162 lines
5.6 KiB
Diff
162 lines
5.6 KiB
Diff
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# HG changeset patch
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# User Keir Fraser <keir.fraser@citrix.com>
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# Date 1250693923 -3600
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# Node ID 44d852862374dff2e734070ac60399f6875f6cd5
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# Parent bea861fb0f20671d41e467557bfdffb67b42f5e7
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x86_emulate: Remove cmpxchg retry loop from protmode_load_seg().
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It is safer to retry in a loop via the caller.
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Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
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xen-unstable changeset: 20031:34bdb5a29963
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xen-unstable date: Thu Aug 06 09:54:22 2009 +0100
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Index: xen-3.4.1-testing/xen/arch/x86/x86_emulate/x86_emulate.c
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===================================================================
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--- xen-3.4.1-testing.orig/xen/arch/x86/x86_emulate/x86_emulate.c
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+++ xen-3.4.1-testing/xen/arch/x86/x86_emulate/x86_emulate.c
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@@ -996,79 +996,75 @@ protmode_load_seg(
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if ( ((sel & 0xfff8) + 7) > desctab.limit )
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goto raise_exn;
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- do {
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- if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8),
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- &val, 4, ctxt, ops)) )
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- return rc;
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- desc.a = val;
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- if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8) + 4,
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- &val, 4, ctxt, ops)) )
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- return rc;
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- desc.b = val;
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+ if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8),
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+ &val, 4, ctxt, ops)) )
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+ return rc;
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+ desc.a = val;
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+ if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8) + 4,
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+ &val, 4, ctxt, ops)) )
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+ return rc;
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+ desc.b = val;
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- /* Segment present in memory? */
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- if ( !(desc.b & (1u<<15)) )
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- {
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- fault_type = EXC_NP;
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- goto raise_exn;
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- }
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+ /* Segment present in memory? */
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+ if ( !(desc.b & (1u<<15)) )
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+ {
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+ fault_type = EXC_NP;
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+ goto raise_exn;
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+ }
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- /* System segments must have the system flag (S) set. */
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- if ( (desc.b & (1u<<12)) == (!is_x86_user_segment(seg) << 12) )
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- goto raise_exn;
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+ /* System segments must have the system flag (S) set. */
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+ if ( (desc.b & (1u<<12)) == (!is_x86_user_segment(seg) << 12) )
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+ goto raise_exn;
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- dpl = (desc.b >> 13) & 3;
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- rpl = sel & 3;
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- cpl = ss.attr.fields.dpl;
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-
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- switch ( seg )
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- {
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- case x86_seg_cs:
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- /* Code segment? */
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- if ( !(desc.b & (1u<<11)) )
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- goto raise_exn;
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- /* Non-conforming segment: check DPL against RPL. */
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- if ( ((desc.b & (6u<<9)) != (6u<<9)) && (dpl != rpl) )
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- goto raise_exn;
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- break;
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- case x86_seg_ss:
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- /* Writable data segment? */
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- if ( (desc.b & (5u<<9)) != (1u<<9) )
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- goto raise_exn;
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- if ( (dpl != cpl) || (dpl != rpl) )
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- goto raise_exn;
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- break;
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- case x86_seg_ldtr:
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- /* LDT system segment? */
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- if ( (desc.b & (15u<<8)) != (2u<<8) )
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- goto raise_exn;
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- goto skip_accessed_flag;
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- case x86_seg_tr:
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- /* Available TSS system segment? */
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- if ( (desc.b & (15u<<8)) != (9u<<8) )
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- goto raise_exn;
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- a_flag = 0x200; /* busy flag */
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- break;
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- default:
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- /* Readable code or data segment? */
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- if ( (desc.b & (5u<<9)) == (4u<<9) )
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- goto raise_exn;
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- /* Non-conforming segment: check DPL against RPL and CPL. */
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- if ( ((desc.b & (6u<<9)) != (6u<<9)) &&
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- ((dpl < cpl) || (dpl < rpl)) )
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- goto raise_exn;
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- break;
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- }
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+ dpl = (desc.b >> 13) & 3;
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+ rpl = sel & 3;
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+ cpl = ss.attr.fields.dpl;
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- /* Ensure Accessed flag is set. */
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- new_desc_b = desc.b | a_flag;
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- rc = ((desc.b & a_flag) ? X86EMUL_OKAY :
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- ops->cmpxchg(
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- x86_seg_none, desctab.base + (sel & 0xfff8) + 4,
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- &desc.b, &new_desc_b, 4, ctxt));
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- } while ( rc == X86EMUL_CMPXCHG_FAILED );
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+ switch ( seg )
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+ {
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+ case x86_seg_cs:
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+ /* Code segment? */
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+ if ( !(desc.b & (1u<<11)) )
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+ goto raise_exn;
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+ /* Non-conforming segment: check DPL against RPL. */
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+ if ( ((desc.b & (6u<<9)) != (6u<<9)) && (dpl != rpl) )
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+ goto raise_exn;
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+ break;
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+ case x86_seg_ss:
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+ /* Writable data segment? */
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+ if ( (desc.b & (5u<<9)) != (1u<<9) )
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+ goto raise_exn;
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+ if ( (dpl != cpl) || (dpl != rpl) )
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+ goto raise_exn;
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+ break;
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+ case x86_seg_ldtr:
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+ /* LDT system segment? */
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+ if ( (desc.b & (15u<<8)) != (2u<<8) )
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+ goto raise_exn;
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+ goto skip_accessed_flag;
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+ case x86_seg_tr:
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+ /* Available TSS system segment? */
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+ if ( (desc.b & (15u<<8)) != (9u<<8) )
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+ goto raise_exn;
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+ a_flag = 0x200; /* busy flag */
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+ break;
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+ default:
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+ /* Readable code or data segment? */
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+ if ( (desc.b & (5u<<9)) == (4u<<9) )
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+ goto raise_exn;
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+ /* Non-conforming segment: check DPL against RPL and CPL. */
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+ if ( ((desc.b & (6u<<9)) != (6u<<9)) &&
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+ ((dpl < cpl) || (dpl < rpl)) )
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+ goto raise_exn;
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+ break;
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+ }
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- if ( rc )
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+ /* Ensure Accessed flag is set. */
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+ new_desc_b = desc.b | a_flag;
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+ if ( !(desc.b & a_flag) &&
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+ ((rc = ops->cmpxchg(
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+ x86_seg_none, desctab.base + (sel & 0xfff8) + 4,
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+ &desc.b, &new_desc_b, 4, ctxt)) != 0) )
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return rc;
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/* Force the Accessed flag in our local copy. */
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