struct mmio_access mmio_parse(struct per_cpu *cpu_data, unsigned long pc,
const struct guest_paging_structures *pg_structs,
bool is_write)
{
struct mmio_access access = { .inst_len = 0 };
bool has_regr, has_modrm, does_write;
struct modrm modrm;
struct sib sib;
u8 *page = NULL;
access.inst_len = 0;
has_regr = false;
restart:
page = map_code_page(cpu_data, pg_structs, pc, page);
if (!page)
goto error_nopage;
has_modrm = false;
switch (page[pc & PAGE_OFFS_MASK]) {
case X86_OP_REGR_PREFIX:
if (has_regr)
goto error_unsupported;
has_regr = true;
pc++;
access.inst_len++;
goto restart;
case X86_OP_MOV_TO_MEM:
access.inst_len += 2;
access.size = 4;
has_modrm = true;
does_write = true;
break;
case X86_OP_MOV_FROM_MEM:
access.inst_len += 2;
access.size = 4;
has_modrm = true;
does_write = false;
break;
default:
goto error_unsupported;
}
if (has_modrm) {
pc++;
page = map_code_page(cpu_data, pg_structs, pc, page);
if (!page)
goto error_nopage;
modrm = *(struct modrm *)&page[pc & PAGE_OFFS_MASK];
switch (modrm.mod) {
case 0:
if (modrm.rm != 4)
goto error_unsupported;
pc++;
page = map_code_page(cpu_data, pg_structs, pc, page);
if (!page)
goto error_nopage;
sib = *(struct sib *)&page[pc & PAGE_OFFS_MASK];
if (sib.ss != 0 || sib.index != 4 || sib.reg != 5)
goto error_unsupported;
access.inst_len += 5;
break;
case 2:
access.inst_len += 4;
break;
default:
goto error_unsupported;
}
if (has_regr)
access.reg = 7 - modrm.reg;
else if (modrm.reg == 4)
goto error_unsupported;
else
access.reg = 15 - modrm.reg;
}
if (does_write != is_write)
goto error_inconsitent;
return access;
error_nopage:
panic_printk("FATAL: unable to map MMIO instruction page\n");
goto error;
error_unsupported:
panic_printk("FATAL: unsupported instruction\n");
goto error;
error_inconsitent:
panic_printk("FATAL: inconsistent access, expected %s instruction\n",
is_write ? "write" : "read");
error:
access.inst_len = 0;
return access;
}
struct mmio_access mmio_parse(unsigned long pc,
const struct guest_paging_structures *pg_structs,
bool is_write)
{
struct mmio_access access = { .inst_len = 0 };
union opcode op[3] = { };
bool has_rex_r = false;
bool does_write;
u8 *page = NULL;
restart:
page = map_code_page(pg_structs, pc, page);
if (!page)
goto error_nopage;
op[0].raw = page[pc & PAGE_OFFS_MASK];
if (op[0].rex.code == X86_REX_CODE) {
/* REX.W is simply over-read since it is only affects the
* memory address in our supported modes which we get from the
* virtualization support. */
if (op[0].rex.r)
has_rex_r = true;
if (op[0].rex.x)
goto error_unsupported;
pc++;
access.inst_len++;
goto restart;
}
switch (op[0].raw) {
case X86_OP_MOV_TO_MEM:
access.inst_len += 2;
access.size = 4;
does_write = true;
break;
case X86_OP_MOV_FROM_MEM:
access.inst_len += 2;
access.size = 4;
does_write = false;
break;
default:
goto error_unsupported;
}
pc++;
page = map_code_page(pg_structs, pc, page);
if (!page)
goto error_nopage;
op[1].raw = page[pc & PAGE_OFFS_MASK];
switch (op[1].modrm.mod) {
case 0:
if (op[1].modrm.rm == 5) /* 32-bit displacement */
goto error_unsupported;
else if (op[1].modrm.rm != 4) /* no SIB */
break;
access.inst_len++;
pc++;
page = map_code_page(pg_structs, pc, page);
if (!page)
goto error_nopage;
op[2].raw = page[pc & PAGE_OFFS_MASK];
if (op[2].sib.base == 5)
access.inst_len += 4;
break;
case 1:
case 2:
if (op[1].modrm.rm == 4) /* SIB */
goto error_unsupported;
access.inst_len += op[1].modrm.mod == 1 ? 1 : 4;
break;
default:
goto error_unsupported;
}
if (has_rex_r)
access.reg = 7 - op[1].modrm.reg;
else if (op[1].modrm.reg == 4)
goto error_unsupported;
else
access.reg = 15 - op[1].modrm.reg;
if (does_write != is_write)
goto error_inconsitent;
return access;
error_nopage:
panic_printk("FATAL: unable to map MMIO instruction page\n");
goto error;
error_unsupported:
panic_printk("FATAL: unsupported instruction (0x%02x 0x%02x 0x%02x)\n",
op[0].raw, op[1].raw, op[2].raw);
goto error;
error_inconsitent:
panic_printk("FATAL: inconsistent access, expected %s instruction\n",
is_write ? "write" : "read");
error:
access.inst_len = 0;
return access;
}
