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re PR libstdc++/64535 (Emergency buffer for exception allocation too small) 

2015-01-22  Richard Biener  <rguenther@suse.de>

	PR libstdc++/64535
	* libsupc++/eh_alloc.cc: Include new.
	(bitmask_type): Remove.
	(one_buffer): Likewise.
	(emergency_buffer): Likewise.
	(emergency_used): Likewise.
	(dependents_buffer): Likewise.
	(dependents_used): Likewise.
	(class pool): New custom fixed-size arena, variable size object
	allocator.
	(emergency_pool): New global.
	(__cxxabiv1::__cxa_allocate_exception): Use new emergency_pool.
	(__cxxabiv1::__cxa_free_exception): Likewise.
	(__cxxabiv1::__cxa_allocate_dependent_exception): Likewise.
	(__cxxabiv1::__cxa_free_dependent_exception): Likewise.

	* g++.old-deja/g++.eh/badalloc1.C: Adjust.

From-SVN: r219988
This commit is contained in:
Richard Biener 2015-01-22 09:21:48 +00:00 committed by Richard Biener
parent 770acfc9e3
commit cce93c76ba
4 changed files with 209 additions and 88 deletions
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5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2015-01-22 Richard Biener <rguenther@suse.de>
PR libstdc++/64535
* g++.old-deja/g++.eh/badalloc1.C: Adjust.
2015-01-21 Segher Boessenkool <segher@kernel.crashing.org>
PR rtl-optimization/64682

9
gcc/testsuite/g++.old-deja/g++.eh/badalloc1.C
View File

@ -12,21 +12,24 @@ typedef __SIZE_TYPE__ size_t;
extern "C" void abort();
extern "C" void *memcpy(void *, const void *, size_t);
// libstdc++ requires a large initialization time allocation for the
// emergency EH allocation pool. Add that to the arena size.
// Assume that STACK_SIZE defined implies a system that does not have a
// large data space either, and additionally that we're not linking against
// a shared libstdc++ (which requires quite a bit more initialization space).
#ifdef STACK_SIZE
const int arena_size = 256;
const int arena_size = 256 + 8 * 128;
#else
#if defined(__FreeBSD__) || defined(__sun__) || defined(__hpux__)
// FreeBSD, Solaris and HP-UX require even more space at initialization time.
// FreeBSD 5 now requires over 131072 bytes.
const int arena_size = 262144;
const int arena_size = 262144 + 72 * 1024;
#else
// Because pointers make up the bulk of our exception-initialization
// allocations, we scale by the pointer size from the original
// 32-bit-systems-based estimate.
const int arena_size = 32768 * ((sizeof (void *) + 3)/4);
const int arena_size = 32768 * ((sizeof (void *) + 3)/4) + 72 * 1024;
#endif
#endif

18
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,21 @@
2015-01-22 Richard Biener <rguenther@suse.de>
PR libstdc++/64535
* libsupc++/eh_alloc.cc: Include new.
(bitmask_type): Remove.
(one_buffer): Likewise.
(emergency_buffer): Likewise.
(emergency_used): Likewise.
(dependents_buffer): Likewise.
(dependents_used): Likewise.
(class pool): New custom fixed-size arena, variable size object
allocator.
(emergency_pool): New global.
(__cxxabiv1::__cxa_allocate_exception): Use new emergency_pool.
(__cxxabiv1::__cxa_free_exception): Likewise.
(__cxxabiv1::__cxa_allocate_dependent_exception): Likewise.
(__cxxabiv1::__cxa_free_dependent_exception): Likewise.
2015-01-22 Tim Shen <timshen@google.com>
PR libstdc++/64680

265
libstdc++-v3/libsupc++/eh_alloc.cc
View File

@ -34,6 +34,7 @@
#include <exception>
#include "unwind-cxx.h"
#include <ext/concurrence.h>
#include <new>
#if _GLIBCXX_HOSTED
using std::free;
@ -72,28 +73,174 @@ using namespace __cxxabiv1;
# define EMERGENCY_OBJ_COUNT 4
#endif
#if INT_MAX == 32767 || EMERGENCY_OBJ_COUNT <= 32
typedef unsigned int bitmask_type;
#else
#if defined (_GLIBCXX_LLP64)
typedef unsigned long long bitmask_type;
#else
typedef unsigned long bitmask_type;
#endif
#endif
typedef char one_buffer[EMERGENCY_OBJ_SIZE] __attribute__((aligned));
static one_buffer emergency_buffer[EMERGENCY_OBJ_COUNT];
static bitmask_type emergency_used;
static __cxa_dependent_exception dependents_buffer[EMERGENCY_OBJ_COUNT];
static bitmask_type dependents_used;
namespace
{
// A single mutex controlling emergency allocations.
__gnu_cxx::__mutex emergency_mutex;
// A fixed-size heap, variable size object allocator
class pool
{
public:
pool();
void *allocate (std::size_t);
void free (void *);
bool in_pool (void *);
private:
struct free_entry {
std::size_t size;
free_entry *next;
};
struct allocated_entry {
std::size_t size;
char data[];
};
// A single mutex controlling emergency allocations.
__gnu_cxx::__mutex emergency_mutex;
// The free-list
free_entry *first_free_entry;
// The arena itself - we need to keep track of these only
// to implement in_pool.
char *arena;
std::size_t arena_size;
};
pool::pool()
{
// Allocate the arena - we could add a GLIBCXX_EH_ARENA_SIZE environment
// to make this tunable.
arena_size = (EMERGENCY_OBJ_SIZE * EMERGENCY_OBJ_COUNT
+ EMERGENCY_OBJ_COUNT * sizeof (__cxa_dependent_exception));
arena = (char *)malloc (arena_size);
if (!arena)
{
// If the allocation failed go without an emergency pool.
arena_size = 0;
first_free_entry = NULL;
return;
}
// Populate the free-list with a single entry covering the whole arena
first_free_entry = reinterpret_cast <free_entry *> (arena);
new (first_free_entry) free_entry;
first_free_entry->size = arena_size;
first_free_entry->next = NULL;
}
void *pool::allocate (std::size_t size)
{
__gnu_cxx::__scoped_lock sentry(emergency_mutex);
// We need an additional size_t member.
size += sizeof (std::size_t);
// And we need to at least hand out objects of the size of
// a freelist entry.
if (size < sizeof (free_entry))
size = sizeof (free_entry);
// And we need to align objects we hand out to the required
// alignment of a freelist entry (this really aligns the
// tail which will become a new freelist entry).
size = ((size + __alignof__(free_entry) - 1)
& ~(__alignof__(free_entry) - 1));
// Search for an entry of proper size on the freelist.
free_entry **e;
for (e = &first_free_entry;
*e && (*e)->size < size;
e = &(*e)->next)
;
if (!*e)
return NULL;
allocated_entry *x;
if ((*e)->size - size >= sizeof (free_entry))
{
// Slit block if it is too large.
free_entry *f = reinterpret_cast <free_entry *>
(reinterpret_cast <char *> (*e) + size);
std::size_t sz = (*e)->size;
free_entry *next = (*e)->next;
new (f) free_entry;
f->next = next;
f->size = sz - size;
x = reinterpret_cast <allocated_entry *> (*e);
new (x) allocated_entry;
x->size = size;
*e = f;
}
else
{
// Exact size match or too small overhead for a free entry.
std::size_t sz = (*e)->size;
free_entry *next = (*e)->next;
x = reinterpret_cast <allocated_entry *> (*e);
new (x) allocated_entry;
x->size = sz;
*e = next;
}
return &x->data;
}
void pool::free (void *data)
{
__gnu_cxx::__scoped_lock sentry(emergency_mutex);
allocated_entry *e = reinterpret_cast <allocated_entry *>
(reinterpret_cast <char *> (data) - sizeof (std::size_t));
std::size_t sz = e->size;
if (!first_free_entry)
{
// If the free list is empty just put the entry there.
free_entry *f = reinterpret_cast <free_entry *> (e);
new (f) free_entry;
f->size = sz;
f->next = NULL;
first_free_entry = f;
}
else if (reinterpret_cast <char *> (e) + sz
== reinterpret_cast <char *> (first_free_entry))
{
// Check if we can merge with the first free entry being right
// after us.
free_entry *f = reinterpret_cast <free_entry *> (e);
new (f) free_entry;
f->size = sz + first_free_entry->size;
f->next = first_free_entry->next;
first_free_entry = f;
}
else
{
// Else search for a free item we can merge with at its end.
free_entry **fe;
for (fe = &first_free_entry;
(*fe)->next
&& (reinterpret_cast <char *> ((*fe)->next)
> reinterpret_cast <char *> (e) + sz);
fe = &(*fe)->next)
;
if (reinterpret_cast <char *> (*fe) + (*fe)->size
== reinterpret_cast <char *> (e))
/* Merge with the freelist entry. */
(*fe)->size += sz;
else
{
// Else put it after it which keeps the freelist sorted.
free_entry *f = reinterpret_cast <free_entry *> (e);
new (f) free_entry;
f->size = sz;
f->next = (*fe)->next;
(*fe)->next = f;
}
}
}
bool pool::in_pool (void *ptr)
{
char *p = reinterpret_cast <char *> (ptr);
return (p > arena
&& p < arena + arena_size);
}
pool emergency_pool;
}
extern "C" void *
@ -104,30 +251,11 @@ __cxxabiv1::__cxa_allocate_exception(std::size_t thrown_size) _GLIBCXX_NOTHROW
thrown_size += sizeof (__cxa_refcounted_exception);
ret = malloc (thrown_size);
if (! ret)
{
__gnu_cxx::__scoped_lock sentry(emergency_mutex);
if (!ret)
ret = emergency_pool.allocate (thrown_size);
bitmask_type used = emergency_used;
unsigned int which = 0;
if (thrown_size > EMERGENCY_OBJ_SIZE)
goto failed;
while (used & 1)
{
used >>= 1;
if (++which >= EMERGENCY_OBJ_COUNT)
goto failed;
}
emergency_used |= (bitmask_type)1 << which;
ret = &emergency_buffer[which][0];
failed:;
if (!ret)
std::terminate ();
}
if (!ret)
std::terminate ();
memset (ret, 0, sizeof (__cxa_refcounted_exception));
@ -138,19 +266,11 @@ __cxxabiv1::__cxa_allocate_exception(std::size_t thrown_size) _GLIBCXX_NOTHROW
extern "C" void
__cxxabiv1::__cxa_free_exception(void *vptr) _GLIBCXX_NOTHROW
{
char *base = (char *) emergency_buffer;
char *ptr = (char *) vptr;
if (ptr >= base
&& ptr < base + sizeof (emergency_buffer))
{
const unsigned int which
= (unsigned) (ptr - base) / EMERGENCY_OBJ_SIZE;
__gnu_cxx::__scoped_lock sentry(emergency_mutex);
emergency_used &= ~((bitmask_type)1 << which);
}
char *ptr = (char *) vptr - sizeof (__cxa_refcounted_exception);
if (emergency_pool.in_pool (ptr))
emergency_pool.free (ptr);
else
free (ptr - sizeof (__cxa_refcounted_exception));
free (ptr);
}
@ -163,27 +283,11 @@ __cxxabiv1::__cxa_allocate_dependent_exception() _GLIBCXX_NOTHROW
(malloc (sizeof (__cxa_dependent_exception)));
if (!ret)
{
__gnu_cxx::__scoped_lock sentry(emergency_mutex);
ret = static_cast <__cxa_dependent_exception*>
(emergency_pool.allocate (sizeof (__cxa_dependent_exception)));
bitmask_type used = dependents_used;
unsigned int which = 0;
while (used & 1)
{
used >>= 1;
if (++which >= EMERGENCY_OBJ_COUNT)
goto failed;
}
dependents_used |= (bitmask_type)1 << which;
ret = &dependents_buffer[which];
failed:;
if (!ret)
std::terminate ();
}
if (!ret)
std::terminate ();
memset (ret, 0, sizeof (__cxa_dependent_exception));
@ -195,17 +299,8 @@ extern "C" void
__cxxabiv1::__cxa_free_dependent_exception
(__cxa_dependent_exception *vptr) _GLIBCXX_NOTHROW
{
char *base = (char *) dependents_buffer;
char *ptr = (char *) vptr;
if (ptr >= base
&& ptr < base + sizeof (dependents_buffer))
{
const unsigned int which
= (unsigned) (ptr - base) / sizeof (__cxa_dependent_exception);
__gnu_cxx::__scoped_lock sentry(emergency_mutex);
dependents_used &= ~((bitmask_type)1 << which);
}
if (emergency_pool.in_pool (vptr))
emergency_pool.free (vptr);
else
free (vptr);
}