From 35293c222967990a0990c64da183b5b9e8e24d78 Mon Sep 17 00:00:00 2001
From: Xu Liangyu <xuliangyu@loongson.cn>
Date: Sat, 16 Mar 2024 12:13:53 +0800
Subject: [PATCH] [LoongArch64] Fix hijack. (#99853)

---
 src/coreclr/unwinder/loongarch64/unwinder.cpp |  4 +++-
 src/coreclr/vm/loongarch64/asmhelpers.S       | 12 ++++++------
 src/coreclr/vm/loongarch64/cgencpu.h          | 18 +++++++++---------
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/coreclr/unwinder/loongarch64/unwinder.cpp b/src/coreclr/unwinder/loongarch64/unwinder.cpp
index 93cc2a7aee65c..2a263f0516ac9 100644
--- a/src/coreclr/unwinder/loongarch64/unwinder.cpp
+++ b/src/coreclr/unwinder/loongarch64/unwinder.cpp
@@ -106,7 +106,9 @@ do {
     if (ARGUMENT_PRESENT(Params)) {                                                   \
         PT_KNONVOLATILE_CONTEXT_POINTERS ContextPointers = (Params)->ContextPointers; \
         if (ARGUMENT_PRESENT(ContextPointers)) {                                      \
-            if (RegisterNumber ==  22)                                                \
+            if (RegisterNumber == 1)                                                  \
+                ContextPointers->Ra = (PDWORD64)Address;                              \
+            else if (RegisterNumber == 22)                                            \
                 ContextPointers->Fp = (PDWORD64)Address;                              \
             else if (RegisterNumber >=  23 && RegisterNumber <= 31) {                 \
                 (&ContextPointers->S0)[RegisterNumber - 23] = (PDWORD64)Address;      \
diff --git a/src/coreclr/vm/loongarch64/asmhelpers.S b/src/coreclr/vm/loongarch64/asmhelpers.S
index 56fb0c0b9247a..3f1f7b827e6d2 100644
--- a/src/coreclr/vm/loongarch64/asmhelpers.S
+++ b/src/coreclr/vm/loongarch64/asmhelpers.S
@@ -822,13 +822,13 @@ NESTED_ENTRY OnHijackTripThread, _TEXT, NoHandler
     PROLOG_SAVE_REG_PAIR   25, 26, 32
     PROLOG_SAVE_REG_PAIR   27, 28, 48
     PROLOG_SAVE_REG_PAIR   29, 30, 64
-    PROLOG_SAVE_REG 31, 80
+    PROLOG_SAVE_REG_PAIR   31, 2, 80
 
     // save any integral return value(s)
     st.d  $a0, $sp, 96
     st.d  $a1, $sp, 104
 
-    // save any FP/HFA return value(s)
+    // save any FP return value(s)
     fst.d  $f0, $sp, 112
     fst.d  $f1, $sp, 120
 
@@ -841,15 +841,15 @@ NESTED_ENTRY OnHijackTripThread, _TEXT, NoHandler
     ld.d  $a0, $sp, 96
     ld.d  $a1, $sp, 104
 
-    // restore any FP/HFA return value(s)
-    fst.d  $f0, $sp, 112
-    fst.d  $f1, $sp, 120
+    // restore any FP return value(s)
+    fld.d  $f0, $sp, 112
+    fld.d  $f1, $sp, 120
 
     EPILOG_RESTORE_REG_PAIR   23, 24, 16
     EPILOG_RESTORE_REG_PAIR   25, 26, 32
     EPILOG_RESTORE_REG_PAIR   27, 28, 48
     EPILOG_RESTORE_REG_PAIR   29, 30, 64
-    EPILOG_RESTORE_REG  31, 80
+    EPILOG_RESTORE_REG_PAIR   31, 2,  80
     //                              $fp,$ra
     EPILOG_RESTORE_REG_PAIR_INDEXED  22, 1, 0x80
     EPILOG_RETURN
diff --git a/src/coreclr/vm/loongarch64/cgencpu.h b/src/coreclr/vm/loongarch64/cgencpu.h
index 6979fa11a9675..0c3a7ca83a8d0 100644
--- a/src/coreclr/vm/loongarch64/cgencpu.h
+++ b/src/coreclr/vm/loongarch64/cgencpu.h
@@ -448,11 +448,18 @@ struct DECLSPEC_ALIGN(16) UMEntryThunkCode
 
 struct HijackArgs
 {
+    DWORD64 Fp; // frame pointer
+    union
+    {
+        DWORD64 Ra;
+        size_t ReturnAddress;
+    };
+    DWORD64 S0, S1, S2, S3, S4, S5, S6, S7, S8, Tp;
     union
     {
         struct {
-             DWORD64 V0;
-             DWORD64 V1;
+             DWORD64 A0;
+             DWORD64 A1;
          };
         size_t ReturnValue[2];
     };
@@ -464,13 +471,6 @@ struct HijackArgs
          };
         size_t FPReturnValue[2];
     };
-    DWORD64 S0, S1, S2, S3, S4, S5, S6, S7, S8, Tp;
-    DWORD64 Fp; // frame pointer
-    union
-    {
-        DWORD64 Ra;
-        size_t ReturnAddress;
-    };
 };
 
 EXTERN_C VOID STDCALL PrecodeFixupThunk();