[Crash-utility] [PATCH] x86_64: Fix that Particular kvaddr is converted to wrong paddr (RHEL6 x86_64)

[Dave Anderson]

----- Original Message -----
> I didn't check XEN HYPER MODE, I don't have XEN.
> If we need similar statement "if (kvaddr < MODULES_END)"
>  please add inside in "if (XEN_HYPER_MODE())" (1859 at x86_64_kvtop)
> 
> 
> 
> 
> >From ed300b74998e0923313e4fd14b9a41e305942b44 Mon Sep 17 00:00:00 2001
> From: Nakajima Akira <nakajima.akira at nttcom.co.jp>
> Date: Tue, 22 Dec 2015 15:46:42 +0900
> Subject: [PATCH] Fix that particular kvaddr is converted to wrong paddr
> 
> BUG INFO
> Particular kvaddr is converted to wrong paddr.
> You can see this bug on RHEL6_x86_64. (at present only RHEL6)
>  (I checked RHEL5, RHEL7, Fedora21, Fedora23)


I am out of the office until January 4th (only checking email until then), and will not
be able to look into this until then.  But because it is such a fundamental change that
you are proposing, it might make sense to create a check/macro that is specific to
the vsyscall region.   

Thanks,
  Dave
 
> 
> from /proc/kallsyms
> ffffffffff6008c0 D __jiffies
> 
> /////////// wrong ///////////
> crash> vtop ffffffffff6008c0
> VIRTUAL           PHYSICAL
> ffffffffff6008c0  7f6008c0
> 
>       PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
> ffffea00000623b8   1c11000                0        0  1 20000000000400
> reserved
> 
> 
> crash> rd ffffffffff6008c0
> ffffffffff6008c0:  0000000000000000                    ........
> 
> 
> /////////// correct ///////////
> crash> vtop ffffffffff6008c0
> VIRTUAL           PHYSICAL
> ffffffffff6008c0  1c118c0
> 
>       PAGE        PHYSICAL      MAPPING       INDEX CNT FLAGS
> ffffea00000623b8   1c11000                0        0  1 20000000000400
> reserved
> 
> 
> crash> rd ffffffffff6008c0
> ffffffffff6008c0:  00000000ffffe43a                    :.......
> 
> Reported-by: Nakajima Akira <nakajima.akira at nttcom.co.jp>
> Signed-off-by: Nakajima Akira <nakajima.akira at nttcom.co.jp>
> 
> ---
>  x86_64.c |   28 +++++++++++++++-------------
>  1 files changed, 15 insertions(+), 13 deletions(-)
> 
> diff --git a/x86_64.c b/x86_64.c
> index ff6fdd5..dab4d43 100644
> --- a/x86_64.c
> +++ b/x86_64.c
> @@ -1872,19 +1872,21 @@ x86_64_kvtop(struct task_context *tc, ulong kvaddr,
> physaddr_t *paddr, int verbo
>                 		fprintf(fp, "PAGE DIRECTORY: %lx\n", *pml4);
>  		}
>  	} else {
> -        	if (!vt->vmalloc_start) {
> -                	*paddr = x86_64_VTOP(kvaddr);
> -                	return TRUE;
> -        	}
> -
> -        	if (!IS_VMALLOC_ADDR(kvaddr)) {
> -                	*paddr = x86_64_VTOP(kvaddr);
> -                	if (!verbose)
> -                        	return TRUE;
> -        	}
> -
> -		if (XEN() && (kt->xen_flags & WRITABLE_PAGE_TABLES))
> -			return (x86_64_kvtop_xen_wpt(tc, kvaddr, paddr, verbose));
> +		if (kvaddr < MODULES_END) {
> +	        	if (!vt->vmalloc_start) {
> +	                	*paddr = x86_64_VTOP(kvaddr);
> +	                	return TRUE;
> +	        	}
> +
> +	        	if (!IS_VMALLOC_ADDR(kvaddr)) {
> +	                	*paddr = x86_64_VTOP(kvaddr);
> +	                	if (!verbose)
> +	                        	return TRUE;
> +	        	}
> +
> +			if (XEN() && (kt->xen_flags & WRITABLE_PAGE_TABLES))
> +				return (x86_64_kvtop_xen_wpt(tc, kvaddr, paddr, verbose));
> +		}
>  
>   		/*
>  		 *  pgd = pgd_offset_k(addr);
> --
> 1.7.1
> 
> 
> --
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