Re: [PATCH kvm-unit-tests 2/2] arm64: Output PC load offset on unhandled exceptions

[Nikos Nikoleris <nikos.nikoleris@arm.com>]

On 25/03/2021 15:56, Andrew Jones wrote:
> Since for arm64 we can load the unit tests at different addresses,
> then let's make it easier to debug by calculating the PC offset for
> the user. The offset can then be directly used when looking at the
> disassembly of the test's elf file.
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

> ---
>   arm/flat.lds          | 1 +
>   lib/arm64/processor.c | 7 +++++++
>   2 files changed, 8 insertions(+)
> 
> diff --git a/arm/flat.lds b/arm/flat.lds
> index 4d43cdfeab41..6ed377c0eaa0 100644
> --- a/arm/flat.lds
> +++ b/arm/flat.lds
> @@ -1,6 +1,7 @@
>   
>   SECTIONS
>   {
> +    PROVIDE(_text = .);
>       .text : { *(.init) *(.text) *(.text.*) }
>       . = ALIGN(64K);
>       PROVIDE(etext = .);
> diff --git a/lib/arm64/processor.c b/lib/arm64/processor.c
> index ef558625e284..831207c16587 100644
> --- a/lib/arm64/processor.c
> +++ b/lib/arm64/processor.c
> @@ -99,12 +99,19 @@ bool get_far(unsigned int esr, unsigned long *far)
>   	return false;
>   }
>   
> +extern unsigned long _text;
> +
>   static void bad_exception(enum vector v, struct pt_regs *regs,
>   			  unsigned int esr, bool esr_valid, bool bad_vector)
>   {
>   	unsigned long far;
>   	bool far_valid = get_far(esr, &far);
>   	unsigned int ec = esr >> ESR_EL1_EC_SHIFT;
> +	uintptr_t text = (uintptr_t)&_text;
> +
> +	printf("Load address: %" PRIxPTR "\n", text);
> +	printf("PC: %" PRIxPTR " PC offset: %" PRIxPTR "\n",
> +	       (uintptr_t)regs->pc, (uintptr_t)regs->pc - text);
>   
>   	if (bad_vector) {
>   		if (v < VECTOR_MAX)
>