pvh: Add test for PVH note parsing

Add a test case as part of the load_elf() tests to verify
the functionality that parses the ELF Note header to look
for a PVH entry point address if one is encoded.
This is done by parsing a minimal ELF binary that encodes
a predefined address of 0x1e1fe1f, and verifying that the
same value is read. A dummy note header is also included
in the binary to verify the ability to ignore irrelevant
notes.

The minimal ELF source code (elfnote.S):

	#define ELFNOTE_START(name, type, flags)	\
	.pushsection .note.name, flags, @note   ;	\
	  .balign 4                             ;	\
	  .long 2f - 1f         /* namesz */    ;	\
	  .long 4484f - 3f      /* descsz */    ;	\
	  .long type                            ;	\
	1:.asciz #name                          ;	\
	2:.balign 4                             ;	\
	3:

	#define ELFNOTE_END				\
	4484:.balign 4                          ;	\
	.popsection                             ;

	#define ELFNOTE(name, type, desc)		\
	        ELFNOTE_START(name, type, "a")		\
	                desc                    ;	\
	        ELFNOTE_END

	#define XEN_ELFNOTE_PHYS32_ENTRY	18
	#define NT_VERSION			1

	ELFNOTE(dummy, NT_VERSION, .quad 0xcafecafe)
	ELFNOTE(PVHNote, XEN_ELFNOTE_PHYS32_ENTRY, .quad 0x1e1fe1f)

	.section        ".text","ax"
	.global _start
	_start:

Built with:
$ gcc elfnote.S -s -nostdlib -o test_elfnote.bin

Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>

Author: aljimenezb

src/loader/mod.rs

@@ -544,6 +544,12 @@ mod test {
         v
     }
 
+    #[cfg(feature = "elf")]
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+    fn make_elfnote() -> Vec<u8> {
+        include_bytes!("test_elfnote.bin").to_vec()
+    }
+
     #[allow(safe_packed_borrows)]
     #[allow(non_snake_case)]
     #[test]
@@ -664,6 +670,14 @@ mod test {
                 Some(highmem_start_address)
             )
         );
+
+        let pvhnote_image = make_elfnote();
+        loader_result = Elf::load(&gm, None, &mut Cursor::new(&pvhnote_image), None).unwrap();
+        println!(
+            "PVH entry point at address {:8x} \n",
+            loader_result.pvh_entry_addr.unwrap().raw_value()
+        );
+        assert_eq!(loader_result.pvh_entry_addr.unwrap().raw_value(), 0x1e1fe1f);
     }
 
     #[test]