elf: Add optional function ptr to load_elf() to parse ELF notes

This patch adds an optional function pointer, 'elf_note_fn', to
load_elf() which causes load_elf() to additionally parse any
ELF program headers of type PT_NOTE and check to see if the ELF
Note is of the type specified by the 'translate_opaque' arg.
If a matching ELF Note is found then the specfied function pointer
is called to process the ELF note.

Passing a NULL function pointer results in ELF Notes being skipped.

The first consumer of this functionality is the PVHboot support
which needs to read the XEN_ELFNOTE_PHYS32_ENTRY ELF Note while
loading the uncompressed kernel binary in order to discover the
boot entry address for the x86/HVM direct boot ABI.

Signed-off-by: Liam Merwick <liam.merwick@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/arm/armv7m.c

@@ -310,7 +310,8 @@ void armv7m_load_kernel(ARMCPU *cpu, const char *kernel_filename, int mem_size)
     as = cpu_get_address_space(cs, asidx);
 
     if (kernel_filename) {
-        image_size = load_elf_as(kernel_filename, NULL, NULL, &entry, &lowaddr,
+        image_size = load_elf_as(kernel_filename, NULL, NULL, NULL,
+                                 &entry, &lowaddr,
                                  NULL, big_endian, EM_ARM, 1, 0, as);
         if (image_size < 0) {
             image_size = load_image_targphys_as(kernel_filename, 0,

hw/arm/boot.c

@@ -881,7 +881,7 @@ static int64_t arm_load_elf(struct arm_boot_info *info, uint64_t *pentry,
         }
     }
 
-    ret = load_elf_as(info->kernel_filename, NULL, NULL,
+    ret = load_elf_as(info->kernel_filename, NULL, NULL, NULL,
                       pentry, lowaddr, highaddr, big_endian, elf_machine,
                       1, data_swab, as);
     if (ret <= 0) {