Can the report builtins be marked with certain attribute such as
'no-return' etc?
David
On Wed, Dec 5, 2012 at 3:48 AM, Konstantin Serebryany
<konstantin.s.serebry...@gmail.com> wrote:
> On Wed, Dec 5, 2012 at 3:39 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>> Hi!
>>
>> Another problem from the compiler side when working on the asan testsuite
>> is that at higher -O* levels the __asan_report_* noreturn calls are
>> cross-jumped, but the library relies on their locus to print accurrate
>> locations when symbolized. Without it, asan might report an error
>> completely elsewhere in a function.
>
> In LLVM we solve this problem by inserting an empty volatile asm blob
> after the __asan_report_* calls.
> Hacky, but works remarkably well.
>
> --kcc
>
>>
>> This patch disables cross-jumping of such builtins.
>> Alternatively, I could introduce some attribute (no_cross_jump?),
>> ECF_NO_CROSS_JUMP, add those attributes to those builtins (and let users
>> add those too to functions they wish), and look at ECF_NO_CROSS_JUMP instead
>> during cross-jumping.
>>
>> 2012-12-05 Jakub Jelinek <ja...@redhat.com>
>>
>> * sanitizer.def: Add comment about importance of ordering of
>> BUILT_IN_ASAN_REPORT* builtins.
>> * cfgcleanup.c (old_insns_match_p): Don't cross-jump __asan_report_*
>> builtins.
>>
>> --- gcc/sanitizer.def.jj 2012-12-04 14:19:36.000000000 +0100
>> +++ gcc/sanitizer.def 2012-12-05 09:38:01.205958515 +0100
>> @@ -29,6 +29,8 @@ along with GCC; see the file COPYING3.
>> /* Address Sanitizer */
>> DEF_SANITIZER_BUILTIN(BUILT_IN_ASAN_INIT, "__asan_init",
>> BT_FN_VOID, ATTR_NOTHROW_LEAF_LIST)
>> +/* Do not reorder the BUILT_IN_ASAN_REPORT* builtins, e.g. cfgcleanup.c
>> + relies on this order. */
>> DEF_SANITIZER_BUILTIN(BUILT_IN_ASAN_REPORT_LOAD1, "__asan_report_load1",
>> BT_FN_VOID_PTR, ATTR_NORETURN_NOTHROW_LEAF_LIST)
>> DEF_SANITIZER_BUILTIN(BUILT_IN_ASAN_REPORT_LOAD2, "__asan_report_load2",
>> --- gcc/cfgcleanup.c.jj 2012-11-20 09:37:47.000000000 +0100
>> +++ gcc/cfgcleanup.c 2012-12-05 09:37:23.389181984 +0100
>> @@ -1138,6 +1138,28 @@ old_insns_match_p (int mode ATTRIBUTE_UN
>> CALL_INSN_FUNCTION_USAGE (i2))
>> || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2))
>> return dir_none;
>> +
>> + /* For address sanitizer, never crossjump __asan_report_* builtins,
>> + otherwise errors might be reported on incorrect lines. */
>> + if (flag_asan)
>> + {
>> + rtx call = get_call_rtx_from (i1);
>> + if (call && GET_CODE (XEXP (XEXP (call, 0), 0)) == SYMBOL_REF)
>> + {
>> + rtx symbol = XEXP (XEXP (call, 0), 0);
>> + if (SYMBOL_REF_DECL (symbol)
>> + && TREE_CODE (SYMBOL_REF_DECL (symbol)) == FUNCTION_DECL)
>> + {
>> + if ((DECL_BUILT_IN_CLASS (SYMBOL_REF_DECL (symbol))
>> + == BUILT_IN_NORMAL)
>> + && DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
>> + >= BUILT_IN_ASAN_REPORT_LOAD1
>> + && DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
>> + <= BUILT_IN_ASAN_REPORT_STORE16)
>> + return dir_none;
>> + }
>> + }
>> + }
>> }
>>
>> #ifdef STACK_REGS
>>
>> Jakub
