diff options
| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2023-02-03 17:09:58 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2023-03-23 12:49:32 +0000 |
| commit | 5834f36d93cabf1a8bcc7dd7654141aed3d296bc (patch) | |
| tree | ecb45f2d82ee4918d25cb43d0798a4dd1c856d6c /bfd | |
| parent | 15b4f66b0a9a3be6caf1898d22a13c39e662006f (diff) | |
| download | gdb-5834f36d93cabf1a8bcc7dd7654141aed3d296bc.zip gdb-5834f36d93cabf1a8bcc7dd7654141aed3d296bc.tar.gz gdb-5834f36d93cabf1a8bcc7dd7654141aed3d296bc.tar.bz2 | |
bfd: aarch64: Optimize BTI stubs PR30076
Don't insert a second stub if the target is already compatible with
an indirect branch.
Diffstat (limited to 'bfd')
| -rw-r--r-- | bfd/elfnn-aarch64.c | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c index d9ebeae..c321ceb 100644 --- a/bfd/elfnn-aarch64.c +++ b/bfd/elfnn-aarch64.c @@ -3670,14 +3670,42 @@ group_sections (struct elf_aarch64_link_hash_table *htab, #undef PREV_SEC #undef PREV_SEC +#define AARCH64_HINT(insn) (((insn) & 0xfffff01f) == 0xd503201f) +#define AARCH64_PACIASP 0xd503233f +#define AARCH64_PACIBSP 0xd503237f +#define AARCH64_BTI_C 0xd503245f +#define AARCH64_BTI_J 0xd503249f +#define AARCH64_BTI_JC 0xd50324df + /* True if the inserted stub does not break BTI compatibility. */ static bool -aarch64_bti_stub_p (struct elf_aarch64_stub_hash_entry *stub_entry) +aarch64_bti_stub_p (bfd *input_bfd, + struct elf_aarch64_stub_hash_entry *stub_entry) { /* Stubs without indirect branch are BTI compatible. */ - return stub_entry->stub_type != aarch64_stub_adrp_branch - && stub_entry->stub_type != aarch64_stub_long_branch; + if (stub_entry->stub_type != aarch64_stub_adrp_branch + && stub_entry->stub_type != aarch64_stub_long_branch) + return true; + + /* Return true if the target instruction is compatible with BR x16. */ + + asection *section = stub_entry->target_section; + bfd_byte loc[4]; + file_ptr off = stub_entry->target_value; + bfd_size_type count = sizeof (loc); + + if (!bfd_get_section_contents (input_bfd, section, loc, off, count)) + return false; + + uint32_t insn = bfd_getl32 (loc); + if (!AARCH64_HINT (insn)) + return false; + return insn == AARCH64_BTI_C + || insn == AARCH64_PACIASP + || insn == AARCH64_BTI_JC + || insn == AARCH64_BTI_J + || insn == AARCH64_PACIBSP; } #define AARCH64_BITS(x, pos, n) (((x) >> (pos)) & ((1 << (n)) - 1)) @@ -4614,7 +4642,7 @@ _bfd_aarch64_add_call_stub_entries (bool *stub_changed, bfd *output_bfd, /* A stub with indirect jump may break BTI compatibility, so insert another stub with direct jump near the target then. */ - if (need_bti && !aarch64_bti_stub_p (stub_entry)) + if (need_bti && !aarch64_bti_stub_p (input_bfd, stub_entry)) { stub_entry->double_stub = true; htab->has_double_stub = true; |