[ELF] Handle relocations in synthetic .eh_frame with a non-zero offset within the output section

lld/ELF/Arch/AArch64.cpp

@@ -770,6 +770,8 @@ void AArch64::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
   uint64_t secAddr = sec.getOutputSection()->addr;
   if (auto *s = dyn_cast<InputSection>(&sec))
     secAddr += s->outSecOff;
+  else if (auto *ehIn = dyn_cast<EhInputSection>(&sec))
+    secAddr += ehIn->getParent()->outSecOff;
   AArch64Relaxer relaxer(sec.relocs());
   for (size_t i = 0, size = sec.relocs().size(); i != size; ++i) {
     const Relocation &rel = sec.relocs()[i];

lld/ELF/Arch/PPC64.cpp

@@ -1563,6 +1563,8 @@ void PPC64::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
   uint64_t secAddr = sec.getOutputSection()->addr;
   if (auto *s = dyn_cast<InputSection>(&sec))
     secAddr += s->outSecOff;
+  else if (auto *ehIn = dyn_cast<EhInputSection>(&sec))
+    secAddr += ehIn->getParent()->outSecOff;
   uint64_t lastPPCRelaxedRelocOff = -1;
   for (const Relocation &rel : sec.relocs()) {
     uint8_t *loc = buf + rel.offset;

lld/ELF/Arch/X86_64.cpp

@@ -989,6 +989,8 @@ void X86_64::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
   uint64_t secAddr = sec.getOutputSection()->addr;
   if (auto *s = dyn_cast<InputSection>(&sec))
     secAddr += s->outSecOff;
+  else if (auto *ehIn = dyn_cast<EhInputSection>(&sec))
+    secAddr += ehIn->getParent()->outSecOff;
   for (const Relocation &rel : sec.relocs()) {
     if (rel.expr == R_NONE) // See deleteFallThruJmpInsn
       continue;

lld/ELF/SyntheticSections.cpp

@@ -583,13 +583,14 @@ static uint64_t readFdeAddr(uint8_t *buf, int size) {
 uint64_t EhFrameSection::getFdePc(uint8_t *buf, size_t fdeOff,
                                   uint8_t enc) const {
   // The starting address to which this FDE applies is
-  // stored at FDE + 8 byte.
+  // stored at FDE + 8 byte. And this offset is within
+  // the .eh_frame section.
   size_t off = fdeOff + 8;
   uint64_t addr = readFdeAddr(buf + off, enc & 0xf);
   if ((enc & 0x70) == DW_EH_PE_absptr)
     return addr;
   if ((enc & 0x70) == DW_EH_PE_pcrel)
-    return addr + getParent()->addr + off;
+    return addr + getParent()->addr + off + outSecOff;
   fatal("unknown FDE size relative encoding");
 }
 

lld/ELF/Target.cpp

@@ -159,6 +159,8 @@ void TargetInfo::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
   uint64_t secAddr = sec.getOutputSection()->addr;
   if (auto *s = dyn_cast<InputSection>(&sec))
     secAddr += s->outSecOff;
+  else if (auto *ehIn = dyn_cast<EhInputSection>(&sec))
+    secAddr += ehIn->getParent()->outSecOff;
   for (const Relocation &rel : sec.relocs()) {
     uint8_t *loc = buf + rel.offset;
     const uint64_t val = SignExtend64(

lld/test/ELF/eh-frame-nonzero-offset-aarch64.s

@@ -0,0 +1,53 @@
+// REQUIRES: aarch64
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+// RUN: llvm-mc -filetype=obj -triple=aarch64 a.s -o a.o
+// RUN: ld.lld a.o -T eh-frame-non-zero-offset.t -o non-zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame non-zero | FileCheck --check-prefix=NONZERO %s
+// RUN: ld.lld a.o -T eh-frame-zero-offset.t -o zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame zero | FileCheck --check-prefix=ZERO %s
+
+// NONZERO:      {{[0-9]+}}: 0000000000000088 {{.*}} __eh_frame_start
+// NONZERO-NEXT: {{[0-9]+}}: 00000000000000b4 {{.*}} __eh_frame_end
+
+// NONZERO:      0x00000088 10000000 00000000 017a5200 017c1e01
+// NONZERO-NEXT: 0x00000098 1b0c1f00 10000000 18000000 5cffffff
+// NONZERO-NEXT: 0x000000a8 04000000 00000000 00000000
+
+// ZERO:      {{[0-9]+}}: 0000000000000008 {{.*}} __eh_frame_start
+// ZERO-NEXT: {{[0-9]+}}: 0000000000000034 {{.*}} __eh_frame_end
+
+// ZERO:      0x00000008 10000000 00000000 017a5200 017c1e01
+// ZERO-NEXT: 0x00000018 1b0c1f00 10000000 18000000 dcffffff
+// ZERO-NEXT: 0x00000028 04000000 00000000 00000000
+
+//--- eh-frame-non-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    /* Padding within .eh_frame */
+    . += 128;
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- eh-frame-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- a.s
+.section .text.01, "ax",%progbits
+.global f1
+.type f1, %function
+f1:
+.cfi_startproc
+.space 4
+.cfi_endproc

lld/test/ELF/eh-frame-nonzero-offset-arm.s

@@ -0,0 +1,54 @@
+// REQUIRES: arm
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+// RUN: llvm-mc -filetype=obj -triple=arm a.s -o a.o
+// RUN: ld.lld a.o -T eh-frame-non-zero-offset.t -o non-zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame non-zero | FileCheck --check-prefix=NONZERO %s
+// RUN: ld.lld a.o -T eh-frame-zero-offset.t -o zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame zero | FileCheck --check-prefix=ZERO %s
+
+// NONZERO:      {{[0-9]+}}: 00000084 {{.*}} __eh_frame_start
+// NONZERO-NEXT: {{[0-9]+}}: 000000b0 {{.*}} __eh_frame_end
+
+// NONZERO:      0x00000084 10000000 00000000 017a5200 017c0e01
+// NONZERO-NEXT: 0x00000094 1b0c0d00 10000000 18000000 60ffffff
+// NONZERO-NEXT: 0x000000a4 04000000 00000000 00000000
+
+// ZERO:      {{[0-9]+}}: 00000004 {{.*}} __eh_frame_start
+// ZERO-NEXT: {{[0-9]+}}: 00000030 {{.*}} __eh_frame_end
+
+// ZERO:      0x00000004 10000000 00000000 017a5200 017c0e01
+// ZERO-NEXT: 0x00000014 1b0c0d00 10000000 18000000 e0ffffff
+// ZERO-NEXT: 0x00000024 04000000 00000000 00000000
+
+//--- eh-frame-non-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    /* Padding within .eh_frame */
+    . += 128;
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- eh-frame-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- a.s
+.section .text.01, "ax",%progbits
+.global f1
+.type f1, %function
+f1:
+.cfi_startproc
+.cfi_sections .eh_frame
+.space 4
+.cfi_endproc

lld/test/ELF/eh-frame-nonzero-offset-ppc.s

@@ -0,0 +1,53 @@
+// REQUIRES: ppc
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+// RUN: llvm-mc -filetype=obj -triple=ppc64le a.s -o a.o
+// RUN: ld.lld a.o -T eh-frame-non-zero-offset.t -o non-zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame non-zero | FileCheck --check-prefix=NONZERO %s
+// RUN: ld.lld a.o -T eh-frame-zero-offset.t -o zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame zero | FileCheck --check-prefix=ZERO %s
+
+// NONZERO:      {{[0-9]+}}: 0000000000000088 {{.*}} __eh_frame_start
+// NONZERO-NEXT: {{[0-9]+}}: 00000000000000b4 {{.*}} __eh_frame_end
+
+// NONZERO:      0x00000088 10000000 00000000 017a5200 04784101
+// NONZERO-NEXT: 0x00000098 1b0c0100 10000000 18000000 5cffffff
+// NONZERO-NEXT: 0x000000a8 04000000 00000000 00000000
+
+// ZERO:      {{[0-9]+}}: 0000000000000008 {{.*}} __eh_frame_start
+// ZERO-NEXT: {{[0-9]+}}: 0000000000000034 {{.*}} __eh_frame_end
+
+// ZERO:      0x00000008 10000000 00000000 017a5200 04784101
+// ZERO-NEXT: 0x00000018 1b0c0100 10000000 18000000 dcffffff
+// ZERO-NEXT: 0x00000028 04000000 00000000 00000000
+
+//--- eh-frame-non-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    /* Padding within .eh_frame */
+    . += 128;
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- eh-frame-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- a.s
+.section .text.01, "ax",%progbits
+.global f1
+.type f1, %function
+f1:
+.cfi_startproc
+.space 4
+.cfi_endproc

lld/test/ELF/eh-frame-nonzero-offset-x86.s

@@ -0,0 +1,55 @@
+// REQUIRES: x86
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64 a.s -o a.o
+// RUN: ld.lld a.o -T eh-frame-non-zero-offset.t -o non-zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame non-zero | FileCheck --check-prefix=NONZERO %s
+// RUN: ld.lld a.o -T eh-frame-zero-offset.t -o zero
+// RUN: llvm-readelf --program-headers --unwind --symbols -x .eh_frame zero | FileCheck --check-prefix=ZERO %s
+
+// NONZERO:      {{[0-9]+}}: 0000000000000088 {{.*}} __eh_frame_start
+// NONZERO-NEXT: {{[0-9]+}}: 00000000000000bc {{.*}} __eh_frame_end
+
+// NONZERO:      0x00000088 14000000 00000000 017a5200 01781001
+// NONZERO-NEXT: 0x00000098 1b0c0708 90010000 14000000 1c000000
+// NONZERO-NEXT: 0x000000a8 58ffffff 04000000 00000000 00000000
+// NONZERO-NEXT: 0x000000b8 00000000
+
+// ZERO:      {{[0-9]+}}: 0000000000000008 {{.*}} __eh_frame_start
+// ZERO-NEXT: {{[0-9]+}}: 000000000000003c {{.*}} __eh_frame_end
+
+// ZERO:      0x00000008 14000000 00000000 017a5200 01781001
+// ZERO-NEXT: 0x00000018 1b0c0708 90010000 14000000 1c000000
+// ZERO-NEXT: 0x00000028 d8ffffff 04000000 00000000 00000000
+// ZERO-NEXT: 0x00000038 00000000
+
+//--- eh-frame-non-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    /* Padding within .eh_frame */
+    . += 128;
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- eh-frame-zero-offset.t
+SECTIONS {
+  .text : { *(.text .text.*) }
+  .eh_frame : {
+    __eh_frame_start = .;
+    *(.eh_frame) ;
+    __eh_frame_end = .;
+  }
+}
+
+//--- a.s
+.section .text.01, "ax",%progbits
+.global f1
+.type f1, %function
+f1:
+.cfi_startproc
+.space 4
+.cfi_endproc