[lld][AArch64][ELF][PAC] Support `.relr.auth.dyn` section (#87635)

Support `R_AARCH64_AUTH_RELATIVE` relocation compression as described in
https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#relocation-compression

1 files changed, 132 insertions, 34 deletions

diff --git a/lld/test/ELF/aarch64-reloc-pauth.s b/lld/test/ELF/aarch64-reloc-pauth.s
index b603d8f..f1ce29e 100644
--- a/lld/test/ELF/aarch64-reloc-pauth.s
+++ b/lld/test/ELF/aarch64-reloc-pauth.s
@@ -1,11 +1,13 @@
 # REQUIRES: aarch64
 
-# RUN: llvm-mc -filetype=obj -triple=aarch64 %p/Inputs/shared2.s -o %t.a.o
-# RUN: ld.lld -shared %t.a.o -soname=so -o %t.a.so
-# RUN: llvm-mc -filetype=obj -triple=aarch64 %s -o %t.o
+# RUN: rm -rf %t && split-file %s %t && cd %t
 
-# RUN: ld.lld -pie %t.o %t.a.so -o %t
-# RUN: llvm-readobj -r %t | FileCheck --check-prefix=UNPACKED %s
+# RUN: llvm-mc -filetype=obj -triple=aarch64 %p/Inputs/shared2.s -o a.o
+# RUN: ld.lld -shared a.o -soname=so -o a.so
+# RUN: llvm-mc -filetype=obj -triple=aarch64 main.s -o main.o
+
+# RUN: ld.lld -pie main.o a.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
@@ -21,8 +23,8 @@
 # UNPACKED-NEXT:       0x304B0 R_AARCH64_AUTH_ABS64 bar2 0x0
 # UNPACKED-NEXT:     }
 
-# RUN: ld.lld %t.o %t.a.so -o %t.nopie
-# RUN: llvm-readobj -r %t.nopie | FileCheck --check-prefix=NOPIE %s
+# RUN: ld.lld main.o a.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
@@ -38,67 +40,95 @@
 # NOPIE-NEXT:   0x2304A0 R_AARCH64_AUTH_ABS64 bar2 0x0
 # NOPIE-NEXT: }
 
-# RUN: ld.lld -pie %t.o %t.a.so -o %t.pie
-# RUN: llvm-readelf -S -d -r -x .test %t.pie | FileCheck --check-prefixes=PIE,HEX %s
-
-# PIE:      Section Headers:
-# PIE-NEXT: Name Type Address Off Size ES Flg Lk Inf Al
-# PIE:      .rela.dyn RELA {{0*}}[[#%x,ADDR1:]]
-# PIE-SAME:                                     {{0*}}[[#ADDR1]] 000108 18 A 1 0 8
-
-# PIE:      Relocation section '.rela.dyn' at offset 0x[[#ADDR1]] contains 11 entries:
-# PIE-NEXT:     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
-# PIE-NEXT: 0000000000030470  0000000000000411 R_AARCH64_AUTH_RELATIVE 1
-# PIE-NEXT: 0000000000030478  0000000000000411 R_AARCH64_AUTH_RELATIVE 30472
-# PIE-NEXT: 0000000000030480  0000000000000411 R_AARCH64_AUTH_RELATIVE fffffffffffffffd
-# PIE-NEXT: 0000000000030488  0000000000000411 R_AARCH64_AUTH_RELATIVE 12345678
-# PIE-NEXT: 0000000000030490  0000000000000411 R_AARCH64_AUTH_RELATIVE 123456789a
-# PIE-NEXT: 0000000000030498  0000000000000411 R_AARCH64_AUTH_RELATIVE ffffffedcba98766
-# PIE-NEXT: 00000000000304a0  0000000000000411 R_AARCH64_AUTH_RELATIVE 8003046f
-# PIE-NEXT: 00000000000304b9  0000000000000411 R_AARCH64_AUTH_RELATIVE 4
-# PIE-NEXT: 00000000000304c2  0000000000000411 R_AARCH64_AUTH_RELATIVE 30475
-# PIE-NEXT: 00000000000304a8  0000000100000244 R_AARCH64_AUTH_ABS64   0000000000000000 zed2 + 1111
-# PIE-NEXT: 00000000000304b0  0000000200000244 R_AARCH64_AUTH_ABS64   0000000000000000 bar2 + 0
+# RUN: ld.lld -pie -z pack-relative-relocs main.o a.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: Index: Entry Address Symbolic Address
+# RELR-NEXT: 0000: 0000000000030440 0000000000030440 $d.0
+# RELR-NEXT: 0001: 000000000000000f 0000000000030448 $d.0 + 0x8
+# RELR-NEXT:  0000000000030450 $d.0 + 0x10
+# RELR-NEXT:  0000000000030458 $d.0 + 0x18
+# RELR-NEXT: 0002: 0000000000030492 0000000000030492 $d.0 + 0x52
 
 # HEX:      Hex dump of section '.test':
-# HEX-NEXT: 0x00030470 00000000 2a000020 00000000 2b000000
+# 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: 0x00030480 00000000 2c000080 00000000 2d000020
+# 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: 0x00030490 00000000 2e000020 00000000 2f000020
+# 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: 0x000304a0 00000000 30000020 00000000 31000020
+# 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: 0x000304b0 00000000 32000000 77000000 00330000
+# 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: 0x000304c0 20770000 00003400 0020{{\ }}
+# 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@AUTH(ia,50)
@@ -106,3 +136,71 @@
 .quad (__ehdr_start + 4)@AUTH(da,51)
 .byte 0x77
 .quad (.test + 5)@AUTH(da,52)
+
+#--- empty-relr.s
+
+## .relr.auth.dyn relocations that do not fit 32 bits are moved to .rela.dyn.
+## In this case .relr.auth.dyn will be made empty, but
+## removeUnusedSyntheticSections fails to remove the section.
+
+# RUN: llvm-mc -filetype=obj -triple=aarch64 empty-relr.s -o empty-relr.o
+# RUN: ld.lld -pie -z pack-relative-relocs empty-relr.o -o empty-relr
+# RUN: llvm-readelf -S -d -r empty-relr | FileCheck --check-prefixes=EMPTY-RELR %s
+
+# EMPTY-RELR:      Section Headers:
+# EMPTY-RELR-NEXT: Name Type Address Off Size ES Flg Lk Inf Al
+# EMPTY-RELR:      .rela.dyn RELA {{0*}}[[ADDR1:.+]] {{0*}}[[ADDR1]] 000018 18 A 0 0 8
+# EMPTY-RELR:      .relr.auth.dyn AARCH64_AUTH_RELR {{0*}}[[ADDR2:.+]] {{0*}}[[ADDR2]] 000000 08 A 0 0 8
+
+# EMPTY-RELR:      Dynamic section at offset {{.+}} contains 12 entries
+# EMPTY-RELR-NOT:  (AARCH64_AUTH_RELR)
+# EMPTY-RELR-NOT:  (AARCH64_AUTH_RELRSZ)
+# EMPTY-RELR-NOT:  (AARCH64_AUTH_RELRENT)
+# EMPTY-RELR:      0x0000000000000007 (RELA) 0x[[ADDR1]]
+# EMPTY-RELR-NEXT: 0x0000000000000008 (RELASZ) 24 (bytes)
+# EMPTY-RELR-NEXT: 0x0000000000000009 (RELAENT) 24 (bytes)
+
+# EMPTY-RELR:      Relocation section '.rela.dyn' at offset {{.+}} contains 1 entries:
+# EMPTY-RELR-NEXT:     Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
+# EMPTY-RELR-NEXT: 0000000000030320  0000000000000411 R_AARCH64_AUTH_RELATIVE           8003031f
+# EMPTY-RELR-EMPTY:
+# EMPTY-RELR-NEXT: Relocation section '.relr.auth.dyn' at offset {{.+}} contains 0 entries:
+# EMPTY-RELR-NEXT: Index: Entry Address Symbolic Address
+
+.section .test, "aw"
+.p2align 3
+.quad (.test + 0x7FFFFFFF)@AUTH(da,42)
+
+#--- empty-rela.s
+
+## .relr.auth.dyn relocations that do not fit 32 bits are moved to .rela.dyn.
+## If this scenario does not happen, .rela.dyn will remain empty,
+## but removeUnusedSyntheticSections fails to remove the section.
+
+# RUN: llvm-mc -filetype=obj -triple=aarch64 empty-rela.s -o empty-rela.o
+# RUN: ld.lld -pie -z pack-relative-relocs empty-rela.o -o empty-rela
+# RUN: llvm-readelf -S -d -r empty-rela | FileCheck --check-prefixes=EMPTY-RELA %s
+
+# EMPTY-RELA:      Section Headers:
+# EMPTY-RELA-NEXT: Name Type Address Off Size ES Flg Lk Inf Al
+# EMPTY-RELA:      .rela.dyn RELA {{0*}}[[ADDR1:.+]] {{0*}}[[ADDR1]] 000000 18 A 0 0 8
+# EMPTY-RELA:      .relr.auth.dyn AARCH64_AUTH_RELR {{0*}}[[ADDR2:.+]] {{0*}}[[ADDR2]] 000008 08 A 0 0 8
+
+# EMPTY-RELA:      Dynamic section at offset {{.+}} contains 12 entries
+# EMPTY-RELA-NOT:  (RELR)
+# EMPTY-RELA-NOT:  (RELRSZ)
+# EMPTY-RELA-NOT:  (RELRENT)
+# EMPTY-RELA:      0x0000000070000012 (AARCH64_AUTH_RELR) 0x[[ADDR2]]
+# EMPTY-RELA-NEXT: 0x0000000070000011 (AARCH64_AUTH_RELRSZ) 8 (bytes)
+# EMPTY-RELA-NEXT: 0x0000000070000013 (AARCH64_AUTH_RELRENT) 8 (bytes)
+
+# EMPTY-RELA:      Relocation section '.rela.dyn' at offset {{.+}} contains 0 entries:
+# EMPTY-RELA-NEXT:     Offset             Info             Type               Symbol's Value  Symbol's Name
+# EMPTY-RELA-EMPTY:
+# EMPTY-RELA-NEXT: Relocation section '.relr.auth.dyn' at offset {{.+}} contains 1 entries:
+# EMPTY-RELA-NEXT: Index: Entry Address Symbolic Address
+# EMPTY-RELA-NEXT: 0000: 0000000000030310 0000000000030310 $d.0
+
+.section .test, "aw"
+.p2align 3
+.quad (.test + 0x12345678)@AUTH(da,42)