[Qemu-devel] Use load addresses for ELF images

[Paul Brook]

The patch below changes the system emulation ELF loader to use load addresses, 
not virtual addresses, when loading images.  Typically a bare metal XIP 
application will have both data and code loaded into the rom area.  The 
application startup code will then take care of copying the data segment to 
its virtual ram address.

All the linux kernels I could find (and any image that doesn't deliberately do 
otherwise) have load address == virtual address.

The new behavior is consistent with the gdb "load" command, grub, and pretty 
much every other ELF system loader I'm aware of.

Signed-off-by: Paul Brook <address@hidden>

Index: loader.c
===================================================================
--- loader.c    (revision 5512)
+++ loader.c    (working copy)
@@ -282,7 +282,7 @@ static void *load_at(int fd, int offset,
 #include "elf_ops.h"
 
 /* return < 0 if error, otherwise the number of bytes loaded in memory */
-int load_elf(const char *filename, int64_t virt_to_phys_addend,
+int load_elf(const char *filename, int64_t address_offset,
              uint64_t *pentry, uint64_t *lowaddr, uint64_t *highaddr)
 {
     int fd, data_order, host_data_order, must_swab, ret;
@@ -317,10 +317,10 @@ int load_elf(const char *filename, int64
 
     lseek(fd, 0, SEEK_SET);
     if (e_ident[EI_CLASS] == ELFCLASS64) {
-        ret = load_elf64(fd, virt_to_phys_addend, must_swab, pentry,
+        ret = load_elf64(fd, address_offset, must_swab, pentry,
                          lowaddr, highaddr);
     } else {
-        ret = load_elf32(fd, virt_to_phys_addend, must_swab, pentry,
+        ret = load_elf32(fd, address_offset, must_swab, pentry,
                          lowaddr, highaddr);
     }
 
Index: sysemu.h
===================================================================
--- sysemu.h    (revision 5512)
+++ sysemu.h    (working copy)
@@ -160,7 +160,7 @@ extern CharDriverState *parallel_hds[MAX
 int get_image_size(const char *filename);
 int load_image(const char *filename, uint8_t *addr); /* deprecated */
 int load_image_targphys(const char *filename, target_phys_addr_t, int 
max_sz);
-int load_elf(const char *filename, int64_t virt_to_phys_addend,
+int load_elf(const char *filename, int64_t address_offset,
              uint64_t *pentry, uint64_t *lowaddr, uint64_t *highaddr);
 int load_aout(const char *filename, target_phys_addr_t addr, int max_sz);
 int load_uboot(const char *filename, target_ulong *ep, int *is_linux);
Index: elf_ops.h
===================================================================
--- elf_ops.h   (revision 5512)
+++ elf_ops.h   (working copy)
@@ -177,7 +177,7 @@ static int glue(load_symbols, SZ)(struct
     return -1;
 }
 
-static int glue(load_elf, SZ)(int fd, int64_t virt_to_phys_addend,
+static int glue(load_elf, SZ)(int fd, int64_t address_offset,
                               int must_swab, uint64_t *pentry,
                               uint64_t *lowaddr, uint64_t *highaddr)
 {
@@ -229,7 +229,9 @@ static int glue(load_elf, SZ)(int fd, in
                 if (read(fd, data, ph->p_filesz) != ph->p_filesz)
                     goto fail;
             }
-            addr = ph->p_vaddr + virt_to_phys_addend;
+            /* address_offset is hack for images that are
+               linked at the wrong physical address.  */
+            addr = ph->p_paddr + address_offset;
 
             cpu_physical_memory_write_rom(addr, data, mem_size);