diff mbox series

[committed,5/6] arm: fix vlldm erratum for Armv8.1-m [PR102035]

Message ID 20210824105928.3869183-6-rearnsha@arm.com
State New
Headers show
Series arm: mitigation for CVE-2021-35465 | expand

Commit Message

Richard Earnshaw Aug. 24, 2021, 10:59 a.m. UTC 
For Armv8.1-m we generate code that emits VLLDM directly and do not
rely on support code in the library, so emit the mitigation directly
as well, when required.  In this case, we can use the compiler options
to determine when to apply the fix and when it is safe to omit it.

gcc:
	PR target/102035
	* config/arm/arm.md (attribute arch): Add fix_vlldm.
	(arch_enabled): Use it.
	* config/arm/vfp.md (lazy_store_multiple_insn): Add alternative to
	use when erratum mitigation is needed.
---
 gcc/config/arm/arm.md | 11 +++++++++--
 gcc/config/arm/vfp.md | 10 +++++++---
 2 files changed, 16 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 064604808cc..5d3f21b91c4 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -132,9 +132,12 @@  (define_attr "length" ""
 ; TARGET_32BIT, "t1" or "t2" to specify a specific Thumb mode.  "v6"
 ; for ARM or Thumb-2 with arm_arch6, and nov6 for ARM without
 ; arm_arch6.  "v6t2" for Thumb-2 with arm_arch6 and "v8mb" for ARMv8-M
-; Baseline.  This attribute is used to compute attribute "enabled",
+; Baseline.  "fix_vlldm" is for fixing the v8-m/v8.1-m VLLDM erratum.
+; This attribute is used to compute attribute "enabled",
 ; use type "any" to enable an alternative in all cases.
-(define_attr "arch" "any,a,t,32,t1,t2,v6,nov6,v6t2,v8mb,iwmmxt,iwmmxt2,armv6_or_vfpv3,neon,mve"
+(define_attr "arch" "any, a, t, 32, t1, t2, v6,nov6, v6t2, \
+		     v8mb, fix_vlldm, iwmmxt, iwmmxt2, armv6_or_vfpv3, \
+		     neon, mve"
   (const_string "any"))
 
 (define_attr "arch_enabled" "no,yes"
@@ -177,6 +180,10 @@  (define_attr "arch_enabled" "no,yes"
 	      (match_test "TARGET_THUMB1 && arm_arch8"))
 	 (const_string "yes")
 
+	 (and (eq_attr "arch" "fix_vlldm")
+	      (match_test "fix_vlldm"))
+	 (const_string "yes")
+
 	 (and (eq_attr "arch" "iwmmxt2")
 	      (match_test "TARGET_REALLY_IWMMXT2"))
 	 (const_string "yes")
diff --git a/gcc/config/arm/vfp.md b/gcc/config/arm/vfp.md
index 9961f9389fe..f0030a8c36a 100644
--- a/gcc/config/arm/vfp.md
+++ b/gcc/config/arm/vfp.md
@@ -1720,11 +1720,15 @@  (define_insn "lazy_store_multiple_insn"
 
 (define_insn "lazy_load_multiple_insn"
   [(unspec_volatile
-    [(mem:BLK (match_operand:SI 0 "s_register_operand" "rk"))]
+    [(mem:BLK (match_operand:SI 0 "s_register_operand" "rk,rk"))]
     VUNSPEC_VLLDM)]
   "use_cmse && reload_completed"
-  "vlldm%?\\t%0"
-  [(set_attr "predicable" "yes")
+  "@
+   vscclrm\\t{vpr}\;vlldm\\t%0
+   vlldm\\t%0"
+  [(set_attr "arch" "fix_vlldm,*")
+   (set_attr "predicable" "no")
+   (set_attr "length" "8,4")
    (set_attr "type" "load_4")]
 )