On Fri, Feb 22, 2013 at 8:32 PM, Jakub Jelinek <ja...@redhat.com> wrote: > On Fri, Feb 15, 2013 at 12:47:30PM +0400, Konstantin Serebryany wrote: >> Sure. ASAN_FIXED_MAPPING should be used for performance measurements >> only -- this is not a release option. >> (Added a more precise comment). > > BTW, today I think I've discovered what looks like a prelink bug, > but perhaps we need to bump kMidMemEnd a little bit. > With prelink -R, the libraries are randomized in the selected range of > addresses, > by picking a random number in between the boundaries of the address range and > first > assigning addresses to libraries above that random offset and when there is > no longer any room > above it, starting from the beginning of the range. Unfortunately the code > seems to have > some issues if the random address is chosen close to the end of the range, > then in some > cases some libraries could start before the range, but end after the range. > > On one of my boxes there is (only 4 libraries out of 822 have this problem, > only discovered it because gdb is linked against one of them and I've tried to > LD_PRELOAD=libasan.so.0 to gdb so that the debugged program would inherit > that): > > prelink -pv 2>&1 | grep 0x0000003.*-.*0x0000004 > /usr/lib64/libgmlib.so.1.0.7 [0x1ea5b3cf] > 0x0000003fffe00000-0x0000004000008460: > /usr/lib64/libiec61883.so.0.1.1 [0x56363ffc] > 0x0000003fffe00000-0x000000400000c3e0: > /usr/lib64/libncurses.so.5.9 [0x120e1b8a] > 0x0000003fffe00000-0x0000004000023860: > /usr/lib64/libsoup-2.4.so.1.5.0 [0x99ff4d51] > 0x0000003fffe00000-0x000000400006a258: > > while on others none. > > So, can kMidMemEnd be slightly incremented above this? Either > 0x4fffffffffULL, > or 0x40ffffffffULL (or replace that 0f with 1f, 2f, etc.). > Small model shared libraries can be only up to 2GB in size, so even > 0x40ffffffffULL should be big enough for most cases, but 0x4fffffffffULL > could be even safer. I've justed tested and 0x4fffffffffULL results in > || `[0x10007fff8000, 0x7fffffffffff]` || HighMem || > || `[0x02008fff7000, 0x10007fff7fff]` || HighShadow || > || `[0x005000000000, 0x02008fff6fff]` || ShadowGap3 || > || `[0x003000000000, 0x004fffffffff]` || MidMem || > || `[0x000a7fff8000, 0x002fffffffff]` || ShadowGap2 || > || `[0x00067fff8000, 0x000a7fff7fff]` || MidShadow || > || `[0x00008fff7000, 0x00067fff7fff]` || ShadowGap || > || `[0x00007fff8000, 0x00008fff6fff]` || LowShadow || > || `[0x000000000000, 0x00007fff7fff]` || LowMem || > MemToShadow(shadow): 0x00008fff7000 0x000091ff6dff 0x004091ff6e00 > 0x02008fff6fff 0x00014fff7000 0x0001cfff6fff > and seems to work just fine.
I am sorry, I missed this message. Indeed, the change looks safe, http://llvm.org/viewvc/llvm-project?rev=176250&view=rev Thanks! --kcc > > Jakub
