[PATCH] ntdll: Improve handling of THUMB_MOV32 relocations

[Martin Storsjo]

Since the delta variable actually is signed, the delta > 0xffff
condition could be false even if the high part of the delta
was nonzero, ending up with not updating the high half of the
relocation at all.

Additionally, carry any overflow from the low word into the
high word delta.
---
 dlls/ntdll/loader.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/dlls/ntdll/loader.c b/dlls/ntdll/loader.c
index e0907e7..1f13424 100644
--- a/dlls/ntdll/loader.c
+++ b/dlls/ntdll/loader.c
@@ -2230,19 +2230,19 @@ IMAGE_BASE_RELOCATION * WINAPI LdrProcessRelocationBlock( void *page, UINT count
             DWORD inst = *(INT_PTR *)((char *)page + offset);
             DWORD imm16 = ((inst << 1) & 0x0800) + ((inst << 12) & 0xf000) +
                           ((inst >> 20) & 0x0700) + ((inst >> 16) & 0x00ff);
+            int hi_delta;
 
             if ((inst & 0x8000fbf0) != 0x0000f240)
                 ERR("wrong Thumb2 instruction %08x, expected MOVW\n", inst);
 
             imm16 += LOWORD(delta);
-            if (imm16 > 0xffff)
-                ERR("resulting immediate value won't fit: %08x\n", imm16);
+            hi_delta = HIWORD(delta) + HIWORD(imm16);
             *(INT_PTR *)((char *)page + offset) = (inst & 0x8f00fbf0) + ((imm16 >> 1) & 0x0400) +
                                                   ((imm16 >> 12) & 0x000f) +
                                                   ((imm16 << 20) & 0x70000000) +
                                                   ((imm16 << 16) & 0xff0000);
 
-            if (delta > 0xffff)
+            if (hi_delta != 0)
             {
                 inst = *(INT_PTR *)((char *)page + offset + 4);
                 imm16 = ((inst << 1) & 0x0800) + ((inst << 12) & 0xf000) +
@@ -2251,7 +2251,7 @@ IMAGE_BASE_RELOCATION * WINAPI LdrProcessRelocationBlock( void *page, UINT count
                 if ((inst & 0x8000fbf0) != 0x0000f2c0)
                     ERR("wrong Thumb2 instruction %08x, expected MOVT\n", inst);
 
-                imm16 += HIWORD(delta);
+                imm16 += hi_delta;
                 if (imm16 > 0xffff)
                     ERR("resulting immediate value won't fit: %08x\n", imm16);
                 *(INT_PTR *)((char *)page + offset + 4) = (inst & 0x8f00fbf0) +
-- 
1.8.1.2