diff options
Diffstat (limited to 'arch/riscv/kernel/entry.S')
| -rw-r--r-- | arch/riscv/kernel/entry.S | 113 |
1 files changed, 104 insertions, 9 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 68a24cf9481a..33a5a9f2a0d4 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -19,6 +19,79 @@ .section .irqentry.text, "ax" +.macro new_vmalloc_check + REG_S a0, TASK_TI_A0(tp) + csrr a0, CSR_CAUSE + /* Exclude IRQs */ + blt a0, zero, .Lnew_vmalloc_restore_context_a0 + + REG_S a1, TASK_TI_A1(tp) + /* Only check new_vmalloc if we are in page/protection fault */ + li a1, EXC_LOAD_PAGE_FAULT + beq a0, a1, .Lnew_vmalloc_kernel_address + li a1, EXC_STORE_PAGE_FAULT + beq a0, a1, .Lnew_vmalloc_kernel_address + li a1, EXC_INST_PAGE_FAULT + bne a0, a1, .Lnew_vmalloc_restore_context_a1 + +.Lnew_vmalloc_kernel_address: + /* Is it a kernel address? */ + csrr a0, CSR_TVAL + bge a0, zero, .Lnew_vmalloc_restore_context_a1 + + /* Check if a new vmalloc mapping appeared that could explain the trap */ + REG_S a2, TASK_TI_A2(tp) + /* + * Computes: + * a0 = &new_vmalloc[BIT_WORD(cpu)] + * a1 = BIT_MASK(cpu) + */ + REG_L a2, TASK_TI_CPU(tp) + /* + * Compute the new_vmalloc element position: + * (cpu / 64) * 8 = (cpu >> 6) << 3 + */ + srli a1, a2, 6 + slli a1, a1, 3 + la a0, new_vmalloc + add a0, a0, a1 + /* + * Compute the bit position in the new_vmalloc element: + * bit_pos = cpu % 64 = cpu - (cpu / 64) * 64 = cpu - (cpu >> 6) << 6 + * = cpu - ((cpu >> 6) << 3) << 3 + */ + slli a1, a1, 3 + sub a1, a2, a1 + /* Compute the "get mask": 1 << bit_pos */ + li a2, 1 + sll a1, a2, a1 + + /* Check the value of new_vmalloc for this cpu */ + REG_L a2, 0(a0) + and a2, a2, a1 + beq a2, zero, .Lnew_vmalloc_restore_context + + /* Atomically reset the current cpu bit in new_vmalloc */ + amoxor.d a0, a1, (a0) + + /* Only emit a sfence.vma if the uarch caches invalid entries */ + ALTERNATIVE("sfence.vma", "nop", 0, RISCV_ISA_EXT_SVVPTC, 1) + + REG_L a0, TASK_TI_A0(tp) + REG_L a1, TASK_TI_A1(tp) + REG_L a2, TASK_TI_A2(tp) + csrw CSR_SCRATCH, x0 + sret + +.Lnew_vmalloc_restore_context: + REG_L a2, TASK_TI_A2(tp) +.Lnew_vmalloc_restore_context_a1: + REG_L a1, TASK_TI_A1(tp) +.Lnew_vmalloc_restore_context_a0: + REG_L a0, TASK_TI_A0(tp) +.endm + + SYM_CODE_START(handle_exception) /* * If coming from userspace, preserve the user thread pointer and load @@ -30,6 +103,20 @@ SYM_CODE_START(handle_exception) .Lrestore_kernel_tpsp: csrr tp, CSR_SCRATCH + +#ifdef CONFIG_64BIT + /* + * The RISC-V kernel does not eagerly emit a sfence.vma after each + * new vmalloc mapping, which may result in exceptions: + * - if the uarch caches invalid entries, the new mapping would not be + * observed by the page table walker and an invalidation is needed. + * - if the uarch does not cache invalid entries, a reordered access + * could "miss" the new mapping and traps: in that case, we only need + * to retry the access, no sfence.vma is required. + */ + new_vmalloc_check +#endif + REG_S sp, TASK_TI_KERNEL_SP(tp) #ifdef CONFIG_VMAP_STACK @@ -88,7 +175,6 @@ SYM_CODE_START(handle_exception) call riscv_v_context_nesting_start #endif move a0, sp /* pt_regs */ - la ra, ret_from_exception /* * MSB of cause differentiates between @@ -97,7 +183,8 @@ SYM_CODE_START(handle_exception) bge s4, zero, 1f /* Handle interrupts */ - tail do_irq + call do_irq + j ret_from_exception 1: /* Handle other exceptions */ slli t0, s4, RISCV_LGPTR @@ -105,11 +192,14 @@ SYM_CODE_START(handle_exception) la t2, excp_vect_table_end 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 + bgeu t0, t2, 3f + REG_L t1, 0(t0) +2: jalr t1 + j ret_from_exception +3: + + la t1, do_trap_unknown + j 2b SYM_CODE_END(handle_exception) ASM_NOKPROBE(handle_exception) @@ -130,6 +220,10 @@ SYM_CODE_START_NOALIGN(ret_from_exception) #endif bnez s0, 1f +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK + call stackleak_erase_on_task_stack +#endif + /* Save unwound kernel stack pointer in thread_info */ addi s0, sp, PT_SIZE_ON_STACK REG_S s0, TASK_TI_KERNEL_SP(tp) @@ -184,6 +278,7 @@ SYM_CODE_START_NOALIGN(ret_from_exception) #else sret #endif +SYM_INNER_LABEL(ret_from_exception_end, SYM_L_GLOBAL) SYM_CODE_END(ret_from_exception) ASM_NOKPROBE(ret_from_exception) @@ -232,8 +327,8 @@ SYM_CODE_START(ret_from_fork) jalr s0 1: move a0, sp /* pt_regs */ - la ra, ret_from_exception - tail syscall_exit_to_user_mode + call syscall_exit_to_user_mode + j ret_from_exception SYM_CODE_END(ret_from_fork) #ifdef CONFIG_IRQ_STACKS |