ARM: Fix handling of concurrent TLS descriptor resolution

The current code for handling concurrent resolution says that the
ABI for _dl_tlsdesc_resolve_hold is the same as that of
_dl_tlsdesc_lazy_resolver. However _dl_tlsdesc_resolve_hold is
called from the trampoline directly rather than the lazy resolver
stub so, for example, r2 has not been pushed so does not needed
to be restored.

This fixes an intermittent failure in nptl/tst-tls3 when building
glibc for arm-linux-gnueabihf with -mtls-dialect=gnu2.

ChangeLog:

2014-05-27  Will Newton  <will.newton@linaro.org>

	[BZ #16990]
	* sysdeps/arm/dl-tlsdesc.S (_dl_tlsdesc_resolve_hold): Save
	and restore r2 rather than just restoring.

diff --git a/ChangeLog b/ChangeLog
index 1c2aff1..0396d3b 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2014-05-27  Will Newton  <will.newton@linaro.org>
+
+       [BZ #16990]
+       * sysdeps/arm/dl-tlsdesc.S (_dl_tlsdesc_resolve_hold): Save
+       and restore r2 rather than just restoring.
+
 2014-05-27  Siddhesh Poyarekar  <siddhesh@redhat.com>
 
        [BZ #16724]

diff --git a/NEWS b/NEWS
index 331601c..6a0c222 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -18,7 +18,7 @@ Version 2.20
   16759, 16760, 16770, 16786, 16789, 16791, 16796, 16799, 16800, 16815,
   16823, 16824, 16831, 16838, 16849, 16854, 16876, 16877, 16878, 16885,
   16888, 16890, 16912, 16915, 16916, 16917, 16922, 16927, 16928, 16932,
-  16943, 16958, 16966, 16967, 16965, 16977, 16978, 16984.
+  16943, 16958, 16966, 16967, 16965, 16977, 16978, 16984, 16990.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.

diff --git a/sysdeps/arm/dl-tlsdesc.S b/sysdeps/arm/dl-tlsdesc.S
index 1644a32..e87e7fb 100644 (file)
--- a/sysdeps/arm/dl-tlsdesc.S
+++ b/sysdeps/arm/dl-tlsdesc.S
@@ -186,7 +186,9 @@ _dl_tlsdesc_lazy_resolver:
        .size   _dl_tlsdesc_lazy_resolver, .-_dl_tlsdesc_lazy_resolver
 
 /* Holder for lazy tls descriptors being resolve in another thread.
-   Same ABI as the lazy resolver itself.  */
+
+   Our calling convention is to clobber r0, r1 and the processor
+   flags.  All others that are modified must be saved */
        .hidden _dl_tlsdesc_resolve_hold
        .global _dl_tlsdesc_resolve_hold
        .type   _dl_tlsdesc_resolve_hold,#function
@@ -194,29 +196,20 @@ _dl_tlsdesc_lazy_resolver:
        eabi_fnstart
        .align 2
 _dl_tlsdesc_resolve_hold:
-       /* Tell the unwinder that r2 has already been pushed.  */
-       eabi_save ({r2})
-       cfi_adjust_cfa_offset (4)
+       eabi_save ({r2,r3,ip,lr})
+       push    {r2, r3, ip, lr}
+       cfi_adjust_cfa_offset (16)
        cfi_rel_offset (r2, 0)
-       eabi_save ({r0,r1,r3,ip,lr})
-       push    {r0, r1, r3, ip, lr}
-       cfi_adjust_cfa_offset (20)
-       cfi_rel_offset (r0, 0)
-       cfi_rel_offset (r1, 4)
-       cfi_rel_offset (r3, 8)
-       cfi_rel_offset (ip, 12)
-       cfi_rel_offset (lr, 16)
-       adr     r2, _dl_tlsdesc_resolve_hold
+       cfi_rel_offset (r3, 4)
+       cfi_rel_offset (ip, 8)
+       cfi_rel_offset (lr, 12)
+       adr     r1, _dl_tlsdesc_resolve_hold
        bl      _dl_tlsdesc_resolve_hold_fixup
-       pop     {r0, r1, r3, ip, lr}
-       cfi_adjust_cfa_offset (-20)
+       pop     {r2, r3, ip, lr}
+       cfi_adjust_cfa_offset (-16)
        cfi_restore (lr)
        cfi_restore (ip)
        cfi_restore (r3)
-       cfi_restore (r1)
-       cfi_restore (r0)
-       pop     {r2}
-       cfi_adjust_cfa_offset (-4)
        cfi_restore (r2)
        sfi_breg r0, \
        ldr     r1, [\B, #4]