fix(goobj): external package and symbol indices and arm64 pair relocations

Assisted-by: GLM 5.3
2026-09-19 23:49:13 +02:00
parent f3c8510a58
commit 87b1081c53
7 changed files with 447 additions and 42 deletions
@@ -74,6 +74,89 @@ DATA callee<>+0(SB)/8, $42
 		t.Error("ELF object missing R_RISCV_JAL relocation")
 	}
 }
+
+// TestELFRISCVPCRELLO12Anchor checks the psABI's LO12 pairing rule: the
+// R_RISCV_PCREL_LO12_I/S relocation must reference a symbol whose value is
+// the AUIPC site of its HI20 partner (psABI §8.4.9; cmd/link generates one
+// local text symbol per AUIPC for exactly this).  The emitter pairs each
+// HI20 (against the target symbol) with a LO12 against the .text section
+// symbol whose addend is the AUIPC's section-relative offset, so S + A is
+// the AUIPC address.
+func TestELFRISCVPCRELLO12Anchor(t *testing.T) {
+	f, errs := parser.Parse("k_riscv64.s", `
+#include "textflag.h"
+
+TEXT ·sb(SB), NOSPLIT, $0-0
+	MOV $answer<>(SB), X10
+	MOV answer<>(SB), X11
+	MOV X12, answer<>(SB)
+	RET
+
+GLOBL answer<>(SB), RODATA, $8
+DATA answer<>+0(SB)/8, $42
+`)
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	img, err := AssembleFileRISCV(f)
+	if err != nil {
+		t.Fatalf("AssembleFileRISCV: %v", err)
+	}
+	obj, err := img.ELFRISCVObject()
+	if err != nil {
+		t.Fatalf("ELFRISCVObject: %v", err)
+	}
+	ef, err := elf.NewFile(bytes.NewReader(obj))
+	if err != nil {
+		t.Fatalf("parse ELF: %v", err)
+	}
+	defer ef.Close()
+	if flags := binary.LittleEndian.Uint32(obj[48:]); flags != efRISCVFloatAbiDouble {
+		t.Errorf("e_flags = %#x, want %#x (EF_RISCV_FLOAT_ABI_DOUBLE)", flags, efRISCVFloatAbiDouble)
+	}
+	rela := ef.Section(".rela.text")
+	if rela == nil {
+		t.Fatal("missing .rela.text")
+	}
+	b, err := rela.Data()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(b) != 6*24 {
+		t.Fatalf(".rela.text holds %d entries, want six (three HI20/LO12 pairs)", len(b)/24)
+	}
+	le := binary.LittleEndian
+	wantLo := []uint32{rRISCVPCRELLO12I, rRISCVPCRELLO12I, rRISCVPCRELLO12S}
+	for p := range 3 {
+		auipc := 8 * p
+		hi := b[p*2*24:]
+		lo := b[(p*2+1)*24:]
+		if off := le.Uint64(hi[0:]); off != uint64(auipc) {
+			t.Errorf("pair %d: HI20 r_offset = %d, want %d (the AUIPC)", p, off, auipc)
+		}
+		if typ := uint32(le.Uint64(hi[8:])); typ != rRISCVPCRELHI20 {
+			t.Errorf("pair %d: HI20 type = %d, want %d", p, typ, rRISCVPCRELHI20)
+		}
+		if sym := int(le.Uint64(hi[8:]) >> 32); sym == 0 || sym == 1 {
+			t.Errorf("pair %d: HI20 against symbol %d, want the target", p, sym)
+		}
+		if off := le.Uint64(lo[0:]); off != uint64(auipc+4) {
+			t.Errorf("pair %d: LO12 r_offset = %d, want %d", p, off, auipc+4)
+		}
+		if typ := uint32(le.Uint64(lo[8:])); typ != wantLo[p] {
+			t.Errorf("pair %d: LO12 type = %d, want %d", p, typ, wantLo[p])
+		}
+		// The LO12 must denote the AUIPC site: the .text section symbol
+		// (index 1) plus the AUIPC's section-relative offset as addend.
+		if sym := int(le.Uint64(lo[8:]) >> 32); sym != 1 {
+			t.Errorf("pair %d: LO12 against symbol %d, want 1 (the .text section symbol)", p, sym)
+		}
+		if add := int64(le.Uint64(lo[16:])); add != int64(auipc) {
+			t.Errorf("pair %d: LO12 addend = %d, want %d (S + A = the AUIPC address)", p, add, auipc)
+		}
+	}
+}
+
 func TestGOObjectRISCVStructure(t *testing.T) {
 	f, errs := parser.Parse("k_riscv64.s", `
 #include "textflag.h"