22467e2595
Similar to the function attribute `prefix` (prefix data), "patchable-function-prefix" inserts data (M NOPs) before the function entry label. -fpatchable-function-entry=2,1 (1 NOP before entry, 1 NOP after entry) will look like: ``` .type foo,@function .Ltmp0: # @foo nop foo: .Lfunc_begin0: # optional `bti c` (AArch64 Branch Target Identification) or # `endbr64` (Intel Indirect Branch Tracking) nop .section __patchable_function_entries,"awo",@progbits,get,unique,0 .p2align 3 .quad .Ltmp0 ``` -fpatchable-function-entry=N,0 + -mbranch-protection=bti/-fcf-protection=branch has two reasonable placements (https://gcc.gnu.org/ml/gcc-patches/2020-01/msg01185.html): ``` (a) (b) func: func: .Ltmp0: bti c bti c .Ltmp0: nop nop ``` (a) needs no additional code. If the consensus is to go for (b), we will need more code in AArch64BranchTargets.cpp / X86IndirectBranchTracking.cpp . Differential Revision: https://reviews.llvm.org/D73070
44 lines
1.3 KiB
LLVM
44 lines
1.3 KiB
LLVM
; RUN: llc -mtriple=aarch64 %s -o - | FileCheck --check-prefixes=CHECK %s
|
|
|
|
define void @f0() "patchable-function-entry"="0" "branch-target-enforcement" {
|
|
; CHECK-LABEL: f0:
|
|
; CHECK-NEXT: .Lfunc_begin0:
|
|
; CHECK: // %bb.0:
|
|
; CHECK-NEXT: hint #34
|
|
; CHECK-NEXT: ret
|
|
; CHECK-NOT: .section __patchable_function_entries
|
|
ret void
|
|
}
|
|
|
|
;; -fpatchable-function-entry=1 -mbranch-protection=bti
|
|
define void @f1() "patchable-function-entry"="1" "branch-target-enforcement" {
|
|
; CHECK-LABEL: f1:
|
|
; CHECK-NEXT: .Lfunc_begin1:
|
|
; CHECK: hint #34
|
|
; CHECK-NEXT: nop
|
|
; CHECK-NEXT: ret
|
|
; CHECK: .section __patchable_function_entries,"awo",@progbits,f1,unique,0
|
|
; CHECK-NEXT: .p2align 3
|
|
; CHECK-NEXT: .xword .Lfunc_begin1
|
|
ret void
|
|
}
|
|
|
|
;; -fpatchable-function-entry=2,1 -mbranch-protection=bti
|
|
define void @f2_1() "patchable-function-entry"="1" "patchable-function-prefix"="1" "branch-target-enforcement" {
|
|
; CHECK-LABEL: .type f2_1,@function
|
|
; CHECK-NEXT: .Ltmp0:
|
|
; CHECK-NEXT: nop
|
|
; CHECK-NEXT: f2_1:
|
|
; CHECK-NEXT: .Lfunc_begin2:
|
|
; CHECK: // %bb.0:
|
|
; CHECK-NEXT: hint #34
|
|
; CHECK-NEXT: nop
|
|
; CHECK-NEXT: ret
|
|
; CHECK: .Lfunc_end2:
|
|
; CHECK-NEXT: .size f2_1, .Lfunc_end2-f2_1
|
|
; CHECK: .section __patchable_function_entries,"awo",@progbits,f1,unique,0
|
|
; CHECK-NEXT: .p2align 3
|
|
; CHECK-NEXT: .xword .Ltmp0
|
|
ret void
|
|
}
|