cmd/internal/objabi,cmd/link: add support for additional riscv64 relocations

These additional relocation types are encountered when using the
Go race detector with riscv64.

Updates #64345

Change-Id: I6de6430165fb378463da1af9402198a3a31485ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/690496
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Meng Zhuo <[email protected]>

Author: 4a6f656c

src/cmd/internal/objabi/reloctype.go

@@ -305,6 +305,14 @@ const (
 	// R_RISCV_BRANCH resolves a 12-bit PC-relative branch offset.
 	R_RISCV_BRANCH
 
+	// R_RISCV_ADD32 resolves a 32-bit label addition, being the stored value,
+	// plus the symbol address plus the addend (V + S + A).
+	R_RISCV_ADD32
+
+	// R_RISCV_SUB32 resolves a 32-bit label subtraction, being the stored value,
+	// minus the symbol address minus the addend (V - S - A).
+	R_RISCV_SUB32
+
 	// R_RISCV_RVC_BRANCH resolves an 8-bit PC-relative offset for a CB-type
 	// instruction.
 	R_RISCV_RVC_BRANCH

src/cmd/internal/objabi/reloctype_string.go

@@ -1178,6 +1178,7 @@ func relSize(arch *sys.Arch, pn string, elftype uint32) (uint8, uint8, error) {
 		RISCV64 | uint32(elf.R_RISCV_SET32)<<16,
 		RISCV64 | uint32(elf.R_RISCV_SUB32)<<16,
 		RISCV64 | uint32(elf.R_RISCV_32_PCREL)<<16,
+		RISCV64 | uint32(elf.R_RISCV_JAL)<<16,
 		RISCV64 | uint32(elf.R_RISCV_RELAX)<<16:
 		return 4, 4, nil
 

src/cmd/link/internal/loadelf/ldelf.go

@@ -118,6 +118,26 @@ func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loade
 		su.SetRelocType(rIdx, objabi.R_RISCV_PCREL_LO12_S)
 		return true
 
+	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_RISCV_32_PCREL):
+		su := ldr.MakeSymbolUpdater(s)
+		su.SetRelocType(rIdx, objabi.R_PCREL)
+		return true
+
+	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_RISCV_64):
+		su := ldr.MakeSymbolUpdater(s)
+		su.SetRelocType(rIdx, objabi.R_ADDR)
+		return true
+
+	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_RISCV_ADD32):
+		su := ldr.MakeSymbolUpdater(s)
+		su.SetRelocType(rIdx, objabi.R_RISCV_ADD32)
+		return true
+
+	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_RISCV_SUB32):
+		su := ldr.MakeSymbolUpdater(s)
+		su.SetRelocType(rIdx, objabi.R_RISCV_SUB32)
+		return true
+
 	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_RISCV_RVC_BRANCH):
 		su := ldr.MakeSymbolUpdater(s)
 		su.SetRelocType(rIdx, objabi.R_RISCV_RVC_BRANCH)
@@ -137,6 +157,11 @@ func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loade
 		// Ignore relaxations, at least for now.
 		return true
 
+	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_RISCV_JAL):
+		su := ldr.MakeSymbolUpdater(s)
+		su.SetRelocType(rIdx, objabi.R_RISCV_JAL)
+		return true
+
 	default:
 		if r.Type() >= objabi.ElfRelocOffset {
 			ldr.Errorf(s, "unexpected relocation type %d (%s)", r.Type(), sym.RelocName(target.Arch, r.Type()))
@@ -639,6 +664,14 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 		second = (second &^ secondImmMask) | int64(uint32(secondImm))
 
 		return second<<32 | auipc, 0, true
+
+	case objabi.R_RISCV_ADD32:
+		addr := val + ldr.SymValue(rs) + r.Add()
+		return int64(uint32(addr)), 0, true
+
+	case objabi.R_RISCV_SUB32:
+		addr := val - ldr.SymValue(rs) - r.Add()
+		return int64(uint32(addr)), 0, true
 	}
 
 	return val, 0, false