1 files changed, 107 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/relocate.c
new file mode 100644
index 000000000000..879c40372fba
--- /dev/null
+++ b/arch/loongarch/kernel/relocate.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support for Kernel relocation at boot time
+ *
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/elf.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/panic_notifier.h>
+#include <asm/inst.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+
+#define RELOCATED(x) ((void *)((long)x + reloc_offset))
+
+static unsigned long reloc_offset;
+
+static inline void __init relocate_relative(void)
+{
+	Elf64_Rela *rela, *rela_end;
+	rela = (Elf64_Rela *)&__rela_dyn_begin;
+	rela_end = (Elf64_Rela *)&__rela_dyn_end;
+
+	for ( ; rela < rela_end; rela++) {
+		Elf64_Addr addr = rela->r_offset;
+		Elf64_Addr relocated_addr = rela->r_addend;
+
+		if (rela->r_info != R_LARCH_RELATIVE)
+			continue;
+
+		if (relocated_addr >= VMLINUX_LOAD_ADDRESS)
+			relocated_addr = (Elf64_Addr)RELOCATED(relocated_addr);
+
+		*(Elf64_Addr *)RELOCATED(addr) = relocated_addr;
+	}
+}
+
+static inline void __init relocate_absolute(void)
+{
+	void *begin, *end;
+	struct rela_la_abs *p;
+
+	begin = &__la_abs_begin;
+	end   = &__la_abs_end;
+
+	for (p = begin; (void *)p < end; p++) {
+		long v = p->symvalue;
+		uint32_t lu12iw, ori, lu32id, lu52id;
+		union loongarch_instruction *insn = (void *)p - p->offset;
+
+		lu12iw = (v >> 12) & 0xfffff;
+		ori    = v & 0xfff;
+		lu32id = (v >> 32) & 0xfffff;
+		lu52id = v >> 52;
+
+		insn[0].reg1i20_format.immediate = lu12iw;
+		insn[1].reg2i12_format.immediate = ori;
+		insn[2].reg1i20_format.immediate = lu32id;
+		insn[3].reg2i12_format.immediate = lu52id;
+	}
+}
+
+void __init relocate_kernel(void)
+{
+	reloc_offset = (unsigned long)_text - VMLINUX_LOAD_ADDRESS;
+
+	if (reloc_offset)
+		relocate_relative();
+
+	relocate_absolute();
+}
+
+/*
+ * Show relocation information on panic.
+ */
+static void show_kernel_relocation(const char *level)
+{
+	if (reloc_offset > 0) {
+		printk(level);
+		pr_cont("Kernel relocated by 0x%lx\n", reloc_offset);
+		pr_cont(" .text @ 0x%px\n", _text);
+		pr_cont(" .data @ 0x%px\n", _sdata);
+		pr_cont(" .bss  @ 0x%px\n", __bss_start);
+	}
+}
+
+static int kernel_location_notifier_fn(struct notifier_block *self,
+				       unsigned long v, void *p)
+{
+	show_kernel_relocation(KERN_EMERG);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kernel_location_notifier = {
+	.notifier_call = kernel_location_notifier_fn
+};
+
+static int __init register_kernel_offset_dumper(void)
+{
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &kernel_location_notifier);
+	return 0;
+}
+
+arch_initcall(register_kernel_offset_dumper);