cmd/link: Add section data slice to Archrelocvariant

PPC64 needs to preserve bits when applying some relocations. DS form
relocations must preserve the lower two bits, and thus needs to inspect
the section data as it streams out.

Similarly, the overflow checking requires inspecting the primary
opcode to see if the value is sign or zero extended.

The existing PPC64 code no longer works as the slice returned by
(loader*).Data is cleared as we layout the symbol and process
relocations.  This data is always the section undergoing relocation,
thus we can directly inspect the contents to preserve bits or
check for overflows.

Change-Id: I239211f7e5e96208673663b6553b3017adae7e01
Reviewed-on: https://go-review.googlesource.com/c/go/+/300555
Run-TryBot: Paul Murphy <murp@ibm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>

11 files changed, 18 insertions, 17 deletions

diff --git a/src/cmd/link/internal/amd64/asm.go b/src/cmd/link/internal/amd64/asm.go
index 2d09a6160a..fb960491de 100644
--- a/src/cmd/link/internal/amd64/asm.go
+++ b/src/cmd/link/internal/amd64/asm.go
@@ -548,7 +548,7 @@ func archreloc(*ld.Target, *loader.Loader, *ld.ArchSyms, loader.Reloc, loader.Sy
 	return -1, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	log.Fatalf("unexpected relocation variant")
 	return -1
 }
diff --git a/src/cmd/link/internal/arm/asm.go b/src/cmd/link/internal/arm/asm.go
index 03caeae7be..efdaff198d 100644
--- a/src/cmd/link/internal/arm/asm.go
+++ b/src/cmd/link/internal/arm/asm.go
@@ -565,7 +565,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	log.Fatalf("unexpected relocation variant")
 	return -1
 }
diff --git a/src/cmd/link/internal/arm64/asm.go b/src/cmd/link/internal/arm64/asm.go
index 72093268c2..90ae38594e 100644
--- a/src/cmd/link/internal/arm64/asm.go
+++ b/src/cmd/link/internal/arm64/asm.go
@@ -865,7 +865,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	log.Fatalf("unexpected relocation variant")
 	return -1
 }
diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go
index a9d17c806e..6de2d893ae 100644
--- a/src/cmd/link/internal/ld/data.go
+++ b/src/cmd/link/internal/ld/data.go
@@ -507,7 +507,7 @@ func (st *relocSymState) relocsym(s loader.Sym, P []byte) {
 
 		if target.IsPPC64() || target.IsS390X() {
 			if rv != sym.RV_NONE {
-				o = thearch.Archrelocvariant(target, ldr, r, rv, s, o)
+				o = thearch.Archrelocvariant(target, ldr, r, rv, s, o, P)
 			}
 		}
 
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index c96a9be355..d136cbad80 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -223,7 +223,7 @@ type Arch struct {
 	// to-be-relocated data item (from sym.P). Return is an updated
 	// offset value.
 	Archrelocvariant func(target *Target, ldr *loader.Loader, rel loader.Reloc,
-		rv sym.RelocVariant, sym loader.Sym, offset int64) (relocatedOffset int64)
+		rv sym.RelocVariant, sym loader.Sym, offset int64, data []byte) (relocatedOffset int64)
 
 	// Generate a trampoline for a call from s to rs if necessary. ri is
 	// index of the relocation.
diff --git a/src/cmd/link/internal/mips/asm.go b/src/cmd/link/internal/mips/asm.go
index 17b1b20aff..8505dc6109 100644
--- a/src/cmd/link/internal/mips/asm.go
+++ b/src/cmd/link/internal/mips/asm.go
@@ -140,7 +140,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	return -1
 }
 
diff --git a/src/cmd/link/internal/mips64/asm.go b/src/cmd/link/internal/mips64/asm.go
index 4789b411eb..55b4ba2fc8 100644
--- a/src/cmd/link/internal/mips64/asm.go
+++ b/src/cmd/link/internal/mips64/asm.go
@@ -138,7 +138,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	return -1
 }
 
diff --git a/src/cmd/link/internal/ppc64/asm.go b/src/cmd/link/internal/ppc64/asm.go
index 83df8a7a13..aa2532ad37 100644
--- a/src/cmd/link/internal/ppc64/asm.go
+++ b/src/cmd/link/internal/ppc64/asm.go
@@ -859,7 +859,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, nExtReloc, false
 }
 
-func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv sym.RelocVariant, s loader.Sym, t int64) (relocatedOffset int64) {
+func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv sym.RelocVariant, s loader.Sym, t int64, p []byte) (relocatedOffset int64) {
 	rs := ldr.ResolveABIAlias(r.Sym())
 	switch rv & sym.RV_TYPE_MASK {
 	default:
@@ -875,9 +875,10 @@ func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv
 			// overflow depends on the instruction
 			var o1 uint32
 			if target.IsBigEndian() {
-				o1 = binary.BigEndian.Uint32(ldr.Data(s)[r.Off()-2:])
+				o1 = binary.BigEndian.Uint32(p[r.Off()-2:])
+
 			} else {
-				o1 = binary.LittleEndian.Uint32(ldr.Data(s)[r.Off():])
+				o1 = binary.LittleEndian.Uint32(p[r.Off():])
 			}
 			switch o1 >> 26 {
 			case 24, // ori
@@ -909,9 +910,9 @@ func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv
 			// overflow depends on the instruction
 			var o1 uint32
 			if target.IsBigEndian() {
-				o1 = binary.BigEndian.Uint32(ldr.Data(s)[r.Off()-2:])
+				o1 = binary.BigEndian.Uint32(p[r.Off()-2:])
 			} else {
-				o1 = binary.LittleEndian.Uint32(ldr.Data(s)[r.Off():])
+				o1 = binary.LittleEndian.Uint32(p[r.Off():])
 			}
 			switch o1 >> 26 {
 			case 25, // oris
@@ -933,9 +934,9 @@ func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv
 	case sym.RV_POWER_DS:
 		var o1 uint32
 		if target.IsBigEndian() {
-			o1 = uint32(binary.BigEndian.Uint16(ldr.Data(s)[r.Off():]))
+			o1 = uint32(binary.BigEndian.Uint16(p[r.Off():]))
 		} else {
-			o1 = uint32(binary.LittleEndian.Uint16(ldr.Data(s)[r.Off():]))
+			o1 = uint32(binary.LittleEndian.Uint16(p[r.Off():]))
 		}
 		if t&3 != 0 {
 			ldr.Errorf(s, "relocation for %s+%d is not aligned: %d", ldr.SymName(rs), r.Off(), t)
diff --git a/src/cmd/link/internal/riscv64/asm.go b/src/cmd/link/internal/riscv64/asm.go
index c18e0540d8..6eace617dc 100644
--- a/src/cmd/link/internal/riscv64/asm.go
+++ b/src/cmd/link/internal/riscv64/asm.go
@@ -230,7 +230,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	log.Fatalf("archrelocvariant")
 	return -1
 }
diff --git a/src/cmd/link/internal/s390x/asm.go b/src/cmd/link/internal/s390x/asm.go
index 78d2cc81e4..1952971dcb 100644
--- a/src/cmd/link/internal/s390x/asm.go
+++ b/src/cmd/link/internal/s390x/asm.go
@@ -371,7 +371,7 @@ func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loade
 	return val, 0, false
 }
 
-func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv sym.RelocVariant, s loader.Sym, t int64) int64 {
+func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv sym.RelocVariant, s loader.Sym, t int64, p []byte) int64 {
 	switch rv & sym.RV_TYPE_MASK {
 	default:
 		ldr.Errorf(s, "unexpected relocation variant %d", rv)
diff --git a/src/cmd/link/internal/x86/asm.go b/src/cmd/link/internal/x86/asm.go
index af0ce11255..5f6bcfb8b1 100644
--- a/src/cmd/link/internal/x86/asm.go
+++ b/src/cmd/link/internal/x86/asm.go
@@ -415,7 +415,7 @@ func archreloc(*ld.Target, *loader.Loader, *ld.ArchSyms, loader.Reloc, loader.Sy
 	return -1, 0, false
 }
 
-func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
+func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64, []byte) int64 {
 	log.Fatalf("unexpected relocation variant")
 	return -1
 }