DR_EXPORT
bool
drx_aflags_are_dead(instr_t *where)
{
instr_t *instr;
uint flags;
for (instr = where; instr != NULL; instr = instr_get_next(instr)) {
/* we treat syscall/interrupt as aflags read */
if (instr_is_syscall(instr) || instr_is_interrupt(instr))
return false;
flags = instr_get_arith_flags(instr, DR_QUERY_DEFAULT);
if (TESTANY(EFLAGS_READ_ARITH, flags))
return false;
if (TESTALL(EFLAGS_WRITE_ARITH, flags))
return true;
if (instr_is_cti(instr)) {
if (instr_is_app(instr) &&
(instr_is_ubr(instr) || instr_is_call_direct(instr))) {
instr_t *next = instr_get_next(instr);
opnd_t tgt = instr_get_target(instr);
/* continue on elision */
if (next != NULL && instr_is_app(next) &&
opnd_is_pc(tgt) &&
opnd_get_pc(tgt) == instr_get_app_pc(next))
continue;
}
/* unknown target, assume aflags is live */
return false;
}
}
return false;
}
static void
look_for_usercall(void *dcontext, byte *entry, const char *sym, LOADED_IMAGE *img,
const char *modpath)
{
bool found_push_imm = false;
int imm = 0;
app_pc pc, pre_pc;
instr_t *instr;
if (entry == NULL)
return;
instr = instr_create(dcontext);
pc = entry;
while (true) {
instr_reset(dcontext, instr);
pre_pc = pc;
pc = decode(dcontext, pc, instr);
if (verbose) {
instr_set_translation(instr, pre_pc);
dr_print_instr(dcontext, STDOUT, instr, "");
}
if (pc == NULL || !instr_valid(instr))
break;
if (instr_get_opcode(instr) == OP_push_imm) {
found_push_imm = true;
imm = (int) opnd_get_immed_int(instr_get_src(instr, 0));
} else if (instr_is_call_direct(instr) && found_push_imm) {
app_pc tgt = opnd_get_pc(instr_get_target(instr));
bool found = false;
int i;
for (i = 0; i < NUM_USERCALL; i++) {
if (tgt == usercall_addr[i]) {
dr_printf("Call #0x%02x to %s at %s+0x%x\n", imm, usercall_names[i],
sym, pre_pc - entry);
found = true;
break;
}
}
if (found)
break;
} else if (instr_is_return(instr))
break;
if (pc - entry > MAX_BYTES_BEFORE_USERCALL)
break;
}
instr_destroy(dcontext, instr);
}
static app_pc
get_function_entry(app_pc C_var)
{
void *drcontext = dr_get_current_drcontext();
byte *pc;
instr_t inst;
instr_init(drcontext, &inst);
pc = decode(drcontext, C_var, &inst);
ASSERT(pc != NULL, "invalid instr at function entry");
if (instr_get_opcode(&inst) == OP_jmp) {
/* skip jmp in ILT */
ASSERT(opnd_is_pc(instr_get_target(&inst)), "decoded jmp should have pc tgt");
pc = opnd_get_pc(instr_get_target(&inst));
} else
pc = C_var;
instr_free(drcontext, &inst);
return pc;
}
/* returns false on failure */
static bool
decode_syscall_num(void *dcontext, byte *entry, syscall_info_t *info, LOADED_IMAGE *img)
{
/* FIXME: would like to fail gracefully rather than have a DR assertion
* on non-code! => use DEBUG=0 INTERNAL=1 DR build!
*/
bool found_syscall = false, found_eax = false, found_edx = false, found_ecx = false;
bool found_ret = false;
byte *pc, *pre_pc;
int num_instr = 0;
instr_t *instr;
byte *preferred = get_preferred_base(img);
if (entry == NULL)
return false;
info->num_args = -1; /* if find sysnum but not args */
info->sysnum = -1;
info->fixup_index = -1;
instr = instr_create(dcontext);
pc = entry;
/* FIXME - we don't support decoding 64bit instructions in 32bit mode, but I want
* this to work on 32bit machines. Hack fix based on the wrapper pattern, we skip
* the first instruction (mov r10, rcx) here, the rest should decode ok.
* Xref PR 236203. */
if (expect_x64 && *pc == 0x4c && *(pc+1) == 0x8b && *(pc+2) == 0xd1)
pc += 3;
while (true) {
instr_reset(dcontext, instr);
pre_pc = pc;
pc = decode(dcontext, pc, instr);
if (verbose) {
instr_set_translation(instr, pre_pc);
dr_print_instr(dcontext, STDOUT, instr, "");
}
if (pc == NULL || !instr_valid(instr))
break;
if (instr_is_syscall(instr) || instr_is_call_indirect(instr)) {
/* If we see a syscall instr or an indirect call which is not syscall,
* we assume this is not a syscall wrapper.
*/
found_syscall = process_syscall_instr(dcontext, instr, found_eax, found_edx);
if (!found_syscall)
break; /* assume not a syscall wrapper, give up gracefully */
} else if (instr_is_return(instr)) {
/* we must break on return to avoid case like win8 x86
* which has sysenter callee adjacent-"inlined"
* ntdll!NtYieldExecution:
* 77d7422c b801000000 mov eax,1
* 77d74231 e801000000 call ntdll!NtYieldExecution+0xb (77d74237)
* 77d74236 c3 ret
* 77d74237 8bd4 mov edx,esp
* 77d74239 0f34 sysenter
* 77d7423b c3 ret
*/
if (!found_ret) {
process_ret(instr, info);
found_ret = true;
}
break;
} else if (instr_get_opcode(instr) == OP_call) {
found_syscall = process_syscall_call(dcontext, pc, instr,
found_eax, found_edx);
/* If we see a call and it is not a sysenter callee,
* we assume this is not a syscall wrapper.
*/
if (!found_syscall)
break; /* assume not a syscall wrapper, give up gracefully */
} else if (instr_is_cti(instr)) {
/* We expect only ctis like ret or ret imm, syscall, and call, which are
* handled above. Give up gracefully if we hit any other cti.
* XXX: what about jmp to shared ret (seen in the past on some syscalls)?
*/
/* Update: win10 TH2 1511 x64 has a cti:
* ntdll!NtContinue:
* 00007ff9`13185630 4c8bd1 mov r10,rcx
* 00007ff9`13185633 b843000000 mov eax,43h
* 00007ff9`13185638 f604250803fe7f01 test byte ptr [SharedUserData+0x308 (00000000`7ffe0308)],1
* 00007ff9`13185640 7503 jne ntdll!NtContinue+0x15 (00007ff9`13185645)
* 00007ff9`13185642 0f05 syscall
* 00007ff9`13185644 c3 ret
* 00007ff9`13185645 cd2e int 2Eh
* 00007ff9`13185647 c3 ret
*/
if (expect_x64 && instr_is_cbr(instr) &&
opnd_get_pc(instr_get_target(instr)) == pc + 3/*syscall;ret*/) {
/* keep going */
} else
break;
} else if ((!found_eax || !found_edx || !found_ecx) &&
instr_get_opcode(instr) == OP_mov_imm &&
opnd_is_reg(instr_get_dst(instr, 0))) {
if (!found_eax && opnd_get_reg(instr_get_dst(instr, 0)) == REG_EAX) {
info->sysnum = (int) opnd_get_immed_int(instr_get_src(instr, 0));
found_eax = true;
} else if (!found_edx && opnd_get_reg(instr_get_dst(instr, 0)) == REG_EDX) {
uint imm = (uint) opnd_get_immed_int(instr_get_src(instr, 0));
if (imm == 0x7ffe0300 ||
/* On Win10 the immed is ntdll!Wow64SystemServiceCall */
(expect_wow && imm > (ptr_uint_t)preferred &&
imm < (ptr_uint_t)preferred + img->SizeOfImage))
found_edx = true;
} else if (!found_ecx && opnd_get_reg(instr_get_dst(instr, 0)) == REG_ECX) {
found_ecx = true;
info->fixup_index = (int) opnd_get_immed_int(instr_get_src(instr, 0));
}
} else if (instr_get_opcode(instr) == OP_xor &&
opnd_is_reg(instr_get_src(instr, 0)) &&
opnd_get_reg(instr_get_src(instr, 0)) == REG_ECX &&
opnd_is_reg(instr_get_dst(instr, 0)) &&
opnd_get_reg(instr_get_dst(instr, 0)) == REG_ECX) {
/* xor to 0 */
found_ecx = true;
info->fixup_index = 0;
}
num_instr++;
if (num_instr > MAX_INSTRS_BEFORE_SYSCALL) /* wrappers should be short! */
break; /* avoid weird cases like NPXEMULATORTABLE */
}
instr_destroy(dcontext, instr);
return found_syscall;
}
/* returns whether found a syscall
* - found_eax: whether the caller has seen "mov imm => %eax"
* - found_edx: whether the caller has seen "mov $0x7ffe0300 => %edx",
* xref the comment in process_syscall_instr.
*/
static bool
process_syscall_call(void *dcontext, byte *next_pc, instr_t *call,
bool found_eax, bool found_edx)
{
int num_instr;
byte *pc;
instr_t instr;
bool found_syscall = false;
assert(instr_get_opcode(call) == OP_call && opnd_is_pc(instr_get_target(call)));
pc = opnd_get_pc(instr_get_target(call));
if (pc > next_pc + MAX_SYSENTER_CALLEE_OFFSET ||
pc <= next_pc /* assuming the call won't go backward */)
return false;
/* handle win8 x86 which has sysenter callee adjacent-"inlined"
* ntdll!NtYieldExecution:
* 77d7422c b801000000 mov eax,1
* 77d74231 e801000000 call ntdll!NtYieldExecution+0xb (77d74237)
* 77d74236 c3 ret
* 77d74237 8bd4 mov edx,esp
* 77d74239 0f34 sysenter
* 77d7423b c3 ret
*
* or DrMem-i#1366-c#2
* USER32!NtUserCreateWindowStation:
* 75caea7a b841110000 mov eax,0x1141
* 75caea7f e838000000 call user32!...+0xd (75caeabc)
* 75caea84 c22000 ret 0x20
* ...
* USER32!GetWindowStationName:
* 75caea8c 8bff mov edi,edi
* 75caea8e 55 push ebp
* ...
* 75caeabc 8bd4 mov edx,esp
* 75caeabe 0f34 sysenter
* 75caeac0 c3 ret
*/
/* We expect the win8 x86 sysenter adjacent "inlined" callee to be as simple as
* 75caeabc 8bd4 mov edx,esp
* 75caeabe 0f34 sysenter
* 75caeac0 c3 ret
*/
instr_init(dcontext, &instr);
num_instr = 0;
do {
instr_reset(dcontext, &instr);
pc = decode(dcontext, pc, &instr);
if (verbose)
dr_print_instr(dcontext, STDOUT, &instr, "");
if (pc == NULL || !instr_valid(&instr))
break;
if (instr_is_syscall(&instr) || instr_is_call_indirect(&instr)) {
found_syscall = process_syscall_instr(dcontext, &instr, found_eax, found_edx);
break;
} else if (instr_is_cti(&instr)) {
break;
}
num_instr++;
} while (num_instr <= MAX_INSTRS_SYSENTER_CALLEE);
instr_free(dcontext, &instr);
return found_syscall;
}
/* returns false on failure */
static bool
decode_syscall_num(void *dcontext, byte *entry, syscall_info_t *info)
{
/* FIXME: would like to fail gracefully rather than have a DR assertion
* on non-code! => use DEBUG=0 INTERNAL=1 DR build!
*/
bool found_syscall = false, found_eax = false, found_edx = false, found_ecx = false;
bool found_ret = false;
byte *pc;
int num_instr = 0;
instr_t *instr;
if (entry == NULL)
return false;
info->num_args = -1; /* if find sysnum but not args */
info->sysnum = -1;
info->fixup_index = -1;
instr = instr_create(dcontext);
pc = entry;
/* FIXME - we don't support decoding 64bit instructions in 32bit mode, but I want
* this to work on 32bit machines. Hack fix based on the wrapper pattern, we skip
* the first instruction (mov r10, rcx) here, the rest should decode ok.
* Xref PR 236203. */
if (expect_x64 && *pc == 0x4c && *(pc+1) == 0x8b && *(pc+2) == 0xd1)
pc += 3;
while (true) {
instr_reset(dcontext, instr);
pc = decode(dcontext, pc, instr);
if (verbose)
dr_print_instr(dcontext, STDOUT, instr, "");
if (pc == NULL || !instr_valid(instr))
break;
/* ASSUMPTION: a mov imm of 0x7ffe0300 into edx followed by an
* indirect call via edx is a system call on XP and later
* On XP SP1 it's call *edx, while on XP SP2 it's call *(edx)
* For wow it's a call through fs.
* FIXME - core exports various is_*_syscall routines (such as
* instr_is_wow64_syscall()) which we could use here instead of
* duplicating if they were more flexible about when they could
* be called (instr_is_wow64_syscall() for ex. asserts if not
* in a wow process).
*/
if (/* int 2e or x64 or win8 sysenter */
(instr_is_syscall(instr) && found_eax && (expect_int2e || expect_x64 || expect_sysenter)) ||
/* sysenter case */
(expect_sysenter && found_edx && found_eax &&
instr_is_call_indirect(instr) &&
/* XP SP{0,1}, 2003 SP0: call *edx */
((opnd_is_reg(instr_get_target(instr)) &&
opnd_get_reg(instr_get_target(instr)) == REG_EDX) ||
/* XP SP2, 2003 SP1: call *(edx) */
(opnd_is_base_disp(instr_get_target(instr)) &&
opnd_get_base(instr_get_target(instr)) == REG_EDX &&
opnd_get_index(instr_get_target(instr)) == REG_NULL &&
opnd_get_disp(instr_get_target(instr)) == 0))) ||
/* wow case
* we don't require found_ecx b/c win8 does not use ecx
*/
(expect_wow && found_eax &&
instr_is_call_indirect(instr) &&
opnd_is_far_base_disp(instr_get_target(instr)) &&
opnd_get_base(instr_get_target(instr)) == REG_NULL &&
opnd_get_index(instr_get_target(instr)) == REG_NULL &&
opnd_get_segment(instr_get_target(instr)) == SEG_FS)) {
found_syscall = true;
} else if (instr_is_return(instr)) {
if (!found_ret) {
process_ret(instr, info);
found_ret = true;
}
break;
} else if (instr_is_cti(instr)) {
if (instr_get_opcode(instr) == OP_call) {
/* handle win8 x86 which has sysenter callee adjacent-"inlined"
* ntdll!NtYieldExecution:
* 77d7422c b801000000 mov eax,1
* 77d74231 e801000000 call ntdll!NtYieldExecution+0xb (77d74237)
* 77d74236 c3 ret
* 77d74237 8bd4 mov edx,esp
* 77d74239 0f34 sysenter
* 77d7423b c3 ret
*/
byte *tgt;
assert(opnd_is_pc(instr_get_target(instr)));
tgt = opnd_get_pc(instr_get_target(instr));
/* we expect only ret or ret imm, and possibly some nops (in gdi32).
* XXX: what about jmp to shared ret (seen in the past on some syscalls)?
*/
if (tgt > pc && tgt <= pc + 16) {
bool ok = false;
do {
if (pc == tgt) {
ok = true;
break;
}
instr_reset(dcontext, instr);
pc = decode(dcontext, pc, instr);
if (verbose)
dr_print_instr(dcontext, STDOUT, instr, "");
if (instr_is_return(instr)) {
process_ret(instr, info);
found_ret = true;
} else if (!instr_is_nop(instr))
break;
num_instr++;
} while (num_instr <= MAX_INSTRS_BEFORE_SYSCALL);
if (ok)
continue;
}
}
/* assume not a syscall wrapper if we hit a cti */
break; /* give up gracefully */
} else if ((!found_eax || !found_edx || !found_ecx) &&
instr_get_opcode(instr) == OP_mov_imm &&
opnd_is_reg(instr_get_dst(instr, 0))) {
if (!found_eax && opnd_get_reg(instr_get_dst(instr, 0)) == REG_EAX) {
info->sysnum = (int) opnd_get_immed_int(instr_get_src(instr, 0));
found_eax = true;
} else if (!found_edx && opnd_get_reg(instr_get_dst(instr, 0)) == REG_EDX) {
int imm = (int) opnd_get_immed_int(instr_get_src(instr, 0));
if (imm == 0x7ffe0300)
found_edx = true;
} else if (!found_ecx && opnd_get_reg(instr_get_dst(instr, 0)) == REG_ECX) {
found_ecx = true;
info->fixup_index = (int) opnd_get_immed_int(instr_get_src(instr, 0));
}
} else if (instr_get_opcode(instr) == OP_xor &&
opnd_is_reg(instr_get_src(instr, 0)) &&
opnd_get_reg(instr_get_src(instr, 0)) == REG_ECX &&
opnd_is_reg(instr_get_dst(instr, 0)) &&
opnd_get_reg(instr_get_dst(instr, 0)) == REG_ECX) {
/* xor to 0 */
found_ecx = true;
info->fixup_index = 0;
}
num_instr++;
if (num_instr > MAX_INSTRS_BEFORE_SYSCALL) /* wrappers should be short! */
break; /* avoid weird cases like NPXEMULATORTABLE */
}
instr_destroy(dcontext, instr);
return found_syscall;
}
static void
module_load_event(void *drcontext, const module_data_t *mod, bool loaded)
{
if (strstr(dr_module_preferred_name(mod),
"client.drwrap-test.appdll.") != NULL) {
bool ok;
instr_t inst;
app_pc init_pc, pc, next_pc;
load_count++;
if (load_count == 2) {
/* test no-frills */
drwrap_set_global_flags(DRWRAP_NO_FRILLS);
}
addr_replace = (app_pc) dr_get_proc_address(mod->handle, "replaceme");
CHECK(addr_replace != NULL, "cannot find lib export");
ok = drwrap_replace(addr_replace, (app_pc) replacewith, false);
CHECK(ok, "replace failed");
addr_replace2 = (app_pc) dr_get_proc_address(mod->handle, "replaceme2");
CHECK(addr_replace2 != NULL, "cannot find lib export");
ok = drwrap_replace_native(addr_replace2, (app_pc) replacewith2, true/*at entry*/,
0, (void *)(ptr_int_t)DRWRAP_NATIVE_PARAM, false);
CHECK(ok, "replace_native failed");
init_pc = (app_pc) dr_get_proc_address(mod->handle, "replace_callsite");
CHECK(init_pc != NULL, "cannot find lib export");
/* Find callsite: we assume we'll linearly hit a ret. We take final call
* to skip any PIC call.
*/
instr_init(drcontext, &inst);
pc = init_pc;
do {
instr_reset(drcontext, &inst);
next_pc = decode(drcontext, pc, &inst);
if (!instr_valid(&inst))
break;
/* if initial jmp, follow it to handle ILT-indirection */
if (pc == init_pc && instr_is_ubr(&inst))
next_pc = opnd_get_pc(instr_get_target(&inst));
else if (instr_is_call(&inst))
addr_replace_callsite = pc;
pc = next_pc;
} while (instr_valid(&inst) && !instr_is_return(&inst));
CHECK(addr_replace_callsite != NULL, "cannot find lib export");
ok = drwrap_replace_native(addr_replace_callsite, (app_pc) replace_callsite,
false/*!at entry*/, 0,
(void *)(ptr_int_t)DRWRAP_NATIVE_PARAM, false);
CHECK(ok, "replace_native failed");
instr_free(drcontext, &inst);
wrap_addr(&addr_level0, "level0", mod, true, true);
wrap_addr(&addr_level1, "level1", mod, true, true);
wrap_addr(&addr_level2, "level2", mod, true, true);
wrap_addr(&addr_tailcall, "makes_tailcall", mod, true, true);
wrap_addr(&addr_skipme, "skipme", mod, true, true);
wrap_addr(&addr_repeat, "repeatme", mod, true, true);
wrap_addr(&addr_preonly, "preonly", mod, true, false);
wrap_addr(&addr_postonly, "postonly", mod, false, true);
wrap_addr(&addr_runlots, "runlots", mod, false, true);
/* test longjmp */
wrap_unwindtest_addr(&addr_long0, "long0", mod);
wrap_unwindtest_addr(&addr_long1, "long1", mod);
wrap_unwindtest_addr(&addr_long2, "long2", mod);
wrap_unwindtest_addr(&addr_long3, "long3", mod);
wrap_unwindtest_addr(&addr_longdone, "longdone", mod);
drmgr_set_tls_field(drcontext, tls_idx, (void *)(ptr_uint_t)0);
#ifdef WINDOWS
/* test SEH */
/* we can't do this test for no-frills b/c only one wrap per addr */
if (load_count == 1) {
ok = drwrap_wrap_ex(addr_long0, wrap_unwindtest_seh_pre,
wrap_unwindtest_seh_post,
NULL, DRWRAP_UNWIND_ON_EXCEPTION);
CHECK(ok, "wrap failed");
ok = drwrap_wrap_ex(addr_long1, wrap_unwindtest_seh_pre,
wrap_unwindtest_seh_post,
NULL, DRWRAP_UNWIND_ON_EXCEPTION);
CHECK(ok, "wrap failed");
ok = drwrap_wrap_ex(addr_long2, wrap_unwindtest_seh_pre,
wrap_unwindtest_seh_post,
NULL, DRWRAP_UNWIND_ON_EXCEPTION);
CHECK(ok, "wrap failed");
ok = drwrap_wrap_ex(addr_long3, wrap_unwindtest_seh_pre,
wrap_unwindtest_seh_post,
NULL, DRWRAP_UNWIND_ON_EXCEPTION);
CHECK(ok, "wrap failed");
ok = drwrap_wrap_ex(addr_longdone, wrap_unwindtest_seh_pre,
wrap_unwindtest_seh_post,
NULL, DRWRAP_UNWIND_ON_EXCEPTION);
CHECK(ok, "wrap failed");
}
#endif
/* test leaner wrapping */
if (load_count == 2)
drwrap_set_global_flags(DRWRAP_NO_FRILLS | DRWRAP_FAST_CLEANCALLS);
wrap_addr(&addr_skip_flags, "skip_flags", mod, true, false);
}
}