cmd/link,cmd/internal: add R_GOT_PCREL_ITYPE_RELOC for riscv64

This CL adds new relocation type for riscv64: R_GOT_PCREL_ITYPE_RELOC
which generate an AUIPC + I-type pair with relocation type of GOT_HI20
and PCREL_LO12_I.
According to RISCV elf psabi doc, medium position independent code
model, the GNU as example is:

```
		# Calculate address of non-local symbol
.Ltmp3: aupipc	a0, %got_pcrel_hi(symbol)
	ld	a0, %pcrel_lo(.Ltmp3)(a0)
```

Change-Id: I719dd05e009ca2d9291f0689b346c059f9c56918
Reviewed-on: https://go-review.googlesource.com/c/go/+/612635
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

5 files changed, 62 insertions, 36 deletions

diff --git a/src/cmd/internal/obj/riscv/cpu.go b/src/cmd/internal/obj/riscv/cpu.go
index 69a8516696..2b75ed38a6 100644
--- a/src/cmd/internal/obj/riscv/cpu.go
+++ b/src/cmd/internal/obj/riscv/cpu.go
@@ -317,6 +317,11 @@ const (
 	// it is the first instruction in an AUIPC + S-type pair that needs a
 	// R_RISCV_PCREL_STYPE relocation.
 	NEED_PCREL_STYPE_RELOC
+
+	// NEED_GOT_PCREL_ITYPE_RELOC is set on AUIPC instructions to indicate that
+	// it is the first instruction in an AUIPC + I-type pair that needs a
+	// R_RISCV_GOT_PCREL_ITYPE relocation.
+	NEED_GOT_PCREL_ITYPE_RELOC
 )
 
 // RISC-V mnemonics, as defined in the "opcodes" and "opcodes-pseudo" files
diff --git a/src/cmd/internal/obj/riscv/obj.go b/src/cmd/internal/obj/riscv/obj.go
index 381dc08560..54c34af2f4 100644
--- a/src/cmd/internal/obj/riscv/obj.go
+++ b/src/cmd/internal/obj/riscv/obj.go
@@ -215,11 +215,15 @@ func markRelocs(p *obj.Prog) {
 			switch p.From.Name {
 			case obj.NAME_EXTERN, obj.NAME_STATIC:
 				p.Mark |= NEED_PCREL_ITYPE_RELOC
+			case obj.NAME_GOTREF:
+				p.Mark |= NEED_GOT_PCREL_ITYPE_RELOC
 			}
 		case p.From.Type == obj.TYPE_MEM && p.To.Type == obj.TYPE_REG:
 			switch p.From.Name {
 			case obj.NAME_EXTERN, obj.NAME_STATIC:
 				p.Mark |= NEED_PCREL_ITYPE_RELOC
+			case obj.NAME_GOTREF:
+				p.Mark |= NEED_GOT_PCREL_ITYPE_RELOC
 			}
 		case p.From.Type == obj.TYPE_REG && p.To.Type == obj.TYPE_MEM:
 			switch p.To.Name {
@@ -2203,7 +2207,7 @@ func instructionsForMOV(p *obj.Prog) []*instruction {
 			// MOV c(Rs), Rd -> L $c, Rs, Rd
 			inss = instructionsForLoad(p, movToLoad(p.As), addrToReg(p.From))
 
-		case obj.NAME_EXTERN, obj.NAME_STATIC:
+		case obj.NAME_EXTERN, obj.NAME_STATIC, obj.NAME_GOTREF:
 			if p.From.Sym.Type == objabi.STLSBSS {
 				return instructionsForTLSLoad(p)
 			}
@@ -2631,6 +2635,9 @@ func assemble(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			} else if p.Mark&NEED_PCREL_STYPE_RELOC == NEED_PCREL_STYPE_RELOC {
 				rt = objabi.R_RISCV_PCREL_STYPE
 				addr = &p.To
+			} else if p.Mark&NEED_GOT_PCREL_ITYPE_RELOC == NEED_GOT_PCREL_ITYPE_RELOC {
+				rt = objabi.R_RISCV_GOT_PCREL_ITYPE
+				addr = &p.From
 			} else {
 				break
 			}
diff --git a/src/cmd/internal/objabi/reloctype.go b/src/cmd/internal/objabi/reloctype.go
index 9106b085ea..8e9bee5082 100644
--- a/src/cmd/internal/objabi/reloctype.go
+++ b/src/cmd/internal/objabi/reloctype.go
@@ -291,6 +291,10 @@ const (
 	// address.
 	R_RISCV_GOT_HI20
 
+	// R_RISCV_GOT_PCREL_ITYPE resolves a 32-bit PC-relative GOT entry
+	// address for an AUIPC + I-type instruction pair.
+	R_RISCV_GOT_PCREL_ITYPE
+
 	// R_RISCV_PCREL_HI20 resolves the high 20 bits of a 32-bit PC-relative
 	// address.
 	R_RISCV_PCREL_HI20
diff --git a/src/cmd/internal/objabi/reloctype_string.go b/src/cmd/internal/objabi/reloctype_string.go
index fd0e401db1..2d8a9554eb 100644
--- a/src/cmd/internal/objabi/reloctype_string.go
+++ b/src/cmd/internal/objabi/reloctype_string.go
@@ -75,39 +75,40 @@ func _() {
 	_ = x[R_RISCV_TLS_IE-65]
 	_ = x[R_RISCV_TLS_LE-66]
 	_ = x[R_RISCV_GOT_HI20-67]
-	_ = x[R_RISCV_PCREL_HI20-68]
-	_ = x[R_RISCV_PCREL_LO12_I-69]
-	_ = x[R_RISCV_PCREL_LO12_S-70]
-	_ = x[R_RISCV_BRANCH-71]
-	_ = x[R_RISCV_RVC_BRANCH-72]
-	_ = x[R_RISCV_RVC_JUMP-73]
-	_ = x[R_PCRELDBL-74]
-	_ = x[R_LOONG64_ADDR_HI-75]
-	_ = x[R_LOONG64_ADDR_LO-76]
-	_ = x[R_LOONG64_TLS_LE_HI-77]
-	_ = x[R_LOONG64_TLS_LE_LO-78]
-	_ = x[R_CALLLOONG64-79]
-	_ = x[R_LOONG64_TLS_IE_HI-80]
-	_ = x[R_LOONG64_TLS_IE_LO-81]
-	_ = x[R_LOONG64_GOT_HI-82]
-	_ = x[R_LOONG64_GOT_LO-83]
-	_ = x[R_LOONG64_ADD64-84]
-	_ = x[R_LOONG64_SUB64-85]
-	_ = x[R_JMP16LOONG64-86]
-	_ = x[R_JMP21LOONG64-87]
-	_ = x[R_JMPLOONG64-88]
-	_ = x[R_ADDRMIPSU-89]
-	_ = x[R_ADDRMIPSTLS-90]
-	_ = x[R_ADDRCUOFF-91]
-	_ = x[R_WASMIMPORT-92]
-	_ = x[R_XCOFFREF-93]
-	_ = x[R_PEIMAGEOFF-94]
-	_ = x[R_INITORDER-95]
+	_ = x[R_RISCV_GOT_PCREL_ITYPE-68]
+	_ = x[R_RISCV_PCREL_HI20-69]
+	_ = x[R_RISCV_PCREL_LO12_I-70]
+	_ = x[R_RISCV_PCREL_LO12_S-71]
+	_ = x[R_RISCV_BRANCH-72]
+	_ = x[R_RISCV_RVC_BRANCH-73]
+	_ = x[R_RISCV_RVC_JUMP-74]
+	_ = x[R_PCRELDBL-75]
+	_ = x[R_LOONG64_ADDR_HI-76]
+	_ = x[R_LOONG64_ADDR_LO-77]
+	_ = x[R_LOONG64_TLS_LE_HI-78]
+	_ = x[R_LOONG64_TLS_LE_LO-79]
+	_ = x[R_CALLLOONG64-80]
+	_ = x[R_LOONG64_TLS_IE_HI-81]
+	_ = x[R_LOONG64_TLS_IE_LO-82]
+	_ = x[R_LOONG64_GOT_HI-83]
+	_ = x[R_LOONG64_GOT_LO-84]
+	_ = x[R_LOONG64_ADD64-85]
+	_ = x[R_LOONG64_SUB64-86]
+	_ = x[R_JMP16LOONG64-87]
+	_ = x[R_JMP21LOONG64-88]
+	_ = x[R_JMPLOONG64-89]
+	_ = x[R_ADDRMIPSU-90]
+	_ = x[R_ADDRMIPSTLS-91]
+	_ = x[R_ADDRCUOFF-92]
+	_ = x[R_WASMIMPORT-93]
+	_ = x[R_XCOFFREF-94]
+	_ = x[R_PEIMAGEOFF-95]
+	_ = x[R_INITORDER-96]
 }
 
-const _RelocType_name = "R_ADDRR_ADDRPOWERR_ADDRARM64R_ADDRMIPSR_ADDROFFR_SIZER_CALLR_CALLARMR_CALLARM64R_CALLINDR_CALLPOWERR_CALLMIPSR_CONSTR_PCRELR_TLS_LER_TLS_IER_GOTOFFR_PLT0R_PLT1R_PLT2R_USEFIELDR_USETYPER_USEIFACER_USEIFACEMETHODR_USENAMEDMETHODR_METHODOFFR_KEEPR_POWER_TOCR_GOTPCRELR_JMPMIPSR_DWARFSECREFR_DWARFFILEREFR_ARM64_TLS_LER_ARM64_TLS_IER_ARM64_GOTPCRELR_ARM64_GOTR_ARM64_PCRELR_ARM64_PCREL_LDST8R_ARM64_PCREL_LDST16R_ARM64_PCREL_LDST32R_ARM64_PCREL_LDST64R_ARM64_LDST8R_ARM64_LDST16R_ARM64_LDST32R_ARM64_LDST64R_ARM64_LDST128R_POWER_TLS_LER_POWER_TLS_IER_POWER_TLSR_POWER_TLS_IE_PCREL34R_POWER_TLS_LE_TPREL34R_ADDRPOWER_DSR_ADDRPOWER_GOTR_ADDRPOWER_GOT_PCREL34R_ADDRPOWER_PCRELR_ADDRPOWER_TOCRELR_ADDRPOWER_TOCREL_DSR_ADDRPOWER_D34R_ADDRPOWER_PCREL34R_RISCV_JALR_RISCV_JAL_TRAMPR_RISCV_CALLR_RISCV_PCREL_ITYPER_RISCV_PCREL_STYPER_RISCV_TLS_IER_RISCV_TLS_LER_RISCV_GOT_HI20R_RISCV_PCREL_HI20R_RISCV_PCREL_LO12_IR_RISCV_PCREL_LO12_SR_RISCV_BRANCHR_RISCV_RVC_BRANCHR_RISCV_RVC_JUMPR_PCRELDBLR_LOONG64_ADDR_HIR_LOONG64_ADDR_LOR_LOONG64_TLS_LE_HIR_LOONG64_TLS_LE_LOR_CALLLOONG64R_LOONG64_TLS_IE_HIR_LOONG64_TLS_IE_LOR_LOONG64_GOT_HIR_LOONG64_GOT_LOR_LOONG64_ADD64R_LOONG64_SUB64R_JMP16LOONG64R_JMP21LOONG64R_JMPLOONG64R_ADDRMIPSUR_ADDRMIPSTLSR_ADDRCUOFFR_WASMIMPORTR_XCOFFREFR_PEIMAGEOFFR_INITORDER"
+const _RelocType_name = "R_ADDRR_ADDRPOWERR_ADDRARM64R_ADDRMIPSR_ADDROFFR_SIZER_CALLR_CALLARMR_CALLARM64R_CALLINDR_CALLPOWERR_CALLMIPSR_CONSTR_PCRELR_TLS_LER_TLS_IER_GOTOFFR_PLT0R_PLT1R_PLT2R_USEFIELDR_USETYPER_USEIFACER_USEIFACEMETHODR_USENAMEDMETHODR_METHODOFFR_KEEPR_POWER_TOCR_GOTPCRELR_JMPMIPSR_DWARFSECREFR_DWARFFILEREFR_ARM64_TLS_LER_ARM64_TLS_IER_ARM64_GOTPCRELR_ARM64_GOTR_ARM64_PCRELR_ARM64_PCREL_LDST8R_ARM64_PCREL_LDST16R_ARM64_PCREL_LDST32R_ARM64_PCREL_LDST64R_ARM64_LDST8R_ARM64_LDST16R_ARM64_LDST32R_ARM64_LDST64R_ARM64_LDST128R_POWER_TLS_LER_POWER_TLS_IER_POWER_TLSR_POWER_TLS_IE_PCREL34R_POWER_TLS_LE_TPREL34R_ADDRPOWER_DSR_ADDRPOWER_GOTR_ADDRPOWER_GOT_PCREL34R_ADDRPOWER_PCRELR_ADDRPOWER_TOCRELR_ADDRPOWER_TOCREL_DSR_ADDRPOWER_D34R_ADDRPOWER_PCREL34R_RISCV_JALR_RISCV_JAL_TRAMPR_RISCV_CALLR_RISCV_PCREL_ITYPER_RISCV_PCREL_STYPER_RISCV_TLS_IER_RISCV_TLS_LER_RISCV_GOT_HI20R_RISCV_GOT_PCREL_ITYPER_RISCV_PCREL_HI20R_RISCV_PCREL_LO12_IR_RISCV_PCREL_LO12_SR_RISCV_BRANCHR_RISCV_RVC_BRANCHR_RISCV_RVC_JUMPR_PCRELDBLR_LOONG64_ADDR_HIR_LOONG64_ADDR_LOR_LOONG64_TLS_LE_HIR_LOONG64_TLS_LE_LOR_CALLLOONG64R_LOONG64_TLS_IE_HIR_LOONG64_TLS_IE_LOR_LOONG64_GOT_HIR_LOONG64_GOT_LOR_LOONG64_ADD64R_LOONG64_SUB64R_JMP16LOONG64R_JMP21LOONG64R_JMPLOONG64R_ADDRMIPSUR_ADDRMIPSTLSR_ADDRCUOFFR_WASMIMPORTR_XCOFFREFR_PEIMAGEOFFR_INITORDER"
 
-var _RelocType_index = [...]uint16{0, 6, 17, 28, 38, 47, 53, 59, 68, 79, 88, 99, 109, 116, 123, 131, 139, 147, 153, 159, 165, 175, 184, 194, 210, 226, 237, 243, 254, 264, 273, 286, 300, 314, 328, 344, 355, 368, 387, 407, 427, 447, 460, 474, 488, 502, 517, 531, 545, 556, 578, 600, 614, 629, 652, 669, 687, 708, 723, 742, 753, 770, 782, 801, 820, 834, 848, 864, 882, 902, 922, 936, 954, 970, 980, 997, 1014, 1033, 1052, 1065, 1084, 1103, 1119, 1135, 1150, 1165, 1179, 1193, 1205, 1216, 1229, 1240, 1252, 1262, 1274, 1285}
+var _RelocType_index = [...]uint16{0, 6, 17, 28, 38, 47, 53, 59, 68, 79, 88, 99, 109, 116, 123, 131, 139, 147, 153, 159, 165, 175, 184, 194, 210, 226, 237, 243, 254, 264, 273, 286, 300, 314, 328, 344, 355, 368, 387, 407, 427, 447, 460, 474, 488, 502, 517, 531, 545, 556, 578, 600, 614, 629, 652, 669, 687, 708, 723, 742, 753, 770, 782, 801, 820, 834, 848, 864, 887, 905, 925, 945, 959, 977, 993, 1003, 1020, 1037, 1056, 1075, 1088, 1107, 1126, 1142, 1158, 1173, 1188, 1202, 1216, 1228, 1239, 1252, 1263, 1275, 1285, 1297, 1308}
 
 func (i RelocType) String() string {
 	i -= 1
diff --git a/src/cmd/link/internal/riscv64/asm.go b/src/cmd/link/internal/riscv64/asm.go
index a3f50dc54f..8e5d5be41e 100644
--- a/src/cmd/link/internal/riscv64/asm.go
+++ b/src/cmd/link/internal/riscv64/asm.go
@@ -170,8 +170,11 @@ func genSymsLate(ctxt *ld.Link, ldr *loader.Loader) {
 		relocs := ldr.Relocs(s)
 		for ri := 0; ri < relocs.Count(); ri++ {
 			r := relocs.At(ri)
-			if r.Type() != objabi.R_RISCV_CALL && r.Type() != objabi.R_RISCV_PCREL_ITYPE &&
-				r.Type() != objabi.R_RISCV_PCREL_STYPE && r.Type() != objabi.R_RISCV_TLS_IE {
+			if r.Type() != objabi.R_RISCV_CALL &&
+				r.Type() != objabi.R_RISCV_PCREL_ITYPE &&
+				r.Type() != objabi.R_RISCV_PCREL_STYPE &&
+				r.Type() != objabi.R_RISCV_TLS_IE &&
+				r.Type() != objabi.R_RISCV_GOT_PCREL_ITYPE {
 				continue
 			}
 			if r.Off() == 0 && ldr.SymType(s).IsText() {
@@ -233,7 +236,11 @@ func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym,
 		out.Write64(uint64(elf.R_RISCV_JAL) | uint64(elfsym)<<32)
 		out.Write64(uint64(r.Xadd))
 
-	case objabi.R_RISCV_CALL, objabi.R_RISCV_PCREL_ITYPE, objabi.R_RISCV_PCREL_STYPE, objabi.R_RISCV_TLS_IE:
+	case objabi.R_RISCV_CALL,
+		objabi.R_RISCV_PCREL_ITYPE,
+		objabi.R_RISCV_PCREL_STYPE,
+		objabi.R_RISCV_TLS_IE,
+		objabi.R_RISCV_GOT_PCREL_ITYPE:
 		// Find the text symbol for the AUIPC instruction targeted
 		// by this relocation.
 		relocs := ldr.Relocs(s)
@@ -262,6 +269,8 @@ func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym,
 			hiRel, loRel = elf.R_RISCV_PCREL_HI20, elf.R_RISCV_PCREL_LO12_S
 		case objabi.R_RISCV_TLS_IE:
 			hiRel, loRel = elf.R_RISCV_TLS_GOT_HI20, elf.R_RISCV_PCREL_LO12_I
+		case objabi.R_RISCV_GOT_PCREL_ITYPE:
+			hiRel, loRel = elf.R_RISCV_GOT_HI20, elf.R_RISCV_PCREL_LO12_I
 		}
 		out.Write64(uint64(sectoff))
 		out.Write64(uint64(hiRel) | uint64(elfsym)<<32)
@@ -426,7 +435,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 		case objabi.R_RISCV_JAL, objabi.R_RISCV_JAL_TRAMP:
 			return val, 1, true
 
-		case objabi.R_RISCV_CALL, objabi.R_RISCV_PCREL_ITYPE, objabi.R_RISCV_PCREL_STYPE, objabi.R_RISCV_TLS_IE, objabi.R_RISCV_TLS_LE:
+		case objabi.R_RISCV_CALL, objabi.R_RISCV_PCREL_ITYPE, objabi.R_RISCV_PCREL_STYPE, objabi.R_RISCV_TLS_IE, objabi.R_RISCV_TLS_LE, objabi.R_RISCV_GOT_PCREL_ITYPE:
 			return val, 2, true
 		}
 
@@ -626,7 +635,7 @@ func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sy
 	case objabi.R_RISCV_JAL, objabi.R_RISCV_JAL_TRAMP:
 		return ld.ExtrelocSimple(ldr, r), true
 
-	case objabi.R_RISCV_CALL, objabi.R_RISCV_PCREL_ITYPE, objabi.R_RISCV_PCREL_STYPE, objabi.R_RISCV_TLS_IE, objabi.R_RISCV_TLS_LE:
+	case objabi.R_RISCV_CALL, objabi.R_RISCV_PCREL_ITYPE, objabi.R_RISCV_PCREL_STYPE, objabi.R_RISCV_TLS_IE, objabi.R_RISCV_TLS_LE, objabi.R_RISCV_GOT_PCREL_ITYPE:
 		return ld.ExtrelocViaOuterSym(ldr, r, s), true
 	}
 	return loader.ExtReloc{}, false