Re: WARNING: kernel stack frame pointer at ffffffff82e03f40 in swapper:0 has bad value (null)

[Borislav Petkov]

On Mon, Dec 12, 2016 at 04:11:47PM -0600, Josh Poimboeuf wrote:
> Yes, please.

Attached.

> That said, the code could probably be made a little clearer by changing
> "call 1f" to "push $1f" and then move the '1' label to after the lretq
> instruction, like:
> 
> 	pushq	$1f		# put return address on stack for unwinder
> 	xorq	%rbp, %rbp	# clear frame pointer
> 	movq	initial_code(%rip), %rax
> 	pushq	$__KERNEL_CS	# set correct cs
> 	pushq	%rax		# target address in negative space
> 	lretq
> 1:
> ENDPROC(start_cpu)
> 
> That shows:
> 
>   start_cpu+0x14/0x14
> 
> Which is more accurate anyway.  I'll make a patch.

Yap, makes more sense. I'll run it tomorrow.

FWIW, I tried

	pushq $1f

before without moving the 1: label but the thing still fired.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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