# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1196960000 0
# Node ID b1ca317793fbc5a3c8090a595fc0727c9050a2b3
# Parent b2ad1ebd96cbb414e138de08fcdbf30d1aa1ddd9
i386: adjustment to segment fixup code.
Clean up and support more instructions.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
xen-unstable changeset: 16407:81aa410fa66242ce6f4b5781b64dc4fe896b4cfd
xen-unstable date: Wed Nov 21 11:49:41 2007 +0000
---
xen/arch/x86/x86_32/seg_fixup.c | 172 ++++++++++++++++++----------------------
1 files changed, 79 insertions(+), 93 deletions(-)
diff -r b2ad1ebd96cb -r b1ca317793fb xen/arch/x86/x86_32/seg_fixup.c
--- a/xen/arch/x86/x86_32/seg_fixup.c Thu Dec 06 16:50:45 2007 +0000
+++ b/xen/arch/x86/x86_32/seg_fixup.c Thu Dec 06 16:53:20 2007 +0000
@@ -42,7 +42,7 @@
#define O OPCODE_BYTE
#define M HAS_MODRM
-static unsigned char insn_decode[256] = {
+static const unsigned char 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,
@@ -69,7 +69,7 @@ static unsigned char insn_decode[256] =
X, X, X, X, X, X, X, X,
/* 0x80 - 0x8F */
O|M|1, O|M|4, O|M|1, O|M|1, O|M, O|M, O|M, O|M,
- O|M, O|M, O|M, O|M, O|M, O|M, O|M, X,
+ O|M, O|M, O|M, O|M, O|M, X|M, O|M, O|M,
/* 0x90 - 0x9F */
X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X,
@@ -89,17 +89,17 @@ static unsigned char insn_decode[256] =
X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X,
/* 0xF0 - 0xFF */
- X, X, X, X, X, X, X, X,
+ X, X, X, X, X, X, O|M, O|M,
X, X, X, X, X, X, O|M, O|M
};
-static unsigned char twobyte_decode[256] = {
+static const unsigned char twobyte_decode[256] = {
/* 0x00 - 0x0F */
X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X,
/* 0x10 - 0x1F */
X, X, X, X, X, X, X, X,
- X, X, X, X, X, X, X, X,
+ O|M, X, X, X, X, X, X, X,
/* 0x20 - 0x2F */
X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X,
@@ -122,16 +122,16 @@ static unsigned char twobyte_decode[256]
X, X, X, X, X, X, X, X,
X, X, X, X, X, X, X, X,
/* 0x90 - 0x9F */
- X, X, X, X, X, X, X, X,
- X, X, X, X, X, X, X, X,
+ O|M, O|M, O|M, O|M, O|M, O|M, O|M, O|M,
+ O|M, O|M, O|M, O|M, O|M, O|M, O|M, O|M,
/* 0xA0 - 0xAF */
- X, X, X, X, X, X, X, X,
- X, X, X, X, X, X, X, X,
+ X, X, X, O|M, O|M|1, O|M, O|M, X,
+ X, X, X, O|M, O|M|1, O|M, X, O|M,
/* 0xB0 - 0xBF */
- X, X, X, X, X, X, X, X,
- X, X, X, X, X, X, X, X,
+ X, X, X, O|M, X, X, O|M, O|M,
+ X, X, O|M|1, O|M, O|M, O|M, O|M, O|M,
/* 0xC0 - 0xCF */
- X, X, X, X, X, X, X, X,
+ O|M, O|M, X, O|M, X, X, X, O|M,
X, X, X, X, X, X, X, X,
/* 0xD0 - 0xDF */
X, X, X, X, X, X, X, X,
@@ -155,22 +155,22 @@ static unsigned char twobyte_decode[256]
*/
int get_baselimit(u16 seg, unsigned long *base, unsigned long *limit)
{
- struct vcpu *d = current;
- unsigned long *table, a, b;
- int ldt = !!(seg & 4);
- int idx = (seg >> 3) & 8191;
+ struct vcpu *curr = current;
+ uint32_t *table, a, b;
+ int ldt = !!(seg & 4);
+ int idx = (seg >> 3) & 8191;
/* Get base and check limit. */
if ( ldt )
{
- table = (unsigned long *)LDT_VIRT_START(d);
- if ( idx >= d->arch.guest_context.ldt_ents )
+ table = (uint32_t *)LDT_VIRT_START(curr);
+ if ( idx >= curr->arch.guest_context.ldt_ents )
goto fail;
}
else /* gdt */
{
- table = (unsigned long *)GDT_VIRT_START(d);
- if ( idx >= d->arch.guest_context.gdt_ents )
+ table = (uint32_t *)GDT_VIRT_START(curr);
+ if ( idx >= curr->arch.guest_context.gdt_ents )
goto fail;
}
@@ -221,29 +221,29 @@ int linearise_address(u16 seg, unsigned
int fixup_seg(u16 seg, unsigned long offset)
{
- struct vcpu *d = current;
- unsigned long *table, a, b, base, limit;
- int ldt = !!(seg & 4);
- int idx = (seg >> 3) & 8191;
+ struct vcpu *curr = current;
+ uint32_t *table, a, b, base, limit;
+ int ldt = !!(seg & 4);
+ int idx = (seg >> 3) & 8191;
/* Get base and check limit. */
if ( ldt )
{
- table = (unsigned long *)LDT_VIRT_START(d);
- if ( idx >= d->arch.guest_context.ldt_ents )
+ table = (uint32_t *)LDT_VIRT_START(curr);
+ if ( idx >= curr->arch.guest_context.ldt_ents )
{
dprintk(XENLOG_DEBUG, "Segment %04x out of LDT range (%ld)\n",
- seg, d->arch.guest_context.ldt_ents);
+ seg, curr->arch.guest_context.ldt_ents);
goto fail;
}
}
else /* gdt */
{
- table = (unsigned long *)GDT_VIRT_START(d);
- if ( idx >= d->arch.guest_context.gdt_ents )
+ table = (uint32_t *)GDT_VIRT_START(curr);
+ if ( idx >= curr->arch.guest_context.gdt_ents )
{
dprintk(XENLOG_DEBUG, "Segment %04x out of GDT range (%ld)\n",
- seg, d->arch.guest_context.gdt_ents);
+ seg, curr->arch.guest_context.gdt_ents);
goto fail;
}
}
@@ -261,7 +261,7 @@ int fixup_seg(u16 seg, unsigned long off
_SEGMENT_G|_SEGMENT_CODE|_SEGMENT_DPL)) !=
(_SEGMENT_P|_SEGMENT_S|_SEGMENT_DB|_SEGMENT_G|_SEGMENT_DPL) )
{
- dprintk(XENLOG_DEBUG, "Bad segment %08lx:%08lx\n", a, b);
+ dprintk(XENLOG_DEBUG, "Bad segment %08x:%08x\n", a, b);
goto fail;
}
@@ -291,8 +291,7 @@ int fixup_seg(u16 seg, unsigned long off
}
}
- dprintk(XENLOG_DEBUG, "None of the above! "
- "(%08lx:%08lx, %08lx, %08lx, %08lx)\n",
+ dprintk(XENLOG_DEBUG, "None of the above! (%08x:%08x, %08x, %08x, %08x)\n",
a, b, base, limit, base+limit);
fail:
@@ -315,18 +314,15 @@ int fixup_seg(u16 seg, unsigned long off
*/
int gpf_emulate_4gb(struct cpu_user_regs *regs)
{
- struct vcpu *d = current;
- struct trap_info *ti;
- struct trap_bounce *tb;
- u8 modrm, mod, reg, rm, decode;
- void *memreg;
- unsigned long offset;
- u8 disp8;
- u32 disp32 = 0;
+ struct vcpu *curr = current;
+ u8 modrm, mod, rm, decode;
+ const u32 *base, *index = NULL;
+ unsigned long offset;
+ s8 disp8;
+ s32 disp32 = 0;
u8 *eip; /* ptr to instruction start */
u8 *pb, b; /* ptr into instr. / current instr. byte */
- int gs_override = 0;
- int twobyte = 0;
+ int gs_override = 0, scale = 0, twobyte = 0;
/* WARNING: We only work for ring-3 segments. */
if ( unlikely(vm86_mode(regs)) || unlikely(!ring_3(regs)) )
@@ -356,6 +352,9 @@ int gpf_emulate_4gb(struct cpu_user_regs
"legal instruction\n");
goto fail;
}
+
+ if ( twobyte )
+ break;
switch ( b )
{
@@ -375,6 +374,9 @@ int gpf_emulate_4gb(struct cpu_user_regs
case 0x65: /* GS override */
gs_override = 1;
break;
+ case 0x0f: /* Not really a prefix byte */
+ twobyte = 1;
+ break;
default: /* Not a prefix byte */
goto done_prefix;
}
@@ -387,32 +389,10 @@ int gpf_emulate_4gb(struct cpu_user_regs
goto fail;
}
- decode = insn_decode[b]; /* opcode byte */
+ decode = (!twobyte ? insn_decode : twobyte_decode)[b];
pb++;
- if ( decode == 0 && b == 0x0f )
- {
- twobyte = 1;
-
- if ( get_user(b, pb) )
- {
- dprintk(XENLOG_DEBUG,
- "Fault while accessing byte %ld of instruction\n",
- (long)(pb-eip));
- goto page_fault;
- }
-
- if ( (pb - eip) >= 15 )
- {
- dprintk(XENLOG_DEBUG, "Too many opcode bytes for a "
- "legal instruction\n");
- goto fail;
- }
-
- decode = twobyte_decode[b];
- pb++;
- }
-
- if ( decode == 0 )
+
+ if ( !(decode & OPCODE_BYTE) )
{
dprintk(XENLOG_DEBUG, "Unsupported %sopcode %02x\n",
twobyte ? "two byte " : "", b);
@@ -422,12 +402,12 @@ int gpf_emulate_4gb(struct cpu_user_regs
if ( !(decode & HAS_MODRM) )
{
/* Must be a <disp32>, or bail. */
- if ( (decode & 7) != 4 )
+ if ( (decode & INSN_SUFFIX_BYTES) != 4 )
goto fail;
if ( get_user(offset, (u32 *)pb) )
{
- dprintk(XENLOG_DEBUG, "Fault while extracting <disp32>.\n");
+ dprintk(XENLOG_DEBUG, "Fault while extracting <moffs32>.\n");
goto page_fault;
}
pb += 4;
@@ -448,29 +428,39 @@ int gpf_emulate_4gb(struct cpu_user_regs
pb++;
mod = (modrm >> 6) & 3;
- reg = (modrm >> 3) & 7;
rm = (modrm >> 0) & 7;
if ( rm == 4 )
{
- dprintk(XENLOG_DEBUG, "FIXME: Add decoding for the SIB byte.\n");
- goto fixme;
+ u8 sib;
+
+ if ( get_user(sib, pb) )
+ {
+ dprintk(XENLOG_DEBUG, "Fault while extracting sib byte\n");
+ goto page_fault;
+ }
+
+ pb++;
+
+ rm = sib & 7;
+ if ( (sib & 0x38) != 0x20 )
+ index = decode_register((sib >> 3) & 7, regs, 0);
+ scale = sib >> 6;
}
/* Decode R/M field. */
- memreg = decode_register(rm, regs, 0);
+ base = decode_register(rm, regs, 0);
/* Decode Mod field. */
- switch ( modrm >> 6 )
+ switch ( mod )
{
case 0:
- disp32 = 0;
if ( rm == 5 ) /* disp32 rather than (EBP) */
{
- memreg = NULL;
+ base = NULL;
if ( get_user(disp32, (u32 *)pb) )
{
- dprintk(XENLOG_DEBUG, "Fault while extracting <disp8>.\n");
+ dprintk(XENLOG_DEBUG, "Fault while extracting <base32>.\n");
goto page_fault;
}
pb += 4;
@@ -484,13 +474,13 @@ int gpf_emulate_4gb(struct cpu_user_regs
goto page_fault;
}
pb++;
- disp32 = (disp8 & 0x80) ? (disp8 | ~0xff) : disp8;;
+ disp32 = disp8;
break;
case 2:
if ( get_user(disp32, (u32 *)pb) )
{
- dprintk(XENLOG_DEBUG, "Fault while extracting <disp8>.\n");
+ dprintk(XENLOG_DEBUG, "Fault while extracting <disp32>.\n");
goto page_fault;
}
pb += 4;
@@ -502,8 +492,10 @@ int gpf_emulate_4gb(struct cpu_user_regs
}
offset = disp32;
- if ( memreg != NULL )
- offset += *(u32 *)memreg;
+ if ( base != NULL )
+ offset += *base;
+ if ( index != NULL )
+ offset += *index << scale;
skip_modrm:
if ( !fixup_seg((u16)regs->gs, offset) )
@@ -513,10 +505,11 @@ int gpf_emulate_4gb(struct cpu_user_regs
perfc_incr(seg_fixups);
/* If requested, give a callback on otherwise unused vector 15. */
- if ( VM_ASSIST(d->domain, VMASST_TYPE_4gb_segments_notify) )
- {
- ti = &d->arch.guest_context.trap_ctxt[15];
- tb = &d->arch.trap_bounce;
+ if ( VM_ASSIST(curr->domain, VMASST_TYPE_4gb_segments_notify) )
+ {
+ struct trap_info *ti = &curr->arch.guest_context.trap_ctxt[15];
+ struct trap_bounce *tb = &curr->arch.trap_bounce;
+
tb->flags = TBF_EXCEPTION | TBF_EXCEPTION_ERRCODE;
tb->error_code = pb - eip;
tb->cs = ti->cs;
@@ -527,13 +520,6 @@ int gpf_emulate_4gb(struct cpu_user_regs
return EXCRET_fault_fixed;
- fixme:
- dprintk(XENLOG_DEBUG, "Undecodable instruction "
- "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x "
- "caused GPF(0) at %04x:%08x\n",
- eip[0], eip[1], eip[2], eip[3],
- eip[4], eip[5], eip[6], eip[7],
- regs->cs, regs->eip);
fail:
return 0;
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