* [PATCH] x86emul: ignore most segment bases for 64-bit mode in is_aligned()
@ 2016-12-14 15:29 Jan Beulich
2016-12-14 16:49 ` Andrew Cooper
0 siblings, 1 reply; 2+ messages in thread
From: Jan Beulich @ 2016-12-14 15:29 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper
[-- Attachment #1: Type: text/plain, Size: 1062 bytes --]
ops->read_segment() will report whatever is actually there in the
register, so we need to actively distinguish ES/CS/SS/DS from FS/GS.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1642,12 +1642,17 @@ static bool is_aligned(enum x86_segment
/* Expecting powers of two only. */
ASSERT(!(size & (size - 1)));
- /* No alignment checking when we have no way to read segment data. */
- if ( !ops->read_segment )
- return true;
+ if ( mode_64bit() && seg < x86_seg_fs )
+ memset(®, 0, sizeof(reg));
+ else
+ {
+ /* No alignment checking when we have no way to read segment data. */
+ if ( !ops->read_segment )
+ return true;
- if ( ops->read_segment(seg, ®, ctxt) != X86EMUL_OKAY )
- return false;
+ if ( ops->read_segment(seg, ®, ctxt) != X86EMUL_OKAY )
+ return false;
+ }
return !((reg.base + offs) & (size - 1));
}
[-- Attachment #2: x86emul-64bit-is_aligned.patch --]
[-- Type: text/plain, Size: 1126 bytes --]
x86emul: ignore most segment bases for 64-bit mode in is_aligned()
ops->read_segment() will report whatever is actually there in the
register, so we need to actively distinguish ES/CS/SS/DS from FS/GS.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1642,12 +1642,17 @@ static bool is_aligned(enum x86_segment
/* Expecting powers of two only. */
ASSERT(!(size & (size - 1)));
- /* No alignment checking when we have no way to read segment data. */
- if ( !ops->read_segment )
- return true;
+ if ( mode_64bit() && seg < x86_seg_fs )
+ memset(®, 0, sizeof(reg));
+ else
+ {
+ /* No alignment checking when we have no way to read segment data. */
+ if ( !ops->read_segment )
+ return true;
- if ( ops->read_segment(seg, ®, ctxt) != X86EMUL_OKAY )
- return false;
+ if ( ops->read_segment(seg, ®, ctxt) != X86EMUL_OKAY )
+ return false;
+ }
return !((reg.base + offs) & (size - 1));
}
[-- Attachment #3: Type: text/plain, Size: 127 bytes --]
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] x86emul: ignore most segment bases for 64-bit mode in is_aligned()
2016-12-14 15:29 [PATCH] x86emul: ignore most segment bases for 64-bit mode in is_aligned() Jan Beulich
@ 2016-12-14 16:49 ` Andrew Cooper
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Cooper @ 2016-12-14 16:49 UTC (permalink / raw)
To: Jan Beulich, xen-devel
On 14/12/16 15:29, Jan Beulich wrote:
> ops->read_segment() will report whatever is actually there in the
> register, so we need to actively distinguish ES/CS/SS/DS from FS/GS.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
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2016-12-14 16:49 ` Andrew Cooper
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