Initial commit

backends/plugins/riscos/plugin.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "common/scummsys.h"
+
+#ifdef USE_ELF_LOADER
+
+/**
+ * These functions are a hack to workaround a GCC limitation
+ * At every function entry, GCC adds a check on the stack size
+ * If the stack is too small, the functions _rt_stkovf_split_small or _rt_stkovf_split_big are called
+ * This call is done using a PC relative 24 bits address but we want to link back to main executable functions
+ * and this is not possible using this relocation type.
+ * So we create wrapper functions which will just jump to the main function using a 32 bits relocation.
+ * The wrapping is done by ld thanks to its --wrap argument
+ */
+
+__asm__ (
+	".global __wrap___rt_stkovf_split_small\n"
+	".type __wrap___rt_stkovf_split_small, %function\n"
+	"__wrap___rt_stkovf_split_small:\n"
+	"LDR	pc, .Lsmall\n"
+	".Lsmall:\n"
+	".word	__real___rt_stkovf_split_small\n"
+);
+
+__asm__ (
+	".global __wrap___rt_stkovf_split_big\n"
+	".type __wrap___rt_stkovf_split_big, %function\n"
+	"__wrap___rt_stkovf_split_big:\n"
+	"LDR	pc, .Lbig\n"
+	".Lbig:\n"
+	".word	__real___rt_stkovf_split_big\n"
+);
+
+#endif