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aarch64: enable PAC and BTI #39

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aarch64: enable PAC and BTI #39

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32 changes: 32 additions & 0 deletions Asm/arm64/LzmaDecOpt.S
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,38 @@
; LzmaDec_DecodeReal_*() must be equal in both versions (C / ASM).
*/

/*
; AAarch64 PAC and BTI Support.
;
; Assembly:
; Since this code base has no indirect calls or jumps to any assembly,
; there is no need to modify the source code with bti or pac instructions.
;
; GNU Notes:
; BTI requires the GNU Elf notes section in order to be enabled. This is
; because linkers/loaders look at this section to determine page protections,
; specifically PROT_BTI when mapping in the instructions. PAC is a nice to
; have for auditing purposes. Note that unconditionally adding PAC and BTI here
; is OK since the linker will just discard the note for the produced linked
; object file.
*/
#if defined(__ELF__)
/* Define the property values for GNU notes section in ELF */
#define GNU_PROPERTY_AARCH64_BTI 0x1
#define GNU_PROPERTY_AARCH64_POINTER_AUTH 0x2

.pushsection .note.gnu.property, "a";
.balign 8;
.long 4;
.long 0x10;
.long 0x5;
.asciz "GNU";
.long 0xc0000000; /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */
.long 4;
.long(GNU_PROPERTY_AARCH64_POINTER_AUTH | GNU_PROPERTY_AARCH64_BTI);
.long 0;
.popsection;
#endif

#include "7zAsm.S"

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