Merge changes from topic "arm64_branch-protection"

* changes:
  libc: Add Armv8.3-A PAuth and Armv8.5-A BTI compatibility to *.S
  Update crtbegin.c and crt*.S to support Armv8.5-A BTI
  libm: Add Armv8.3-A PAuth and Armv8.5-A BTI support to assembly files
  libc: Prepare support for Armv8.3-A PAuth and Armv8.5-A BTI in *.S
diff --git a/libc/arch-arm64/bionic/__bionic_clone.S b/libc/arch-arm64/bionic/__bionic_clone.S
index c3ff0e5..e9932ad 100644
--- a/libc/arch-arm64/bionic/__bionic_clone.S
+++ b/libc/arch-arm64/bionic/__bionic_clone.S
@@ -57,3 +57,5 @@
     ldp     x0, x1, [sp], #16
     b       __start_thread
 END(__bionic_clone)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/bionic/_exit_with_stack_teardown.S b/libc/arch-arm64/bionic/_exit_with_stack_teardown.S
index 6a7b1e5..c53a1f4 100644
--- a/libc/arch-arm64/bionic/_exit_with_stack_teardown.S
+++ b/libc/arch-arm64/bionic/_exit_with_stack_teardown.S
@@ -39,3 +39,5 @@
   svc #0
   // The exit syscall does not return.
 END(_exit_with_stack_teardown)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/bionic/setjmp.S b/libc/arch-arm64/bionic/setjmp.S
index a2b2370..07270c9 100644
--- a/libc/arch-arm64/bionic/setjmp.S
+++ b/libc/arch-arm64/bionic/setjmp.S
@@ -118,6 +118,8 @@
 // int sigsetjmp(sigjmp_buf env, int save_signal_mask);
 ENTRY(sigsetjmp)
 __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(sigsetjmp)
+  hint #25 // paciasp
+  .cfi_negate_ra_state
   stp x0, x30, [sp, #-16]!
   .cfi_def_cfa_offset 16
   .cfi_rel_offset x0, 0
@@ -184,6 +186,8 @@
 #endif
 
   mov w0, #0
+  hint #29 // autiasp
+  .cfi_negate_ra_state
   ret
 END(sigsetjmp)
 
@@ -250,7 +254,9 @@
 1:
   // Restore core registers.
   bic x2, x2, #1
+  // x30 was saved with PAC to jmp_buf in sigsetjmp().
   ldp x30, x10, [x0, #(_JB_X30_SP  * 8)]
+  .cfi_negate_ra_state
   ldp x28, x29, [x0, #(_JB_X28_X29 * 8)]
   ldp x26, x27, [x0, #(_JB_X26_X27 * 8)]
   ldp x24, x25, [x0, #(_JB_X24_X25 * 8)]
@@ -290,6 +296,8 @@
   // Set return value.
   cmp w1, wzr
   csinc w0, w1, wzr, ne
+  hint #29 // autiasp
+  .cfi_negate_ra_state
   ret
 END(siglongjmp)
 
@@ -297,3 +305,5 @@
 __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(longjmp)
 ALIAS_SYMBOL(_longjmp, siglongjmp)
 __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(_longjmp)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/bionic/syscall.S b/libc/arch-arm64/bionic/syscall.S
index 8389f98..9e6f68a 100644
--- a/libc/arch-arm64/bionic/syscall.S
+++ b/libc/arch-arm64/bionic/syscall.S
@@ -47,3 +47,5 @@
 
     ret
 END(syscall)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/bionic/vfork.S b/libc/arch-arm64/bionic/vfork.S
index 5cfb8b0..81b84a3 100644
--- a/libc/arch-arm64/bionic/vfork.S
+++ b/libc/arch-arm64/bionic/vfork.S
@@ -67,6 +67,8 @@
 
     // Clean up stack shadow in the parent process.
     // https://github.com/google/sanitizers/issues/925
+    hint #25 // paciasp
+    .cfi_negate_ra_state
     stp x0, x30, [sp, #-16]!
     .cfi_adjust_cfa_offset 16
     .cfi_rel_offset x0, 0
@@ -79,9 +81,13 @@
     .cfi_adjust_cfa_offset -16
     .cfi_restore x0
     .cfi_restore x30
+    hint #29 // autiasp
+    .cfi_negate_ra_state
 
 #endif
 
 .L_exit:
     ret
 END(vfork)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/generic/bionic/__memcpy_chk.S b/libc/arch-arm64/generic/bionic/__memcpy_chk.S
index a6eeca4..a8e9e83 100644
--- a/libc/arch-arm64/generic/bionic/__memcpy_chk.S
+++ b/libc/arch-arm64/generic/bionic/__memcpy_chk.S
@@ -43,3 +43,5 @@
 
   bl __memcpy_chk_fail
 END(__memcpy_chk)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/generic/bionic/memcpy.S b/libc/arch-arm64/generic/bionic/memcpy.S
index baadb92..bc1945c 100644
--- a/libc/arch-arm64/generic/bionic/memcpy.S
+++ b/libc/arch-arm64/generic/bionic/memcpy.S
@@ -33,3 +33,5 @@
 ENTRY(__memcpy)
   #include "memcpy_base.S"
 END(__memcpy)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/generic/bionic/memmove.S b/libc/arch-arm64/generic/bionic/memmove.S
index 335b7d6..0f752ea 100644
--- a/libc/arch-arm64/generic/bionic/memmove.S
+++ b/libc/arch-arm64/generic/bionic/memmove.S
@@ -153,3 +153,5 @@
 
 ALIAS_SYMBOL(memcpy, memmove)
 #endif
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/generic/bionic/memset.S b/libc/arch-arm64/generic/bionic/memset.S
index 12fc09d..19d3510 100644
--- a/libc/arch-arm64/generic/bionic/memset.S
+++ b/libc/arch-arm64/generic/bionic/memset.S
@@ -249,3 +249,5 @@
 	b	L(tail64)
 
 END(memset)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/generic/bionic/wmemmove.S b/libc/arch-arm64/generic/bionic/wmemmove.S
index e4f67f7..b130530 100644
--- a/libc/arch-arm64/generic/bionic/wmemmove.S
+++ b/libc/arch-arm64/generic/bionic/wmemmove.S
@@ -28,3 +28,5 @@
 #define WMEMMOVE
 #include "memmove.S"
 #undef WMEMMOVE
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-arm64/static_function_dispatch.S b/libc/arch-arm64/static_function_dispatch.S
index 65a1492..161ece8 100644
--- a/libc/arch-arm64/static_function_dispatch.S
+++ b/libc/arch-arm64/static_function_dispatch.S
@@ -42,3 +42,5 @@
 FUNCTION_DELEGATE(strlen, __strlen_aarch64_mte)
 FUNCTION_DELEGATE(strrchr, __strrchr_aarch64_mte)
 FUNCTION_DELEGATE(strncmp, __strncmp_aarch64_mte)
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-common/bionic/crtbegin.c b/libc/arch-common/bionic/crtbegin.c
index b7043dc..1f8dfd2 100644
--- a/libc/arch-common/bionic/crtbegin.c
+++ b/libc/arch-common/bionic/crtbegin.c
@@ -49,7 +49,7 @@
 #define POST "; .size _start, .-_start"
 
 #if defined(__aarch64__)
-__asm__(PRE "mov x0,sp; b _start_main" POST);
+__asm__(PRE "/* BTI J */ hint #36; mov x0,sp; b _start_main" POST);
 #elif defined(__arm__)
 __asm__(PRE "mov r0,sp; b _start_main" POST);
 #elif defined(__i386__)
diff --git a/libc/arch-common/bionic/crtbrand.S b/libc/arch-common/bionic/crtbrand.S
index 34d6480..3d80d73 100644
--- a/libc/arch-common/bionic/crtbrand.S
+++ b/libc/arch-common/bionic/crtbrand.S
@@ -26,6 +26,12 @@
  * SUCH DAMAGE.
  */
 
+#if defined(__aarch64__)
+#include <private/bionic_asm_arm64.h>
+
+__bionic_asm_custom_note_gnu_section()
+#endif
+
   .section .note.android.ident,"a",%note
   .balign 4
   .type abitag, %object
diff --git a/libc/arch-common/bionic/crtend.S b/libc/arch-common/bionic/crtend.S
index 87d1120..0166428 100644
--- a/libc/arch-common/bionic/crtend.S
+++ b/libc/arch-common/bionic/crtend.S
@@ -28,6 +28,12 @@
 
 #include "asm_multiarch.h"
 
+#if defined(__aarch64__)
+#include <private/bionic_asm_arm64.h>
+
+__bionic_asm_custom_note_gnu_section()
+#endif
+
 	.section .preinit_array, "aw"
 	ASM_ALIGN_TO_PTR_SIZE
 	ASM_PTR_SIZE(0)
diff --git a/libc/arch-common/bionic/crtend_so.S b/libc/arch-common/bionic/crtend_so.S
index e7b8cac..426d098 100644
--- a/libc/arch-common/bionic/crtend_so.S
+++ b/libc/arch-common/bionic/crtend_so.S
@@ -26,6 +26,12 @@
  * SUCH DAMAGE.
  */
 
+#if defined(__aarch64__)
+#include <private/bionic_asm_arm64.h>
+
+__bionic_asm_custom_note_gnu_section()
+#endif
+
 #if defined(__linux__) && defined(__ELF__)
 	.section .note.GNU-stack,"",%progbits
 #endif
diff --git a/libc/private/bionic_asm.h b/libc/private/bionic_asm.h
index 6409563..6d4f7d5 100644
--- a/libc/private/bionic_asm.h
+++ b/libc/private/bionic_asm.h
@@ -35,6 +35,7 @@
 #define __bionic_asm_custom_entry(f)
 #define __bionic_asm_custom_end(f)
 #define __bionic_asm_function_type @function
+#define __bionic_asm_custom_note_gnu_section()
 
 #if defined(__aarch64__)
 #include <private/bionic_asm_arm64.h>
@@ -83,4 +84,7 @@
     .globl alias; \
     .equ alias, original
 
+#define NOTE_GNU_PROPERTY() \
+    __bionic_asm_custom_note_gnu_section()
+
 #endif
diff --git a/libc/private/bionic_asm_arm64.h b/libc/private/bionic_asm_arm64.h
index 463ca31..c11732a 100644
--- a/libc/private/bionic_asm_arm64.h
+++ b/libc/private/bionic_asm_arm64.h
@@ -41,3 +41,32 @@
 
 #undef __bionic_asm_function_type
 #define __bionic_asm_function_type %function
+
+#if defined(__ARM_FEATURE_BTI_DEFAULT)
+#define __bionic_asm_aarch64_feature_bti    (1 << 0)
+#undef __bionic_asm_custom_entry
+#define __bionic_asm_custom_entry(f)        hint #34  // BTI C
+#else
+#define __bionic_asm_aarch64_feature_bti    0
+#endif
+
+#if defined(__ARM_FEATURE_PAC_DEFAULT)
+#define __bionic_asm_aarch64_feature_pac    (1 << 1)
+#else
+#define __bionic_asm_aarch64_feature_pac    0
+#endif
+
+#undef __bionic_asm_custom_note_gnu_section
+#define __bionic_asm_custom_note_gnu_section() \
+    .pushsection .note.gnu.property, "a"; \
+    .balign 8; \
+    .long 4; \
+    .long 0x10; \
+    .long 0x5; /* NT_GNU_PROPERTY_TYPE_0 */ \
+    .asciz "GNU"; \
+    .long 0xc0000000; /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */ \
+    .long 4; \
+    .long (__bionic_asm_aarch64_feature_pac | \
+           __bionic_asm_aarch64_feature_bti); \
+    .long 0; \
+    .popsection; \
diff --git a/libc/tools/gensyscalls.py b/libc/tools/gensyscalls.py
index 0271a04..0e0e25f 100755
--- a/libc/tools/gensyscalls.py
+++ b/libc/tools/gensyscalls.py
@@ -459,6 +459,8 @@
         if syscall.has_key("asm-%s" % arch):
             print(syscall["asm-%s" % arch])
 
+    if arch == 'arm64':
+        print('\nNOTE_GNU_PROPERTY()\n')
 
 if __name__ == "__main__":
     if len(sys.argv) < 2:
diff --git a/libm/arm64/lrint.S b/libm/arm64/lrint.S
index 5f95ae8..e835d08 100644
--- a/libm/arm64/lrint.S
+++ b/libm/arm64/lrint.S
@@ -32,3 +32,5 @@
 ALIAS_SYMBOL(llrint, lrint);
 
 ALIAS_SYMBOL(llrintf, lrintf);
+
+NOTE_GNU_PROPERTY()
diff --git a/libm/arm64/sqrt.S b/libm/arm64/sqrt.S
index 3a58ef3..0659b13 100644
--- a/libm/arm64/sqrt.S
+++ b/libm/arm64/sqrt.S
@@ -25,3 +25,5 @@
   fsqrt s0, s0
   ret
 END(sqrtf)
+
+NOTE_GNU_PROPERTY()