commit c2894790640da2c0761924ff1b06efddbdfa031e
Author: Segher Boessenkool <segher@kernel.crashing.org>
Date:   Fri Aug 30 16:15:39 2019 +0200

    backport: re PR target/91481 (POWER9 "DARN" RNG intrinsic produces repeated output (CVE-2019-15847))
    
            Backport from trunk
            2019-08-22  Segher Boessenkool  <segher@kernel.crashing.org>
    
            PR target/91481
            * config/rs6000/rs6000.md (unspec): Delete UNSPEC_DARN, UNSPEC_DARN_32,
            and UNSPEC_DARN_RAW.
            (unspecv): New enumerator values UNSPECV_DARN, UNSPECV_DARN_32, and
            UNSPECV_DARN_RAW.
            (darn_32): Use an unspec_volatile, and UNSPECV_DARN_32.
            (darn_raw): Use an unspec_volatile, and UNSPECV_DARN_RAW.
            (darn): Use an unspec_volatile, and UNSPECV_DARN.
    
    From-SVN: r275181

--- gcc/config/rs6000/rs6000.md
+++ gcc/config/rs6000/rs6000.md
@@ -136,9 +136,6 @@
    UNSPEC_LSQ
    UNSPEC_FUSION_GPR
    UNSPEC_STACK_CHECK
-   UNSPEC_DARN
-   UNSPEC_DARN_32
-   UNSPEC_DARN_RAW
    UNSPEC_CMPRB
    UNSPEC_CMPRB2
    UNSPEC_CMPEQB
@@ -168,6 +165,9 @@
    UNSPECV_EH_RR		; eh_reg_restore
    UNSPECV_ISYNC		; isync instruction
    UNSPECV_MFTB			; move from time base
+   UNSPECV_DARN			; darn 1 (deliver a random number)
+   UNSPECV_DARN_32		; darn 2
+   UNSPECV_DARN_RAW		; darn 0
    UNSPECV_NLGR			; non-local goto receiver
    UNSPECV_MFFS			; Move from FPSCR
    UNSPECV_MTFSF		; Move to FPSCR Fields
@@ -14611,21 +14611,21 @@
 
 (define_insn "darn_32"
   [(set (match_operand:SI 0 "register_operand" "=r")
-        (unspec:SI [(const_int 0)] UNSPEC_DARN_32))]
+        (unspec_volatile:SI [(const_int 0)] UNSPECV_DARN_32))]
   "TARGET_P9_MISC"
   "darn %0,0"
   [(set_attr "type" "integer")])
 
 (define_insn "darn_raw"
   [(set (match_operand:DI 0 "register_operand" "=r")
-        (unspec:DI [(const_int 0)] UNSPEC_DARN_RAW))]
+        (unspec_volatile:DI [(const_int 0)] UNSPECV_DARN_RAW))]
   "TARGET_P9_MISC && TARGET_64BIT"
   "darn %0,2"
   [(set_attr "type" "integer")])
 
 (define_insn "darn"
   [(set (match_operand:DI 0 "register_operand" "=r")
-        (unspec:DI [(const_int 0)] UNSPEC_DARN))]
+        (unspec_volatile:DI [(const_int 0)] UNSPECV_DARN))]
   "TARGET_P9_MISC && TARGET_64BIT"
   "darn %0,1"
   [(set_attr "type" "integer")])