CRO0: Difference between revisions

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@@ Line 347: / Line 347: @@
 | 0x4
 | 0x1
-| Patch type (0=nothing/ignore, 2=38=write u32 absolute (base+addend), 3=write u32 relative (base+addend-in_ptr), 10=THUMB branch, 28=ARM32 branch, 29=modify ARM32 branch offset, 42=write u32 relative (((signed int)base*2)/2+addend-in_ptr), otherwise err) (This is apparently a subset of relocation type for ARM ELF)
+| Patch type (R_ARM_NONE = 0, R_ARM_ABS32 = 2, R_ARM_REL32 = 3, R_ARM_THM_PC22 = 10, R_ARM_CALL = 28, R_ARM_JUMP24 = 29, R_ARM_TARGET1 = 38, R_ARM_PREL31 = 42)
 |-
 | 0x5
@@ Line 366: / Line 366: @@
 |}
-ARM32 branch instruction is constructed as follows:
+Relocation code from RO:
-  If addend > 0x2000000 or addend < 0xFE000000, then skip.
-  If (addend&1) == 1 then write "b +4" (nop).
-  Else write as normal.
-----
+ static Result writePatch(u32* out, u32 patchType, u32 addend, u32 base, u32 inputPtr) {
+     const s32 branchOffset = inputPtr - base;
+     u32 offset = base + addend - inputPtr;
+     if (patchType == R_ARM_NONE)
+         return 0;
+     if (patchType == R_ARM_ABS32 || patchType == R_ARM_TARGET1) {
+         *out = base + addend;
+         return 0;
+     }
+     if (patchType == R_ARM_REL32) {
+         *out = offset;
+         return 0;
+     }
+     if (patchType == R_ARM_THM_PC22) {
+         // +-4MB.
+         if (branchOffset >= 0x400000 || branchOffset <= -0x400000)
+             return 0xD9012C23;
+         if (base & 1) {
+             *out = (((offset >> 12) | 0xF000) << 16) | ((offset << 4) >> 5) | 0xF800;
+         } else {
+             if (offset & 2)
+                 offset += 2;
+             *out = ((offset >> 12) | 0xF000) << 16 | ((offset << 4) >> 5) | 0xE800;
+         }
+         return 0;
+     }
+     if (patchType == R_ARM_CALL) {
+         // +-32MB.
+         if (branchOffset >= 0x2000000 || branchOffset <= -0x2000000)
+             return 0xD9012C23;
+         if (base & 1) {
+             *out = ((offset << 23) & 0x1000000) | ((offset << 6) >> 8) | 0xFA000000;
+         } else {
+             *out = 0xEB000000 | ((offset << 6) >> 8);
+         }
+         return 0;
+     }
+     if (patchType == R_ARM_JUMP24) {
+         // +-32MB.
+         if (branchOffset >= 0x2000000 || branchOffset <= -0x2000000 || (base & 1))
+             return 0xD9012C23;
+         *out = (*out & 0xFF000000) | ((offset << 6) >> 8);
+         return 0;
+     }
+     if (patchType == R_ARM_PREL31) {
+         *out = addend + ((base << 1) >> 1) - inputPtr;
+         return 0;
+     }
+     return 0xD9012C22;
+ }