Re: libpthread breaking various pkg builds

[christos%zoulas.com@localhost (Christos Zoulas)]

On Dec 26, 11:59pm, aniou%smutek.pl@localhost (Piotr Meyer) wrote:
-- Subject: Re: libpthread breaking various pkg builds

| On Sun, Dec 26, 2010 at 11:53:24AM -0500, Christos Zoulas wrote:
|  
| > I know. Any help debugging it is appreciated, but I think that
| > in the end TLS will come to the rescue.
| 
| I think, in this case we hit protected pages due to change from
| rev. 1.119 of src/lib/libpthread/pthread.c (mprotect base only
| if we move it). Program faults in pthread__stackid_setup on write:
| 
| t->pt_stack.ss_size = size - 2 * pagesize;
| 
| Data from two faults (: marks my own debug from pthread__initmain
| and pthread__stackid_setup):
| 
| stack 0xbfc00000 d=0x5ff000 0xbf601000
| applying to 0xbbbf8000
| : pthread__sp: bf5ff494
| :: redaddr: 0xbf401000 base: 0xbf400000
| [segfault]
| 
| stack 0xbfc00000 d=0xdfe000 0xbee02000
| applying to 0xbbbf8000 orig_addr=0x0 f=1002
| result 0xb78b1000
| applying to 0xbbbf
| : pthread__sp: bedffc80
| :: redaddr: 0xbec01000 base: 0xbec00000 
| [segfault]
| 
| 
| ...but with unconditionally mprotect we hit already mentioned
| problem, when pthread_self() returns different bases for same
| thread when stack pointer crosses boundaries, for example:
| 
| * sp: 0xbf800060 va: 0xbf800000 
| * sp: 0xbf8001b0 va: 0xbf800000
| * sp: 0xbf7ff3b0 va: 0xbf600000
| * sp: 0xbf7ff394 va: 0xbf600000
| [hang]

Right, so what to do here? How do we detect if we need the mprotect call?

christos