[PATCH] ntoskrnl.exe: Add emulation of rdmsr for MSR_LSTAR control register.

[Derek Lesho]

Signed-off-by: Derek Lesho <dereklesho52(a)Gmail.com>
---
 dlls/ntoskrnl.exe/instr.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/dlls/ntoskrnl.exe/instr.c b/dlls/ntoskrnl.exe/instr.c
index 67cdd327ee..192ba05ee4 100644
--- a/dlls/ntoskrnl.exe/instr.c
+++ b/dlls/ntoskrnl.exe/instr.c
@@ -586,6 +586,12 @@ static BYTE *INSTR_GetOperandAddr( CONTEXT *context, BYTE *instr,
 }
 
 
+static void fake_syscall_function(void)
+{
+    TRACE("() stub\n");
+}
+
+
 /***********************************************************************
  *           emulate_instruction
  *
@@ -757,6 +763,25 @@ static DWORD emulate_instruction( EXCEPTION_RECORD *rec, CONTEXT *context )
             context->Rip += prefixlen + 3;
             return ExceptionContinueExecution;
         }
+        case 0x32: /* rdmsr */
+        {
+            int reg = context->Rcx & 0xffffffff;
+            TRACE("rdmsr CR 0x%08x\n", reg);
+            switch (reg)
+            {
+            case 0xc0000082:
+            {
+                ULONGLONG syscall_address = (ULONGLONG) fake_syscall_function;
+
+                context->Rdx = (syscall_address >> 32) & 0xffffffff;
+                context->Rax = syscall_address & 0xffffffff;
+            }
+            break;
+            default: return ExceptionContinueSearch;
+            }
+            context->Rip += prefixlen + 2;
+            return ExceptionContinueExecution;
+        }
         case 0xb6: /* movzx Eb, Gv */
         case 0xb7: /* movzx Ew, Gv */
         {
-- 
2.20.1

[Marvin]

Hi,

While running your changed tests, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?

Full results can be found at:
https://testbot.winehq.org/JobDetails.pl?Key=49664

Your paranoid android.


=== debian9b (64 bit WoW report) ===

ntoskrnl.exe:
driver.c:565: Test failed: got 0
driver.c:568: Test failed: got 0x102

[Ken Thomases]

On Mar 20, 2019, at 11:19 PM, Derek Lesho <dereklesho52(a)gmail.com> wrote:
> Signed-off-by: Derek Lesho <dereklesho52(a)Gmail.com>
> ---
> dlls/ntoskrnl.exe/instr.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/dlls/ntoskrnl.exe/instr.c b/dlls/ntoskrnl.exe/instr.c
> index 67cdd327ee..192ba05ee4 100644
> --- a/dlls/ntoskrnl.exe/instr.c
> +++ b/dlls/ntoskrnl.exe/instr.c
> @@ -586,6 +586,12 @@ static BYTE *INSTR_GetOperandAddr( CONTEXT *context, BYTE *instr,
> }
>
> +static void fake_syscall_function(void)
> +{
> +    TRACE("() stub\n");
> +}
> +
> +
> /***********************************************************************
>  *           emulate_instruction
>  *
> @@ -757,6 +763,25 @@ static DWORD emulate_instruction( EXCEPTION_RECORD *rec, CONTEXT *context )
>             context->Rip += prefixlen + 3;
>             return ExceptionContinueExecution;
>         }
> +        case 0x32: /* rdmsr */
> +        {
> +            int reg = context->Rcx & 0xffffffff;
> +            TRACE("rdmsr CR 0x%08x\n", reg);
> +            switch (reg)
> +            {
> +            case 0xc0000082:

You should probably use a symbolic constant here, rather than a bare magic number.  Define one, if needed (and it probably will be).

-Ken