diff --git a/lib/Support/Unix/Memory.inc b/lib/Support/Unix/Memory.inc index a66e3c7aeee..e00394ec6aa 100644 --- a/lib/Support/Unix/Memory.inc +++ b/lib/Support/Unix/Memory.inc @@ -52,6 +52,13 @@ int getPosixProtectionFlags(unsigned Flags) { return PROT_READ | PROT_WRITE | PROT_EXEC; case llvm::sys::Memory::MF_EXEC: #if defined(__FreeBSD__) + // On PowerPC, having an executable page that has no read permission + // can have unintended consequences. The function InvalidateInstruction- + // Cache uses instructions dcbf and icbi, both of which are treated by + // the processor as loads. If the page has no read permissions, + // executing these instructions will result in a segmentation fault. + // Somehow, this problem is not present on Linux, but it does happen + // on FreeBSD. return PROT_READ | PROT_EXEC; #else return PROT_EXEC;