact duplicates.
} else if (start1 >= start2 && end1 <= end2 && isCustom1 && !isCustom2) {
// Block i is MALLOCLIKE and entirely within block i+1.
// Remove block i+1.
for (j = i+1; j < lc_n_chunks-1; j++) {
lc_chunks[j] = lc_chunks[j+1];
}
lc_n_chunks--;
} else if (start2 >= start1 && end2 <= end1 && isCustom2 && !isCustom1) {
// Block i+1 is MALLOCLIKE and entirely within block i.
// Remove block i.
for (j = i; j < lc_n_chunks-1; j++) {
lc_chunks[j] = lc_chunks[j+1];
}
lc_n_chunks--;
} else {
VG_(umsg)("Block 0x%lx..0x%lx overlaps with block 0x%lx..0x%lx",
start1, end1, start1, end2);
VG_(umsg)("This is usually caused by using VALGRIND_MALLOCLIKE_BLOCK");
VG_(umsg)("in an inappropriate way.");
tl_assert (0);
}
}
// Initialise lc_extras.
lc_extras = VG_(malloc)( "mc.dml.2", lc_n_chunks * sizeof(LC_Extra) );
for (i = 0; i < lc_n_chunks; i++) {
lc_extras[i].state = Unreached;
lc_extras[i].indirect_szB = 0;
}
// Initialise lc_markstack.
lc_markstack = VG_(malloc)( "mc.dml.2", lc_n_chunks * sizeof(Int) );
for (i = 0; i < lc_n_chunks; i++) {
lc_markstack[i] = -1;
}
lc_markstack_top = -1;
// Verbosity.
if (VG_(clo_verbosity) > 1 && !VG_(clo_xml)) {
VG_(umsg)( "Searching for pointers to %'d not-freed blocks\n",
lc_n_chunks );
}
// Scan the memory root-set, pushing onto the mark stack any blocks
// pointed to.
{
Int n_seg_starts;
Addr* seg_starts = VG_(get_segment_starts)( &n_seg_starts );
tl_assert(seg_starts && n_seg_starts > 0);
lc_scanned_szB = 0;
// VG_(am_show_nsegments)( 0, "leakcheck");
for (i = 0; i < n_seg_starts; i++) {
SizeT seg_size;
NSegment const* seg = VG_(am_find_nsegment)( seg_starts[i] );
tl_assert(seg);
if (seg->kind != SkFileC && seg->kind != SkAnonC) continue;
if (!(seg->hasR && seg->hasW)) continue;
if (seg->isCH) continue;
// Don't poke around in device segments as this may cause
// hangs. Exclude /dev/zero just in case someone allocated
// memory by explicitly mapping /dev/zero.
if (seg->kind == SkFileC
&& (VKI_S_ISCHR(seg->mode) || VKI_S_ISBLK(seg->mode))) {
HChar* dev_name = VG_(am_get_filename)( (NSegment*)seg );
if (dev_name && 0 == VG_(strcmp)(dev_name, "/dev/zero")) {
// Don't skip /dev/zero.
} else {
// Skip this device mapping.
continue;
}
}
if (0)
VG_(printf)("ACCEPT %2d %#lx %#lx\n", i, seg->start, seg->end);
// Scan the segment. We use -1 for the clique number, because this
// is a root-set.
seg_size = seg->end - seg->start + 1;
if (VG_(clo_verbosity) > 2) {
VG_(message)(Vg_DebugMsg,
" Scanning root segment: %#lx..%#lx (%lu)\n",
seg->start, seg->end, seg_size);
}
lc_scan_memory(seg->start, seg_size, /*is_prior_definite*/True, -1);
}
}
// Scan GP registers for chunk pointers.
VG_(apply_to_GP_regs)(lc_push_if_a_chunk_ptr_register);
// Process the pushed blocks. After this, every block that is reachable
// from the root-set has been traced.
lc_process_markstack(/*clique*/-1);
if (VG_(clo_verbosity) > 1 && !VG_(clo_xml)) {
VG_(umsg)("Checked %'lu bytes\n", lc_scanned_szB);
VG_(umsg)( "\n" );
}
// Trace all the leaked blocks to determine which are directly leaked and
// which are indirectly leaked. For each Unreached block, push it onto
// the mark stack, and find all the as-yet-Unreached blocks reachable
// from it. These form a clique and are marked IndirectLeak, and their
// size is added to the clique leader's indirect size. If one of the
// found blocks was itself a clique leader (from a previous clique), then
// the cliques are merged.
for (i = 0; i < lc_n_chunks; i++) {
MC_Chunk* ch = lc_chunks[i];
LC_Extra* ex = &(lc_extras[i]);
if (VG_DEBUG_CLIQUE)
VG_(printf)("cliques: %d at %#lx -> Loss state %d\n",
i, ch->data, ex->state);
tl_assert(lc_markstack_top == -1);
if (ex->state == Unreached) {
if (VG_DEBUG_CLIQUE)
VG_(printf)("%d: gathering clique %#lx\n", i, ch->data);
// Push this Unreached block onto the stack and process it.
lc_push(i, ch);
lc_process_markstack(i);
tl_assert(lc_markstack_top == -1);
tl_assert(ex->state == Unreached);
}
}
print_results( tid, ( mode == LC_Full ? True : False ) );
VG_(free) ( lc_chunks );
VG_(free) ( lc_extras );
VG_(free) ( lc_markstack );
}
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
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