From 9a1b74d49e2e25b29675fac4322bb7ba6cec5894 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: Backport from mainline. 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. gcc/testsuite/ChangeLog: Backport from mainline. 2020-04-30 Szabolcs Nagy PR target/94748 * gcc.target/aarch64/pr94748.c: New test. --- gcc/ChangeLog | 9 +++++++++ gcc/config/aarch64/aarch64-bti-insert.c | 8 ++------ gcc/testsuite/ChangeLog | 8 ++++++++ gcc/testsuite/gcc.target/aarch64/pr94748.c | 10 ++++++++++ 4 files changed, 29 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/gcc.target/aarch64/pr94748.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1b814c7308bd..80a48f8341ca 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2020-05-14 Szabolcs Nagy + + Backport from mainline. + 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. + 2020-05-14 Szabolcs Nagy Backport from mainline. diff --git a/gcc/config/aarch64/aarch64-bti-insert.c b/gcc/config/aarch64/aarch64-bti-insert.c index 9e0fc168435d..7da89074ce02 100644 --- a/gcc/config/aarch64/aarch64-bti-insert.c +++ b/gcc/config/aarch64/aarch64-bti-insert.c @@ -137,14 +137,10 @@ 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 a642d0f9a19c..b69958e23d09 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,11 @@ +2020-05-14 Szabolcs Nagy + + Backport from mainline. + 2020-04-30 Szabolcs Nagy + + PR target/94748 + * gcc.target/aarch64/pr94748.c: New test. + 2020-05-14 Szabolcs Nagy Backport from mainline. diff --git a/gcc/testsuite/gcc.target/aarch64/pr94748.c b/gcc/testsuite/gcc.target/aarch64/pr94748.c new file mode 100644 index 000000000000..2a2850d2fac0 --- /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)} } } */ -- 2.47.3