MIPS: Only use .set mips* assembler directives when necessary

There are a few .set mips* assembler directives used in the MIPS specific
sysdep code that force an instruction to be assembled for a specific ISA.
The reason for these is to allow an instruction to be encoded when it might
not be supported in the current ISA (when the code is run the Linux kernel
will trap and emulate any unsupported instructions).  Unfortunately forcing
a specific ISA means that when assembling for a newer ISA, where the
instruction has a different encoding, the wrong encoding will be used.

        * sysdeps/mips/bits/atomic.h [_MIPS_SIM == _ABIO32] (MIPS_PUSH_MIPS2):
        Only use .set mips2 if the current ISA is below mips2.
        * sysdeps/mips/sys/tas.h [_MIPS_SIM == _ABIO32] (_test_and_set):
        Likewise.
        * sysdeps/mips/nptl/tls.h (READ_THREAD_POINTER): Only use .set
        mips32r2 if the current ISA is below mips32r2.
        * sysdeps/mips/tls-macros.h (TLS_RDHWR): New define.
        (TLS_IE): Updated to use the TLD_RDHWR macro.
        (TLS_LE): Likewise.
        * sysdeps/unix/mips/sysdep.h (__mips_isa_rev): Moved out of #ifdef
        __ASSEMBLER__ condition.

1 files changed, 23 insertions, 13 deletions

diff --git a/sysdeps/mips/nptl/tls.h b/sysdeps/mips/nptl/tls.h
index ef1145779d..e69c3970df 100644
--- a/sysdeps/mips/nptl/tls.h
+++ b/sysdeps/mips/nptl/tls.h
@@ -25,6 +25,8 @@
 # include <stdbool.h>
 # include <stddef.h>
 # include <stdint.h>
+/* Get system call information.  */
+# include <sysdep.h>
 
 /* Type for the dtv.  */
 typedef union dtv
@@ -42,29 +44,37 @@ typedef union dtv
 # define READ_THREAD_POINTER() (__builtin_thread_pointer ())
 #else
 /* Note: rd must be $v1 to be ABI-conformant.  */
-# define READ_THREAD_POINTER() \
-    ({ void *__result;							      \
-       asm volatile (".set\tpush\n\t.set\tmips32r2\n\t"			      \
-		     "rdhwr\t%0, $29\n\t.set\tpop" : "=v" (__result));	      \
-       __result; })
+# if __mips_isa_rev >= 2
+#  define READ_THREAD_POINTER() \
+     ({ void *__result;							      \
+        asm volatile ("rdhwr\t%0, $29" : "=v" (__result));	      	      \
+        __result; })
+# else
+#  define READ_THREAD_POINTER() \
+     ({ void *__result;							      \
+        asm volatile (".set\tpush\n\t.set\tmips32r2\n\t"			      \
+		      "rdhwr\t%0, $29\n\t.set\tpop" : "=v" (__result));	      \
+        __result; })
+# endif
 #endif
 
 #else /* __ASSEMBLER__ */
 # include <tcb-offsets.h>
 
-# define READ_THREAD_POINTER(rd) \
-	.set	push;							      \
-	.set	mips32r2;						      \
-	rdhwr	rd, $29;						      \
-	.set	pop
+# if __mips_isa_rev >= 2
+#  define READ_THREAD_POINTER(rd) rdhwr	rd, $29
+# else
+#  define READ_THREAD_POINTER(rd) \
+	 .set	push;							      \
+	 .set	mips32r2;						      \
+	 rdhwr	rd, $29;						      \
+	 .set	pop
+# endif
 #endif /* __ASSEMBLER__ */
 
 
 #ifndef __ASSEMBLER__
 
-/* Get system call information.  */
-# include <sysdep.h>
-
 /* The TP points to the start of the thread blocks.  */
 # define TLS_DTV_AT_TP	1
 # define TLS_TCB_AT_TP	0