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The "SUB" instruction used in getcc() actually does 'x -= y' so use the

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proper constraint for 'x'. The "+r" constraint indicates that 'x' is an
input and output register operand.

While here generate code for different variants of getcc() using a macro
GETCC(sz) where 'sz' indicates the operand size.

Update the status bits in %rflags when emulating AND and OR opcodes.

Reviewed by:	grehan
This commit is contained in:
Neel Natu 2014-08-30 19:59:42 +00:00
parent 1bffa9511f
commit 4c98655ece
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=270857
1 changed files with 65 additions and 41 deletions
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106
sys/amd64/vmm/vmm_instruction_emul.c
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@ -316,46 +316,36 @@ vie_update_register(void *vm, int vcpuid, enum vm_reg_name reg,
return (error);
}
#define RFLAGS_STATUS_BITS (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_V)
/*
* Return the status flags that would result from doing (x - y).
*/
static u_long
getcc16(uint16_t x, uint16_t y)
{
u_long rflags;
#define GETCC(sz) \
static u_long \
getcc##sz(uint##sz##_t x, uint##sz##_t y) \
{ \
u_long rflags; \
\
__asm __volatile("sub %2,%1; pushfq; popq %0" : \
"=r" (rflags), "+r" (x) : "m" (y)); \
return (rflags); \
} struct __hack
__asm __volatile("sub %1,%2; pushfq; popq %0" :
"=r" (rflags) : "m" (y), "r" (x));
return (rflags);
}
static u_long
getcc32(uint32_t x, uint32_t y)
{
u_long rflags;
__asm __volatile("sub %1,%2; pushfq; popq %0" :
"=r" (rflags) : "m" (y), "r" (x));
return (rflags);
}
static u_long
getcc64(uint64_t x, uint64_t y)
{
u_long rflags;
__asm __volatile("sub %1,%2; pushfq; popq %0" :
"=r" (rflags) : "m" (y), "r" (x));
return (rflags);
}
GETCC(8);
GETCC(16);
GETCC(32);
GETCC(64);
static u_long
getcc(int opsize, uint64_t x, uint64_t y)
{
KASSERT(opsize == 2 || opsize == 4 || opsize == 8,
KASSERT(opsize == 1 || opsize == 2 || opsize == 4 || opsize == 8,
("getcc: invalid operand size %d", opsize));
if (opsize == 2)
if (opsize == 1)
return (getcc8(x, y));
else if (opsize == 2)
return (getcc16(x, y));
else if (opsize == 4)
return (getcc32(x, y));
@ -569,7 +559,7 @@ emulate_and(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
{
int error, size;
enum vm_reg_name reg;
uint64_t val1, val2;
uint64_t result, rflags, rflags2, val1, val2;
size = vie->opsize;
error = EINVAL;
@ -597,8 +587,8 @@ emulate_and(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
break;
/* perform the operation and write the result */
val1 &= val2;
error = vie_update_register(vm, vcpuid, reg, val1, size);
result = val1 & val2;
error = vie_update_register(vm, vcpuid, reg, result, size);
break;
case 0x81:
/*
@ -625,11 +615,11 @@ emulate_and(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
switch (vie->reg & 7) {
case 0x4:
/* modrm:reg == b100, AND */
val1 &= vie->immediate;
result = val1 & vie->immediate;
break;
case 0x1:
/* modrm:reg == b001, OR */
val1 |= vie->immediate;
result = val1 | vie->immediate;
break;
default:
error = EINVAL;
@ -638,11 +628,29 @@ emulate_and(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
if (error)
break;
error = memwrite(vm, vcpuid, gpa, val1, size, arg);
error = memwrite(vm, vcpuid, gpa, result, size, arg);
break;
default:
break;
}
if (error)
return (error);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
if (error)
return (error);
/*
* OF and CF are cleared; the SF, ZF and PF flags are set according
* to the result; AF is undefined.
*
* The updated status flags are obtained by subtracting 0 from 'result'.
*/
rflags2 = getcc(size, result, 0);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & (PSL_PF | PSL_Z | PSL_N);
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
return (error);
}
@ -651,7 +659,7 @@ emulate_or(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
{
int error, size;
uint64_t val1;
uint64_t val1, result, rflags, rflags2;
size = vie->opsize;
error = EINVAL;
@ -681,17 +689,33 @@ emulate_or(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
* perform the operation with the pre-fetched immediate
* operand and write the result
*/
val1 |= vie->immediate;
error = memwrite(vm, vcpuid, gpa, val1, size, arg);
result = val1 | vie->immediate;
error = memwrite(vm, vcpuid, gpa, result, size, arg);
break;
default:
break;
}
if (error)
return (error);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
if (error)
return (error);
/*
* OF and CF are cleared; the SF, ZF and PF flags are set according
* to the result; AF is undefined.
*
* The updated status flags are obtained by subtracting 0 from 'result'.
*/
rflags2 = getcc(size, result, 0);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & (PSL_PF | PSL_Z | PSL_N);
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
return (error);
}
#define RFLAGS_STATUS_BITS (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_V)
static int
emulate_cmp(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)