From 37de058ab2e9619fbb6dea52ec2773a5d65619c4 Mon Sep 17 00:00:00 2001 From: Jiong Wang Date: Thu, 15 Jun 2017 10:35:28 +0100 Subject: [GOLD] Don't install branch-to-stub for TLS relaxed ERRATUM 843419 sequences on AArch64 TLS relaxation may change erratum 843419 sequences that those offending ADRP instructions actually transformed into other instructions in which case there is erratum 843419 risk anymore that we should avoid installing unnecessary branch-to-stub. gold/ * aarch64.cc (Insn_utilities::is_mrs_tpidr_el0): New method. (AArch64_relobj::try_fix_erratum_843419_optimized): Return ture for some TLS relaxed sequences. --- gold/aarch64.cc | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) (limited to 'gold/aarch64.cc') diff --git a/gold/aarch64.cc b/gold/aarch64.cc index 2470986..7309ded 100644 --- a/gold/aarch64.cc +++ b/gold/aarch64.cc @@ -110,6 +110,10 @@ public: is_adrp(const Insntype insn) { return (insn & 0x9F000000) == 0x90000000; } + static bool + is_mrs_tpidr_el0(const Insntype insn) + { return (insn & 0xFFFFFFE0) == 0xd53bd040; } + static unsigned int aarch64_rm(const Insntype insn) { return aarch64_bits(insn, 16, 5); } @@ -2010,9 +2014,32 @@ AArch64_relobj::try_fix_erratum_843419_optimized( E843419_stub* e843419_stub = reinterpret_cast*>(stub); AArch64_address pc = pview.address + e843419_stub->adrp_sh_offset(); - Insntype* adrp_view = reinterpret_cast( - pview.view + e843419_stub->adrp_sh_offset()); + unsigned int adrp_offset = e843419_stub->adrp_sh_offset (); + Insntype* adrp_view = reinterpret_cast(pview.view + adrp_offset); Insntype adrp_insn = adrp_view[0]; + + // If the instruction at adrp_sh_offset is "mrs R, tpidr_el0", it may come + // from IE -> LE relaxation etc. This is a side-effect of TLS relaxation that + // ADRP has been turned into MRS, there is no erratum risk anymore. + // Therefore, we return true to avoid doing unnecessary branch-to-stub. + if (Insn_utilities::is_mrs_tpidr_el0(adrp_insn)) + return true; + + // If the instruction at adrp_sh_offset is not ADRP and the instruction before + // it is "mrs R, tpidr_el0", it may come from LD -> LE relaxation etc. + // Like the above case, there is no erratum risk any more, we can safely + // return true. + if (!Insn_utilities::is_adrp(adrp_insn) && adrp_offset) + { + Insntype* prev_view + = reinterpret_cast(pview.view + adrp_offset - 4); + Insntype prev_insn = prev_view[0]; + + if (Insn_utilities::is_mrs_tpidr_el0(prev_insn)) + return true; + } + + /* If we reach here, the first instruction must be ADRP. */ gold_assert(Insn_utilities::is_adrp(adrp_insn)); // Get adrp 33-bit signed imm value. int64_t adrp_imm = Insn_utilities:: -- cgit v1.1