[LLD][RISCV] Error on PCREL_LO referencing other Section

lld/ELF/InputSection.cpp

@@ -625,27 +625,40 @@ static uint64_t getARMStaticBase(const Symbol &sym) {
 // points the corresponding R_RISCV_PCREL_HI20 relocation, and the target VA
 // is calculated using PCREL_HI20's symbol.
 //
-// This function returns the R_RISCV_PCREL_HI20 relocation from
-// R_RISCV_PCREL_LO12's symbol and addend.
-static Relocation *getRISCVPCRelHi20(const Symbol *sym, uint64_t addend) {
+// This function returns the R_RISCV_PCREL_HI20 relocation from the
+// R_RISCV_PCREL_LO12 relocation.
+static Relocation *getRISCVPCRelHi20(const InputSectionBase *loSec,
+                                     const Relocation &loReloc) {
+  uint64_t addend = loReloc.addend;
+  Symbol *sym = loReloc.sym;
+
   const Defined *d = cast<Defined>(sym);
   if (!d->section) {
-    errorOrWarn("R_RISCV_PCREL_LO12 relocation points to an absolute symbol: " +
-                sym->getName());
+    errorOrWarn(
+        loSec->getLocation(loReloc.offset) +
+        ": R_RISCV_PCREL_LO12 relocation points to an absolute symbol: " +
+        sym->getName());
     return nullptr;
   }
-  InputSection *isec = cast<InputSection>(d->section);
+  InputSection *hiSec = cast<InputSection>(d->section);
+
+  if (hiSec != loSec)
+    errorOrWarn(loSec->getLocation(loReloc.offset) +
+                ": R_RISCV_PCREL_LO12 relocation points to a symbol '" +
+                sym->getName() + "' in a different section '" + hiSec->name +
+                "'");
 
   if (addend != 0)
-    warn("non-zero addend in R_RISCV_PCREL_LO12 relocation to " +
-         isec->getObjMsg(d->value) + " is ignored");
+    warn(loSec->getLocation(loReloc.offset) +
+         ": non-zero addend in R_RISCV_PCREL_LO12 relocation to " +
+         hiSec->getObjMsg(d->value) + " is ignored");
 
   // Relocations are sorted by offset, so we can use std::equal_range to do
   // binary search.
-  Relocation r;
-  r.offset = d->value;
+  Relocation hiReloc;
+  hiReloc.offset = d->value;
   auto range =
-      std::equal_range(isec->relocs().begin(), isec->relocs().end(), r,
+      std::equal_range(hiSec->relocs().begin(), hiSec->relocs().end(), hiReloc,
                        [](const Relocation &lhs, const Relocation &rhs) {
                          return lhs.offset < rhs.offset;
                        });
@@ -655,8 +668,9 @@ static Relocation *getRISCVPCRelHi20(const Symbol *sym, uint64_t addend) {
         it->type == R_RISCV_TLS_GD_HI20 || it->type == R_RISCV_TLS_GOT_HI20)
       return &*it;
 
-  errorOrWarn("R_RISCV_PCREL_LO12 relocation points to " +
-              isec->getObjMsg(d->value) +
+  errorOrWarn(loSec->getLocation(loReloc.offset) +
+              ": R_RISCV_PCREL_LO12 relocation points to " +
+              hiSec->getObjMsg(d->value) +
               " without an associated R_RISCV_PCREL_HI20 relocation");
   return nullptr;
 }
@@ -825,7 +839,7 @@ uint64_t InputSectionBase::getRelocTargetVA(Ctx &ctx, const Relocation &r,
     return getAArch64Page(val) - getAArch64Page(p);
   }
   case R_RISCV_PC_INDIRECT: {
-    if (const Relocation *hiRel = getRISCVPCRelHi20(r.sym, a))
+    if (const Relocation *hiRel = getRISCVPCRelHi20(this, r))
       return getRelocTargetVA(ctx, *hiRel, r.sym->getVA());
     return 0;
   }

lld/test/ELF/riscv-pcrel-hilo-error-sections.s

@@ -0,0 +1,32 @@
+# REQUIRES: riscv
+
+# RUN: llvm-mc -filetype=obj -triple=riscv64 %s -o %t.o
+# RUN: not ld.lld %t.o 2>&1 | FileCheck %s
+
+# CHECK: error: {{.*}}:(.text.sec_one+0x0): R_RISCV_PCREL_LO12 relocation points to a symbol '.Lpcrel_hi0' in a different section '.text.sec_two'
+# CHECK: error: {{.*}}:(.text.sec_one+0x4): R_RISCV_PCREL_LO12 relocation points to a symbol '.Lpcrel_hi1' in a different section '.text.sec_two'
+# CHECK-NOT: R_RISCV_PCREL_LO12 relocation points to a symbol '.Lpcrel_hi2'
+
+## This test is checking that we warn the user when the relocations in their
+## object don't follow the RISC-V psABI. In particular, the psABI requires
+## that PCREL_LO12 relocations are in the same section as the pcrel_hi
+## instruction they point to.
+
+  .section .text.sec_one,"ax"
+  addi a0, a0, %pcrel_lo(.Lpcrel_hi0)
+  sw a0, %pcrel_lo(.Lpcrel_hi1)(a1)
+
+  .section .text.sec_two,"ax"
+.Lpcrel_hi0:
+  auipc a0, %pcrel_hi(a)
+.Lpcrel_hi1:
+  auipc a1, %pcrel_hi(a)
+
+.Lpcrel_hi2:
+  auipc a2, %pcrel_hi(a)
+  addi a2, a2, %pcrel_lo(.Lpcrel_hi2)
+
+  .data
+  .global a
+a:
+  .word 50

lld/test/ELF/riscv-pcrel-hilo-error.s

@@ -2,7 +2,7 @@
 # RUN: llvm-mc -filetype=obj -triple=riscv64 %s -o %t.o
 # RUN: not ld.lld %t.o --defsym external=0 2>&1 | FileCheck %s
 
-# CHECK: error: R_RISCV_PCREL_LO12 relocation points to an absolute symbol: external
+# CHECK: error: {{.*}}:(.text+0x4): R_RISCV_PCREL_LO12 relocation points to an absolute symbol: external
 
 # We provide a dummy %pcrel_hi referred to by external to appease the
 # assembler, but make external weak so --defsym can still override it at link