[lld] [lld][AArch64][ELF][PAC] Support AUTH relocations and AUTH ELF marking (PR #72714)
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Mon Mar 18 00:48:10 PDT 2024
================
@@ -0,0 +1,228 @@
+# REQUIRES: aarch64
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+
+# RUN: llvm-mc -filetype=obj -triple=aarch64 %p/Inputs/shared2.s -o main.so.o
+# RUN: ld.lld -shared main.so.o -soname=so -o main.so
+# RUN: llvm-mc -filetype=obj -triple=aarch64 main.s -o main.o
+
+# RUN: ld.lld -pie main.o main.so -o main
+# RUN: llvm-readobj -r main | FileCheck --check-prefix=UNPACKED %s
+
+# UNPACKED: Section ({{.+}}) .rela.dyn {
+# UNPACKED-NEXT: 0x30470 R_AARCH64_AUTH_RELATIVE - 0x1
+# UNPACKED-NEXT: 0x30478 R_AARCH64_AUTH_RELATIVE - 0x30472
+# UNPACKED-NEXT: 0x30480 R_AARCH64_AUTH_RELATIVE - 0xFFFFFFFFFFFFFFFD
+# UNPACKED-NEXT: 0x30488 R_AARCH64_AUTH_RELATIVE - 0x12345678
+# UNPACKED-NEXT: 0x30490 R_AARCH64_AUTH_RELATIVE - 0x123456789A
+# UNPACKED-NEXT: 0x30498 R_AARCH64_AUTH_RELATIVE - 0xFFFFFFEDCBA98766
+# UNPACKED-NEXT: 0x304A0 R_AARCH64_AUTH_RELATIVE - 0x8003046F
+# UNPACKED-NEXT: 0x304B9 R_AARCH64_AUTH_RELATIVE - 0x4
+# UNPACKED-NEXT: 0x304C2 R_AARCH64_AUTH_RELATIVE - 0x30475
+# UNPACKED-NEXT: 0x304A8 R_AARCH64_AUTH_ABS64 zed2 0x1111
+# UNPACKED-NEXT: 0x304B0 R_AARCH64_AUTH_ABS64 bar2 0x0
+# UNPACKED-NEXT: }
+
+# RUN: ld.lld main.o main.so -o main.nopie
+# RUN: llvm-readobj -r main.nopie | FileCheck --check-prefix=NOPIE %s
+
+# NOPIE: Section ({{.+}}) .rela.dyn {
+# NOPIE: 0x230460 R_AARCH64_AUTH_RELATIVE - 0x200001
+# NOPIE-NEXT: 0x230468 R_AARCH64_AUTH_RELATIVE - 0x230462
+# NOPIE-NEXT: 0x230470 R_AARCH64_AUTH_RELATIVE - 0x1FFFFD
+# NOPIE-NEXT: 0x230478 R_AARCH64_AUTH_RELATIVE - 0x12545678
+# NOPIE-NEXT: 0x230480 R_AARCH64_AUTH_RELATIVE - 0x123476789A
+# NOPIE-NEXT: 0x230488 R_AARCH64_AUTH_RELATIVE - 0xFFFFFFEDCBC98766
+# NOPIE-NEXT: 0x230490 R_AARCH64_AUTH_RELATIVE - 0x8023045F
+# NOPIE-NEXT: 0x2304A9 R_AARCH64_AUTH_RELATIVE - 0x200004
+# NOPIE-NEXT: 0x2304B2 R_AARCH64_AUTH_RELATIVE - 0x230465
+# NOPIE-NEXT: 0x230498 R_AARCH64_AUTH_ABS64 zed2 0x1111
+# NOPIE-NEXT: 0x2304A0 R_AARCH64_AUTH_ABS64 bar2 0x0
+# NOPIE-NEXT: }
+
+# RUN: ld.lld -pie -z pack-relative-relocs main.o main.so -o main.pie
+# RUN: llvm-readelf -S -d -r -x .test main.pie | FileCheck --check-prefixes=RELR,HEX %s
+
+# RELR: Section Headers:
+# RELR-NEXT: Name Type Address Off Size ES Flg Lk Inf Al
+# RELR: .rela.dyn RELA {{0*}}[[ADDR1:.*]] {{0*}}[[ADDR1]] 000090 18 A 1 0 8
+# RELR: .relr.auth.dyn AARCH64_AUTH_RELR {{0*}}[[ADDR2:.*]] {{0*}}[[ADDR2]] 000018 08 A 0 0 8
+
+# RELR: Dynamic section at offset {{.*}} contains 16 entries
+# RELR: 0x0000000070000012 (AARCH64_AUTH_RELR) 0x[[ADDR2]]
+# RELR-NEXT: 0x0000000070000011 (AARCH64_AUTH_RELRSZ) 24 (bytes)
+# RELR-NEXT: 0x0000000070000013 (AARCH64_AUTH_RELRENT) 8 (bytes)
+
+## Decoded SHT_RELR section is same as UNPACKED,
+## but contains only the relative relocations.
+## Any relative relocations with odd offset or value wider than 32 bits stay in SHT_RELA.
+
+# RELR: Relocation section '.rela.dyn' at offset 0x[[ADDR1]] contains 6 entries:
+# RELR-NEXT: Offset Info Type Symbol's Value Symbol's Name + Addend
+# RELR-NEXT: 0000000000030460 0000000000000411 R_AARCH64_AUTH_RELATIVE 123456789a
+# RELR-NEXT: 0000000000030468 0000000000000411 R_AARCH64_AUTH_RELATIVE ffffffedcba98766
+# RELR-NEXT: 0000000000030470 0000000000000411 R_AARCH64_AUTH_RELATIVE 8003043f
+# RELR-NEXT: 0000000000030489 0000000000000411 R_AARCH64_AUTH_RELATIVE 4
+# RELR-NEXT: 0000000000030478 0000000100000244 R_AARCH64_AUTH_ABS64 0000000000000000 zed2 + 1111
+# RELR-NEXT: 0000000000030480 0000000200000244 R_AARCH64_AUTH_ABS64 0000000000000000 bar2 + 0
+# RELR-EMPTY:
+# RELR-NEXT: Relocation section '.relr.auth.dyn' at offset 0x[[ADDR2]] contains 5 entries:
+# RELR-NEXT: Offset Info Type Symbol's Value Symbol's Name
+# RELR-NEXT: 0000000000030440 0000000000000403 R_AARCH64_RELATIVE
+# RELR-NEXT: 0000000000030448 0000000000000403 R_AARCH64_RELATIVE
+# RELR-NEXT: 0000000000030450 0000000000000403 R_AARCH64_RELATIVE
+# RELR-NEXT: 0000000000030458 0000000000000403 R_AARCH64_RELATIVE
+# RELR-NEXT: 0000000000030492 0000000000000403 R_AARCH64_RELATIVE
+
+# RUN: llvm-readobj -r --raw-relr main.pie | \
+# RUN: FileCheck --match-full-lines --check-prefix=RAW-RELR %s
+
+## SHT_RELR section contains address/bitmap entries
+## encoding the offsets for relative relocation.
+
+# RAW-RELR: Section ({{.+}}) .relr.auth.dyn {
+# RAW-RELR-NEXT: 0x30440
+# RAW-RELR-NEXT: 0xF
+## 0xF = 0b111100..00
+## lsb hsb
+## Bits 1..3 are set, we have relocs at 0x30440 and the next 3 places: 0x30448, 0x3450, 0x30458
+# RAW-RELR-NEXT: 0x30492
+## A single reloc at ^^^^^^^
+# RAW-RELR-NEXT: }
+
+# HEX: Hex dump of section '.test':
+# HEX-NEXT: 0x00030440 01000000 2a000020 42040300 2b000000
+## ^^^^^^^^ Implicit val = 1 = __ehdr_start + 1
+## ^^^^ Discr = 42
+## ^^ Key (bits 5..6) = DA
+## ^^^^^^^^ Implicit val = 0x30442 = 0x30440 + 2 = .test + 2
+## ^^^^ Discr = 43
+## ^^ Key (bits 5..6) = IA
+# HEX-NEXT: 0x00030450 fdffffff 2c000080 78563412 2d000020
+## ^^^^^^^^ Implicit val = -3 = __ehdr_start - 3
+## ^^^^ Discr = 44
+## ^^ Key (bits 5..6) = IA
+## ^^ Addr diversity (bit 7) = true
+## ^^^^^^^^ Implicit val = 0x12345678 = __ehdr_start + 0x12345678
+## ^^^^ Discr = 45
+## ^^ Key (bits 5..6) = DA
+# HEX-NEXT: 0x00030460 00000000 2e000020 00000000 2f000020
+## ^^^^^^^^ No implicit val (rela reloc due val wider than 32 bits)
+## ^^^^ Discr = 46
+## ^^ Key (bits 5..6) = DA
+## ^^^^^^^^ No implicit val (rela reloc due to val wider than 32 bits)
+## ^^^^ Discr = 47
+## ^^ Key (bits 5..6) = DA
+# HEX-NEXT: 0x00030470 00000000 30000020 00000000 31000020
+## ^^^^^^^^ No implicit val (rela reloc due val wider than 32 bits)
+## ^^^^ Discr = 48
+## ^^ Key (bits 5..6) = DA
+## ^^^^^^^^ No implicit val (rela reloc due to a preemptible symbol)
+## ^^^^ Discr = 49
+## ^^ Key (bits 5..6) = DA
+# HEX-NEXT: 0x00030480 00000000 32000000 77000000 00330000
+## ^^^^^^^^ No implicit val (rela reloc due to a preemptible symbol)
+## ^^^^ Discr = 50
+## ^^ Key (bits 5..6) = IA
+## ^^^^^^ ^^ No implicit val (rela reloc due to odd offset)
+## ^^^^ Discr = 51
+# HEX-NEXT: 0x00030490 20774504 03003400 0020{{\ }}
+## ^^ Key (bits 5..6) = DA
+## ^^^^ ^^^^ Implicit val = 0x30445 = 0x30440 + 5 = .test + 5
+## ^^^^ Discr = 52
+## ^^ Key (bits 5..6) = DA
+
+#--- main.s
+
+.section .test, "aw"
+.p2align 3
+.quad (__ehdr_start + 1)@AUTH(da,42)
+.quad (.test + 2)@AUTH(ia,43)
+.quad (__ehdr_start - 3)@AUTH(ia,44,addr)
+.quad (__ehdr_start + 0x12345678)@AUTH(da,45)
+## Addend wider than 32 bits, not enough room for storing implicitly, would go to rela
+.quad (__ehdr_start + 0x123456789A)@AUTH(da,46)
+## Negative addend wider than 32 bits, not enough room for storing implicitly, would go to rela
+.quad (__ehdr_start - 0x123456789A)@AUTH(da,47)
+## INT32_MAX plus non-zero .test is wider than 32 bits, not enough room for storing implicitly, would go to rela
+.quad (.test + 0x7FFFFFFF)@AUTH(da,48)
+.quad (zed2 + 0x1111)@AUTH(da,49)
+.quad bar2 at AUTH(ia,50)
+.byte 0x77
+.quad (__ehdr_start + 4)@AUTH(da,51)
+.byte 0x77
+.quad (.test + 5)@AUTH(da,52)
+
+#--- empty-relr.s
+
+## During relocation scanning, we might put some AUTH relocs into the packed
+## relocation section when not knowing the final implicit value to be stored in
+## the place to be relocated. If the value turns out to be wider than 32 bits
+## after computing the final layout, we convert the relocation from relr to
+## rela. A side effect is having an empty .relr.auth.dyn section if all the
+## packed relocations were converted to rela.
+## TODO: avoid empty .relr.auth.dyn in the output binary
----------------
MaskRay wrote:
This TODO may be impractical to implement. We have such cases in tests, and we just avoid using "TODO". Simplify the comment:
.relr.auth.dyn relocations that do not fit 32-bit are moved to .relr.dyn. In this case .relr.auth.dyn will be makde empty, but removeUnusedSyntheticSections fails to remove the section.
https://github.com/llvm/llvm-project/pull/72714
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