On Thu, 15 Mar 2007 09:57:28 -0600 "David Mosberger-Tang" <[EMAIL PROTECTED]> wrote:
> But aren't you going to be limited to less than a page worth of > register-backing store even with your patch applied because the > backing store will end up overflowing the memory stack? > I think pthread's stack, which is created by malloc, is also shared among register-stack and memory-stack. (glibc's pthread's stack is limited by ulimit, too.) So, it seems stack_size_limit = register_stack_limit + memory_stack_limit is a consistent way. I'm sorry if I don't catch your point. --Kame > --david > > On 3/15/07, KAMEZAWA Hiroyuki <[EMAIL PROTECTED]> wrote: > > This patch fixes ia64's bug in ulimit -s handling. against 2.6.21-rc3. > > > > At first,the address of register stack is defined by this > > == ia64_set_rbs_bot() > > unsigned long stack_size = current->signal->rlim[RLIMIT_STACK].rlim_max & > > -16; > > > > if (stack_size > MAX_USER_STACK_SIZE) > > stack_size = MAX_USER_STACK_SIZE; > > current->thread.rbs_bot = STACK_TOP - stack_size; > > } > > == > > default rlim[RLIMIT_STACK].rlim_max is very big. > > > > If ulimit -s is used, rlim_max can be small. As a result, rbs_bot can be > > very high address. Because of stack-address-randomize, there is a case that > > "regiter stack" is placed in the higher address than "memory stack". > > == example... > > [EMAIL PROTECTED] linux-2.6.21-rc2]$ ulimit -s > > 8192 > > [EMAIL PROTECTED] linux-2.6.21-rc2]$ cat /proc/self/maps > > 00000000-00004000 r--p 00000000 00:00 0 > > 2000000000000000-2000000000038000 r-xp 00000000 08:02 5991525 > > /lib/ld-2.5.so > > 2000000000044000-2000000000050000 rw-p 00034000 08:02 5991525 > > /lib/ld-2.5.so > > 2000000000064000-20000000002c8000 r-xp 00000000 08:02 5990699 > > /lib/libc-2.5.so > > 20000000002c8000-20000000002d4000 ---p 00264000 08:02 5990699 > > /lib/libc-2.5.so > > 20000000002d4000-20000000002e0000 rw-p 00260000 08:02 5990699 > > /lib/libc-2.5.so > > 20000000002e0000-20000000002ec000 rw-p 20000000002e0000 00:00 0 > > 20000000002ec000-2000000003a24000 r--p 00000000 08:02 9472842 > > /usr/lib/locale/locale-archive > > 4000000000000000-4000000000008000 r-xp 00000000 08:02 4157490 > > /bin/cat > > 6000000000004000-600000000000c000 rw-p 00004000 08:02 4157490 > > /bin/cat > > 600000000000c000-6000000000030000 rw-p 600000000000c000 00:00 0 > > [heap] > > 60000fffff5f4000-60000fffff648000 rw-p 60000fffff5f4000 00:00 0 > > [stack] > > 60000fffff7fc000-60000fffff800000 rw-p 60000fffff7fc000 00:00 0 (*) > > a000000000000000-a000000000020000 ---p 00000000 00:00 0 > > [vdso] > > (*) is register stack. > > == > > This register-stack/memory-stack upside down is not expected. > > Current ia64 page fault handler doesn't handle this case. In this case, > > register stack expansion causes SEGV. > > This means that the user program can use only 1 page for its register stack. > > > > This patch fixes the above case by moving register stack to suitable place. > > Note) fixing page fault handler seems to be another way...but a bit > > complicated. > > > > Signed-off-by: KAMEZAWA Hiroyuki <[EMAIL PROTECTED]> > > --- > > Index: linux-2.6.21-rc3/arch/ia64/mm/init.c > > =================================================================== > > --- linux-2.6.21-rc3.orig/arch/ia64/mm/init.c > > +++ linux-2.6.21-rc3/arch/ia64/mm/init.c > > @@ -155,7 +155,7 @@ ia64_set_rbs_bot (void) > > > > if (stack_size > MAX_USER_STACK_SIZE) > > stack_size = MAX_USER_STACK_SIZE; > > - current->thread.rbs_bot = STACK_TOP - stack_size; > > + current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - > > stack_size); > > } > > > > /* > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > > the body of a message to [EMAIL PROTECTED] > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > -- > Mosberger Consulting LLC, http://www.mosberger-consulting.com/ > - > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
