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-rw-r--r--arch/loongarch/kernel/relocate_kernel.S112
1 files changed, 112 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
new file mode 100644
index 000000000..d13252553
--- /dev/null
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * relocate_kernel.S for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kexec.h>
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/regdef.h>
+#include <asm/loongarch.h>
+#include <asm/stackframe.h>
+#include <asm/addrspace.h>
+
+SYM_CODE_START(relocate_new_kernel)
+ /*
+ * a0: EFI boot flag for the new kernel
+ * a1: Command line pointer for the new kernel
+ * a2: System table pointer for the new kernel
+ * a3: Start address to jump to after relocation
+ * a4: Pointer to the current indirection page entry
+ */
+ move s0, a4
+
+ /*
+ * In case of a kdump/crash kernel, the indirection page is not
+ * populated as the kernel is directly copied to a reserved location
+ */
+ beqz s0, done
+
+process_entry:
+ PTR_L s1, s0, 0
+ PTR_ADDI s0, s0, SZREG
+
+ /* destination page */
+ andi s2, s1, IND_DESTINATION
+ beqz s2, 1f
+ li.w t0, ~0x1
+ and s3, s1, t0 /* store destination addr in s3 */
+ b process_entry
+
+1:
+ /* indirection page, update s0 */
+ andi s2, s1, IND_INDIRECTION
+ beqz s2, 1f
+ li.w t0, ~0x2
+ and s0, s1, t0
+ b process_entry
+
+1:
+ /* done page */
+ andi s2, s1, IND_DONE
+ beqz s2, 1f
+ b done
+
+1:
+ /* source page */
+ andi s2, s1, IND_SOURCE
+ beqz s2, process_entry
+ li.w t0, ~0x8
+ and s1, s1, t0
+ li.w s5, (1 << _PAGE_SHIFT) / SZREG
+
+copy_word:
+ /* copy page word by word */
+ REG_L s4, s1, 0
+ REG_S s4, s3, 0
+ PTR_ADDI s3, s3, SZREG
+ PTR_ADDI s1, s1, SZREG
+ LONG_ADDI s5, s5, -1
+ beqz s5, process_entry
+ b copy_word
+ b process_entry
+
+done:
+ ibar 0
+ dbar 0
+
+ /*
+ * Jump to the new kernel,
+ * make sure the values of a0, a1, a2 and a3 are not changed.
+ */
+ jr a3
+SYM_CODE_END(relocate_new_kernel)
+
+#ifdef CONFIG_SMP
+/*
+ * Other CPUs should wait until code is relocated and
+ * then start at the entry point from LOONGARCH_IOCSR_MBUF0.
+ */
+SYM_CODE_START(kexec_smp_wait)
+1: li.w t0, 0x100 /* wait for init loop */
+2: addi.w t0, t0, -1 /* limit mailbox access */
+ bnez t0, 2b
+ li.w t1, LOONGARCH_IOCSR_MBUF0
+ iocsrrd.w s0, t1 /* check PC as an indicator */
+ beqz s0, 1b
+ iocsrrd.d s0, t1 /* get PC via mailbox */
+
+ li.d t0, CACHE_BASE
+ or s0, s0, t0 /* s0 = TO_CACHE(s0) */
+ jr s0 /* jump to initial PC */
+SYM_CODE_END(kexec_smp_wait)
+#endif
+
+relocate_new_kernel_end:
+
+SYM_DATA_START(relocate_new_kernel_size)
+ PTR relocate_new_kernel_end - relocate_new_kernel
+SYM_DATA_END(relocate_new_kernel_size)