Re: [PATCH 11/16] turn priviled operation into a macro in head_64.S

Jeremy Fitzhardinge
2007-11-01T04:50:50Z

Glauber de Oliveira Costa wrote:
> under paravirt, read cr2 cannot be issued directly anymore.
> So wrap it in a macro, defined to the operation itself in case
> paravirt is off, but to something else if we have paravirt
> in the game
>

Is this actually needed? It's only used in the early fault handler in
head_64.S. Will we be taking that path in the paravirt case? If so,
should we disable the fault handler altogether, since the hypervisor can
probably provide better diagnositcs.

J
> Signed-off-by: Glauber de Oliveira Costa <gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>
> Acked-by: Jeremy Fitzhardinge <jeremy-8XJ3FbD+ij9l57MIdRCFDg@public.gmane.org>
> ---
> arch/x86/kernel/head_64.S | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index b6167fe..c31b1c9 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -19,6 +19,13 @@
> #include <asm/msr.h>
> #include <asm/cache.h>
>
> +#ifdef CONFIG_PARAVIRT
> +#include <asm/asm-offsets.h>
> +#include <asm/paravirt.h>
> +#else
> +#define GET_CR2_INTO_RCX movq %cr2, %rcx
> +#endif
> +
> /* we are not able to switch in one step to the final KERNEL ADRESS SPACE
> * because we need identity-mapped pages.
> *
> @@ -267,7 +274,7 @@ ENTRY(early_idt_handler)
> xorl %eax,%eax
> movq 8(%rsp),%rsi # get rip
> movq (%rsp),%rdx
> - movq %cr2,%rcx
> + GET_CR2_INTO_RCX
> leaq early_idt_msg(%rip),%rdi
> call early_printk
> cmpl $2,early_recursion_flag(%rip)
>

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