diff options
| author | Avi Kivity | 2012-08-19 14:34:31 +0300 |
|---|---|---|
| committer | Marcelo Tosatti | 2012-08-22 18:54:26 -0300 |
| commit | 5ad105e569c45dcfad50d724c61d5061248be755 (patch) | |
| tree | 4cae79db5826d07b07ed815c5d763fa095cae3f2 | |
| parent | 35f2d16bb9ace0fb2671b8232839944ad9057c6f (diff) | |
KVM: x86 emulator: use stack size attribute to mask rsp in stack ops
The sub-register used to access the stack (sp, esp, or rsp) is not
determined by the address size attribute like other memory references,
but by the stack segment's B bit (if not in x86_64 mode).
Fix by using the existing stack_mask() to figure out the correct mask.
This long-existing bug was exposed by a combination of a27685c33acccce
(emulate invalid guest state by default), which causes many more
instructions to be emulated, and a seabios change (possibly a bug) which
causes the high 16 bits of esp to become polluted across calls to real
mode software interrupts.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
| -rw-r--r-- | arch/x86/kvm/emulate.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 97d9a9914ba8..a3b57a27be88 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -475,13 +475,26 @@ register_address(struct x86_emulate_ctxt *ctxt, unsigned long reg) return address_mask(ctxt, reg); } +static void masked_increment(ulong *reg, ulong mask, int inc) +{ + assign_masked(reg, *reg + inc, mask); +} + static inline void register_address_increment(struct x86_emulate_ctxt *ctxt, unsigned long *reg, int inc) { + ulong mask; + if (ctxt->ad_bytes == sizeof(unsigned long)) - *reg += inc; + mask = ~0UL; else - *reg = (*reg & ~ad_mask(ctxt)) | ((*reg + inc) & ad_mask(ctxt)); + mask = ad_mask(ctxt); + masked_increment(reg, mask, inc); +} + +static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc) +{ + masked_increment(&ctxt->regs[VCPU_REGS_RSP], stack_mask(ctxt), inc); } static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel) @@ -1522,8 +1535,8 @@ static int push(struct x86_emulate_ctxt *ctxt, void *data, int bytes) { struct segmented_address addr; - register_address_increment(ctxt, &ctxt->regs[VCPU_REGS_RSP], -bytes); - addr.ea = register_address(ctxt, ctxt->regs[VCPU_REGS_RSP]); + rsp_increment(ctxt, -bytes); + addr.ea = ctxt->regs[VCPU_REGS_RSP] & stack_mask(ctxt); addr.seg = VCPU_SREG_SS; return segmented_write(ctxt, addr, data, bytes); @@ -1542,13 +1555,13 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt, int rc; struct segmented_address addr; - addr.ea = register_address(ctxt, ctxt->regs[VCPU_REGS_RSP]); + addr.ea = ctxt->regs[VCPU_REGS_RSP] & stack_mask(ctxt); addr.seg = VCPU_SREG_SS; rc = segmented_read(ctxt, addr, dest, len); if (rc != X86EMUL_CONTINUE) return rc; - register_address_increment(ctxt, &ctxt->regs[VCPU_REGS_RSP], len); + rsp_increment(ctxt, len); return rc; } @@ -1688,8 +1701,7 @@ static int em_popa(struct x86_emulate_ctxt *ctxt) while (reg >= VCPU_REGS_RAX) { if (reg == VCPU_REGS_RSP) { - register_address_increment(ctxt, &ctxt->regs[VCPU_REGS_RSP], - ctxt->op_bytes); + rsp_increment(ctxt, ctxt->op_bytes); --reg; } @@ -2825,7 +2837,7 @@ static int em_ret_near_imm(struct x86_emulate_ctxt *ctxt) rc = emulate_pop(ctxt, &ctxt->dst.val, ctxt->op_bytes); if (rc != X86EMUL_CONTINUE) return rc; - register_address_increment(ctxt, &ctxt->regs[VCPU_REGS_RSP], ctxt->src.val); + rsp_increment(ctxt, ctxt->src.val); return X86EMUL_CONTINUE; } |