[Qemu-devel] [PATCH] target-arm: Load ELF images with the correct machine type for CPU

[Peter Maydell <peter.maydell@linaro.org>]

When trying to load an ELF file specified via -kernel, we need to
pass load_elf() the ELF machine type corresponding to the CPU we're
booting with, not the one corresponding to the softmmu binary
we happen to be running. (The two are different in the case of
loading a 32-bit ARM ELF file into a 32 bit CPU being emulated
by qemu-system aarch64.) This was causing us to incorrectly fail
to load ELF images in this situation.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
This isn't really a big deal since we can just say "use the
qemu-system-arm binary instead". However maybe we should put
this into 2.0. Opinions?

Incidentally I suspect hw/i386/multiboot.c has a similar
problem where it calls load_elf() passing ELF_MACHINE.
---
 hw/arm/boot.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index dc62918..3d1f4a2 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -448,6 +448,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
     int initrd_size;
     int is_linux = 0;
     uint64_t elf_entry;
+    int elf_machine;
     hwaddr entry, kernel_load_offset;
     int big_endian;
     static const ARMInsnFixup *primary_loader;
@@ -463,9 +464,11 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
     if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
         primary_loader = bootloader_aarch64;
         kernel_load_offset = KERNEL64_LOAD_ADDR;
+        elf_machine = EM_AARCH64;
     } else {
         primary_loader = bootloader;
         kernel_load_offset = KERNEL_LOAD_ADDR;
+        elf_machine = EM_ARM;
     }
 
     info->dtb_filename = qemu_opt_get(qemu_get_machine_opts(), "dtb");
@@ -501,7 +504,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
 
     /* Assume that raw images are linux kernels, and ELF images are not.  */
     kernel_size = load_elf(info->kernel_filename, NULL, NULL, &elf_entry,
-                           NULL, NULL, big_endian, ELF_MACHINE, 1);
+                           NULL, NULL, big_endian, elf_machine, 1);
     entry = elf_entry;
     if (kernel_size < 0) {
         kernel_size = load_uimage(info->kernel_filename, &entry, NULL,
-- 
1.9.0