diff options
Diffstat (limited to 'arch/riscv/kernel/entry.S')
| -rw-r--r-- | arch/riscv/kernel/entry.S | 447 |
1 files changed, 175 insertions, 272 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index a1349ca64669..9d1a305d5508 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -9,74 +9,54 @@ #include <asm/asm.h> #include <asm/csr.h> +#include <asm/scs.h> #include <asm/unistd.h> +#include <asm/page.h> #include <asm/thread_info.h> #include <asm/asm-offsets.h> +#include <asm/errata_list.h> +#include <linux/sizes.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 + .section .irqentry.text, "ax" +SYM_CODE_START(handle_exception) /* * If coming from userspace, preserve the user thread pointer and load * the kernel thread pointer. If we came from the kernel, the scratch * register will contain 0, and we should continue on the current TP. */ csrrw tp, CSR_SCRATCH, tp - bnez tp, _save_context + bnez tp, .Lsave_context -_restore_kernel_tpsp: +.Lrestore_kernel_tpsp: csrr tp, CSR_SCRATCH REG_S sp, TASK_TI_KERNEL_SP(tp) -_save_context: + +#ifdef CONFIG_VMAP_STACK + addi sp, sp, -(PT_SIZE_ON_STACK) + srli sp, sp, THREAD_SHIFT + andi sp, sp, 0x1 + bnez sp, handle_kernel_stack_overflow + REG_L sp, TASK_TI_KERNEL_SP(tp) +#endif + +.Lsave_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) + save_from_x6_to_x31 /* * 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. + * Disable the FPU/Vector to detect illegal usage of floating point + * or vector in kernel space. */ - li t0, SR_SUM | SR_FS + li t0, SR_SUM | SR_FS_VS REG_L s0, TASK_TI_USER_SP(tp) csrrc s1, CSR_STATUS, t0 @@ -90,77 +70,6 @@ _save_context: REG_S s3, PT_BADADDR(sp) REG_S s4, PT_CAUSE(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_STATUS(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_EPC(sp) - REG_SC x0, a2, PT_EPC(sp) - - csrw CSR_STATUS, a0 - csrw CSR_EPC, 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 the scratch register to 0, so that if a recursive exception @@ -169,12 +78,18 @@ ENTRY(handle_exception) csrw CSR_SCRATCH, x0 /* Load the global pointer */ -.option push -.option norelax - la gp, __global_pointer$ -.option pop + load_global_pointer + + /* Load the kernel shadow call stack pointer if coming from userspace */ + scs_load_current_if_task_changed s5 +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + move a0, sp + call riscv_v_context_nesting_start +#endif + move a0, sp /* pt_regs */ la ra, ret_from_exception + /* * MSB of cause differentiates between * interrupts and exceptions @@ -182,27 +97,12 @@ ENTRY(handle_exception) 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 SR_PIE in m/sstatus. - */ - andi t0, s1, SR_PIE - beqz t0, 1f - csrs CSR_STATUS, SR_IE - + tail do_irq 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 @@ -210,67 +110,16 @@ ENTRY(handle_exception) jr t0 1: tail do_trap_unknown +SYM_CODE_END(handle_exception) -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_EPC(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 - /* - * The tracer can change syscall number to valid/invalid value. - * We use syscall_set_nr helper in syscall_trace_enter thus we - * cannot trust the current value in a7 and have to reload from - * the current task pt_regs. - */ - REG_L a7, PT_A7(sp) - /* - * Syscall number held in a7. - * If syscall number is above allowed value, redirect to ni_syscall. - */ - bge a7, t0, 1f - /* - * Check if syscall is rejected by tracer or seccomp, i.e., a7 == -1. - * If yes, we pretend it was executed. - */ - li t1, -1 - beq a7, t1, ret_from_syscall_rejected - /* Call syscall */ - 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) - /* - * We didn't execute the actual syscall. - * Seccomp already set return value for the current task pt_regs. - * (If it was configured with SECCOMP_RET_ERRNO/TRACE) - */ -ret_from_syscall_rejected: - /* 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: +/* + * The ret_from_exception must be called with interrupt disabled. Here is the + * caller list: + * - handle_exception + * - ret_from_fork + */ +SYM_CODE_START_NOALIGN(ret_from_exception) REG_L s0, PT_STATUS(sp) - csrc CSR_STATUS, SR_IE #ifdef CONFIG_RISCV_M_MODE /* the MPP value is too large to be used as an immediate arg for addi */ li t0, SR_MPP @@ -278,90 +127,148 @@ ret_from_exception: #else andi s0, s0, SR_SPP #endif - 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 + bnez s0, 1f /* Save unwound kernel stack pointer in thread_info */ addi s0, sp, PT_SIZE_ON_STACK REG_S s0, TASK_TI_KERNEL_SP(tp) + /* Save the kernel shadow call stack pointer */ + scs_save_current + /* * Save TP into the scratch register , so we can find the kernel data * structures again. */ csrw CSR_SCRATCH, tp +1: +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + move a0, sp + call riscv_v_context_nesting_end +#endif + REG_L a0, PT_STATUS(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_EPC(sp) + REG_SC x0, a2, PT_EPC(sp) + + csrw CSR_STATUS, a0 + csrw CSR_EPC, 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) + restore_from_x6_to_x31 + + REG_L x2, PT_SP(sp) -restore_all: - RESTORE_ALL #ifdef CONFIG_RISCV_M_MODE mret #else sret #endif +SYM_CODE_END(ret_from_exception) + +#ifdef CONFIG_VMAP_STACK +SYM_CODE_START_LOCAL(handle_kernel_stack_overflow) + /* we reach here from kernel context, sscratch must be 0 */ + csrrw x31, CSR_SCRATCH, x31 + asm_per_cpu sp, overflow_stack, x31 + li x31, OVERFLOW_STACK_SIZE + add sp, sp, x31 + /* zero out x31 again and restore x31 */ + xor x31, x31, x31 + csrrw x31, CSR_SCRATCH, x31 -#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 + addi sp, sp, -(PT_SIZE_ON_STACK) -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_STATUS, SR_IE /* 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 + //save context to overflow stack + REG_S x1, PT_RA(sp) + REG_S x3, PT_GP(sp) + REG_S x5, PT_T0(sp) + save_from_x6_to_x31 -/* 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: + REG_L s0, TASK_TI_KERNEL_SP(tp) + csrr s1, CSR_STATUS + csrr s2, CSR_EPC + csrr s3, CSR_TVAL + csrr s4, CSR_CAUSE + csrr s5, CSR_SCRATCH + REG_S s0, PT_SP(sp) + REG_S s1, PT_STATUS(sp) + REG_S s2, PT_EPC(sp) + REG_S s3, PT_BADADDR(sp) + REG_S s4, PT_CAUSE(sp) + REG_S s5, PT_TP(sp) 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) + tail handle_bad_stack +SYM_CODE_END(handle_kernel_stack_overflow) +#endif -ENTRY(ret_from_kernel_thread) +SYM_CODE_START(ret_from_fork) call schedule_tail + beqz s0, 1f /* not from kernel thread */ /* Call fn(arg) */ - la ra, ret_from_exception move a0, s1 - jr s0 -ENDPROC(ret_from_kernel_thread) + jalr s0 +1: + move a0, sp /* pt_regs */ + la ra, ret_from_exception + tail syscall_exit_to_user_mode +SYM_CODE_END(ret_from_fork) + +#ifdef CONFIG_IRQ_STACKS +/* + * void call_on_irq_stack(struct pt_regs *regs, + * void (*func)(struct pt_regs *)); + * + * Calls func(regs) using the per-CPU IRQ stack. + */ +SYM_FUNC_START(call_on_irq_stack) + /* Create a frame record to save ra and s0 (fp) */ + addi sp, sp, -STACKFRAME_SIZE_ON_STACK + REG_S ra, STACKFRAME_RA(sp) + REG_S s0, STACKFRAME_FP(sp) + addi s0, sp, STACKFRAME_SIZE_ON_STACK + + /* Switch to the per-CPU shadow call stack */ + scs_save_current + scs_load_irq_stack t0 + + /* Switch to the per-CPU IRQ stack and call the handler */ + load_per_cpu t0, irq_stack_ptr, t1 + li t1, IRQ_STACK_SIZE + add sp, t0, t1 + jalr a1 + + /* Switch back to the thread shadow call stack */ + scs_load_current + + /* Switch back to the thread stack and restore ra and s0 */ + addi sp, s0, -STACKFRAME_SIZE_ON_STACK + REG_L ra, STACKFRAME_RA(sp) + REG_L s0, STACKFRAME_FP(sp) + addi sp, sp, STACKFRAME_SIZE_ON_STACK + ret +SYM_FUNC_END(call_on_irq_stack) +#endif /* CONFIG_IRQ_STACKS */ /* * Integer register context switch @@ -373,7 +280,7 @@ ENDPROC(ret_from_kernel_thread) * 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) +SYM_FUNC_START(__switch_to) /* Save context into prev->thread */ li a4, TASK_THREAD_RA add a3, a0, a4 @@ -392,6 +299,8 @@ ENTRY(__switch_to) REG_S s9, TASK_THREAD_S9_RA(a3) REG_S s10, TASK_THREAD_S10_RA(a3) REG_S s11, TASK_THREAD_S11_RA(a3) + /* Save the kernel shadow call stack pointer */ + scs_save_current /* Restore context from next->thread */ REG_L ra, TASK_THREAD_RA_RA(a4) REG_L sp, TASK_THREAD_SP_RA(a4) @@ -407,49 +316,43 @@ ENTRY(__switch_to) 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 + /* The offset of thread_info in task_struct is zero. */ move tp, a1 -#endif + /* Switch to the next shadow call stack */ + scs_load_current ret -ENDPROC(__switch_to) +SYM_FUNC_END(__switch_to) #ifndef CONFIG_MMU #define do_page_fault do_trap_unknown #endif .section ".rodata" + .align LGREG /* Exception vector table */ -ENTRY(excp_vect_table) +SYM_DATA_START_LOCAL(excp_vect_table) RISCV_PTR do_trap_insn_misaligned - RISCV_PTR do_trap_insn_fault + ALT_INSN_FAULT(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_u /* system call */ 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 */ + /* instruciton page fault */ + ALT_PAGE_FAULT(RISCV_PTR do_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) +SYM_DATA_END_LABEL(excp_vect_table, SYM_L_LOCAL, excp_vect_table_end) #ifndef CONFIG_MMU -ENTRY(__user_rt_sigreturn) +SYM_DATA_START(__user_rt_sigreturn) li a7, __NR_rt_sigreturn - scall -END(__user_rt_sigreturn) + ecall +SYM_DATA_END(__user_rt_sigreturn) #endif |