Re: [Xen-devel] [PATCH for-xen-4-5 v3] xen/arm: dump guest stack even if not the current VCPU

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-10-23 at 09:46 +0100, Frediano Ziglio wrote:
> From: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>
> 
> If show_guest_stack was called from Xen context (for instance hitting
> '0' key on Xen console) get_page_from_gva was not able to get the
> page returning NULL.
> Detecting different domain and changing VTTBR register make
> get_page_from_gva works for different domains.
> 
> Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>
> ---
>  xen/arch/arm/p2m.c   | 22 +++++++++++++++++++---
>  xen/arch/arm/traps.c |  2 +-
>  2 files changed, 20 insertions(+), 4 deletions(-)
> 
> This is a bug fix to fix guest stack dumps.
> 
> The function get_page_from_gva is used in hot path (see
> arch/arm/guestcopy.c) but always with the current domain. The function
> will be used with another domain than current only when the stack of
> the guest will be dumped. The code added is self-containted.
> 
> Changed from v2:
> - add comment suggested by Julien Grall;
> 
> - modify code path to avoid keeping IRQ disabled too much (Julien Grall);
> - collapse change in a single if to improve performances.
> 
> Tested manually.

I succeeding in applying for real this time but:
p2m.c: In function âget_page_from_gvaâ:
p2m.c:1185:45: error: âmaddrâ may be used uninitialized in this function 
[-Werror=uninitialized]
cc1: all warnings being treated as errors
make[4]: *** [p2m.o] Error 1

This was on arm32. So not pushed.

> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 1585d35..2345199 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1177,12 +1177,28 @@ struct page_info *get_page_from_gva(struct
> domain *d, vaddr_t va,

Please avoid word wrapping patches in the future.
http://wiki.xen.org/wiki/Submitting_Xen_Patches has some guidance for
different mail clients. I fixed it by hand this time.

Ian.


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