[PATCH] D54854: [LLD][AArch64] Cortex-a53-843419 erratum should not apply to relaxed TLS.

[Peter Smith via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL347649: [AArch64] Cortex-a53-843419 erratum should not apply to relaxed TLS. (authored by psmith, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D54854?vs=175109&id=175432#toc

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D54854/new/

https://reviews.llvm.org/D54854

Files:
  lld/trunk/ELF/AArch64ErrataFix.cpp
  lld/trunk/test/ELF/aarch64-cortex-a53-843419-tlsrelax.s


Index: lld/trunk/test/ELF/aarch64-cortex-a53-843419-tlsrelax.s
===================================================================
--- lld/trunk/test/ELF/aarch64-cortex-a53-843419-tlsrelax.s
+++ lld/trunk/test/ELF/aarch64-cortex-a53-843419-tlsrelax.s
@@ -0,0 +1,38 @@
+// REQUIRES: aarch64
+// RUN: llvm-mc -filetype=obj -triple=aarch64-none-linux %s -o %t.o
+// RUN: ld.lld -fix-cortex-a53-843419 %t.o -o %t2
+// RUN: llvm-objdump -triple=aarch64-linux-gnu -d %t2 | FileCheck %s
+
+// The following code sequence is covered by the TLS IE to LE relaxation. It
+// transforms the ADRP, LDR to MOVZ, MOVK. The former can trigger a
+// cortex-a53-843419 patch, whereas the latter can not. As both
+// relaxation and patching transform instructions very late in the
+// link there is a possibility of them both being simultaneously
+// applied. In this case the relaxed sequence is immune from the erratum so we
+// prefer to keep it.
+ .text
+ .balign 4096
+ .space  4096 - 8
+ .globl _start
+ .type  _start, at function
+_start:
+ mrs    x1, tpidr_el0
+ adrp   x0, :gottprel:v
+ ldr    x1, [x0, #:gottprel_lo12:v]
+ adrp   x0, :gottprel:v
+ ldr    x1, [x0, #:gottprel_lo12:v]
+ ret
+
+// CHECK: _start:
+// CHECK-NEXT:   210ff8:        41 d0 3b d5     mrs     x1, TPIDR_EL0
+// CHECK-NEXT:   210ffc:        00 00 a0 d2     movz    x0, #0, lsl #16
+// CHECK-NEXT:   211000:        01 02 80 f2     movk    x1, #16
+// CHECK-NEXT:   211004:        00 00 a0 d2     movz    x0, #0, lsl #16
+// CHECK-NEXT:   211008:        01 02 80 f2     movk    x1, #16
+// CHECK-NEXT:   21100c:        c0 03 5f d6     ret
+
+ .type  v, at object
+ .section       .tbss,"awT", at nobits
+ .globl v
+v:
+ .word 0
Index: lld/trunk/ELF/AArch64ErrataFix.cpp
===================================================================
--- lld/trunk/ELF/AArch64ErrataFix.cpp
+++ lld/trunk/ELF/AArch64ErrataFix.cpp
@@ -538,20 +538,24 @@
                            InputSection *IS,
                            std::vector<Patch843419Section *> &Patches) {
   // There may be a relocation at the same offset that we are patching. There
-  // are three cases that we need to consider.
+  // are four cases that we need to consider.
   // Case 1: R_AARCH64_JUMP26 branch relocation. We have already patched this
   // instance of the erratum on a previous patch and altered the relocation. We
   // have nothing more to do.
-  // Case 2: A load/store register (unsigned immediate) class relocation. There
+  // Case 2: A TLS Relaxation R_RELAX_TLS_IE_TO_LE. In this case the ADRP that
+  // we read will be transformed into a MOVZ later so we actually don't match
+  // the sequence and have nothing more to do.
+  // Case 3: A load/store register (unsigned immediate) class relocation. There
   // are two of these R_AARCH_LD64_ABS_LO12_NC and R_AARCH_LD64_GOT_LO12_NC and
   // they are both absolute. We need to add the same relocation to the patch,
   // and replace the relocation with a R_AARCH_JUMP26 branch relocation.
-  // Case 3: No relocation. We must create a new R_AARCH64_JUMP26 branch
+  // Case 4: No relocation. We must create a new R_AARCH64_JUMP26 branch
   // relocation at the offset.
   auto RelIt = std::find_if(
       IS->Relocations.begin(), IS->Relocations.end(),
       [=](const Relocation &R) { return R.Offset == PatcheeOffset; });
-  if (RelIt != IS->Relocations.end() && RelIt->Type == R_AARCH64_JUMP26)
+  if (RelIt != IS->Relocations.end() &&
+      (RelIt->Type == R_AARCH64_JUMP26 || RelIt->Expr == R_RELAX_TLS_IE_TO_LE))
     return;
 
   log("detected cortex-a53-843419 erratum sequence starting at " +


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