# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1219157839 -3600
# Node ID a3fe573a0e1eb98246e09db98f12e13de117a52b
# Parent 6e3c97f43f9c79506c834fe0661b4ceb7ba21a99
x86, hvm: Observe EFLAGS.DF when performing segmentation checks and
address translations on multi-iteration string instructions.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
xen/arch/x86/hvm/emulate.c | 93 ++++++++++++++++++++++++++++++---------------
1 files changed, 63 insertions(+), 30 deletions(-)
diff -r 6e3c97f43f9c -r a3fe573a0e1e xen/arch/x86/hvm/emulate.c
--- a/xen/arch/x86/hvm/emulate.c Tue Aug 19 15:56:31 2008 +0100
+++ b/xen/arch/x86/hvm/emulate.c Tue Aug 19 15:57:19 2008 +0100
@@ -208,6 +208,7 @@ static int hvmemul_linear_to_phys(
{
struct vcpu *curr = current;
unsigned long pfn, npfn, done, todo, i;
+ int reverse;
/* Clip repetitions to a sensible maximum. */
*reps = min_t(unsigned long, *reps, 4096);
@@ -221,41 +222,53 @@ static int hvmemul_linear_to_phys(
*paddr = addr & ~PAGE_MASK;
- /* Get the first PFN in the range. */
- if ( (pfn = paging_gva_to_gfn(curr, addr, &pfec)) == INVALID_GFN )
+ /* Reverse mode if this is a backwards multi-iteration string operation. */
+ reverse = (hvmemul_ctxt->ctxt.regs->eflags & X86_EFLAGS_DF) && (*reps > 1);
+
+ if ( reverse && ((-addr & ~PAGE_MASK) < bytes_per_rep) )
+ {
+ /* Do page-straddling first iteration forwards via recursion. */
+ unsigned long _paddr, one_rep = 1;
+ int rc = hvmemul_linear_to_phys(
+ addr, &_paddr, bytes_per_rep, &one_rep, pfec, hvmemul_ctxt);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+ pfn = _paddr >> PAGE_SHIFT;
+ }
+ else if ( (pfn = paging_gva_to_gfn(curr, addr, &pfec)) == INVALID_GFN )
{
hvm_inject_exception(TRAP_page_fault, pfec, addr);
return X86EMUL_EXCEPTION;
}
/* If the range does not straddle a page boundary then we're done. */
- done = PAGE_SIZE - (addr & ~PAGE_MASK);
+ done = reverse ? bytes_per_rep + (addr & ~PAGE_MASK) : -addr & ~PAGE_MASK;
todo = *reps * bytes_per_rep;
if ( done >= todo )
goto done;
- addr += done;
for ( i = 1; done < todo; i++ )
{
/* Get the next PFN in the range. */
+ addr += reverse ? -PAGE_SIZE : PAGE_SIZE;
npfn = paging_gva_to_gfn(curr, addr, &pfec);
/* Is it contiguous with the preceding PFNs? If not then we're done. */
- if ( (npfn == INVALID_GFN) || (npfn != (pfn + i)) )
+ if ( (npfn == INVALID_GFN) || (npfn != (pfn + (reverse ? -i : i))) )
{
done /= bytes_per_rep;
if ( done == 0 )
{
+ ASSERT(!reverse);
if ( npfn != INVALID_GFN )
return X86EMUL_UNHANDLEABLE;
- hvm_inject_exception(TRAP_page_fault, pfec, addr);
+ hvm_inject_exception(TRAP_page_fault, pfec, addr & PAGE_MASK);
return X86EMUL_EXCEPTION;
}
*reps = done;
break;
}
- addr += PAGE_SIZE;
done += PAGE_SIZE;
}
@@ -268,7 +281,8 @@ static int hvmemul_virtual_to_linear(
static int hvmemul_virtual_to_linear(
enum x86_segment seg,
unsigned long offset,
- unsigned int bytes,
+ unsigned int bytes_per_rep,
+ unsigned long *reps,
enum hvm_access_type access_type,
struct hvm_emulate_ctxt *hvmemul_ctxt,
unsigned long *paddr)
@@ -282,21 +296,40 @@ static int hvmemul_virtual_to_linear(
return X86EMUL_OKAY;
}
+ *reps = min_t(unsigned long, *reps, 4096);
reg = hvmemul_get_seg_reg(seg, hvmemul_ctxt);
- okay = hvm_virtual_to_linear_addr(
- seg, reg, offset, bytes, access_type,
- hvmemul_ctxt->ctxt.addr_size, paddr);
-
- if ( !okay )
- {
- hvmemul_ctxt->exn_pending = 1;
- hvmemul_ctxt->exn_vector = TRAP_gp_fault;
- hvmemul_ctxt->exn_error_code = 0;
- hvmemul_ctxt->exn_insn_len = 0;
- return X86EMUL_EXCEPTION;
- }
-
- return X86EMUL_OKAY;
+
+ if ( (hvmemul_ctxt->ctxt.regs->eflags & X86_EFLAGS_DF) && (*reps > 1) )
+ {
+ ASSERT(offset >= ((*reps - 1) * bytes_per_rep));
+ okay = hvm_virtual_to_linear_addr(
+ seg, reg, offset - (*reps - 1) * bytes_per_rep,
+ *reps * bytes_per_rep, access_type,
+ hvmemul_ctxt->ctxt.addr_size, paddr);
+ *paddr += (*reps - 1) * bytes_per_rep;
+ if ( hvmemul_ctxt->ctxt.addr_size != 64 )
+ *paddr = (uint32_t)*paddr;
+ }
+ else
+ {
+ okay = hvm_virtual_to_linear_addr(
+ seg, reg, offset, *reps * bytes_per_rep, access_type,
+ hvmemul_ctxt->ctxt.addr_size, paddr);
+ }
+
+ if ( okay )
+ return X86EMUL_OKAY;
+
+ /* If this is a string operation, emulate each iteration separately. */
+ if ( *reps != 1 )
+ return X86EMUL_UNHANDLEABLE;
+
+ /* This is a singleton operation: fail it with an exception. */
+ hvmemul_ctxt->exn_pending = 1;
+ hvmemul_ctxt->exn_vector = TRAP_gp_fault;
+ hvmemul_ctxt->exn_error_code = 0;
+ hvmemul_ctxt->exn_insn_len = 0;
+ return X86EMUL_EXCEPTION;
}
static int __hvmemul_read(
@@ -314,7 +347,7 @@ static int __hvmemul_read(
int rc;
rc = hvmemul_virtual_to_linear(
- seg, offset, bytes, access_type, hvmemul_ctxt, &addr);
+ seg, offset, bytes, &reps, access_type, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
@@ -406,7 +439,7 @@ static int hvmemul_write(
int rc;
rc = hvmemul_virtual_to_linear(
- seg, offset, bytes, hvm_access_write, hvmemul_ctxt, &addr);
+ seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
@@ -470,7 +503,7 @@ static int hvmemul_rep_ins(
int rc;
rc = hvmemul_virtual_to_linear(
- dst_seg, dst_offset, *reps * bytes_per_rep, hvm_access_write,
+ dst_seg, dst_offset, bytes_per_rep, reps, hvm_access_write,
hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
@@ -503,7 +536,7 @@ static int hvmemul_rep_outs(
int rc;
rc = hvmemul_virtual_to_linear(
- src_seg, src_offset, *reps * bytes_per_rep, hvm_access_read,
+ src_seg, src_offset, bytes_per_rep, reps, hvm_access_read,
hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
@@ -538,13 +571,13 @@ static int hvmemul_rep_movs(
int rc;
rc = hvmemul_virtual_to_linear(
- src_seg, src_offset, *reps * bytes_per_rep, hvm_access_read,
+ src_seg, src_offset, bytes_per_rep, reps, hvm_access_read,
hvmemul_ctxt, &saddr);
if ( rc != X86EMUL_OKAY )
return rc;
rc = hvmemul_virtual_to_linear(
- dst_seg, dst_offset, *reps * bytes_per_rep, hvm_access_write,
+ dst_seg, dst_offset, bytes_per_rep, reps, hvm_access_write,
hvmemul_ctxt, &daddr);
if ( rc != X86EMUL_OKAY )
return rc;
@@ -792,11 +825,11 @@ static int hvmemul_invlpg(
{
struct hvm_emulate_ctxt *hvmemul_ctxt =
container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
- unsigned long addr;
+ unsigned long addr, reps = 1;
int rc;
rc = hvmemul_virtual_to_linear(
- seg, offset, 1, hvm_access_none, hvmemul_ctxt, &addr);
+ seg, offset, 1, &reps, hvm_access_none, hvmemul_ctxt, &addr);
if ( rc == X86EMUL_OKAY )
hvm_funcs.invlpg_intercept(addr);
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