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asan.c
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/* AddressSanitizer, a fast memory error detector.
Copyright (C) 2012-2013 Free Software Foundation, Inc.
Contributed by Kostya Serebryany <[email protected]>
This file is part of GCC.
GCC 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 3, or (at your option) any later
version.
GCC 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 GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "gimple.h"
#include "tree-iterator.h"
#include "tree-flow.h"
#include "tree-pass.h"
#include "asan.h"
#include "gimple-pretty-print.h"
#include "target.h"
#include "expr.h"
#include "optabs.h"
#include "output.h"
#include "tm_p.h"
#include "langhooks.h"
#include "hash-table.h"
#include "alloc-pool.h"
/* AddressSanitizer finds out-of-bounds and use-after-free bugs
with <2x slowdown on average.
The tool consists of two parts:
instrumentation module (this file) and a run-time library.
The instrumentation module adds a run-time check before every memory insn.
For a 8- or 16- byte load accessing address X:
ShadowAddr = (X >> 3) + Offset
ShadowValue = *(char*)ShadowAddr; // *(short*) for 16-byte access.
if (ShadowValue)
__asan_report_load8(X);
For a load of N bytes (N=1, 2 or 4) from address X:
ShadowAddr = (X >> 3) + Offset
ShadowValue = *(char*)ShadowAddr;
if (ShadowValue)
if ((X & 7) + N - 1 > ShadowValue)
__asan_report_loadN(X);
Stores are instrumented similarly, but using __asan_report_storeN functions.
A call too __asan_init() is inserted to the list of module CTORs.
The run-time library redefines malloc (so that redzone are inserted around
the allocated memory) and free (so that reuse of free-ed memory is delayed),
provides __asan_report* and __asan_init functions.
Read more:
http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
The current implementation supports detection of out-of-bounds and
use-after-free in the heap, on the stack and for global variables.
[Protection of stack variables]
To understand how detection of out-of-bounds and use-after-free works
for stack variables, lets look at this example on x86_64 where the
stack grows downward:
int
foo ()
{
char a[23] = {0};
int b[2] = {0};
a[5] = 1;
b[1] = 2;
return a[5] + b[1];
}
For this function, the stack protected by asan will be organized as
follows, from the top of the stack to the bottom:
Slot 1/ [red zone of 32 bytes called 'RIGHT RedZone']
Slot 2/ [8 bytes of red zone, that adds up to the space of 'a' to make
the next slot be 32 bytes aligned; this one is called Partial
Redzone; this 32 bytes alignment is an asan constraint]
Slot 3/ [24 bytes for variable 'a']
Slot 4/ [red zone of 32 bytes called 'Middle RedZone']
Slot 5/ [24 bytes of Partial Red Zone (similar to slot 2]
Slot 6/ [8 bytes for variable 'b']
Slot 7/ [32 bytes of Red Zone at the bottom of the stack, called
'LEFT RedZone']
The 32 bytes of LEFT red zone at the bottom of the stack can be
decomposed as such:
1/ The first 8 bytes contain a magical asan number that is always
0x41B58AB3.
2/ The following 8 bytes contains a pointer to a string (to be
parsed at runtime by the runtime asan library), which format is
the following:
"<function-name> <space> <num-of-variables-on-the-stack>
(<32-bytes-aligned-offset-in-bytes-of-variable> <space>
<length-of-var-in-bytes> ){n} "
where '(...){n}' means the content inside the parenthesis occurs 'n'
times, with 'n' being the number of variables on the stack.
3/ The following 16 bytes of the red zone have no particular
format.
The shadow memory for that stack layout is going to look like this:
- content of shadow memory 8 bytes for slot 7: 0xF1F1F1F1.
The F1 byte pattern is a magic number called
ASAN_STACK_MAGIC_LEFT and is a way for the runtime to know that
the memory for that shadow byte is part of a the LEFT red zone
intended to seat at the bottom of the variables on the stack.
- content of shadow memory 8 bytes for slots 6 and 5:
0xF4F4F400. The F4 byte pattern is a magic number
called ASAN_STACK_MAGIC_PARTIAL. It flags the fact that the
memory region for this shadow byte is a PARTIAL red zone
intended to pad a variable A, so that the slot following
{A,padding} is 32 bytes aligned.
Note that the fact that the least significant byte of this
shadow memory content is 00 means that 8 bytes of its
corresponding memory (which corresponds to the memory of
variable 'b') is addressable.
- content of shadow memory 8 bytes for slot 4: 0xF2F2F2F2.
The F2 byte pattern is a magic number called
ASAN_STACK_MAGIC_MIDDLE. It flags the fact that the memory
region for this shadow byte is a MIDDLE red zone intended to
seat between two 32 aligned slots of {variable,padding}.
- content of shadow memory 8 bytes for slot 3 and 2:
0xF4000000. This represents is the concatenation of
variable 'a' and the partial red zone following it, like what we
had for variable 'b'. The least significant 3 bytes being 00
means that the 3 bytes of variable 'a' are addressable.
- content of shadow memory 8 bytes for slot 1: 0xF3F3F3F3.
The F3 byte pattern is a magic number called
ASAN_STACK_MAGIC_RIGHT. It flags the fact that the memory
region for this shadow byte is a RIGHT red zone intended to seat
at the top of the variables of the stack.
Note that the real variable layout is done in expand_used_vars in
cfgexpand.c. As far as Address Sanitizer is concerned, it lays out
stack variables as well as the different red zones, emits some
prologue code to populate the shadow memory as to poison (mark as
non-accessible) the regions of the red zones and mark the regions of
stack variables as accessible, and emit some epilogue code to
un-poison (mark as accessible) the regions of red zones right before
the function exits.
[Protection of global variables]
The basic idea is to insert a red zone between two global variables
and install a constructor function that calls the asan runtime to do
the populating of the relevant shadow memory regions at load time.
So the global variables are laid out as to insert a red zone between
them. The size of the red zones is so that each variable starts on a
32 bytes boundary.
Then a constructor function is installed so that, for each global
variable, it calls the runtime asan library function
__asan_register_globals_with an instance of this type:
struct __asan_global
{
// Address of the beginning of the global variable.
const void *__beg;
// Initial size of the global variable.
uptr __size;
// Size of the global variable + size of the red zone. This
// size is 32 bytes aligned.
uptr __size_with_redzone;
// Name of the global variable.
const void *__name;
// This is always set to NULL for now.
uptr __has_dynamic_init;
}
A destructor function that calls the runtime asan library function
_asan_unregister_globals is also installed. */
alias_set_type asan_shadow_set = -1;
/* Pointer types to 1 resp. 2 byte integers in shadow memory. A separate
alias set is used for all shadow memory accesses. */
static GTY(()) tree shadow_ptr_types[2];
/* Hashtable support for memory references used by gimple
statements. */
/* This type represents a reference to a memory region. */
struct asan_mem_ref
{
/* The expression of the begining of the memory region. */
tree start;
/* The size of the access (can be 1, 2, 4, 8, 16 for now). */
char access_size;
};
static alloc_pool asan_mem_ref_alloc_pool;
/* This creates the alloc pool used to store the instances of
asan_mem_ref that are stored in the hash table asan_mem_ref_ht. */
static alloc_pool
asan_mem_ref_get_alloc_pool ()
{
if (asan_mem_ref_alloc_pool == NULL)
asan_mem_ref_alloc_pool = create_alloc_pool ("asan_mem_ref",
sizeof (asan_mem_ref),
10);
return asan_mem_ref_alloc_pool;
}
/* Initializes an instance of asan_mem_ref. */
static void
asan_mem_ref_init (asan_mem_ref *ref, tree start, char access_size)
{
ref->start = start;
ref->access_size = access_size;
}
/* Allocates memory for an instance of asan_mem_ref into the memory
pool returned by asan_mem_ref_get_alloc_pool and initialize it.
START is the address of (or the expression pointing to) the
beginning of memory reference. ACCESS_SIZE is the size of the
access to the referenced memory. */
static asan_mem_ref*
asan_mem_ref_new (tree start, char access_size)
{
asan_mem_ref *ref =
(asan_mem_ref *) pool_alloc (asan_mem_ref_get_alloc_pool ());
asan_mem_ref_init (ref, start, access_size);
return ref;
}
/* This builds and returns a pointer to the end of the memory region
that starts at START and of length LEN. */
tree
asan_mem_ref_get_end (tree start, tree len)
{
if (len == NULL_TREE || integer_zerop (len))
return start;
return fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (start), start, len);
}
/* Return a tree expression that represents the end of the referenced
memory region. Beware that this function can actually build a new
tree expression. */
tree
asan_mem_ref_get_end (const asan_mem_ref *ref, tree len)
{
return asan_mem_ref_get_end (ref->start, len);
}
struct asan_mem_ref_hasher
: typed_noop_remove <asan_mem_ref>
{
typedef asan_mem_ref value_type;
typedef asan_mem_ref compare_type;
static inline hashval_t hash (const value_type *);
static inline bool equal (const value_type *, const compare_type *);
};
/* Hash a memory reference. */
inline hashval_t
asan_mem_ref_hasher::hash (const asan_mem_ref *mem_ref)
{
hashval_t h = iterative_hash_expr (mem_ref->start, 0);
h = iterative_hash_hashval_t (h, mem_ref->access_size);
return h;
}
/* Compare two memory references. We accept the length of either
memory references to be NULL_TREE. */
inline bool
asan_mem_ref_hasher::equal (const asan_mem_ref *m1,
const asan_mem_ref *m2)
{
return (m1->access_size == m2->access_size
&& operand_equal_p (m1->start, m2->start, 0));
}
static hash_table <asan_mem_ref_hasher> asan_mem_ref_ht;
/* Returns a reference to the hash table containing memory references.
This function ensures that the hash table is created. Note that
this hash table is updated by the function
update_mem_ref_hash_table. */
static hash_table <asan_mem_ref_hasher> &
get_mem_ref_hash_table ()
{
if (!asan_mem_ref_ht.is_created ())
asan_mem_ref_ht.create (10);
return asan_mem_ref_ht;
}
/* Clear all entries from the memory references hash table. */
static void
empty_mem_ref_hash_table ()
{
if (asan_mem_ref_ht.is_created ())
asan_mem_ref_ht.empty ();
}
/* Free the memory references hash table. */
static void
free_mem_ref_resources ()
{
if (asan_mem_ref_ht.is_created ())
asan_mem_ref_ht.dispose ();
if (asan_mem_ref_alloc_pool)
{
free_alloc_pool (asan_mem_ref_alloc_pool);
asan_mem_ref_alloc_pool = NULL;
}
}
/* Return true iff the memory reference REF has been instrumented. */
static bool
has_mem_ref_been_instrumented (tree ref, char access_size)
{
asan_mem_ref r;
asan_mem_ref_init (&r, ref, access_size);
return (get_mem_ref_hash_table ().find (&r) != NULL);
}
/* Return true iff the memory reference REF has been instrumented. */
static bool
has_mem_ref_been_instrumented (const asan_mem_ref *ref)
{
return has_mem_ref_been_instrumented (ref->start, ref->access_size);
}
/* Return true iff access to memory region starting at REF and of
length LEN has been instrumented. */
static bool
has_mem_ref_been_instrumented (const asan_mem_ref *ref, tree len)
{
/* First let's see if the address of the beginning of REF has been
instrumented. */
if (!has_mem_ref_been_instrumented (ref))
return false;
if (len != 0)
{
/* Let's see if the end of the region has been instrumented. */
if (!has_mem_ref_been_instrumented (asan_mem_ref_get_end (ref, len),
ref->access_size))
return false;
}
return true;
}
/* Set REF to the memory reference present in a gimple assignment
ASSIGNMENT. Return true upon successful completion, false
otherwise. */
static bool
get_mem_ref_of_assignment (const gimple assignment,
asan_mem_ref *ref,
bool *ref_is_store)
{
gcc_assert (gimple_assign_single_p (assignment));
if (gimple_store_p (assignment))
{
ref->start = gimple_assign_lhs (assignment);
*ref_is_store = true;
}
else if (gimple_assign_load_p (assignment))
{
ref->start = gimple_assign_rhs1 (assignment);
*ref_is_store = false;
}
else
return false;
ref->access_size = int_size_in_bytes (TREE_TYPE (ref->start));
return true;
}
/* Return the memory references contained in a gimple statement
representing a builtin call that has to do with memory access. */
static bool
get_mem_refs_of_builtin_call (const gimple call,
asan_mem_ref *src0,
tree *src0_len,
bool *src0_is_store,
asan_mem_ref *src1,
tree *src1_len,
bool *src1_is_store,
asan_mem_ref *dst,
tree *dst_len,
bool *dst_is_store,
bool *dest_is_deref)
{
gcc_checking_assert (gimple_call_builtin_p (call, BUILT_IN_NORMAL));
tree callee = gimple_call_fndecl (call);
tree source0 = NULL_TREE, source1 = NULL_TREE,
dest = NULL_TREE, len = NULL_TREE;
bool is_store = true, got_reference_p = false;
char access_size = 1;
switch (DECL_FUNCTION_CODE (callee))
{
/* (s, s, n) style memops. */
case BUILT_IN_BCMP:
case BUILT_IN_MEMCMP:
source0 = gimple_call_arg (call, 0);
source1 = gimple_call_arg (call, 1);
len = gimple_call_arg (call, 2);
break;
/* (src, dest, n) style memops. */
case BUILT_IN_BCOPY:
source0 = gimple_call_arg (call, 0);
dest = gimple_call_arg (call, 1);
len = gimple_call_arg (call, 2);
break;
/* (dest, src, n) style memops. */
case BUILT_IN_MEMCPY:
case BUILT_IN_MEMCPY_CHK:
case BUILT_IN_MEMMOVE:
case BUILT_IN_MEMMOVE_CHK:
case BUILT_IN_MEMPCPY:
case BUILT_IN_MEMPCPY_CHK:
dest = gimple_call_arg (call, 0);
source0 = gimple_call_arg (call, 1);
len = gimple_call_arg (call, 2);
break;
/* (dest, n) style memops. */
case BUILT_IN_BZERO:
dest = gimple_call_arg (call, 0);
len = gimple_call_arg (call, 1);
break;
/* (dest, x, n) style memops*/
case BUILT_IN_MEMSET:
case BUILT_IN_MEMSET_CHK:
dest = gimple_call_arg (call, 0);
len = gimple_call_arg (call, 2);
break;
case BUILT_IN_STRLEN:
source0 = gimple_call_arg (call, 0);
len = gimple_call_lhs (call);
break ;
/* And now the __atomic* and __sync builtins.
These are handled differently from the classical memory memory
access builtins above. */
case BUILT_IN_ATOMIC_LOAD_1:
case BUILT_IN_ATOMIC_LOAD_2:
case BUILT_IN_ATOMIC_LOAD_4:
case BUILT_IN_ATOMIC_LOAD_8:
case BUILT_IN_ATOMIC_LOAD_16:
is_store = false;
/* fall through. */
case BUILT_IN_SYNC_FETCH_AND_ADD_1:
case BUILT_IN_SYNC_FETCH_AND_ADD_2:
case BUILT_IN_SYNC_FETCH_AND_ADD_4:
case BUILT_IN_SYNC_FETCH_AND_ADD_8:
case BUILT_IN_SYNC_FETCH_AND_ADD_16:
case BUILT_IN_SYNC_FETCH_AND_SUB_1:
case BUILT_IN_SYNC_FETCH_AND_SUB_2:
case BUILT_IN_SYNC_FETCH_AND_SUB_4:
case BUILT_IN_SYNC_FETCH_AND_SUB_8:
case BUILT_IN_SYNC_FETCH_AND_SUB_16:
case BUILT_IN_SYNC_FETCH_AND_OR_1:
case BUILT_IN_SYNC_FETCH_AND_OR_2:
case BUILT_IN_SYNC_FETCH_AND_OR_4:
case BUILT_IN_SYNC_FETCH_AND_OR_8:
case BUILT_IN_SYNC_FETCH_AND_OR_16:
case BUILT_IN_SYNC_FETCH_AND_AND_1:
case BUILT_IN_SYNC_FETCH_AND_AND_2:
case BUILT_IN_SYNC_FETCH_AND_AND_4:
case BUILT_IN_SYNC_FETCH_AND_AND_8:
case BUILT_IN_SYNC_FETCH_AND_AND_16:
case BUILT_IN_SYNC_FETCH_AND_XOR_1:
case BUILT_IN_SYNC_FETCH_AND_XOR_2:
case BUILT_IN_SYNC_FETCH_AND_XOR_4:
case BUILT_IN_SYNC_FETCH_AND_XOR_8:
case BUILT_IN_SYNC_FETCH_AND_XOR_16:
case BUILT_IN_SYNC_FETCH_AND_NAND_1:
case BUILT_IN_SYNC_FETCH_AND_NAND_2:
case BUILT_IN_SYNC_FETCH_AND_NAND_4:
case BUILT_IN_SYNC_FETCH_AND_NAND_8:
case BUILT_IN_SYNC_ADD_AND_FETCH_1:
case BUILT_IN_SYNC_ADD_AND_FETCH_2:
case BUILT_IN_SYNC_ADD_AND_FETCH_4:
case BUILT_IN_SYNC_ADD_AND_FETCH_8:
case BUILT_IN_SYNC_ADD_AND_FETCH_16:
case BUILT_IN_SYNC_SUB_AND_FETCH_1:
case BUILT_IN_SYNC_SUB_AND_FETCH_2:
case BUILT_IN_SYNC_SUB_AND_FETCH_4:
case BUILT_IN_SYNC_SUB_AND_FETCH_8:
case BUILT_IN_SYNC_SUB_AND_FETCH_16:
case BUILT_IN_SYNC_OR_AND_FETCH_1:
case BUILT_IN_SYNC_OR_AND_FETCH_2:
case BUILT_IN_SYNC_OR_AND_FETCH_4:
case BUILT_IN_SYNC_OR_AND_FETCH_8:
case BUILT_IN_SYNC_OR_AND_FETCH_16:
case BUILT_IN_SYNC_AND_AND_FETCH_1:
case BUILT_IN_SYNC_AND_AND_FETCH_2:
case BUILT_IN_SYNC_AND_AND_FETCH_4:
case BUILT_IN_SYNC_AND_AND_FETCH_8:
case BUILT_IN_SYNC_AND_AND_FETCH_16:
case BUILT_IN_SYNC_XOR_AND_FETCH_1:
case BUILT_IN_SYNC_XOR_AND_FETCH_2:
case BUILT_IN_SYNC_XOR_AND_FETCH_4:
case BUILT_IN_SYNC_XOR_AND_FETCH_8:
case BUILT_IN_SYNC_XOR_AND_FETCH_16:
case BUILT_IN_SYNC_NAND_AND_FETCH_1:
case BUILT_IN_SYNC_NAND_AND_FETCH_2:
case BUILT_IN_SYNC_NAND_AND_FETCH_4:
case BUILT_IN_SYNC_NAND_AND_FETCH_8:
case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1:
case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2:
case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4:
case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8:
case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16:
case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_1:
case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_2:
case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_4:
case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_8:
case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_16:
case BUILT_IN_SYNC_LOCK_TEST_AND_SET_1:
case BUILT_IN_SYNC_LOCK_TEST_AND_SET_2:
case BUILT_IN_SYNC_LOCK_TEST_AND_SET_4:
case BUILT_IN_SYNC_LOCK_TEST_AND_SET_8:
case BUILT_IN_SYNC_LOCK_TEST_AND_SET_16:
case BUILT_IN_SYNC_LOCK_RELEASE_1:
case BUILT_IN_SYNC_LOCK_RELEASE_2:
case BUILT_IN_SYNC_LOCK_RELEASE_4:
case BUILT_IN_SYNC_LOCK_RELEASE_8:
case BUILT_IN_SYNC_LOCK_RELEASE_16:
case BUILT_IN_ATOMIC_EXCHANGE_1:
case BUILT_IN_ATOMIC_EXCHANGE_2:
case BUILT_IN_ATOMIC_EXCHANGE_4:
case BUILT_IN_ATOMIC_EXCHANGE_8:
case BUILT_IN_ATOMIC_EXCHANGE_16:
case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1:
case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2:
case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4:
case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8:
case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16:
case BUILT_IN_ATOMIC_STORE_1:
case BUILT_IN_ATOMIC_STORE_2:
case BUILT_IN_ATOMIC_STORE_4:
case BUILT_IN_ATOMIC_STORE_8:
case BUILT_IN_ATOMIC_STORE_16:
case BUILT_IN_ATOMIC_ADD_FETCH_1:
case BUILT_IN_ATOMIC_ADD_FETCH_2:
case BUILT_IN_ATOMIC_ADD_FETCH_4:
case BUILT_IN_ATOMIC_ADD_FETCH_8:
case BUILT_IN_ATOMIC_ADD_FETCH_16:
case BUILT_IN_ATOMIC_SUB_FETCH_1:
case BUILT_IN_ATOMIC_SUB_FETCH_2:
case BUILT_IN_ATOMIC_SUB_FETCH_4:
case BUILT_IN_ATOMIC_SUB_FETCH_8:
case BUILT_IN_ATOMIC_SUB_FETCH_16:
case BUILT_IN_ATOMIC_AND_FETCH_1:
case BUILT_IN_ATOMIC_AND_FETCH_2:
case BUILT_IN_ATOMIC_AND_FETCH_4:
case BUILT_IN_ATOMIC_AND_FETCH_8:
case BUILT_IN_ATOMIC_AND_FETCH_16:
case BUILT_IN_ATOMIC_NAND_FETCH_1:
case BUILT_IN_ATOMIC_NAND_FETCH_2:
case BUILT_IN_ATOMIC_NAND_FETCH_4:
case BUILT_IN_ATOMIC_NAND_FETCH_8:
case BUILT_IN_ATOMIC_NAND_FETCH_16:
case BUILT_IN_ATOMIC_XOR_FETCH_1:
case BUILT_IN_ATOMIC_XOR_FETCH_2:
case BUILT_IN_ATOMIC_XOR_FETCH_4:
case BUILT_IN_ATOMIC_XOR_FETCH_8:
case BUILT_IN_ATOMIC_XOR_FETCH_16:
case BUILT_IN_ATOMIC_OR_FETCH_1:
case BUILT_IN_ATOMIC_OR_FETCH_2:
case BUILT_IN_ATOMIC_OR_FETCH_4:
case BUILT_IN_ATOMIC_OR_FETCH_8:
case BUILT_IN_ATOMIC_OR_FETCH_16:
case BUILT_IN_ATOMIC_FETCH_ADD_1:
case BUILT_IN_ATOMIC_FETCH_ADD_2:
case BUILT_IN_ATOMIC_FETCH_ADD_4:
case BUILT_IN_ATOMIC_FETCH_ADD_8:
case BUILT_IN_ATOMIC_FETCH_ADD_16:
case BUILT_IN_ATOMIC_FETCH_SUB_1:
case BUILT_IN_ATOMIC_FETCH_SUB_2:
case BUILT_IN_ATOMIC_FETCH_SUB_4:
case BUILT_IN_ATOMIC_FETCH_SUB_8:
case BUILT_IN_ATOMIC_FETCH_SUB_16:
case BUILT_IN_ATOMIC_FETCH_AND_1:
case BUILT_IN_ATOMIC_FETCH_AND_2:
case BUILT_IN_ATOMIC_FETCH_AND_4:
case BUILT_IN_ATOMIC_FETCH_AND_8:
case BUILT_IN_ATOMIC_FETCH_AND_16:
case BUILT_IN_ATOMIC_FETCH_NAND_1:
case BUILT_IN_ATOMIC_FETCH_NAND_2:
case BUILT_IN_ATOMIC_FETCH_NAND_4:
case BUILT_IN_ATOMIC_FETCH_NAND_8:
case BUILT_IN_ATOMIC_FETCH_NAND_16:
case BUILT_IN_ATOMIC_FETCH_XOR_1:
case BUILT_IN_ATOMIC_FETCH_XOR_2:
case BUILT_IN_ATOMIC_FETCH_XOR_4:
case BUILT_IN_ATOMIC_FETCH_XOR_8:
case BUILT_IN_ATOMIC_FETCH_XOR_16:
case BUILT_IN_ATOMIC_FETCH_OR_1:
case BUILT_IN_ATOMIC_FETCH_OR_2:
case BUILT_IN_ATOMIC_FETCH_OR_4:
case BUILT_IN_ATOMIC_FETCH_OR_8:
case BUILT_IN_ATOMIC_FETCH_OR_16:
{
dest = gimple_call_arg (call, 0);
/* DEST represents the address of a memory location.
instrument_derefs wants the memory location, so lets
dereference the address DEST before handing it to
instrument_derefs. */
if (TREE_CODE (dest) == ADDR_EXPR)
dest = TREE_OPERAND (dest, 0);
else if (TREE_CODE (dest) == SSA_NAME)
dest = build2 (MEM_REF, TREE_TYPE (TREE_TYPE (dest)),
dest, build_int_cst (TREE_TYPE (dest), 0));
else
gcc_unreachable ();
access_size = int_size_in_bytes (TREE_TYPE (dest));
}
default:
/* The other builtins memory access are not instrumented in this
function because they either don't have any length parameter,
or their length parameter is just a limit. */
break;
}
if (len != NULL_TREE)
{
if (source0 != NULL_TREE)
{
src0->start = source0;
src0->access_size = access_size;
*src0_len = len;
*src0_is_store = false;
}
if (source1 != NULL_TREE)
{
src1->start = source1;
src1->access_size = access_size;
*src1_len = len;
*src1_is_store = false;
}
if (dest != NULL_TREE)
{
dst->start = dest;
dst->access_size = access_size;
*dst_len = len;
*dst_is_store = true;
}
got_reference_p = true;
}
else if (dest)
{
dst->start = dest;
dst->access_size = access_size;
*dst_len = NULL_TREE;
*dst_is_store = is_store;
*dest_is_deref = true;
got_reference_p = true;
}
return got_reference_p;
}
/* Return true iff a given gimple statement has been instrumented.
Note that the statement is "defined" by the memory references it
contains. */
static bool
has_stmt_been_instrumented_p (gimple stmt)
{
if (gimple_assign_single_p (stmt))
{
bool r_is_store;
asan_mem_ref r;
asan_mem_ref_init (&r, NULL, 1);
if (get_mem_ref_of_assignment (stmt, &r, &r_is_store))
return has_mem_ref_been_instrumented (&r);
}
else if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
{
asan_mem_ref src0, src1, dest;
asan_mem_ref_init (&src0, NULL, 1);
asan_mem_ref_init (&src1, NULL, 1);
asan_mem_ref_init (&dest, NULL, 1);
tree src0_len = NULL_TREE, src1_len = NULL_TREE, dest_len = NULL_TREE;
bool src0_is_store = false, src1_is_store = false,
dest_is_store = false, dest_is_deref = false;
if (get_mem_refs_of_builtin_call (stmt,
&src0, &src0_len, &src0_is_store,
&src1, &src1_len, &src1_is_store,
&dest, &dest_len, &dest_is_store,
&dest_is_deref))
{
if (src0.start != NULL_TREE
&& !has_mem_ref_been_instrumented (&src0, src0_len))
return false;
if (src1.start != NULL_TREE
&& !has_mem_ref_been_instrumented (&src1, src1_len))
return false;
if (dest.start != NULL_TREE
&& !has_mem_ref_been_instrumented (&dest, dest_len))
return false;
return true;
}
}
return false;
}
/* Insert a memory reference into the hash table. */
static void
update_mem_ref_hash_table (tree ref, char access_size)
{
hash_table <asan_mem_ref_hasher> ht = get_mem_ref_hash_table ();
asan_mem_ref r;
asan_mem_ref_init (&r, ref, access_size);
asan_mem_ref **slot = ht.find_slot (&r, INSERT);
if (*slot == NULL)
*slot = asan_mem_ref_new (ref, access_size);
}
/* Initialize shadow_ptr_types array. */
static void
asan_init_shadow_ptr_types (void)
{
asan_shadow_set = new_alias_set ();
shadow_ptr_types[0] = build_distinct_type_copy (signed_char_type_node);
TYPE_ALIAS_SET (shadow_ptr_types[0]) = asan_shadow_set;
shadow_ptr_types[0] = build_pointer_type (shadow_ptr_types[0]);
shadow_ptr_types[1] = build_distinct_type_copy (short_integer_type_node);
TYPE_ALIAS_SET (shadow_ptr_types[1]) = asan_shadow_set;
shadow_ptr_types[1] = build_pointer_type (shadow_ptr_types[1]);
initialize_sanitizer_builtins ();
}
/* Asan pretty-printer, used for buidling of the description STRING_CSTs. */
static pretty_printer asan_pp;
static bool asan_pp_initialized;
/* Initialize asan_pp. */
static void
asan_pp_initialize (void)
{
pp_construct (&asan_pp, /* prefix */NULL, /* line-width */0);
asan_pp_initialized = true;
}
/* Create ADDR_EXPR of STRING_CST with asan_pp text. */
static tree
asan_pp_string (void)
{
const char *buf = pp_base_formatted_text (&asan_pp);
size_t len = strlen (buf);
tree ret = build_string (len + 1, buf);
TREE_TYPE (ret)
= build_array_type (TREE_TYPE (shadow_ptr_types[0]),
build_index_type (size_int (len)));
TREE_READONLY (ret) = 1;
TREE_STATIC (ret) = 1;
return build1 (ADDR_EXPR, shadow_ptr_types[0], ret);
}
/* Return a CONST_INT representing 4 subsequent shadow memory bytes. */
static rtx
asan_shadow_cst (unsigned char shadow_bytes[4])
{
int i;
unsigned HOST_WIDE_INT val = 0;
gcc_assert (WORDS_BIG_ENDIAN == BYTES_BIG_ENDIAN);
for (i = 0; i < 4; i++)
val |= (unsigned HOST_WIDE_INT) shadow_bytes[BYTES_BIG_ENDIAN ? 3 - i : i]
<< (BITS_PER_UNIT * i);
return GEN_INT (trunc_int_for_mode (val, SImode));
}
/* Clear shadow memory at SHADOW_MEM, LEN bytes. Can't call a library call here
though. */
static void
asan_clear_shadow (rtx shadow_mem, HOST_WIDE_INT len)
{
rtx insn, insns, top_label, end, addr, tmp, jump;
start_sequence ();
clear_storage (shadow_mem, GEN_INT (len), BLOCK_OP_NORMAL);
insns = get_insns ();
end_sequence ();
for (insn = insns; insn; insn = NEXT_INSN (insn))
if (CALL_P (insn))
break;
if (insn == NULL_RTX)
{
emit_insn (insns);
return;
}
gcc_assert ((len & 3) == 0);
top_label = gen_label_rtx ();
addr = force_reg (Pmode, XEXP (shadow_mem, 0));
shadow_mem = adjust_automodify_address (shadow_mem, SImode, addr, 0);
end = force_reg (Pmode, plus_constant (Pmode, addr, len));
emit_label (top_label);
emit_move_insn (shadow_mem, const0_rtx);
tmp = expand_simple_binop (Pmode, PLUS, addr, GEN_INT (4), addr,
true, OPTAB_LIB_WIDEN);
if (tmp != addr)
emit_move_insn (addr, tmp);
emit_cmp_and_jump_insns (addr, end, LT, NULL_RTX, Pmode, true, top_label);
jump = get_last_insn ();
gcc_assert (JUMP_P (jump));
add_reg_note (jump, REG_BR_PROB, GEN_INT (REG_BR_PROB_BASE * 80 / 100));
}
/* Insert code to protect stack vars. The prologue sequence should be emitted
directly, epilogue sequence returned. BASE is the register holding the
stack base, against which OFFSETS array offsets are relative to, OFFSETS
array contains pairs of offsets in reverse order, always the end offset
of some gap that needs protection followed by starting offset,
and DECLS is an array of representative decls for each var partition.
LENGTH is the length of the OFFSETS array, DECLS array is LENGTH / 2 - 1
elements long (OFFSETS include gap before the first variable as well
as gaps after each stack variable). */
rtx
asan_emit_stack_protection (rtx base, HOST_WIDE_INT *offsets, tree *decls,
int length)
{
rtx shadow_base, shadow_mem, ret, mem;
unsigned char shadow_bytes[4];
HOST_WIDE_INT base_offset = offsets[length - 1], offset, prev_offset;
HOST_WIDE_INT last_offset, last_size;
int l;
unsigned char cur_shadow_byte = ASAN_STACK_MAGIC_LEFT;
tree str_cst;
if (shadow_ptr_types[0] == NULL_TREE)
asan_init_shadow_ptr_types ();
/* First of all, prepare the description string. */
if (!asan_pp_initialized)
asan_pp_initialize ();
pp_clear_output_area (&asan_pp);
if (DECL_NAME (current_function_decl))
pp_base_tree_identifier (&asan_pp, DECL_NAME (current_function_decl));
else
pp_string (&asan_pp, "<unknown>");
pp_space (&asan_pp);
pp_decimal_int (&asan_pp, length / 2 - 1);
pp_space (&asan_pp);
for (l = length - 2; l; l -= 2)
{
tree decl = decls[l / 2 - 1];
pp_wide_integer (&asan_pp, offsets[l] - base_offset);
pp_space (&asan_pp);
pp_wide_integer (&asan_pp, offsets[l - 1] - offsets[l]);
pp_space (&asan_pp);
if (DECL_P (decl) && DECL_NAME (decl))
{
pp_decimal_int (&asan_pp, IDENTIFIER_LENGTH (DECL_NAME (decl)));
pp_space (&asan_pp);
pp_base_tree_identifier (&asan_pp, DECL_NAME (decl));
}
else
pp_string (&asan_pp, "9 <unknown>");
pp_space (&asan_pp);
}
str_cst = asan_pp_string ();
/* Emit the prologue sequence. */
base = expand_binop (Pmode, add_optab, base, GEN_INT (base_offset),
NULL_RTX, 1, OPTAB_DIRECT);
mem = gen_rtx_MEM (ptr_mode, base);
emit_move_insn (mem, GEN_INT (ASAN_STACK_FRAME_MAGIC));
mem = adjust_address (mem, VOIDmode, GET_MODE_SIZE (ptr_mode));
emit_move_insn (mem, expand_normal (str_cst));
shadow_base = expand_binop (Pmode, lshr_optab, base,
GEN_INT (ASAN_SHADOW_SHIFT),
NULL_RTX, 1, OPTAB_DIRECT);
shadow_base = expand_binop (Pmode, add_optab, shadow_base,
GEN_INT (targetm.asan_shadow_offset ()),
NULL_RTX, 1, OPTAB_DIRECT);
gcc_assert (asan_shadow_set != -1
&& (ASAN_RED_ZONE_SIZE >> ASAN_SHADOW_SHIFT) == 4);
shadow_mem = gen_rtx_MEM (SImode, shadow_base);
set_mem_alias_set (shadow_mem, asan_shadow_set);
prev_offset = base_offset;
for (l = length; l; l -= 2)
{