[v2,12/13] aarch64: Add pac-ret support to asm files

Message ID 989dc57137130a177cce15b181d2a95e3214a8b3.1589277641.git.szabolcs.nagy@arm.com
State New
Headers show
Series
  • aarch64: branch protection support
Related show

Commit Message

Szabolcs Nagy May 12, 2020, 10:14 a.m.
Use return address signing in assembly files when pac-ret
is enabled in the compiler.

The GNU property note for PAC-RET is not meaningful to the
dynamic linker so it is not strictly required, but it may
be used to track the security property of binaries.
(The PAC-RET property is only set if BTI is set too because
BTI implies working GNU property support.)
---
 sysdeps/aarch64/crti.S          |  8 ++++++++
 sysdeps/aarch64/crtn.S          |  6 ++++++
 sysdeps/aarch64/dl-tlsdesc.S    |  8 ++++++++
 sysdeps/aarch64/dl-trampoline.S | 18 ++++++++++++++++++
 sysdeps/aarch64/sysdep.h        |  8 +++++++-
 5 files changed, 47 insertions(+), 1 deletion(-)

-- 
2.17.1

Patch

diff --git a/sysdeps/aarch64/crti.S b/sysdeps/aarch64/crti.S
index 89a9e25f5b..1ac3d26c75 100644
--- a/sysdeps/aarch64/crti.S
+++ b/sysdeps/aarch64/crti.S
@@ -75,7 +75,11 @@  call_weak_fn:
 	.hidden	_init
 	.type	_init, %function
 _init:
+#ifdef HAVE_AARCH64_PAC_RET
+	PACIASP
+#else
 	BTI_C
+#endif
 	stp	x29, x30, [sp, -16]!
 	mov	x29, sp
 #if PREINIT_FUNCTION_WEAK
@@ -90,7 +94,11 @@  _init:
 	.hidden	_fini
 	.type	_fini, %function
 _fini:
+#ifdef HAVE_AARCH64_PAC_RET
+	PACIASP
+#else
 	BTI_C
+#endif
 	stp	x29, x30, [sp, -16]!
 	mov	x29, sp
 
diff --git a/sysdeps/aarch64/crtn.S b/sysdeps/aarch64/crtn.S
index 94a6f970ef..84741701f3 100644
--- a/sysdeps/aarch64/crtn.S
+++ b/sysdeps/aarch64/crtn.S
@@ -41,10 +41,16 @@ 
 
 	.section .init,"ax",%progbits
 	ldp	x29, x30, [sp], 16
+#ifdef HAVE_AARCH64_PAC_RET
+	AUTIASP
+#endif
 	RET
 
 	.section .fini,"ax",%progbits
 	ldp	x29, x30, [sp], 16
+#ifdef HAVE_AARCH64_PAC_RET
+	AUTIASP
+#endif
 	RET
 
 END_FILE
diff --git a/sysdeps/aarch64/dl-tlsdesc.S b/sysdeps/aarch64/dl-tlsdesc.S
index d55e0443aa..272952e4f5 100644
--- a/sysdeps/aarch64/dl-tlsdesc.S
+++ b/sysdeps/aarch64/dl-tlsdesc.S
@@ -183,6 +183,10 @@  _dl_tlsdesc_dynamic:
 	   callee will trash.  */
 
 	/* Save the remaining registers that we must treat as caller save.  */
+# ifdef HAVE_AARCH64_PAC_RET
+	PACIASP
+	cfi_window_save
+# endif
 # define NSAVEXREGPAIRS 8
 	stp	x29, x30, [sp,#-16*NSAVEXREGPAIRS]!
 	cfi_adjust_cfa_offset (16*NSAVEXREGPAIRS)
@@ -233,6 +237,10 @@  _dl_tlsdesc_dynamic:
 	cfi_adjust_cfa_offset (-16*NSAVEXREGPAIRS)
 	cfi_restore (x29)
 	cfi_restore (x30)
+# ifdef HAVE_AARCH64_PAC_RET
+	AUTIASP
+	cfi_window_save
+# endif
 	b	1b
 	cfi_endproc
 	.size	_dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
diff --git a/sysdeps/aarch64/dl-trampoline.S b/sysdeps/aarch64/dl-trampoline.S
index fba5689d09..3ff9bddc7b 100644
--- a/sysdeps/aarch64/dl-trampoline.S
+++ b/sysdeps/aarch64/dl-trampoline.S
@@ -127,7 +127,12 @@  _dl_runtime_resolve:
 	cfi_startproc
 	.align 2
 _dl_runtime_profile:
+# ifdef HAVE_AARCH64_PAC_RET
+	PACIASP
+	cfi_window_save
+# else
 	BTI_C
+# endif
 	/* AArch64 we get called with:
 	   ip0		&PLTGOT[2]
 	   ip1		temp(dl resolver entry point)
@@ -239,8 +244,17 @@  _dl_runtime_profile:
 	cfi_restore(x29)
 	cfi_restore(x30)
 
+# ifdef HAVE_AARCH64_PAC_RET
+	add	sp, sp, SF_SIZE
+	cfi_adjust_cfa_offset (-SF_SIZE)
+	AUTIASP
+	cfi_window_save
+	add	sp, sp, 16
+	cfi_adjust_cfa_offset (-16)
+# else
 	add	sp, sp, SF_SIZE + 16
 	cfi_adjust_cfa_offset (- SF_SIZE - 16)
+# endif
 
 	/* Jump to the newly found address.  */
 	br	ip0
@@ -287,6 +301,10 @@  _dl_runtime_profile:
 	/* LR from within La_aarch64_reg */
 	ldr	lr, [x29, #OFFSET_RG + DL_OFFSET_RG_LR]
 	cfi_restore(lr)
+# ifdef HAVE_AARCH64_PAC_RET
+	/* Note: LR restored from La_aarch64_reg has no PAC.  */
+	cfi_window_save
+# endif
 	mov	sp, x29
 	cfi_def_cfa_register (sp)
 	ldr	x29, [x29, #0]
diff --git a/sysdeps/aarch64/sysdep.h b/sysdeps/aarch64/sysdep.h
index 161d63c782..d8a5445b7e 100644
--- a/sysdeps/aarch64/sysdep.h
+++ b/sysdeps/aarch64/sysdep.h
@@ -45,6 +45,10 @@ 
 #define BTI_C		hint	34
 #define BTI_J		hint	36
 
+/* Return address signing support (pac-ret).  */
+#define PACIASP		hint	25
+#define AUTIASP		hint	29
+
 #define FEATURE_1_BTI 1
 #define FEATURE_1_PAC 2
 
@@ -62,7 +66,9 @@ 
   .word 0;
 
 /* GNU property note with the supported features.  */
-#ifdef HAVE_AARCH64_BTI
+#if defined HAVE_AARCH64_BTI && defined HAVE_AARCH64_PAC_RET
+# define END_FILE GNU_PROPERTY (FEATURE_1_BTI|FEATURE_1_PAC)
+#elif defined HAVE_AARCH64_BTI
 # define END_FILE GNU_PROPERTY (FEATURE_1_BTI)
 #else
 # define END_FILE