hw/core/loader: Let load_elf() populate a field with CPU-specific flags

While loading the executable, some platforms (like AVR) need to
detect CPU type that executable is built for - and, with this patch,
this is enabled by reading the field 'e_flags' of the ELF header of
the executable in question. The change expands functionality of
the following functions:

  - load_elf()
  - load_elf_as()
  - load_elf_ram()
  - load_elf_ram_sym()

The argument added to these functions is called 'pflags' and is of
type 'uint32_t*' (that matches 'pointer to 'elf_word'', 'elf_word'
being the type of the field 'e_flags', in both 32-bit and 64-bit
variants of ELF header). Callers are allowed to pass NULL as that
argument, and in such case no lookup to the field 'e_flags' will
happen, and no information will be returned, of course.

CC: Richard Henderson <rth@twiddle.net>
CC: Peter Maydell <peter.maydell@linaro.org>
CC: Edgar E. Iglesias <edgar.iglesias@gmail.com>
CC: Michael Walle <michael@walle.cc>
CC: Thomas Huth <huth@tuxfamily.org>
CC: Laurent Vivier <laurent@vivier.eu>
CC: Philippe Mathieu-Daudé <f4bug@amsat.org>
CC: Aleksandar Rikalo <aleksandar.rikalo@rt-rk.com>
CC: Aurelien Jarno <aurelien@aurel32.net>
CC: Jia Liu <proljc@gmail.com>
CC: David Gibson <david@gibson.dropbear.id.au>
CC: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
CC: BALATON Zoltan <balaton@eik.bme.hu>
CC: Christian Borntraeger <borntraeger@de.ibm.com>
CC: Thomas Huth <thuth@redhat.com>
CC: Artyom Tarasenko <atar4qemu@gmail.com>
CC: Fabien Chouteau <chouteau@adacore.com>
CC: KONRAD Frederic <frederic.konrad@adacore.com>
CC: Max Filippov <jcmvbkbc@gmail.com>

Reviewed-by: Aleksandar Rikalo <aleksandar.rikalo@rt-rk.com>
Signed-off-by: Michael Rolnik <mrolnik@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Message-Id: <1580079311-20447-24-git-send-email-aleksandar.markovic@rt-rk.com>

2 files changed, 17 insertions, 10 deletions

diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
index e07d276df7..a1411bfcab 100644
--- a/include/hw/elf_ops.h
+++ b/include/hw/elf_ops.h
@@ -316,7 +316,8 @@ static int glue(load_elf, SZ)(const char *name, int fd,
                               void *translate_opaque,
                               int must_swab, uint64_t *pentry,
                               uint64_t *lowaddr, uint64_t *highaddr,
-                              int elf_machine, int clear_lsb, int data_swab,
+                              uint32_t *pflags, int elf_machine,
+                              int clear_lsb, int data_swab,
                               AddressSpace *as, bool load_rom,
                               symbol_fn_t sym_cb)
 {
@@ -389,6 +390,9 @@ static int glue(load_elf, SZ)(const char *name, int fd,
             }
     }
 
+    if (pflags) {
+        *pflags = (elf_word)ehdr.e_flags;
+    }
     if (pentry)
         *pentry = (uint64_t)(elf_sword)ehdr.e_entry;
 
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 48a96cd559..a9eeea3952 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -101,6 +101,7 @@ const char *load_elf_strerror(int error);
  * @pentry: Populated with program entry point. Ignored if NULL.
  * @lowaddr: Populated with lowest loaded address. Ignored if NULL.
  * @highaddr: Populated with highest loaded address. Ignored if NULL.
+ * @pflags: Populated with ELF processor-specific flags. Ignore if NULL.
  * @bigendian: Expected ELF endianness. 0 for LE otherwise BE
  * @elf_machine: Expected ELF machine type
  * @clear_lsb: Set to mask off LSB of addresses (Some architectures use
@@ -131,8 +132,9 @@ 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,
-                     int elf_machine, int clear_lsb, int data_swab,
+                     uint64_t *lowaddr, uint64_t *highaddr, uint32_t *pflags,
+                     int big_endian, int elf_machine,
+                     int clear_lsb, int data_swab,
                      AddressSpace *as, bool load_rom, symbol_fn_t sym_cb);
 
 /** load_elf_ram:
@@ -143,9 +145,9 @@ 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,
-                 int clear_lsb, int data_swab, AddressSpace *as,
-                 bool load_rom);
+                 uint64_t *highaddr, uint32_t *pflags, int big_endian,
+                 int elf_machine, int clear_lsb, int data_swab,
+                 AddressSpace *as, bool load_rom);
 
 /** load_elf_as:
  * Same as load_elf_ram(), but always loads the elf as ROM
@@ -154,8 +156,9 @@ 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,
-                int clear_lsb, int data_swab, AddressSpace *as);
+                uint64_t *highaddr, uint32_t *pflags, int big_endian,
+                int elf_machine, int clear_lsb, int data_swab,
+                AddressSpace *as);
 
 /** load_elf:
  * Same as load_elf_as(), but doesn't allow the caller to specify an
@@ -165,8 +168,8 @@ 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);
+             uint64_t *highaddr, uint32_t *pflags, int big_endian,
+             int elf_machine, int clear_lsb, int data_swab);
 
 /** load_elf_hdr:
  * @filename: Path of ELF file