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>

2 files changed, 10 insertions, 1 deletions

diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
index e2cb675195..3438d6f69e 100644
--- a/include/hw/elf_ops.h
+++ b/include/hw/elf_ops.h
@@ -266,6 +266,7 @@ fail:
 }
 
 static int glue(load_elf, SZ)(const char *name, int fd,
+                              uint64_t (*elf_note_fn)(void *, void *, bool),
                               uint64_t (*translate_fn)(void *, uint64_t),
                               void *translate_opaque,
                               int must_swab, uint64_t *pentry,
@@ -498,6 +499,7 @@ static int glue(load_elf, SZ)(const char *name, int fd,
             data = NULL;
         }
     }
+
     g_free(phdr);
     if (lowaddr)
         *lowaddr = (uint64_t)(elf_sword)low;
diff --git a/include/hw/loader.h b/include/hw/loader.h
index de8a29603b..3e1b3a4566 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -93,6 +93,8 @@ const char *load_elf_strerror(int error);
 
 /** load_elf_ram_sym:
  * @filename: Path of ELF file
+ * @elf_note_fn: optional function to parse ELF Note type
+ *               passed via @translate_opaque
  * @translate_fn: optional function to translate load addresses
  * @translate_opaque: opaque data passed to @translate_fn
  * @pentry: Populated with program entry point. Ignored if NULL.
@@ -125,6 +127,7 @@ typedef void (*symbol_fn_t)(const char *st_name, int st_info,
                             uint64_t st_value, uint64_t st_size);
 
 int load_elf_ram_sym(const char *filename,
+                     uint64_t (*elf_note_fn)(void *, void *, bool),
                      uint64_t (*translate_fn)(void *, uint64_t),
                      void *translate_opaque, uint64_t *pentry,
                      uint64_t *lowaddr, uint64_t *highaddr, int big_endian,
@@ -136,6 +139,7 @@ int load_elf_ram_sym(const char *filename,
  * symbol callback function
  */
 int load_elf_ram(const char *filename,
+                 uint64_t (*elf_note_fn)(void *, void *, bool),
                  uint64_t (*translate_fn)(void *, uint64_t),
                  void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
                  uint64_t *highaddr, int big_endian, int elf_machine,
@@ -146,6 +150,7 @@ int load_elf_ram(const char *filename,
  * Same as load_elf_ram(), but always loads the elf as ROM
  */
 int load_elf_as(const char *filename,
+                uint64_t (*elf_note_fn)(void *, void *, bool),
                 uint64_t (*translate_fn)(void *, uint64_t),
                 void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
                 uint64_t *highaddr, int big_endian, int elf_machine,
@@ -155,7 +160,9 @@ int load_elf_as(const char *filename,
  * Same as load_elf_as(), but doesn't allow the caller to specify an
  * AddressSpace.
  */
-int load_elf(const char *filename, uint64_t (*translate_fn)(void *, uint64_t),
+int load_elf(const char *filename,
+             uint64_t (*elf_note_fn)(void *, void *, bool),
+             uint64_t (*translate_fn)(void *, uint64_t),
              void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
              uint64_t *highaddr, int big_endian, int elf_machine,
              int clear_lsb, int data_swab);