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elf: Avoid using memalign for TLS allocations [BZ #17730]

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Instead of a flag which indicates the pointer can be freed, dtv_t
now includes the pointer which should be freed.  Due to padding,
the size of dtv_t does not increase.

To avoid using memalign, the new allocate_dtv_entry function
allocates a sufficiently large buffer so that a sub-buffer
can be found in it which starts with an aligned pointer.  Both
the aligned and original pointers are kept, the latter for calling
free later.
This commit is contained in:
Florian Weimer
2016-08-03 16:15:38 +02:00
parent 5bc17330eb
commit a2ff21f825
5 changed files with 77 additions and 38 deletions
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4
nptl/allocatestack.c
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@ -245,9 +245,7 @@ get_cached_stack (size_t *sizep, void **memp)
/* Clear the DTV. */
dtv_t *dtv = GET_DTV (TLS_TPADJ (result));
for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt)
if (! dtv[1 + cnt].pointer.is_static
&& dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED)
free (dtv[1 + cnt].pointer.val);
free (dtv[1 + cnt].pointer.to_free);
memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t));
/* Re-initialize the TLS. */