pvh: Add ELF Note definitions

Define ELF Note header structure and constants necessary for parsing
the PVH entry point address encoded in the kernel ELF header.

Signed-off-by: Alejandro Jimenez <[email protected]>

Author: aljimenezb

src/loader/elf.rs

@@ -1,3 +1,5 @@
+// Copyright © 2020, Oracle and/or its affiliates.
+//
 // Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 //
 // Portions Copyright 2017 The Chromium OS Authors. All rights reserved.
@@ -22,6 +24,16 @@ pub const ELFMAG0: ::std::os::raw::c_uint = 127;
 pub const ELFDATA2LSB: ::std::os::raw::c_uint = 1;
 pub const PT_LOAD: ::std::os::raw::c_uint = 1;
 
+// ELF Note p_type used to parse PVH entry point address
+pub const PT_NOTE: ::std::os::raw::c_uint = 4;
+
+// 32bit entry point into the kernel. When requested to boot the
+// guest kernel using the PVH boot protocol, use this entry point
+// to start the guest in 32-bit protected mode with paging disabled.
+//
+// [ Corresponding definition in Linux kernel: include/xen/interface/elfnote.h ]
+pub const XEN_ELFNOTE_PHYS32_ENTRY: u32 = 18;
+
 pub const ELFMAG1: u8 = b'E';
 pub const ELFMAG2: u8 = b'L';
 pub const ELFMAG3: u8 = b'F';
@@ -86,6 +98,16 @@ impl Clone for elf64_phdr {
 }
 pub type Elf64_Phdr = elf64_phdr;
 
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct elf64_nhdr {
+    pub n_namesz: Elf64_Word, // Name size
+    pub n_descsz: Elf64_Word, // Content size
+    pub n_type: Elf64_Word,   // Content type
+}
+
+pub type Elf64_Nhdr = elf64_nhdr;
+
 #[cfg(test)]
 mod tests {
     use super::*;