Re: [Qemu-devel] [PATCH target-arm] arm: armv7m: Respect elf entry point

[Peter Crosthwaite]

On Mon, Aug 4, 2014 at 5:54 PM, Alistair Francis <address@hidden> wrote:
> On Sat, Aug 2, 2014 at 9:41 AM, Peter Crosthwaite
> <address@hidden> wrote:
>> ARMv7M has it's own bootloader (separate from the regular ARM
>> bootloader) that is elf aware. It is able to load elfs but it does
>> not set the program counter to the elf entry point. Make it more
>> consistent with the regular ARM bootloader by setting the program
>> counter to the given elf entry point.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>> ---
>>  hw/arm/armv7m.c | 19 ++++++++++++++++---
>>  1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
>> index 397e8df..d1b983f 100644
>> --- a/hw/arm/armv7m.c
>> +++ b/hw/arm/armv7m.c
>> @@ -155,11 +155,18 @@ static void armv7m_bitband_init(void)
>>
>>  /* Board init.  */
>>
>> +typedef struct ARMV7MResetArgs {
>> +    ARMCPU *cpu;
>> +    uint32_t reset_pc;
>> +} ARMV7MResetArgs;
>> +
>>  static void armv7m_reset(void *opaque)
>>  {
>> -    ARMCPU *cpu = opaque;
>> +    ARMV7MResetArgs *args = opaque;
>>
>> -    cpu_reset(CPU(cpu));
>> +    cpu_reset(CPU(args->cpu));
>> +    args->cpu->env.regs[15] = args->reset_pc;
>> +    args->cpu->env.thumb = args->reset_pc & 1;
>>  }
>
> This breaks a simple test case that I have.

Can you send me a replicator? I'll give it a go.

> It now starts at a an
> address one one bit larger but causes the program to hang.
> If the 'cpu_reset(CPU(args->cpu))' is moved to the end of the function
> the test boots (the same as it did before).
>

Hmm but I think that loses you the elf entry point again.

Regards,
Peter

>>
>>  /* Init CPU and memory for a v7-M based board.
>> @@ -183,6 +190,7 @@ qemu_irq *armv7m_init(MemoryRegion *address_space_mem,
>>      MemoryRegion *sram = g_new(MemoryRegion, 1);
>>      MemoryRegion *flash = g_new(MemoryRegion, 1);
>>      MemoryRegion *hack = g_new(MemoryRegion, 1);
>> +    ARMV7MResetArgs reset_args;
>>
>>      flash_size *= 1024;
>>      sram_size *= 1024;
>> @@ -259,7 +267,12 @@ qemu_irq *armv7m_init(MemoryRegion *address_space_mem,
>>      vmstate_register_ram_global(hack);
>>      memory_region_add_subregion(address_space_mem, 0xfffff000, hack);
>>
>> -    qemu_register_reset(armv7m_reset, cpu);
>> +    reset_args = (ARMV7MResetArgs) {
>> +        .cpu = cpu,
>> +        .reset_pc = entry,
>> +    };
>> +    qemu_register_reset(armv7m_reset,
>> +                        g_memdup(&reset_args, sizeof(reset_args)));
>>      return pic;
>>  }
>>
>> --
>> 1.9.1
>>
>