ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/marvell/linux/arch/riscv/kernel/entry.S b/marvell/linux/arch/riscv/kernel/entry.S
new file mode 100644
index 0000000..9c87ae7
--- /dev/null
+++ b/marvell/linux/arch/riscv/kernel/entry.S
@@ -0,0 +1,410 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2017 SiFive
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+
+#include <asm/asm.h>
+#include <asm/csr.h>
+#include <asm/unistd.h>
+#include <asm/thread_info.h>
+#include <asm/asm-offsets.h>
+
+ .text
+ .altmacro
+
+/*
+ * Prepares to enter a system call or exception by saving all registers to the
+ * stack.
+ */
+ .macro SAVE_ALL
+ LOCAL _restore_kernel_tpsp
+ LOCAL _save_context
+
+ /*
+ * If coming from userspace, preserve the user thread pointer and load
+ * the kernel thread pointer. If we came from the kernel, sscratch
+ * will contain 0, and we should continue on the current TP.
+ */
+ csrrw tp, CSR_SSCRATCH, tp
+ bnez tp, _save_context
+
+_restore_kernel_tpsp:
+ csrr tp, CSR_SSCRATCH
+ REG_S sp, TASK_TI_KERNEL_SP(tp)
+_save_context:
+ REG_S sp, TASK_TI_USER_SP(tp)
+ REG_L sp, TASK_TI_KERNEL_SP(tp)
+ addi sp, sp, -(PT_SIZE_ON_STACK)
+ REG_S x1, PT_RA(sp)
+ REG_S x3, PT_GP(sp)
+ REG_S x5, PT_T0(sp)
+ REG_S x6, PT_T1(sp)
+ REG_S x7, PT_T2(sp)
+ REG_S x8, PT_S0(sp)
+ REG_S x9, PT_S1(sp)
+ REG_S x10, PT_A0(sp)
+ REG_S x11, PT_A1(sp)
+ REG_S x12, PT_A2(sp)
+ REG_S x13, PT_A3(sp)
+ REG_S x14, PT_A4(sp)
+ REG_S x15, PT_A5(sp)
+ REG_S x16, PT_A6(sp)
+ REG_S x17, PT_A7(sp)
+ REG_S x18, PT_S2(sp)
+ REG_S x19, PT_S3(sp)
+ REG_S x20, PT_S4(sp)
+ REG_S x21, PT_S5(sp)
+ REG_S x22, PT_S6(sp)
+ REG_S x23, PT_S7(sp)
+ REG_S x24, PT_S8(sp)
+ REG_S x25, PT_S9(sp)
+ REG_S x26, PT_S10(sp)
+ REG_S x27, PT_S11(sp)
+ REG_S x28, PT_T3(sp)
+ REG_S x29, PT_T4(sp)
+ REG_S x30, PT_T5(sp)
+ REG_S x31, PT_T6(sp)
+
+ /*
+ * Disable user-mode memory access as it should only be set in the
+ * actual user copy routines.
+ *
+ * Disable the FPU to detect illegal usage of floating point in kernel
+ * space.
+ */
+ li t0, SR_SUM | SR_FS
+
+ REG_L s0, TASK_TI_USER_SP(tp)
+ csrrc s1, CSR_SSTATUS, t0
+ csrr s2, CSR_SEPC
+ csrr s3, CSR_STVAL
+ csrr s4, CSR_SCAUSE
+ csrr s5, CSR_SSCRATCH
+ REG_S s0, PT_SP(sp)
+ REG_S s1, PT_SSTATUS(sp)
+ REG_S s2, PT_SEPC(sp)
+ REG_S s3, PT_SBADADDR(sp)
+ REG_S s4, PT_SCAUSE(sp)
+ REG_S s5, PT_TP(sp)
+ .endm
+
+/*
+ * Prepares to return from a system call or exception by restoring all
+ * registers from the stack.
+ */
+ .macro RESTORE_ALL
+ REG_L a0, PT_SSTATUS(sp)
+ /*
+ * The current load reservation is effectively part of the processor's
+ * state, in the sense that load reservations cannot be shared between
+ * different hart contexts. We can't actually save and restore a load
+ * reservation, so instead here we clear any existing reservation --
+ * it's always legal for implementations to clear load reservations at
+ * any point (as long as the forward progress guarantee is kept, but
+ * we'll ignore that here).
+ *
+ * Dangling load reservations can be the result of taking a trap in the
+ * middle of an LR/SC sequence, but can also be the result of a taken
+ * forward branch around an SC -- which is how we implement CAS. As a
+ * result we need to clear reservations between the last CAS and the
+ * jump back to the new context. While it is unlikely the store
+ * completes, implementations are allowed to expand reservations to be
+ * arbitrarily large.
+ */
+ REG_L a2, PT_SEPC(sp)
+ REG_SC x0, a2, PT_SEPC(sp)
+
+ csrw CSR_SSTATUS, a0
+ csrw CSR_SEPC, a2
+
+ REG_L x1, PT_RA(sp)
+ REG_L x3, PT_GP(sp)
+ REG_L x4, PT_TP(sp)
+ REG_L x5, PT_T0(sp)
+ REG_L x6, PT_T1(sp)
+ REG_L x7, PT_T2(sp)
+ REG_L x8, PT_S0(sp)
+ REG_L x9, PT_S1(sp)
+ REG_L x10, PT_A0(sp)
+ REG_L x11, PT_A1(sp)
+ REG_L x12, PT_A2(sp)
+ REG_L x13, PT_A3(sp)
+ REG_L x14, PT_A4(sp)
+ REG_L x15, PT_A5(sp)
+ REG_L x16, PT_A6(sp)
+ REG_L x17, PT_A7(sp)
+ REG_L x18, PT_S2(sp)
+ REG_L x19, PT_S3(sp)
+ REG_L x20, PT_S4(sp)
+ REG_L x21, PT_S5(sp)
+ REG_L x22, PT_S6(sp)
+ REG_L x23, PT_S7(sp)
+ REG_L x24, PT_S8(sp)
+ REG_L x25, PT_S9(sp)
+ REG_L x26, PT_S10(sp)
+ REG_L x27, PT_S11(sp)
+ REG_L x28, PT_T3(sp)
+ REG_L x29, PT_T4(sp)
+ REG_L x30, PT_T5(sp)
+ REG_L x31, PT_T6(sp)
+
+ REG_L x2, PT_SP(sp)
+ .endm
+
+#if !IS_ENABLED(CONFIG_PREEMPT)
+.set resume_kernel, restore_all
+#endif
+
+ENTRY(handle_exception)
+ SAVE_ALL
+
+ /*
+ * Set sscratch register to 0, so that if a recursive exception
+ * occurs, the exception vector knows it came from the kernel
+ */
+ csrw CSR_SSCRATCH, x0
+
+ /* Load the global pointer */
+.option push
+.option norelax
+ la gp, __global_pointer$
+.option pop
+
+ la ra, ret_from_exception
+ /*
+ * MSB of cause differentiates between
+ * interrupts and exceptions
+ */
+ bge s4, zero, 1f
+
+ /* Handle interrupts */
+ move a0, sp /* pt_regs */
+ tail do_IRQ
+1:
+ /* Exceptions run with interrupts enabled or disabled
+ depending on the state of sstatus.SR_SPIE */
+ andi t0, s1, SR_SPIE
+ beqz t0, 1f
+ csrs CSR_SSTATUS, SR_SIE
+
+1:
+ /* Handle syscalls */
+ li t0, EXC_SYSCALL
+ beq s4, t0, handle_syscall
+
+ /* Handle other exceptions */
+ slli t0, s4, RISCV_LGPTR
+ la t1, excp_vect_table
+ la t2, excp_vect_table_end
+ move a0, sp /* pt_regs */
+ add t0, t1, t0
+ /* Check if exception code lies within bounds */
+ bgeu t0, t2, 1f
+ REG_L t0, 0(t0)
+ jr t0
+1:
+ tail do_trap_unknown
+
+handle_syscall:
+ /* save the initial A0 value (needed in signal handlers) */
+ REG_S a0, PT_ORIG_A0(sp)
+ /*
+ * Advance SEPC to avoid executing the original
+ * scall instruction on sret
+ */
+ addi s2, s2, 0x4
+ REG_S s2, PT_SEPC(sp)
+ /* Trace syscalls, but only if requested by the user. */
+ REG_L t0, TASK_TI_FLAGS(tp)
+ andi t0, t0, _TIF_SYSCALL_WORK
+ bnez t0, handle_syscall_trace_enter
+check_syscall_nr:
+ /* Check to make sure we don't jump to a bogus syscall number. */
+ li t0, __NR_syscalls
+ la s0, sys_ni_syscall
+ /* Syscall number held in a7 */
+ bgeu a7, t0, 1f
+ la s0, sys_call_table
+ slli t0, a7, RISCV_LGPTR
+ add s0, s0, t0
+ REG_L s0, 0(s0)
+1:
+ jalr s0
+
+ret_from_syscall:
+ /* Set user a0 to kernel a0 */
+ REG_S a0, PT_A0(sp)
+ /* Trace syscalls, but only if requested by the user. */
+ REG_L t0, TASK_TI_FLAGS(tp)
+ andi t0, t0, _TIF_SYSCALL_WORK
+ bnez t0, handle_syscall_trace_exit
+
+ret_from_exception:
+ REG_L s0, PT_SSTATUS(sp)
+ csrc CSR_SSTATUS, SR_SIE
+ andi s0, s0, SR_SPP
+ bnez s0, resume_kernel
+
+resume_userspace:
+ /* Interrupts must be disabled here so flags are checked atomically */
+ REG_L s0, TASK_TI_FLAGS(tp) /* current_thread_info->flags */
+ andi s1, s0, _TIF_WORK_MASK
+ bnez s1, work_pending
+
+ /* Save unwound kernel stack pointer in thread_info */
+ addi s0, sp, PT_SIZE_ON_STACK
+ REG_S s0, TASK_TI_KERNEL_SP(tp)
+
+ /*
+ * Save TP into sscratch, so we can find the kernel data structures
+ * again.
+ */
+ csrw CSR_SSCRATCH, tp
+
+restore_all:
+ RESTORE_ALL
+ sret
+
+#if IS_ENABLED(CONFIG_PREEMPT)
+resume_kernel:
+ REG_L s0, TASK_TI_PREEMPT_COUNT(tp)
+ bnez s0, restore_all
+ REG_L s0, TASK_TI_FLAGS(tp)
+ andi s0, s0, _TIF_NEED_RESCHED
+ beqz s0, restore_all
+ call preempt_schedule_irq
+ j restore_all
+#endif
+
+work_pending:
+ /* Enter slow path for supplementary processing */
+ la ra, ret_from_exception
+ andi s1, s0, _TIF_NEED_RESCHED
+ bnez s1, work_resched
+work_notifysig:
+ /* Handle pending signals and notify-resume requests */
+ csrs CSR_SSTATUS, SR_SIE /* Enable interrupts for do_notify_resume() */
+ move a0, sp /* pt_regs */
+ move a1, s0 /* current_thread_info->flags */
+ tail do_notify_resume
+work_resched:
+ tail schedule
+
+/* Slow paths for ptrace. */
+handle_syscall_trace_enter:
+ move a0, sp
+ call do_syscall_trace_enter
+ REG_L a0, PT_A0(sp)
+ REG_L a1, PT_A1(sp)
+ REG_L a2, PT_A2(sp)
+ REG_L a3, PT_A3(sp)
+ REG_L a4, PT_A4(sp)
+ REG_L a5, PT_A5(sp)
+ REG_L a6, PT_A6(sp)
+ REG_L a7, PT_A7(sp)
+ j check_syscall_nr
+handle_syscall_trace_exit:
+ move a0, sp
+ call do_syscall_trace_exit
+ j ret_from_exception
+
+END(handle_exception)
+
+ENTRY(ret_from_fork)
+ la ra, ret_from_exception
+ tail schedule_tail
+ENDPROC(ret_from_fork)
+
+ENTRY(ret_from_kernel_thread)
+ call schedule_tail
+ /* Call fn(arg) */
+ la ra, ret_from_exception
+ move a0, s1
+ jr s0
+ENDPROC(ret_from_kernel_thread)
+
+
+/*
+ * Integer register context switch
+ * The callee-saved registers must be saved and restored.
+ *
+ * a0: previous task_struct (must be preserved across the switch)
+ * a1: next task_struct
+ *
+ * The value of a0 and a1 must be preserved by this function, as that's how
+ * arguments are passed to schedule_tail.
+ */
+ENTRY(__switch_to)
+ /* Save context into prev->thread */
+ li a4, TASK_THREAD_RA
+ add a3, a0, a4
+ add a4, a1, a4
+ REG_S ra, TASK_THREAD_RA_RA(a3)
+ REG_S sp, TASK_THREAD_SP_RA(a3)
+ REG_S s0, TASK_THREAD_S0_RA(a3)
+ REG_S s1, TASK_THREAD_S1_RA(a3)
+ REG_S s2, TASK_THREAD_S2_RA(a3)
+ REG_S s3, TASK_THREAD_S3_RA(a3)
+ REG_S s4, TASK_THREAD_S4_RA(a3)
+ REG_S s5, TASK_THREAD_S5_RA(a3)
+ REG_S s6, TASK_THREAD_S6_RA(a3)
+ REG_S s7, TASK_THREAD_S7_RA(a3)
+ REG_S s8, TASK_THREAD_S8_RA(a3)
+ REG_S s9, TASK_THREAD_S9_RA(a3)
+ REG_S s10, TASK_THREAD_S10_RA(a3)
+ REG_S s11, TASK_THREAD_S11_RA(a3)
+ /* Restore context from next->thread */
+ REG_L ra, TASK_THREAD_RA_RA(a4)
+ REG_L sp, TASK_THREAD_SP_RA(a4)
+ REG_L s0, TASK_THREAD_S0_RA(a4)
+ REG_L s1, TASK_THREAD_S1_RA(a4)
+ REG_L s2, TASK_THREAD_S2_RA(a4)
+ REG_L s3, TASK_THREAD_S3_RA(a4)
+ REG_L s4, TASK_THREAD_S4_RA(a4)
+ REG_L s5, TASK_THREAD_S5_RA(a4)
+ REG_L s6, TASK_THREAD_S6_RA(a4)
+ REG_L s7, TASK_THREAD_S7_RA(a4)
+ REG_L s8, TASK_THREAD_S8_RA(a4)
+ REG_L s9, TASK_THREAD_S9_RA(a4)
+ REG_L s10, TASK_THREAD_S10_RA(a4)
+ REG_L s11, TASK_THREAD_S11_RA(a4)
+ /* Swap the CPU entry around. */
+ lw a3, TASK_TI_CPU(a0)
+ lw a4, TASK_TI_CPU(a1)
+ sw a3, TASK_TI_CPU(a1)
+ sw a4, TASK_TI_CPU(a0)
+#if TASK_TI != 0
+#error "TASK_TI != 0: tp will contain a 'struct thread_info', not a 'struct task_struct' so get_current() won't work."
+ addi tp, a1, TASK_TI
+#else
+ move tp, a1
+#endif
+ ret
+ENDPROC(__switch_to)
+
+ .section ".rodata"
+ .align LGREG
+ /* Exception vector table */
+ENTRY(excp_vect_table)
+ RISCV_PTR do_trap_insn_misaligned
+ RISCV_PTR do_trap_insn_fault
+ RISCV_PTR do_trap_insn_illegal
+ RISCV_PTR do_trap_break
+ RISCV_PTR do_trap_load_misaligned
+ RISCV_PTR do_trap_load_fault
+ RISCV_PTR do_trap_store_misaligned
+ RISCV_PTR do_trap_store_fault
+ RISCV_PTR do_trap_ecall_u /* system call, gets intercepted */
+ RISCV_PTR do_trap_ecall_s
+ RISCV_PTR do_trap_unknown
+ RISCV_PTR do_trap_ecall_m
+ RISCV_PTR do_page_fault /* instruction page fault */
+ RISCV_PTR do_page_fault /* load page fault */
+ RISCV_PTR do_trap_unknown
+ RISCV_PTR do_page_fault /* store page fault */
+excp_vect_table_end:
+END(excp_vect_table)