From 038e51de2e7ae2c8e9d8a0b15231f8509875dc33 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 22 Jan 2007 20:40:40 -0800 Subject: [PATCH] [PATCH] KVM: x86 emulator: fix bit string instructions The various bit string instructions (bts, btc, etc.) fail to adjust the address correctly if the bit address is beyond BITS_PER_LONG. This bug creeped in as the emulator originally relied on cr2 to contain the memory address; however we now decode it from the mod r/m bits, and must adjust the offset to account for large bit indices. The patch is rather large because it switches src and dst decoding around, so that the bit index is available when decoding the memory address. This fixes workloads like the FC5 installer. Signed-off-by: Avi Kivity Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/kvm/x86_emulate.c | 98 +++++++++++++++++++++------------------ 1 file changed, 52 insertions(+), 46 deletions(-) diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c index be70795b48..7513cddb92 100644 --- a/drivers/kvm/x86_emulate.c +++ b/drivers/kvm/x86_emulate.c @@ -61,6 +61,7 @@ #define ModRM (1<<6) /* Destination is only written; never read. */ #define Mov (1<<7) +#define BitOp (1<<8) static u8 opcode_table[256] = { /* 0x00 - 0x07 */ @@ -148,7 +149,7 @@ static u8 opcode_table[256] = { 0, 0, ByteOp | DstMem | SrcNone | ModRM, DstMem | SrcNone | ModRM }; -static u8 twobyte_table[256] = { +static u16 twobyte_table[256] = { /* 0x00 - 0x0F */ 0, SrcMem | ModRM | DstReg, 0, 0, 0, 0, ImplicitOps, 0, 0, 0, 0, 0, 0, ImplicitOps | ModRM, 0, 0, @@ -180,16 +181,16 @@ static u8 twobyte_table[256] = { /* 0x90 - 0x9F */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0xA0 - 0xA7 */ - 0, 0, 0, DstMem | SrcReg | ModRM, 0, 0, 0, 0, + 0, 0, 0, DstMem | SrcReg | ModRM | BitOp, 0, 0, 0, 0, /* 0xA8 - 0xAF */ - 0, 0, 0, DstMem | SrcReg | ModRM, 0, 0, 0, 0, + 0, 0, 0, DstMem | SrcReg | ModRM | BitOp, 0, 0, 0, 0, /* 0xB0 - 0xB7 */ ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM, 0, - DstMem | SrcReg | ModRM, + DstMem | SrcReg | ModRM | BitOp, 0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem16 | ModRM | Mov, /* 0xB8 - 0xBF */ - 0, 0, DstMem | SrcImmByte | ModRM, DstMem | SrcReg | ModRM, + 0, 0, DstMem | SrcImmByte | ModRM, DstMem | SrcReg | ModRM | BitOp, 0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem16 | ModRM | Mov, /* 0xC0 - 0xCF */ @@ -469,7 +470,8 @@ static int read_descriptor(struct x86_emulate_ctxt *ctxt, int x86_emulate_memop(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { - u8 b, d, sib, twobyte = 0, rex_prefix = 0; + unsigned d; + u8 b, sib, twobyte = 0, rex_prefix = 0; u8 modrm, modrm_mod = 0, modrm_reg = 0, modrm_rm = 0; unsigned long *override_base = NULL; unsigned int op_bytes, ad_bytes, lock_prefix = 0, rep_prefix = 0, i; @@ -726,46 +728,6 @@ done_prefixes: ; } - /* Decode and fetch the destination operand: register or memory. */ - switch (d & DstMask) { - case ImplicitOps: - /* Special instructions do their own operand decoding. */ - goto special_insn; - case DstReg: - dst.type = OP_REG; - if ((d & ByteOp) - && !(twobyte_table && (b == 0xb6 || b == 0xb7))) { - dst.ptr = decode_register(modrm_reg, _regs, - (rex_prefix == 0)); - dst.val = *(u8 *) dst.ptr; - dst.bytes = 1; - } else { - dst.ptr = decode_register(modrm_reg, _regs, 0); - switch ((dst.bytes = op_bytes)) { - case 2: - dst.val = *(u16 *)dst.ptr; - break; - case 4: - dst.val = *(u32 *)dst.ptr; - break; - case 8: - dst.val = *(u64 *)dst.ptr; - break; - } - } - break; - case DstMem: - dst.type = OP_MEM; - dst.ptr = (unsigned long *)cr2; - dst.bytes = (d & ByteOp) ? 1 : op_bytes; - if (!(d & Mov) && /* optimisation - avoid slow emulated read */ - ((rc = ops->read_emulated((unsigned long)dst.ptr, - &dst.val, dst.bytes, ctxt)) != 0)) - goto done; - break; - } - dst.orig_val = dst.val; - /* * Decode and fetch the source operand: register, memory * or immediate. @@ -838,6 +800,50 @@ done_prefixes: break; } + /* Decode and fetch the destination operand: register or memory. */ + switch (d & DstMask) { + case ImplicitOps: + /* Special instructions do their own operand decoding. */ + goto special_insn; + case DstReg: + dst.type = OP_REG; + if ((d & ByteOp) + && !(twobyte_table && (b == 0xb6 || b == 0xb7))) { + dst.ptr = decode_register(modrm_reg, _regs, + (rex_prefix == 0)); + dst.val = *(u8 *) dst.ptr; + dst.bytes = 1; + } else { + dst.ptr = decode_register(modrm_reg, _regs, 0); + switch ((dst.bytes = op_bytes)) { + case 2: + dst.val = *(u16 *)dst.ptr; + break; + case 4: + dst.val = *(u32 *)dst.ptr; + break; + case 8: + dst.val = *(u64 *)dst.ptr; + break; + } + } + break; + case DstMem: + dst.type = OP_MEM; + dst.ptr = (unsigned long *)cr2; + dst.bytes = (d & ByteOp) ? 1 : op_bytes; + if (d & BitOp) { + dst.ptr += src.val / BITS_PER_LONG; + dst.bytes = sizeof(long); + } + if (!(d & Mov) && /* optimisation - avoid slow emulated read */ + ((rc = ops->read_emulated((unsigned long)dst.ptr, + &dst.val, dst.bytes, ctxt)) != 0)) + goto done; + break; + } + dst.orig_val = dst.val; + if (twobyte) goto twobyte_insn; -- 2.39.5