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-rw-r--r--arch/riscv/kernel/head.S458
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diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
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+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ */
+
+#include <asm/asm-offsets.h>
+#include <asm/asm.h>
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/thread_info.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/csr.h>
+#include <asm/cpu_ops_sbi.h>
+#include <asm/hwcap.h>
+#include <asm/image.h>
+#include <asm/xip_fixup.h>
+#include "efi-header.S"
+
+__HEAD
+ENTRY(_start)
+ /*
+ * Image header expected by Linux boot-loaders. The image header data
+ * structure is described in asm/image.h.
+ * Do not modify it without modifying the structure and all bootloaders
+ * that expects this header format!!
+ */
+#ifdef CONFIG_EFI
+ /*
+ * This instruction decodes to "MZ" ASCII required by UEFI.
+ */
+ c.li s4,-13
+ j _start_kernel
+#else
+ /* jump to start kernel */
+ j _start_kernel
+ /* reserved */
+ .word 0
+#endif
+ .balign 8
+#ifdef CONFIG_RISCV_M_MODE
+ /* Image load offset (0MB) from start of RAM for M-mode */
+ .dword 0
+#else
+#if __riscv_xlen == 64
+ /* Image load offset(2MB) from start of RAM */
+ .dword 0x200000
+#else
+ /* Image load offset(4MB) from start of RAM */
+ .dword 0x400000
+#endif
+#endif
+ /* Effective size of kernel image */
+ .dword _end - _start
+ .dword __HEAD_FLAGS
+ .word RISCV_HEADER_VERSION
+ .word 0
+ .dword 0
+ .ascii RISCV_IMAGE_MAGIC
+ .balign 4
+ .ascii RISCV_IMAGE_MAGIC2
+#ifdef CONFIG_EFI
+ .word pe_head_start - _start
+pe_head_start:
+
+ __EFI_PE_HEADER
+#else
+ .word 0
+#endif
+
+.align 2
+#ifdef CONFIG_MMU
+ .global relocate_enable_mmu
+relocate_enable_mmu:
+ /* Relocate return address */
+ la a1, kernel_map
+ XIP_FIXUP_OFFSET a1
+ REG_L a1, KERNEL_MAP_VIRT_ADDR(a1)
+ la a2, _start
+ sub a1, a1, a2
+ add ra, ra, a1
+
+ /* Point stvec to virtual address of intruction after satp write */
+ la a2, 1f
+ add a2, a2, a1
+ csrw CSR_TVEC, a2
+
+ /* Compute satp for kernel page tables, but don't load it yet */
+ srl a2, a0, PAGE_SHIFT
+ la a1, satp_mode
+ REG_L a1, 0(a1)
+ or a2, a2, a1
+
+ /*
+ * Load trampoline page directory, which will cause us to trap to
+ * stvec if VA != PA, or simply fall through if VA == PA. We need a
+ * full fence here because setup_vm() just wrote these PTEs and we need
+ * to ensure the new translations are in use.
+ */
+ la a0, trampoline_pg_dir
+ XIP_FIXUP_OFFSET a0
+ srl a0, a0, PAGE_SHIFT
+ or a0, a0, a1
+ sfence.vma
+ csrw CSR_SATP, a0
+.align 2
+1:
+ /* Set trap vector to spin forever to help debug */
+ la a0, .Lsecondary_park
+ csrw CSR_TVEC, a0
+
+ /* Reload the global pointer */
+.option push
+.option norelax
+ la gp, __global_pointer$
+.option pop
+
+ /*
+ * Switch to kernel page tables. A full fence is necessary in order to
+ * avoid using the trampoline translations, which are only correct for
+ * the first superpage. Fetching the fence is guaranteed to work
+ * because that first superpage is translated the same way.
+ */
+ csrw CSR_SATP, a2
+ sfence.vma
+
+ ret
+#endif /* CONFIG_MMU */
+#ifdef CONFIG_SMP
+ .global secondary_start_sbi
+secondary_start_sbi:
+ /* Mask all interrupts */
+ csrw CSR_IE, zero
+ csrw CSR_IP, zero
+
+ /* Load the global pointer */
+ .option push
+ .option norelax
+ la gp, __global_pointer$
+ .option pop
+
+ /*
+ * Disable FPU & VECTOR to detect illegal usage of
+ * floating point or vector in kernel space
+ */
+ li t0, SR_FS_VS
+ csrc CSR_STATUS, t0
+
+ /* Set trap vector to spin forever to help debug */
+ la a3, .Lsecondary_park
+ csrw CSR_TVEC, a3
+
+ /* a0 contains the hartid & a1 contains boot data */
+ li a2, SBI_HART_BOOT_TASK_PTR_OFFSET
+ XIP_FIXUP_OFFSET a2
+ add a2, a2, a1
+ REG_L tp, (a2)
+ li a3, SBI_HART_BOOT_STACK_PTR_OFFSET
+ XIP_FIXUP_OFFSET a3
+ add a3, a3, a1
+ REG_L sp, (a3)
+
+.Lsecondary_start_common:
+
+#ifdef CONFIG_MMU
+ /* Enable virtual memory and relocate to virtual address */
+ la a0, swapper_pg_dir
+ XIP_FIXUP_OFFSET a0
+ call relocate_enable_mmu
+#endif
+ call setup_trap_vector
+ tail smp_callin
+#endif /* CONFIG_SMP */
+
+.align 2
+setup_trap_vector:
+ /* Set trap vector to exception handler */
+ la a0, handle_exception
+ csrw CSR_TVEC, a0
+
+ /*
+ * Set sup0 scratch register to 0, indicating to exception vector that
+ * we are presently executing in kernel.
+ */
+ csrw CSR_SCRATCH, zero
+ ret
+
+.align 2
+.Lsecondary_park:
+ /* We lack SMP support or have too many harts, so park this hart */
+ wfi
+ j .Lsecondary_park
+
+END(_start)
+
+ENTRY(_start_kernel)
+ /* Mask all interrupts */
+ csrw CSR_IE, zero
+ csrw CSR_IP, zero
+
+#ifdef CONFIG_RISCV_M_MODE
+ /* flush the instruction cache */
+ fence.i
+
+ /* Reset all registers except ra, a0, a1 */
+ call reset_regs
+
+ /*
+ * Setup a PMP to permit access to all of memory. Some machines may
+ * not implement PMPs, so we set up a quick trap handler to just skip
+ * touching the PMPs on any trap.
+ */
+ la a0, pmp_done
+ csrw CSR_TVEC, a0
+
+ li a0, -1
+ csrw CSR_PMPADDR0, a0
+ li a0, (PMP_A_NAPOT | PMP_R | PMP_W | PMP_X)
+ csrw CSR_PMPCFG0, a0
+.align 2
+pmp_done:
+
+ /*
+ * The hartid in a0 is expected later on, and we have no firmware
+ * to hand it to us.
+ */
+ csrr a0, CSR_MHARTID
+#endif /* CONFIG_RISCV_M_MODE */
+
+ /* Load the global pointer */
+.option push
+.option norelax
+ la gp, __global_pointer$
+.option pop
+
+ /*
+ * Disable FPU & VECTOR to detect illegal usage of
+ * floating point or vector in kernel space
+ */
+ li t0, SR_FS_VS
+ csrc CSR_STATUS, t0
+
+#ifdef CONFIG_RISCV_BOOT_SPINWAIT
+ li t0, CONFIG_NR_CPUS
+ blt a0, t0, .Lgood_cores
+ tail .Lsecondary_park
+.Lgood_cores:
+
+ /* The lottery system is only required for spinwait booting method */
+#ifndef CONFIG_XIP_KERNEL
+ /* Pick one hart to run the main boot sequence */
+ la a3, hart_lottery
+ li a2, 1
+ amoadd.w a3, a2, (a3)
+ bnez a3, .Lsecondary_start
+
+#else
+ /* hart_lottery in flash contains a magic number */
+ la a3, hart_lottery
+ mv a2, a3
+ XIP_FIXUP_OFFSET a2
+ XIP_FIXUP_FLASH_OFFSET a3
+ lw t1, (a3)
+ amoswap.w t0, t1, (a2)
+ /* first time here if hart_lottery in RAM is not set */
+ beq t0, t1, .Lsecondary_start
+
+#endif /* CONFIG_XIP */
+#endif /* CONFIG_RISCV_BOOT_SPINWAIT */
+
+#ifdef CONFIG_XIP_KERNEL
+ la sp, _end + THREAD_SIZE
+ XIP_FIXUP_OFFSET sp
+ mv s0, a0
+ call __copy_data
+
+ /* Restore a0 copy */
+ mv a0, s0
+#endif
+
+#ifndef CONFIG_XIP_KERNEL
+ /* Clear BSS for flat non-ELF images */
+ la a3, __bss_start
+ la a4, __bss_stop
+ ble a4, a3, clear_bss_done
+clear_bss:
+ REG_S zero, (a3)
+ add a3, a3, RISCV_SZPTR
+ blt a3, a4, clear_bss
+clear_bss_done:
+#endif
+ la a2, boot_cpu_hartid
+ XIP_FIXUP_OFFSET a2
+ REG_S a0, (a2)
+
+ /* Initialize page tables and relocate to virtual addresses */
+ la tp, init_task
+ la sp, init_thread_union + THREAD_SIZE
+ XIP_FIXUP_OFFSET sp
+ addi sp, sp, -PT_SIZE_ON_STACK
+#ifdef CONFIG_BUILTIN_DTB
+ la a0, __dtb_start
+ XIP_FIXUP_OFFSET a0
+#else
+ mv a0, a1
+#endif /* CONFIG_BUILTIN_DTB */
+ call setup_vm
+#ifdef CONFIG_MMU
+ la a0, early_pg_dir
+ XIP_FIXUP_OFFSET a0
+ call relocate_enable_mmu
+#endif /* CONFIG_MMU */
+
+ call setup_trap_vector
+ /* Restore C environment */
+ la tp, init_task
+ la sp, init_thread_union + THREAD_SIZE
+ addi sp, sp, -PT_SIZE_ON_STACK
+
+#ifdef CONFIG_KASAN
+ call kasan_early_init
+#endif
+ /* Start the kernel */
+ call soc_early_init
+ tail start_kernel
+
+#ifdef CONFIG_RISCV_BOOT_SPINWAIT
+.Lsecondary_start:
+ /* Set trap vector to spin forever to help debug */
+ la a3, .Lsecondary_park
+ csrw CSR_TVEC, a3
+
+ slli a3, a0, LGREG
+ la a1, __cpu_spinwait_stack_pointer
+ XIP_FIXUP_OFFSET a1
+ la a2, __cpu_spinwait_task_pointer
+ XIP_FIXUP_OFFSET a2
+ add a1, a3, a1
+ add a2, a3, a2
+
+ /*
+ * This hart didn't win the lottery, so we wait for the winning hart to
+ * get far enough along the boot process that it should continue.
+ */
+.Lwait_for_cpu_up:
+ /* FIXME: We should WFI to save some energy here. */
+ REG_L sp, (a1)
+ REG_L tp, (a2)
+ beqz sp, .Lwait_for_cpu_up
+ beqz tp, .Lwait_for_cpu_up
+ fence
+
+ tail .Lsecondary_start_common
+#endif /* CONFIG_RISCV_BOOT_SPINWAIT */
+
+END(_start_kernel)
+
+#ifdef CONFIG_RISCV_M_MODE
+ENTRY(reset_regs)
+ li sp, 0
+ li gp, 0
+ li tp, 0
+ li t0, 0
+ li t1, 0
+ li t2, 0
+ li s0, 0
+ li s1, 0
+ li a2, 0
+ li a3, 0
+ li a4, 0
+ li a5, 0
+ li a6, 0
+ li a7, 0
+ li s2, 0
+ li s3, 0
+ li s4, 0
+ li s5, 0
+ li s6, 0
+ li s7, 0
+ li s8, 0
+ li s9, 0
+ li s10, 0
+ li s11, 0
+ li t3, 0
+ li t4, 0
+ li t5, 0
+ li t6, 0
+ csrw CSR_SCRATCH, 0
+
+#ifdef CONFIG_FPU
+ csrr t0, CSR_MISA
+ andi t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)
+ beqz t0, .Lreset_regs_done_fpu
+
+ li t1, SR_FS
+ csrs CSR_STATUS, t1
+ fmv.s.x f0, zero
+ fmv.s.x f1, zero
+ fmv.s.x f2, zero
+ fmv.s.x f3, zero
+ fmv.s.x f4, zero
+ fmv.s.x f5, zero
+ fmv.s.x f6, zero
+ fmv.s.x f7, zero
+ fmv.s.x f8, zero
+ fmv.s.x f9, zero
+ fmv.s.x f10, zero
+ fmv.s.x f11, zero
+ fmv.s.x f12, zero
+ fmv.s.x f13, zero
+ fmv.s.x f14, zero
+ fmv.s.x f15, zero
+ fmv.s.x f16, zero
+ fmv.s.x f17, zero
+ fmv.s.x f18, zero
+ fmv.s.x f19, zero
+ fmv.s.x f20, zero
+ fmv.s.x f21, zero
+ fmv.s.x f22, zero
+ fmv.s.x f23, zero
+ fmv.s.x f24, zero
+ fmv.s.x f25, zero
+ fmv.s.x f26, zero
+ fmv.s.x f27, zero
+ fmv.s.x f28, zero
+ fmv.s.x f29, zero
+ fmv.s.x f30, zero
+ fmv.s.x f31, zero
+ csrw fcsr, 0
+ /* note that the caller must clear SR_FS */
+.Lreset_regs_done_fpu:
+#endif /* CONFIG_FPU */
+
+#ifdef CONFIG_RISCV_ISA_V
+ csrr t0, CSR_MISA
+ li t1, COMPAT_HWCAP_ISA_V
+ and t0, t0, t1
+ beqz t0, .Lreset_regs_done_vector
+
+ /*
+ * Clear vector registers and reset vcsr
+ * VLMAX has a defined value, VLEN is a constant,
+ * and this form of vsetvli is defined to set vl to VLMAX.
+ */
+ li t1, SR_VS
+ csrs CSR_STATUS, t1
+ csrs CSR_VCSR, x0
+ vsetvli t1, x0, e8, m8, ta, ma
+ vmv.v.i v0, 0
+ vmv.v.i v8, 0
+ vmv.v.i v16, 0
+ vmv.v.i v24, 0
+ /* note that the caller must clear SR_VS */
+.Lreset_regs_done_vector:
+#endif /* CONFIG_RISCV_ISA_V */
+ ret
+END(reset_regs)
+#endif /* CONFIG_RISCV_M_MODE */