[PATCH] D74537: [LLD][ELF][AArch64] Fix plt generation for PAC/BTI.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

> Unless I missed something, the || config->forceBTI shouldn't be necessary due to forceBTI always adding GNU_PROPERTY_AARCH64_FEATURE_1_BTI to all objects if it isn't there already.

Adding `config->pacPlt` to `getTargetInfo()` is problematic. `getTargetInfo()` is called twice.

  readConfig(); // config->pacPlt is set. config->andFeatures is 0
  target = getTarget();
  
  config->andFeatures = getAndFeatures<ELFT>();
  target = getTarget();

I think the following change should be made.

  --- i/lld/ELF/Arch/AArch64.cpp
  +++ w/lld/ELF/Arch/AArch64.cpp
  @@ -595,4 +595,3 @@ private:
   AArch64BtiPac::AArch64BtiPac() {
  -  btiHeader = (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_BTI) ||
  -              config->forceBTI;
  +  btiHeader = config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_BTI;
     // A BTI (Branch Target Indicator) Plt Entry is only required if the
  @@ -693,3 +692,3 @@ static TargetInfo *getTargetInfo() {
     if ((config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_BTI) ||
  -      config->pacPlt) {
  +      (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_PAC)) {
       static AArch64BtiPac t;


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D74537/new/

https://reviews.llvm.org/D74537