[U-Boot] [PATCH 1/1] arm: print instructions pointed to by pc

[Alexander Graf]

> Am 09.05.2018 um 22:16 schrieb Heinrich Schuchardt <xypron.glpk at gmx.de>:
> 
> If an exception occurs in a loaded image and the relocation offset is
> unknown, it is helful to know the instructions pointed to by the
> program counter. This patch adds the missing output.
> 
> A possible output is:
> *pc: defe e7ff 8010 e8bd abb9 9ffc f7d5 9ffc
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
> arch/arm/lib/interrupts.c | 4 ++++
> 1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm/lib/interrupts.c b/arch/arm/lib/interrupts.c
> index cda4d48460..24fa3d433d 100644
> --- a/arch/arm/lib/interrupts.c
> +++ b/arch/arm/lib/interrupts.c
> @@ -60,6 +60,8 @@ static void show_efi_loaded_images(struct pt_regs *regs)
> void show_regs (struct pt_regs *regs)
> {
>    unsigned long __maybe_unused flags;
> +    /* The least significant bit chooses thumb, remove it. */
> +    u16 *pc = (u16 *)(instruction_pointer(regs) & ~1);

u16 values are quite bad for this. Non-thumb instruuctions are 32bit, so will be swapped in the output. Even with thumb you may get 32bit long ones.

Better just output everything as bytes. Then a simple xxd -ps -r can convert it into a binary you can throw objdump on.

Alex

>    const char __maybe_unused *processor_modes[] = {
>    "USER_26",    "FIQ_26",    "IRQ_26",    "SVC_26",
>    "UK4_26",    "UK5_26",    "UK6_26",    "UK7_26",
> @@ -97,6 +99,8 @@ void show_regs (struct pt_regs *regs)
>        fast_interrupts_enabled (regs) ? "on" : "off",
>        processor_modes[processor_mode (regs)],
>        thumb_mode (regs) ? " (T)" : "");
> +    printf("*pc: %04x %04x %04x %04x %04x %04x %04x %04x\n",
> +           pc[0], pc[1], pc[2], pc[3], pc[4], pc[5], pc[6], pc[7]);
> }
> 
> /* fixup PC to point to the instruction leading to the exception */
> -- 
> 2.17.0
>