From 6ac83d350604c3e934d5e8a455ba7ec1c1c0240b Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Fri, 24 Apr 2020 17:36:02 +0100 Subject: [PATCH] aarch64: don't emit bti j after NOTE_INSN_DELETED_LABEL [PR94748] It was previously discussed that indirect branches cannot go to NOTE_INSN_DELETED_LABEL so inserting a landing pad is unnecessary. See https://gcc.gnu.org/pipermail/gcc-patches/2019-May/522625.html Before the patch a bti j was inserted after the label in __attribute__((target("branch-protection=bti"))) int foo (void) { label: return 0; } This is not necessary and weakens the security protection. gcc/ChangeLog: PR target/94748 * config/aarch64/aarch64-bti-insert.c (rest_of_insert_bti): Remove the check for NOTE_INSN_DELETED_LABEL. gcc/testsuite/ChangeLog: PR target/94748 * gcc.target/aarch64/pr94748.c: New test. --- gcc/ChangeLog | 6 ++++++ gcc/config/aarch64/aarch64-bti-insert.c | 8 ++------ gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.target/aarch64/pr94748.c | 10 ++++++++++ 4 files changed, 23 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/gcc.target/aarch64/pr94748.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 5b69334a26b..c81801f289e 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-04-30 Szabolcs Nagy + + PR target/94748 + * config/aarch64/aarch64-bti-insert.c (rest_of_insert_bti): Remove + the check for NOTE_INSN_DELETED_LABEL. + 2020-04-30 Jakub Jelinek * configure.ac (--with-documentation-root-url, diff --git a/gcc/config/aarch64/aarch64-bti-insert.c b/gcc/config/aarch64/aarch64-bti-insert.c index aa091c308f6..57663ee23b4 100644 --- a/gcc/config/aarch64/aarch64-bti-insert.c +++ b/gcc/config/aarch64/aarch64-bti-insert.c @@ -139,14 +139,10 @@ rest_of_insert_bti (void) insn = NEXT_INSN (insn)) { /* If a label is marked to be preserved or can be a non-local goto - target, it must be protected with a BTI J. The same applies to - NOTE_INSN_DELETED_LABEL since they are basically labels that might - be referenced via variables or constant pool. */ - if ((LABEL_P (insn) + target, it must be protected with a BTI J. */ + if (LABEL_P (insn) && (LABEL_PRESERVE_P (insn) || bb->flags & BB_NON_LOCAL_GOTO_TARGET)) - || (NOTE_P (insn) - && NOTE_KIND (insn) == NOTE_INSN_DELETED_LABEL)) { bti_insn = gen_bti_j (); emit_insn_after (bti_insn, insn); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 9d5944b6886..66ac6705a05 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-04-30 Szabolcs Nagy + + PR target/94748 + * gcc.target/aarch64/pr94748.c: New test. + 2020-04-30 Andreas Krebbel * gcc.target/s390/zvector/vec_load_len_r.c: New test. diff --git a/gcc/testsuite/gcc.target/aarch64/pr94748.c b/gcc/testsuite/gcc.target/aarch64/pr94748.c new file mode 100644 index 00000000000..2a2850d2fac --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/pr94748.c @@ -0,0 +1,10 @@ +/* { dg-do compile } */ + +__attribute__ ((target("branch-protection=bti"))) +int foo () +{ +label: + return 0; +} + +/* { dg-final { scan-assembler-not {hint (36|38) // bti (j|jc)} } } */ -- 2.30.2