Rémi Denis-Courmont pushed to branch master at VideoLAN / VLC
Commits:
6550059e by Rémi Denis-Courmont at 2022-02-06T07:14:38+00:00
aarch64: advertise assembler BTI support
As per the AArch64 ELF ABI, object files that support BTI need to
advertise it via a dedicated Linux ELF object file property in an ELF
note section. The linker can then check if all input object files
support the feature to advertise it at the shared object or executable
level.
In the case of BTI, this is necessary to enable the guarded page bit
in the memory mapping for BTI-capable .text sections.
This defines a macro to populate the note section and uses it.
- - - - -
3 changed files:
- modules/isa/arm/asm.S
- modules/video_filter/deinterlace/merge_arm64.S
- modules/video_filter/deinterlace/merge_sve.S
Changes:
=====================================
modules/isa/arm/asm.S
=====================================
@@ -39,6 +39,36 @@
EXTERN_ASM\name:
.endm
+#ifdef __ELF__
+.macro bti_advertise
+/* See SysV ABI Linux extensions */
+#define NT_GNU_PROPERTY_TYPE_0 5
+
+/* See ARM IHI0056 */
+#define GNU_PROPERTY_AARCH64_FEATURE_1_AND 0xc0000000
+#define GNU_PROPERTY_AARCH64_FEATURE_1_BTI 0x00000001
+#define GNU_PROPERTY_AARCH64_FEATURE_1_PAC 0x00000002
+
+ .pushsection .note.gnu.property, "a"
+ .align 3
+ .word 2f - 1f
+ .word 4f - 3f
+ .word NT_GNU_PROPERTY_TYPE_0
+1: .asciz "GNU"
+
+2: .align 3
+3: .word GNU_PROPERTY_AARCH64_FEATURE_1_AND /* type */
+ .word 6f - 5f /* size */
+5: .word GNU_PROPERTY_AARCH64_FEATURE_1_BTI /* value */
+
+6: .align 3
+4: .popsection
+.endm
+#else
+.macro bti_advertise
+.endm
+#endif
+
.macro bti targets=
.ifb \targets
hint #32
=====================================
modules/video_filter/deinterlace/merge_arm64.S
=====================================
@@ -23,6 +23,7 @@
.arch armv8-a+simd
.text
+ bti_advertise
#define DEST x0
#define SRC1 x1
=====================================
modules/video_filter/deinterlace/merge_sve.S
=====================================
@@ -25,6 +25,7 @@
/* TODO: prefetch, unroll */
.text
+ bti_advertise
function merge8_arm_sve
bti c
mov x4, #0
View it on GitLab:
https://code.videolan.org/videolan/vlc/-/commit/6550059ef2cd9751f39661b1b60b83c27c58696b
--
View it on GitLab:
https://code.videolan.org/videolan/vlc/-/commit/6550059ef2cd9751f39661b1b60b83c27c58696b
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