* [binutils-gdb] bfd: aarch64: Optimize BTI stubs PR30076
@ 2023-03-23 12:50 Szabolcs Nagy
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From: Szabolcs Nagy @ 2023-03-23 12:50 UTC (permalink / raw)
To: bfd-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5834f36d93cabf1a8bcc7dd7654141aed3d296bc
commit 5834f36d93cabf1a8bcc7dd7654141aed3d296bc
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Fri Feb 3 17:09:58 2023 +0000
bfd: aarch64: Optimize BTI stubs PR30076
Don't insert a second stub if the target is already compatible with
an indirect branch.
Diff:
---
bfd/elfnn-aarch64.c | 36 +++++++-
ld/testsuite/ld-aarch64/aarch64-elf.exp | 1 +
ld/testsuite/ld-aarch64/bti-far-opt.d | 153 ++++++++++++++++++++++++++++++++
ld/testsuite/ld-aarch64/bti-far-opt.s | 53 +++++++++++
4 files changed, 239 insertions(+), 4 deletions(-)
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index d9ebeae922c..c321ceb382e 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;
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index 80662de7e44..ec55bf49931 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -463,6 +463,7 @@ run_dump_test "undef-tls"
run_dump_test "bti-far-1"
run_dump_test "bti-far-2"
+run_dump_test "bti-far-opt"
if { ![skip_sframe_tests] } {
run_dump_test "sframe-simple-1"
diff --git a/ld/testsuite/ld-aarch64/bti-far-opt.d b/ld/testsuite/ld-aarch64/bti-far-opt.d
new file mode 100644
index 00000000000..ff20d0c2825
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/bti-far-opt.d
@@ -0,0 +1,153 @@
+#name: Check linker stubs with indirect calls handle BTI when target has BTI.
+#source: bti-far-opt.s
+#target: [check_shared_lib_support]
+#as: -mabi=lp64
+#ld: -shared -T bti-far.ld
+#objdump: -dr
+
+[^:]*: *file format elf64-.*aarch64
+
+
+Disassembly of section \.plt:
+
+0000000000018000 <\.plt>:
+ 18000: d503245f bti c
+ 18004: a9bf7bf0 stp x16, x30, \[sp, #-16\]!
+ 18008: 900000d0 adrp x16, 30000 <_GLOBAL_OFFSET_TABLE_>
+ 1800c: f9400e11 ldr x17, \[x16, #24\]
+ 18010: 91006210 add x16, x16, #0x18
+ 18014: d61f0220 br x17
+ 18018: d503201f nop
+ 1801c: d503201f nop
+
+0000000000018020 <foo@plt>:
+ 18020: 900000d0 adrp x16, 30000 <_GLOBAL_OFFSET_TABLE_>
+ 18024: f9401211 ldr x17, \[x16, #32\]
+ 18028: 91008210 add x16, x16, #0x20
+ 1802c: d61f0220 br x17
+ 18030: 14000004 b 18040 <__foo_bti_veneer\+0x8>
+ 18034: d503201f nop
+
+0000000000018038 <__foo_bti_veneer>:
+ 18038: d503245f bti c
+ 1803c: 17fffff9 b 18020 <foo@plt>
+
+Disassembly of section \.text:
+
+0000000000020000 <_start>:
+ 20000: 97ffe008 bl 18020 <foo@plt>
+ 20004: 9400000f bl 20040 <___veneer>
+ 20008: 94000001 bl 2000c <baz>
+
+000000000002000c <baz>:
+ 2000c: d503201f nop
+
+0000000000020010 <baz_bti_>:
+ 20010: d503241f bti
+
+0000000000020014 <baz_bti_c>:
+ 20014: d503245f bti c
+
+0000000000020018 <baz_bti_j>:
+ 20018: d503249f bti j
+
+000000000002001c <baz_bti_jc>:
+ 2001c: d50324df bti jc
+
+0000000000020020 <baz_paciasp>:
+ 20020: d503233f paciasp
+
+0000000000020024 <baz_pacibsp>:
+ 20024: d503237f pacibsp
+ 20028: 1400000c b 20058 <___veneer\+0x18>
+ 2002c: d503201f nop
+
+0000000000020030 <___bti_veneer>:
+ 20030: d503245f bti c
+ 20034: 17fffff6 b 2000c <baz>
+
+0000000000020038 <___bti_veneer>:
+ 20038: d503245f bti c
+ 2003c: 17fffff5 b 20010 <baz_bti_>
+
+0000000000020040 <___veneer>:
+ 20040: 90091910 adrp x16, 12340000 <foo>
+ 20044: 9101e210 add x16, x16, #0x78
+ 20048: d61f0200 br x16
+ \.\.\.
+
+Disassembly of section \.far:
+
+0000000012340000 <foo>:
+ 12340000: 94000018 bl 12340060 <___veneer>
+ 12340004: 9400003d bl 123400f8 <___veneer>
+ 12340008: 9400002a bl 123400b0 <___veneer>
+ 1234000c: 94000023 bl 12340098 <___veneer>
+ 12340010: 9400002e bl 123400c8 <___veneer>
+ 12340014: 94000033 bl 123400e0 <___veneer>
+ 12340018: 9400001a bl 12340080 <___veneer>
+
+000000001234001c <bar>:
+ 1234001c: 1400000b b 12340048 <__foo_veneer>
+ 12340020: 14000010 b 12340060 <___veneer>
+ 12340024: 14000035 b 123400f8 <___veneer>
+ 12340028: 14000022 b 123400b0 <___veneer>
+ 1234002c: 1400001b b 12340098 <___veneer>
+ 12340030: 14000026 b 123400c8 <___veneer>
+ 12340034: 1400002b b 123400e0 <___veneer>
+ 12340038: 14000012 b 12340080 <___veneer>
+ 1234003c: 00000000 udf #0
+ 12340040: 14000034 b 12340110 <___veneer\+0x18>
+ 12340044: d503201f nop
+
+0000000012340048 <__foo_veneer>:
+ 12340048: 90f6e6d0 adrp x16, 18000 <\.plt>
+ 1234004c: 9100e210 add x16, x16, #0x38
+ 12340050: d61f0200 br x16
+ \.\.\.
+
+0000000012340060 <___veneer>:
+ 12340060: 90f6e710 adrp x16, 20000 <_start>
+ 12340064: 9100c210 add x16, x16, #0x30
+ 12340068: d61f0200 br x16
+ \.\.\.
+
+0000000012340078 <___bti_veneer>:
+ 12340078: d503245f bti c
+ 1234007c: 17ffffe8 b 1234001c <bar>
+
+0000000012340080 <___veneer>:
+ 12340080: 90f6e710 adrp x16, 20000 <_start>
+ 12340084: 91009210 add x16, x16, #0x24
+ 12340088: d61f0200 br x16
+ \.\.\.
+
+0000000012340098 <___veneer>:
+ 12340098: 90f6e710 adrp x16, 20000 <_start>
+ 1234009c: 91006210 add x16, x16, #0x18
+ 123400a0: d61f0200 br x16
+ \.\.\.
+
+00000000123400b0 <___veneer>:
+ 123400b0: 90f6e710 adrp x16, 20000 <_start>
+ 123400b4: 91005210 add x16, x16, #0x14
+ 123400b8: d61f0200 br x16
+ \.\.\.
+
+00000000123400c8 <___veneer>:
+ 123400c8: 90f6e710 adrp x16, 20000 <_start>
+ 123400cc: 91007210 add x16, x16, #0x1c
+ 123400d0: d61f0200 br x16
+ \.\.\.
+
+00000000123400e0 <___veneer>:
+ 123400e0: 90f6e710 adrp x16, 20000 <_start>
+ 123400e4: 91008210 add x16, x16, #0x20
+ 123400e8: d61f0200 br x16
+ \.\.\.
+
+00000000123400f8 <___veneer>:
+ 123400f8: 90f6e710 adrp x16, 20000 <_start>
+ 123400fc: 9100e210 add x16, x16, #0x38
+ 12340100: d61f0200 br x16
+ \.\.\.
diff --git a/ld/testsuite/ld-aarch64/bti-far-opt.s b/ld/testsuite/ld-aarch64/bti-far-opt.s
new file mode 100644
index 00000000000..516b901f20f
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/bti-far-opt.s
@@ -0,0 +1,53 @@
+ .text
+ .global _start
+ .type _start, %function
+_start:
+ bl foo
+ bl bar
+ bl baz
+baz:
+ nop
+baz_bti_:
+ bti
+baz_bti_c:
+ bti c
+baz_bti_j:
+ bti j
+baz_bti_jc:
+ bti jc
+baz_paciasp:
+ paciasp
+baz_pacibsp:
+ pacibsp
+
+ .section .far,"ax",@progbits
+ .global foo
+ .type foo, %function
+foo:
+ bl baz
+ bl baz_bti_
+ bl baz_bti_c
+ bl baz_bti_j
+ bl baz_bti_jc
+ bl baz_paciasp
+ bl baz_pacibsp
+bar:
+ b foo
+ b baz
+ b baz_bti_
+ b baz_bti_c
+ b baz_bti_j
+ b baz_bti_jc
+ b baz_paciasp
+ b baz_pacibsp
+
+ .section .note.gnu.property,"a"
+ .align 3
+ .word 4
+ .word 16
+ .word 5
+ .string "GNU"
+ .word 0xc0000000
+ .word 4
+ .word 1
+ .align 3
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