>>> On 14.07.15 at 18:15, <andrew.coop...@citrix.com> wrote:
> Currently limited to just hypervisor context, but it could be extended
> to vcpus as well.
Considering this ...
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -115,6 +115,31 @@
> #define stack_words_per_line 4
> #define ESP_BEFORE_EXCEPTION(regs) ((unsigned long *)regs->rsp)
>
> +static void show_code(const struct cpu_user_regs *regs)
> +{
> + char insns[24];
> + unsigned int i, not_copied;
> + void *__user start_ip = (void *)regs->rip - 8;
> +
> + if ( guest_mode(regs) )
> + return;
> +
> + not_copied = __copy_from_user(insns, start_ip, ARRAY_SIZE(insns));
> +
> + printk("Xen code around %04x:%p (%ps)%s:\n",
... I'd prefer the "Xen " here to be dropped.
> + regs->cs, _p(regs->rip), _p(regs->rip),
> + !!not_copied ? " [fault on access]" : "");
Pointless !!.
> + for ( i = 0; i < ARRAY_SIZE(insns) - not_copied; ++i )
> + {
> + if ( (unsigned long)(start_ip + i) == regs->rip )
> + printk(" <%02x>", (unsigned char)insns[i]);
> + else
> + printk(" %02x", (unsigned char)insns[i]);
Why not have insns[] be unsigned char right away?
Also I think you should avoid the subtraction from regs->rip to wrap
through zero, or even bail when RIP doesn't point into Xen space.
Jan
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