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-rw-r--r--arch/riscv/kernel/kexec_relocate.S221
1 files changed, 221 insertions, 0 deletions
diff --git a/arch/riscv/kernel/kexec_relocate.S b/arch/riscv/kernel/kexec_relocate.S
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 FORTH-ICS/CARV
+ * Nick Kossifidis <mick@ics.forth.gr>
+ */
+
+#include <asm/asm.h> /* For RISCV_* and REG_* macros */
+#include <asm/csr.h> /* For CSR_* macros */
+#include <asm/page.h> /* For PAGE_SIZE */
+#include <linux/linkage.h> /* For SYM_* macros */
+
+.section ".rodata"
+SYM_CODE_START(riscv_kexec_relocate)
+
+ /*
+ * s0: Pointer to the current entry
+ * s1: (const) Phys address to jump to after relocation
+ * s2: (const) Phys address of the FDT image
+ * s3: (const) The hartid of the current hart
+ * s4: Pointer to the destination address for the relocation
+ * s5: (const) Number of words per page
+ * s6: (const) 1, used for subtraction
+ * s7: (const) kernel_map.va_pa_offset, used when switching MMU off
+ * s8: (const) Physical address of the main loop
+ * s9: (debug) indirection page counter
+ * s10: (debug) entry counter
+ * s11: (debug) copied words counter
+ */
+ mv s0, a0
+ mv s1, a1
+ mv s2, a2
+ mv s3, a3
+ mv s4, zero
+ li s5, (PAGE_SIZE / RISCV_SZPTR)
+ li s6, 1
+ mv s7, a4
+ mv s8, zero
+ mv s9, zero
+ mv s10, zero
+ mv s11, zero
+
+ /* Disable / cleanup interrupts */
+ csrw CSR_SIE, zero
+ csrw CSR_SIP, zero
+
+ /*
+ * When we switch SATP.MODE to "Bare" we'll only
+ * play with physical addresses. However the first time
+ * we try to jump somewhere, the offset on the jump
+ * will be relative to pc which will still be on VA. To
+ * deal with this we set stvec to the physical address at
+ * the start of the loop below so that we jump there in
+ * any case.
+ */
+ la s8, 1f
+ sub s8, s8, s7
+ csrw CSR_STVEC, s8
+
+ /* Process entries in a loop */
+.align 2
+1:
+ addi s10, s10, 1
+ REG_L t0, 0(s0) /* t0 = *image->entry */
+ addi s0, s0, RISCV_SZPTR /* image->entry++ */
+
+ /* IND_DESTINATION entry ? -> save destination address */
+ andi t1, t0, 0x1
+ beqz t1, 2f
+ andi s4, t0, ~0x1
+ j 1b
+
+2:
+ /* IND_INDIRECTION entry ? -> update next entry ptr (PA) */
+ andi t1, t0, 0x2
+ beqz t1, 2f
+ andi s0, t0, ~0x2
+ addi s9, s9, 1
+ csrw CSR_SATP, zero
+ jalr zero, s8, 0
+
+2:
+ /* IND_DONE entry ? -> jump to done label */
+ andi t1, t0, 0x4
+ beqz t1, 2f
+ j 4f
+
+2:
+ /*
+ * IND_SOURCE entry ? -> copy page word by word to the
+ * destination address we got from IND_DESTINATION
+ */
+ andi t1, t0, 0x8
+ beqz t1, 1b /* Unknown entry type, ignore it */
+ andi t0, t0, ~0x8
+ mv t3, s5 /* i = num words per page */
+3: /* copy loop */
+ REG_L t1, (t0) /* t1 = *src_ptr */
+ REG_S t1, (s4) /* *dst_ptr = *src_ptr */
+ addi t0, t0, RISCV_SZPTR /* stc_ptr++ */
+ addi s4, s4, RISCV_SZPTR /* dst_ptr++ */
+ sub t3, t3, s6 /* i-- */
+ addi s11, s11, 1 /* c++ */
+ beqz t3, 1b /* copy done ? */
+ j 3b
+
+4:
+ /* Pass the arguments to the next kernel / Cleanup*/
+ mv a0, s3
+ mv a1, s2
+ mv a2, s1
+
+ /* Cleanup */
+ mv a3, zero
+ mv a4, zero
+ mv a5, zero
+ mv a6, zero
+ mv a7, zero
+
+ mv s0, zero
+ mv s1, zero
+ mv s2, zero
+ mv s3, zero
+ mv s4, zero
+ mv s5, zero
+ mv s6, zero
+ mv s7, zero
+ mv s8, zero
+ mv s9, zero
+ mv s10, zero
+ mv s11, zero
+
+ mv t0, zero
+ mv t1, zero
+ mv t2, zero
+ mv t3, zero
+ mv t4, zero
+ mv t5, zero
+ mv t6, zero
+ csrw CSR_SEPC, zero
+ csrw CSR_SCAUSE, zero
+ csrw CSR_SSCRATCH, zero
+
+ /*
+ * Make sure the relocated code is visible
+ * and jump to the new kernel
+ */
+ fence.i
+
+ jalr zero, a2, 0
+
+SYM_CODE_END(riscv_kexec_relocate)
+riscv_kexec_relocate_end:
+
+
+/* Used for jumping to crashkernel */
+.section ".text"
+SYM_CODE_START(riscv_kexec_norelocate)
+ /*
+ * s0: (const) Phys address to jump to
+ * s1: (const) Phys address of the FDT image
+ * s2: (const) The hartid of the current hart
+ */
+ mv s0, a1
+ mv s1, a2
+ mv s2, a3
+
+ /* Disable / cleanup interrupts */
+ csrw CSR_SIE, zero
+ csrw CSR_SIP, zero
+
+ /* Pass the arguments to the next kernel / Cleanup*/
+ mv a0, s2
+ mv a1, s1
+ mv a2, s0
+
+ /* Cleanup */
+ mv a3, zero
+ mv a4, zero
+ mv a5, zero
+ mv a6, zero
+ mv a7, zero
+
+ mv s0, zero
+ mv s1, zero
+ mv s2, zero
+ mv s3, zero
+ mv s4, zero
+ mv s5, zero
+ mv s6, zero
+ mv s7, zero
+ mv s8, zero
+ mv s9, zero
+ mv s10, zero
+ mv s11, zero
+
+ mv t0, zero
+ mv t1, zero
+ mv t2, zero
+ mv t3, zero
+ mv t4, zero
+ mv t5, zero
+ mv t6, zero
+ csrw CSR_SEPC, zero
+ csrw CSR_SCAUSE, zero
+ csrw CSR_SSCRATCH, zero
+
+ /*
+ * Switch to physical addressing
+ * This will also trigger a jump to CSR_STVEC
+ * which in this case is the address of the new
+ * kernel.
+ */
+ csrw CSR_STVEC, a2
+ csrw CSR_SATP, zero
+
+SYM_CODE_END(riscv_kexec_norelocate)
+
+.section ".rodata"
+SYM_DATA(riscv_kexec_relocate_size,
+ .long riscv_kexec_relocate_end - riscv_kexec_relocate)
+