Add basic support for x86_64_x32 architecture (#320)

This corresponds to the Rust `x86_64-unknown-linux-gnux32` target,
notably that the architecture listed is x86_64 but the word size is 32

Author: alexcrichton

src/common.rs

@@ -10,6 +10,8 @@ pub enum Architecture {
     Bpf,
     I386,
     X86_64,
+    #[allow(non_camel_case_types)]
+    X86_64_X32,
     Hexagon,
     Mips,
     Mips64,
@@ -36,6 +38,7 @@ impl Architecture {
             Architecture::Bpf => Some(AddressSize::U64),
             Architecture::I386 => Some(AddressSize::U32),
             Architecture::X86_64 => Some(AddressSize::U64),
+            Architecture::X86_64_X32 => Some(AddressSize::U32),
             Architecture::Hexagon => Some(AddressSize::U32),
             Architecture::Mips => Some(AddressSize::U32),
             Architecture::Mips64 => Some(AddressSize::U64),

src/read/elf/file.rs

@@ -158,7 +158,8 @@ where
             (elf::EM_AVR, _) => Architecture::Avr,
             (elf::EM_BPF, _) => Architecture::Bpf,
             (elf::EM_386, _) => Architecture::I386,
-            (elf::EM_X86_64, _) => Architecture::X86_64,
+            (elf::EM_X86_64, false) => Architecture::X86_64_X32,
+            (elf::EM_X86_64, true) => Architecture::X86_64,
             (elf::EM_HEXAGON, _) => Architecture::Hexagon,
             (elf::EM_MIPS, false) => Architecture::Mips,
             (elf::EM_MIPS, true) => Architecture::Mips64,

src/write/elf.rs

@@ -78,6 +78,7 @@ impl Object {
             Architecture::Bpf => false,
             Architecture::I386 => false,
             Architecture::X86_64 => true,
+            Architecture::X86_64_X32 => true,
             Architecture::Hexagon => true,
             Architecture::Mips => false,
             Architecture::Mips64 => true,
@@ -360,6 +361,7 @@ impl Object {
             Architecture::Bpf => elf::EM_BPF,
             Architecture::I386 => elf::EM_386,
             Architecture::X86_64 => elf::EM_X86_64,
+            Architecture::X86_64_X32 => elf::EM_X86_64,
             Architecture::Hexagon => elf::EM_HEXAGON,
             Architecture::Mips => elf::EM_MIPS,
             Architecture::Mips64 => elf::EM_MIPS,
@@ -639,29 +641,34 @@ impl Object {
                                 return Err(Error(format!("unimplemented relocation {:?}", reloc)));
                             }
                         },
-                        Architecture::X86_64 => match (reloc.kind, reloc.encoding, reloc.size) {
-                            (RelocationKind::Absolute, RelocationEncoding::Generic, 64) => {
-                                elf::R_X86_64_64
-                            }
-                            (RelocationKind::Relative, _, 32) => elf::R_X86_64_PC32,
-                            (RelocationKind::Got, _, 32) => elf::R_X86_64_GOT32,
-                            (RelocationKind::PltRelative, _, 32) => elf::R_X86_64_PLT32,
-                            (RelocationKind::GotRelative, _, 32) => elf::R_X86_64_GOTPCREL,
-                            (RelocationKind::Absolute, RelocationEncoding::Generic, 32) => {
-                                elf::R_X86_64_32
-                            }
-                            (RelocationKind::Absolute, RelocationEncoding::X86Signed, 32) => {
-                                elf::R_X86_64_32S
-                            }
-                            (RelocationKind::Absolute, _, 16) => elf::R_X86_64_16,
-                            (RelocationKind::Relative, _, 16) => elf::R_X86_64_PC16,
-                            (RelocationKind::Absolute, _, 8) => elf::R_X86_64_8,
-                            (RelocationKind::Relative, _, 8) => elf::R_X86_64_PC8,
-                            (RelocationKind::Elf(x), _, _) => x,
-                            _ => {
-                                return Err(Error(format!("unimplemented relocation {:?}", reloc)));
+                        Architecture::X86_64 | Architecture::X86_64_X32 => {
+                            match (reloc.kind, reloc.encoding, reloc.size) {
+                                (RelocationKind::Absolute, RelocationEncoding::Generic, 64) => {
+                                    elf::R_X86_64_64
+                                }
+                                (RelocationKind::Relative, _, 32) => elf::R_X86_64_PC32,
+                                (RelocationKind::Got, _, 32) => elf::R_X86_64_GOT32,
+                                (RelocationKind::PltRelative, _, 32) => elf::R_X86_64_PLT32,
+                                (RelocationKind::GotRelative, _, 32) => elf::R_X86_64_GOTPCREL,
+                                (RelocationKind::Absolute, RelocationEncoding::Generic, 32) => {
+                                    elf::R_X86_64_32
+                                }
+                                (RelocationKind::Absolute, RelocationEncoding::X86Signed, 32) => {
+                                    elf::R_X86_64_32S
+                                }
+                                (RelocationKind::Absolute, _, 16) => elf::R_X86_64_16,
+                                (RelocationKind::Relative, _, 16) => elf::R_X86_64_PC16,
+                                (RelocationKind::Absolute, _, 8) => elf::R_X86_64_8,
+                                (RelocationKind::Relative, _, 8) => elf::R_X86_64_PC8,
+                                (RelocationKind::Elf(x), _, _) => x,
+                                _ => {
+                                    return Err(Error(format!(
+                                        "unimplemented relocation {:?}",
+                                        reloc
+                                    )));
+                                }
                             }
-                        },
+                        }
                         Architecture::Hexagon => match (reloc.kind, reloc.encoding, reloc.size) {
                             (RelocationKind::Absolute, _, 32) => elf::R_HEX_32,
                             (RelocationKind::Elf(x), _, _) => x,

tests/round_trip/mod.rs

@@ -234,6 +234,7 @@ fn elf_any() {
         (Architecture::Bpf, Endianness::Little),
         (Architecture::I386, Endianness::Little),
         (Architecture::X86_64, Endianness::Little),
+        (Architecture::X86_64_X32, Endianness::Little),
         (Architecture::Hexagon, Endianness::Little),
         (Architecture::Mips, Endianness::Little),
         (Architecture::Mips64, Endianness::Little),