On Fri, Dec 06, 2013 at 01:34:43PM +0100, Jakub Jelinek wrote:
> On Fri, Dec 06, 2013 at 01:32:42PM +0100, Ondřej Bílka wrote:
> > On second though besides of decreasing of code size there is no reason
> > to complicate compilation for these features. A more flexible way is add
> > environment variable that will disable these at runtime.
>
> That is not possible, the instrumentation is inserted inline by the
> compiler.
>
> Jakub
Currently this code with sanitize=address gets expanded
int foo(char *x, char *y, int i)
{
x[i] = y[i];
}
to
snip
movq %rsi, %rax
movq %rsi, %rdx
shrq $3, %rax
andl $7, %edx
movzbl 2147450880(%rax), %eax
cmpb %dl, %al
jle .L18
.L2:
snip
.L18:
.cfi_restore_state
testb %al, %al
je .L2
movq %rsi, %rdi
call __asan_report_load1
There is nothing imposible about disabling these checks. You just fill a
page to make this check pass and use mmap to make entire shadow memory point
to that page.
