# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1248794118 -3600
# Node ID 95eec4e77c3c60e8f4e53436f6a259613a9094d8
# Parent 8af26fef898c88d1b929e597d3b232673b8e777d
x86_32: handle x87 opcodes in TLS segment fixups
This patch adds support to the TLS fixup code for x87 opcodes. These
can be treated like 2-byte opcodes with a weird encoding.
The patch includes some extra changes because, now that we have >2
opcode tables and 9 different lead bytes in a two-byte opcode, a
simple boolean code will not be enough to differentiate one- and
two-byte opcodes. Besides this, the patch is trivial since the
segment fixup code cares about the operands of the instruction, not
about its semantics.
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
xen/arch/x86/x86_32/seg_fixup.c | 55 ++++++++++++++++++++++++++++++++++------
1 files changed, 47 insertions(+), 8 deletions(-)
diff -r 8af26fef898c -r 95eec4e77c3c xen/arch/x86/x86_32/seg_fixup.c
--- a/xen/arch/x86/x86_32/seg_fixup.c Fri Jul 24 12:08:54 2009 +0100
+++ b/xen/arch/x86/x86_32/seg_fixup.c Tue Jul 28 16:15:18 2009 +0100
@@ -42,7 +42,7 @@
#define O OPCODE_BYTE
#define M HAS_MODRM
-static const unsigned char insn_decode[256] = {
+static const u8 insn_decode[256] = {
/* 0x00 - 0x0F */
O|M, O|M, O|M, O|M, X, X, X, X,
O|M, O|M, O|M, O|M, X, X, X, X,
@@ -93,7 +93,18 @@ static const unsigned char insn_decode[2
X, X, X, X, X, X, O|M, O|M
};
-static const unsigned char twobyte_decode[256] = {
+static const u8 float_decode[64] = {
+ O|M, O|M, O|M, O|M, O|M, O|M, O|M, O|M, /* 0xD8 */
+ O|M, X, O|M, O|M, O|M, O|M, O|M, O|M, /* 0xD9 */
+ O|M, O|M, O|M, O|M, O|M, O|M, O|M, O|M, /* 0xDA */
+ O|M, X, O|M, O|M, X, O|M, X, O|M, /* 0xDB */
+ O|M, O|M, O|M, O|M, O|M, O|M, O|M, O|M, /* 0xDC */
+ O|M, O|M, O|M, O|M, O|M, X, O|M, O|M, /* 0xDD */
+ O|M, O|M, O|M, O|M, O|M, O|M, O|M, O|M, /* 0xDE */
+ O|M, X, O|M, O|M, O|M, O|M, O|M, O|M, /* 0xDF */
+};
+
+static const u8 twobyte_decode[256] = {
/* 0x00 - 0x0F */
X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X,
@@ -321,7 +332,8 @@ int gpf_emulate_4gb(struct cpu_user_regs
s32 disp32 = 0;
u8 *eip; /* ptr to instruction start */
u8 *pb, b; /* ptr into instr. / current instr. byte */
- int gs_override = 0, scale = 0, twobyte = 0;
+ int gs_override = 0, scale = 0, opcode = -1;
+ const u8 *table = insn_decode;
/* WARNING: We only work for ring-3 segments. */
if ( unlikely(vm86_mode(regs)) || unlikely(!ring_3(regs)) )
@@ -352,8 +364,11 @@ int gpf_emulate_4gb(struct cpu_user_regs
goto fail;
}
- if ( twobyte )
+ if ( opcode != -1 )
+ {
+ opcode = (opcode << 8) | b;
break;
+ }
switch ( b )
{
@@ -374,8 +389,29 @@ int gpf_emulate_4gb(struct cpu_user_regs
gs_override = 1;
break;
case 0x0f: /* Not really a prefix byte */
- twobyte = 1;
+ table = twobyte_decode;
+ opcode = b;
break;
+ case 0xd8: /* Math coprocessor instructions. */
+ case 0xd9:
+ case 0xda:
+ case 0xdb:
+ case 0xdc:
+ case 0xdd:
+ case 0xde:
+ case 0xdf:
+ /* Float opcodes have a secondary opcode in the modrm byte. */
+ table = float_decode;
+ if ( get_user(modrm, pb + 1) )
+ {
+ dprintk(XENLOG_DEBUG, "Fault while extracting modrm byte\n");
+ goto page_fault;
+ }
+
+ opcode = (b << 8) | modrm;
+ b = ((b & 7) << 3) + ((modrm >> 3) & 7);
+ goto done_prefix;
+
default: /* Not a prefix byte */
goto done_prefix;
}
@@ -388,13 +424,16 @@ int gpf_emulate_4gb(struct cpu_user_regs
goto fail;
}
- decode = (!twobyte ? insn_decode : twobyte_decode)[b];
+ decode = table[b];
pb++;
if ( !(decode & OPCODE_BYTE) )
{
- dprintk(XENLOG_DEBUG, "Unsupported %sopcode %02x\n",
- twobyte ? "two byte " : "", b);
+ if (opcode == -1)
+ dprintk(XENLOG_DEBUG, "Unsupported opcode %02x\n", b);
+ else
+ dprintk(XENLOG_DEBUG, "Unsupported opcode %02x %02x\n",
+ opcode >> 8, opcode & 255);
goto fail;
}
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