[PATCH 0/1] MR10210: kernelbase: Fix GetNativeSystemInfo() in an x86_64 process on ARM64.

[Brendan Shanks (＠bshanks)]

In an emulated x86 or x86_64 process on ARM64, GetNativeSystemInfo() should return information as if the native system is x86_64 (assuming x86_64 emulation is supported). This is working correctly for x86 processes, but x86_64 processes are returning PROCESSOR_ARCHITECTURE_ARM64.

Fixes test failure when running as x86_64 on ARM64:
```
process.c:2424: Test failed: Expected no difference for wProcessorArchitecture, got 9 and 12
process.c:2427: Test failed: Expected no difference for dwProcessorType, got 8664 and 0
```

---

I listed all the possibilities to help reason about this.

If native_machine is I386:
- is_wow64 is FALSE
- GetNativeSystemInfo equivalent to GetSystemInfo

If native_machine is AMD64, process is I386:
- is_wow64 is TRUE
- native system info should have processor architecture AMD64

If native_machine is AMD64, process is AMD64:
- is_wow64 is FALSE
- GetNativeSystemInfo equivalent to GetSystemInfo

If native_machine is ARM64, process is ARM64:
- is_wow64 is FALSE
- GetNativeSystemInfo equivalent to GetSystemInfo

If native_machine is ARM64, process is I386:
- is_wow64 is TRUE
- native system info should have processor architecture AMD64

If native_machine is ARM64, process is AMD64:
- is_wow64 is FALSE
- GetNativeSystemInfo equivalent to GetSystemInfo

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10210

[PATCH 1/1] kernelbase: Fix GetNativeSystemInfo() in an x86_64 process on ARM64.

[Brendan Shanks]

From: Brendan Shanks <[e-mail]>

---
 dlls/kernelbase/memory.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/dlls/kernelbase/memory.c b/dlls/kernelbase/memory.c
index c0a3d65d341..fd06bddb543 100644
--- a/dlls/kernelbase/memory.c
+++ b/dlls/kernelbase/memory.c
@@ -209,18 +209,16 @@ void WINAPI DECLSPEC_HOTPATCH GetNativeSystemInfo( SYSTEM_INFO *si )
 {
     SYSTEM_BASIC_INFORMATION basic_info;
     SYSTEM_CPU_INFORMATION cpu_info;
+    USHORT current_machine, native_machine;
 
-    if (is_wow64)
-    {
-        USHORT current_machine, native_machine;
+    RtlWow64GetProcessMachines( 0, ¤t_machine, &native_machine );
 
-        RtlWow64GetProcessMachines( 0, ¤t_machine, &native_machine );
-        if (native_machine != IMAGE_FILE_MACHINE_AMD64)
-        {
-            GetSystemInfo( si );
+    if (!is_wow64 || native_machine != IMAGE_FILE_MACHINE_AMD64)
+    {
+        GetSystemInfo( si );
+        if (is_wow64 && native_machine != IMAGE_FILE_MACHINE_AMD64)
             si->wProcessorArchitecture = PROCESSOR_ARCHITECTURE_AMD64;
-            return;
-        }
+        return;
     }
 
     if (!set_ntstatus( RtlGetNativeSystemInformation( SystemBasicInformation,
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10210

[Alexandre Julliard (＠julliard)]

There is some uncertainty about the correct behavior, cf. !9740.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10210#note_130781