[PATCH v2 15/21] nptl: tile: Fix Race conditions in pthread cancellation (BZ#12683)

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

This patch adds the tile modifications required for the BZ#12683.
It basically adds the required ucontext_get_pc function

The default syscall_cancel.c should be as expected for TILE. With
GCC 6.1 syscall_cancel.c generates the following code:

* TILEGX

0000000000000000 <__GI___syscall_cancel_arch>:
   0:   c7bf46ce576bfd9d        { move r29, sp ; addi r28, sp, -24 ; st sp, lr }
   8:   283bf825401e0db6        { addi sp, sp, -32 ; move r10, r1 }
  10:   eeedf85b85c18d9b        { addi r27, sp, 24 ; move lr, r2 ; st r28, r29 }
  18:   eef5f88155bbf0c1        { move r1, r3 ; move r2, r4 ; st r27, r30 }
  20:   283bf8c25107f143        { move r3, r5 ; move r4, r6 }
  28:   283bf8e2d1483000        { move r5, r7 }

0000000000000030 <__syscall_cancel_arch_start>:
  30:   9c5e4000340c3000        { ld4s r11, r0 }
  38:   18182165d1483000        { andi r11, r11, 4 }
  40:   17c00163d1483000        { bnez r11, 78 <__syscall_cancel_arch_end+0x20> }
  48:   283bfee051483000        { move r0, lr }
  50:   286b180051485000        { swint1 }

0000000000000058 <__syscall_cancel_arch_end>:
  58:   180906ced1401ff7        { subx lr, zero, r1 ; addi r29, sp, 32 }
  60:   87b8c6ce4dd77040        { cmovnez r0, r1, lr ; addi r28, sp, 24 ; ld lr, r29 }
  68:   9ef6400035cc3000        { ld r30, r28 }
  70:   286a6ee040120db6        { addi sp, sp, 32 ; jrp lr }
  78:   2000000051483000        { jal 78 <__syscall_cancel_arch_end+0x20> }

* TILEGX32

00000000 <__GI___syscall_cancel_arch>:
   0:   cbbfc6ce576bfd9d        { move r29, sp ; addxi r28, sp, -8 ; st sp, lr }
   8:   283bf825402f0db6        { addxi sp, sp, -16 ; move r10, r1 }
  10:   eeedf860d5cbf0b7        { move lr, r2 ; move r1, r3 ; st r28, r29 }
  18:   283bf8a1d107f102        { move r2, r4 ; move r3, r5 }
  20:   283bf8e2d107f184        { move r4, r6 ; move r5, r7 }

00000028 <__syscall_cancel_arch_start>:
  28:   9c5e4000340c3000        { ld4s r11, r0 }
  30:   18182165d1483000        { andi r11, r11, 4 }
  38:   17c0016351483000        { bnez r11, 68 <__syscall_cancel_arch_end+0x18> }
  40:   283bfee051483000        { move r0, lr }
  48:   286b180051485000        { swint1 }

00000050 <__syscall_cancel_arch_end>:
  50:   28660fe540210d9d        { addxi r29, sp, 16 ; subx r10, zero, r1 }
  58:   9fbe40004dd4a040        { cmovnez r0, r1, r10 ; ld lr, r29 }
  60:   286a6ee040210db6        { addxi sp, sp, 16 ; jrp lr }
  68:   2000000051483000        { jal 68 <__syscall_cancel_arch_end+0x18> }

Checked with build and make check run-built-tests=no for tilegx{32}-linux-gnu.

	[BZ #12683]
	* sysdeps/unix/sysv/linux/tile/sigcontextinfo.h (ucontext_get_pc):
	New function.
---
 ChangeLog                                     |  4 ++++
 sysdeps/unix/sysv/linux/tile/sigcontextinfo.h | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/sysdeps/unix/sysv/linux/tile/sigcontextinfo.h b/sysdeps/unix/sysv/linux/tile/sigcontextinfo.h
index 82bc0c7..c6edd2a 100644
--- a/sysdeps/unix/sysv/linux/tile/sigcontextinfo.h
+++ b/sysdeps/unix/sysv/linux/tile/sigcontextinfo.h
@@ -16,6 +16,10 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _SIGCONTEXTINFO_H
+#define _SIGCONTEXTINFO_H
+
+#include <stdint.h>
 #include <arch/abi.h>
 
 #define SIGCONTEXT siginfo_t *_si, ucontext_t *
@@ -25,3 +29,11 @@
 #define GET_STACK(ctx)	((void *) (long) ctx->uc_mcontext.sp)
 #define CALL_SIGHANDLER(handler, signo, ctx) \
   (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
+
+static inline uintptr_t
+ucontext_get_pc (const ucontext_t *uc)
+{
+  return uc->uc_mcontext.pc;
+}
+
+#endif /* _SIGCONTEXTINFO_H  */
-- 
2.7.4