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[AArch64][BTI] Add BTI hint + GNU property to fcontext trampolines #312

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Merged
merged 1 commit into from
Aug 26, 2025
Merged

[AArch64][BTI] Add BTI hint + GNU property to fcontext trampolines #312

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18 changes: 18 additions & 0 deletions src/asm/jump_arm64_aapcs_elf_gas.S
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Original file line number Diff line number Diff line change
Expand Up @@ -53,11 +53,29 @@

.file "jump_arm64_aapcs_elf_gas.S"
.text
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
/* Mark this object as requiring BTI, enabling the linker to set BTI on the output */
.pushsection .note.gnu.property, "a", %note
.p2align 3
.long 4 /* namesz */
.long 16 /* descsz (16 bytes) */
.long 5 /* type = NT_GNU_PROPERTY_TYPE_0 */
.asciz "GNU"
.p2align 3
.long 0xc0000000 /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */
.long 4 /* datasz = 4 */
.long 1 /* GNU_PROPERTY_AARCH64_FEATURE_1_BTI */
.long 0 /* pad to 8-byte alignment */
.popsection
#endif
.align 2
.global jump_fcontext
.hidden jump_fcontext
.type jump_fcontext, %function
jump_fcontext:
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
hint #34 /* bti c: valid indirect-entry target */
#endif
# prepare stack for GP + FPU
sub sp, sp, #0xb0

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18 changes: 18 additions & 0 deletions src/asm/make_arm64_aapcs_elf_gas.S
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Expand Up @@ -53,11 +53,29 @@

.file "make_arm64_aapcs_elf_gas.S"
.text
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
/* Mark this object as requiring BTI, enabling the linker to set BTI on the output */
.pushsection .note.gnu.property, "a", %note
.p2align 3
.long 4 /* namesz */
.long 16 /* descsz (16 bytes) */
.long 5 /* type = NT_GNU_PROPERTY_TYPE_0 */
.asciz "GNU"
.p2align 3
.long 0xc0000000 /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */
.long 4 /* datasz = 4 */
.long 1 /* GNU_PROPERTY_AARCH64_FEATURE_1_BTI */
.long 0 /* pad to 8-byte alignment */
.popsection
#endif
.align 2
.global make_fcontext
.hidden make_fcontext
.type make_fcontext, %function
make_fcontext:
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
hint #34 /* bti c */
#endif
# shift address in x0 (allocated stack) to lower 16 byte boundary
and x0, x0, ~0xF

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18 changes: 18 additions & 0 deletions src/asm/ontop_arm64_aapcs_elf_gas.S
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Original file line number Diff line number Diff line change
Expand Up @@ -53,11 +53,29 @@

.file "ontop_arm64_aapcs_elf_gas.S"
.text
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
/* Mark this object as requiring BTI, enabling the linker to set BTI on the output */
.pushsection .note.gnu.property, "a", %note
.p2align 3
.long 4 /* namesz */
.long 16 /* descsz (16 bytes) */
.long 5 /* type = NT_GNU_PROPERTY_TYPE_0 */
.asciz "GNU"
.p2align 3
.long 0xc0000000 /* GNU_PROPERTY_AARCH64_FEATURE_1_AND */
.long 4 /* datasz = 4 */
.long 1 /* GNU_PROPERTY_AARCH64_FEATURE_1_BTI */
.long 0 /* pad to 8-byte alignment */
.popsection
#endif
.align 2
.global ontop_fcontext
.hidden ontop_fcontext
.type ontop_fcontext, %function
ontop_fcontext:
#if defined(__ARM_FEATURE_BTI_DEFAULT) && (__ARM_FEATURE_BTI_DEFAULT == 1)
hint #34 /* bti c */
#endif
# prepare stack for GP + FPU
sub sp, sp, #0xb0

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