[PATCH 2/2] ntdll: Simplify the arm version of a stub function

[Martin Storsjo]

Skip the "mov pc, pc" instructions (used for skipping over an inline
4 byte address) by moving all the addresses to the end of the function.
This makes it 2 instructions and 10 lines of code shorter.

Signed-off-by: Martin Storsjo <martin at martin.st>
---
 dlls/ntdll/loader.c | 28 +++++++++-------------------
 1 file changed, 9 insertions(+), 19 deletions(-)

diff --git a/dlls/ntdll/loader.c b/dlls/ntdll/loader.c
index 55470e6..76edd2a 100644
--- a/dlls/ntdll/loader.c
+++ b/dlls/ntdll/loader.c
@@ -237,13 +237,11 @@ struct stub
 struct stub
 {
     BYTE ldr_r0[4];        /* ldr r0, $dll */
-    BYTE mov_pc_pc1[4];    /* mov pc,pc */
-    const char *dll;
     BYTE ldr_r1[4];        /* ldr r1, $name */
-    BYTE mov_pc_pc2[4];    /* mov pc,pc */
-    const char *name;
     BYTE mov_r2_lr[4];     /* mov r2, lr */
-    BYTE ldr_pc_pc[4];     /* ldr pc, [pc, #-4] */
+    BYTE ldr_pc_pc[4];     /* ldr pc, [pc, #4] */
+    const char *dll;
+    const char *name;
     const void* entry;
 };
 #elif defined(__aarch64__)
@@ -303,32 +301,24 @@ static ULONG_PTR allocate_stub( const char *dll, const char *name )
     stub->call      = 0xe8;  /* call stub_entry_point */
     stub->entry     = (BYTE *)stub_entry_point - (BYTE *)(&stub->entry + 1);
 #elif defined(__arm__)
-    stub->ldr_r0[0]     = 0x00;   /* ldr r0, $dll */
+    stub->ldr_r0[0]     = 0x08;   /* ldr r0, [pc, #8] ($dll) */
     stub->ldr_r0[1]     = 0x00;
     stub->ldr_r0[2]     = 0x9f;
     stub->ldr_r0[3]     = 0xe5;
-    stub->mov_pc_pc1[0] = 0x0f;   /* mov pc,pc */
-    stub->mov_pc_pc1[1] = 0xf0;
-    stub->mov_pc_pc1[2] = 0xa0;
-    stub->mov_pc_pc1[3] = 0xe1;
-    stub->dll           = dll;
-    stub->ldr_r1[0]     = 0x00;   /* ldr r1, $name */
+    stub->ldr_r1[0]     = 0x08;   /* ldr r1, [pc, #8] ($name) */
     stub->ldr_r1[1]     = 0x10;
     stub->ldr_r1[2]     = 0x9f;
     stub->ldr_r1[3]     = 0xe5;
-    stub->mov_pc_pc2[0] = 0x0f;   /* mov pc,pc */
-    stub->mov_pc_pc2[1] = 0xf0;
-    stub->mov_pc_pc2[2] = 0xa0;
-    stub->mov_pc_pc2[3] = 0xe1;
-    stub->name          = name;
     stub->mov_r2_lr[0]  = 0x0e;   /* mov r2, lr */
     stub->mov_r2_lr[1]  = 0x20;
     stub->mov_r2_lr[2]  = 0xa0;
     stub->mov_r2_lr[3]  = 0xe1;
-    stub->ldr_pc_pc[0]  = 0x04;   /* ldr pc, [pc, #-4] */
+    stub->ldr_pc_pc[0]  = 0x04;   /* ldr pc, [pc, #4] */
     stub->ldr_pc_pc[1]  = 0xf0;
-    stub->ldr_pc_pc[2]  = 0x1f;
+    stub->ldr_pc_pc[2]  = 0x9f;
     stub->ldr_pc_pc[3]  = 0xe5;
+    stub->dll           = dll;
+    stub->name          = name;
     stub->entry         = stub_entry_point;
 #elif defined(__aarch64__)
     stub->ldr_x0[0]     = 0xa0; /* ldr x0, #20 ($dll) */
-- 
2.7.4