[RISC-V] Port Mono for RISC-V 64 Arch (2/3) thunk & tramponlie (#83715)

* thunk & tramponlie for riscv64, also exception call

* format

Author: Xinlong-Wu

src/mono/mono/arch/riscv/riscv-codegen.h

@@ -614,6 +614,20 @@ enum {
 		                  ((funct5) << 27)); \
 	} while (0)
 
+static G_GNUC_UNUSED inline gboolean
+riscv_is_jal_disp (void *code, void *target)
+{
+	gint64 disp = ((char *)(target) - (char *)(code)) / 2;
+
+	return (disp > -(1 << 19)) && (disp < (1 << 19));
+}
+
+static G_GNUC_UNUSED inline gsize
+riscv_get_jal_disp (void *code, void *target)
+{
+	return ((char *)(target) - (char *)(code)) & 0xfffffffe;
+}
+
 /*
  * NOTE: When you add new codegen macros or change existing ones, you must
  * expand riscv-codegen-test.c to cover them, and update riscv-codegen.exp32

src/mono/mono/mini/exceptions-riscv.c

@@ -147,6 +147,14 @@ mono_arch_exceptions_init (void)
 	// NOT_IMPLEMENTED;
 }
 
+/*
+ * mono_arch_unwind_frame:
+ *
+ * This function is used to gather information from @ctx, and store it in @frame_info.
+ * It unwinds one stack frame, and stores the resulting context into @new_ctx. @lmf
+ * is modified if needed.
+ * Returns TRUE on success, FALSE otherwise.
+ */
 gboolean
 mono_arch_unwind_frame (MonoJitTlsData *jit_tls, MonoJitInfo *ji,
                         MonoContext *ctx, MonoContext *new_ctx, MonoLMF **lmf,
@@ -160,7 +168,7 @@ mono_arch_unwind_frame (MonoJitTlsData *jit_tls, MonoJitInfo *ji,
 	*new_ctx = *ctx;
 
 	if (ji != NULL) {
-		NOT_IMPLEMENTED;
+		// all GREG + Callee saved FREG
 		host_mgreg_t regs [MONO_MAX_IREGS + 12 + 1];
 		guint8 *cfa;
 		guint32 unwind_info_len;
@@ -182,10 +190,9 @@ mono_arch_unwind_frame (MonoJitTlsData *jit_tls, MonoJitInfo *ji,
 		for (int i = 0; i < 10; i++)
 			(regs + MONO_MAX_IREGS) [i] = *((host_mgreg_t*)&new_ctx->fregs [RISCV_F18 + i]);
 
-		gboolean success = mono_unwind_frame (unwind_info, unwind_info_len, (guint8*)ji->code_start,
-						   (guint8*)ji->code_start + ji->code_size,
-						   (guint8*)ip, NULL, regs, MONO_MAX_IREGS + 8,
-						   save_locations, MONO_MAX_IREGS, (guint8**)&cfa);
+		gboolean success = mono_unwind_frame (unwind_info, unwind_info_len, (guint8 *)ji->code_start,
+		                                      (guint8 *)ji->code_start + ji->code_size, (guint8 *)ip, NULL, regs,
+		                                      MONO_MAX_IREGS + 12 + 1, save_locations, MONO_MAX_IREGS, (guint8 **)&cfa);
 
 		if (!success)
 			return FALSE;
@@ -198,15 +205,33 @@ mono_arch_unwind_frame (MonoJitTlsData *jit_tls, MonoJitInfo *ji,
 
 		new_ctx->gregs [RISCV_SP] = (host_mgreg_t)(gsize)cfa;
 
-		if (*lmf)
-			NOT_IMPLEMENTED;
+		if (*lmf && (*lmf)->gregs [RISCV_FP] && (MONO_CONTEXT_GET_SP (ctx) >= (gpointer)(*lmf)->gregs [RISCV_SP])) {
+			/* remove any unused lmf */
+			*lmf = (MonoLMF *)(((gsize)(*lmf)->previous_lmf) & ~(TARGET_SIZEOF_VOID_P - 1));
+		}
 
-		/* we subtract 1, so that the IP points into the call instruction */
+		/* we substract 1, so that the pc points into the call instruction */
 		new_ctx->gregs [RISCV_ZERO]--;
 
 		return TRUE;
 	} else if (*lmf) {
-		NOT_IMPLEMENTED;
+		g_assert ((((guint64)(*lmf)->previous_lmf) & 2) == 0);
+
+		frame->type = FRAME_TYPE_MANAGED_TO_NATIVE;
+
+		ji = mini_jit_info_table_find ((gpointer)(*lmf)->pc);
+		if (!ji)
+			return FALSE;
+
+		memcpy (&new_ctx->gregs, (*lmf)->gregs, sizeof (host_mgreg_t) * RISCV_N_GREGS);
+		new_ctx->gregs [0] = (*lmf)->pc; // use [0] as pc reg since x0 is hard-wired zero
+
+		/* we substract 1, so that the IP points into the call instruction */
+		new_ctx->gregs [0]--;
+
+		*lmf = (MonoLMF *)(((gsize)(*lmf)->previous_lmf) & ~(TARGET_SIZEOF_VOID_P - 1));
+
+		return TRUE;
 	}
 
 	return FALSE;