/* SPDX-License-Identifier: GPL-2.0-only */ /* * Low-level exception handling code * * Copyright (C) 2012 ARM Ltd. * Authors: Catalin Marinas * Will Deacon */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Context tracking and irqflag tracing need to instrument transitions between * user and kernel mode. */ .macro user_exit_irqoff #if defined(CONFIG_CONTEXT_TRACKING) || defined(CONFIG_TRACE_IRQFLAGS) bl enter_from_user_mode #endif .endm .macro user_enter_irqoff #if defined(CONFIG_CONTEXT_TRACKING) || defined(CONFIG_TRACE_IRQFLAGS) bl exit_to_user_mode #endif .endm .macro clear_gp_regs .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 mov x\n, xzr .endr .endm /* * Bad Abort numbers *----------------- */ #define BAD_SYNC 0 #define BAD_IRQ 1 #define BAD_FIQ 2 #define BAD_ERROR 3 .macro kernel_ventry, el, label, regsize = 64 .align 7 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 .if \el == 0 alternative_if ARM64_UNMAP_KERNEL_AT_EL0 .if \regsize == 64 mrs x30, tpidrro_el0 msr tpidrro_el0, xzr .else mov x30, xzr .endif alternative_else_nop_endif .endif #endif sub sp, sp, #PT_REGS_SIZE #ifdef CONFIG_VMAP_STACK /* * Test whether the SP has overflowed, without corrupting a GPR. * Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT) * should always be zero. */ add sp, sp, x0 // sp' = sp + x0 sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp tbnz x0, #THREAD_SHIFT, 0f sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0 sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp b el\()\el\()_\label 0: /* * Either we've just detected an overflow, or we've taken an exception * while on the overflow stack. Either way, we won't return to * userspace, and can clobber EL0 registers to free up GPRs. */ /* Stash the original SP (minus PT_REGS_SIZE) in tpidr_el0. */ msr tpidr_el0, x0 /* Recover the original x0 value and stash it in tpidrro_el0 */ sub x0, sp, x0 msr tpidrro_el0, x0 /* Switch to the overflow stack */ adr_this_cpu sp, overflow_stack + OVERFLOW_STACK_SIZE, x0 /* * Check whether we were already on the overflow stack. This may happen * after panic() re-enables interrupts. */ mrs x0, tpidr_el0 // sp of interrupted context sub x0, sp, x0 // delta with top of overflow stack tst x0, #~(OVERFLOW_STACK_SIZE - 1) // within range? b.ne __bad_stack // no? -> bad stack pointer /* We were already on the overflow stack. Restore sp/x0 and carry on. */ sub sp, sp, x0 mrs x0, tpidrro_el0 #endif b el\()\el\()_\label .endm .macro tramp_alias, dst, sym mov_q \dst, TRAMP_VALIAS add \dst, \dst, #(\sym - .entry.tramp.text) .endm /* * This macro corrupts x0-x3. It is the caller's duty to save/restore * them if required. */ .macro apply_ssbd, state, tmp1, tmp2 alternative_cb spectre_v4_patch_fw_mitigation_enable b .L__asm_ssbd_skip\@ // Patched to NOP alternative_cb_end ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 cbz \tmp2, .L__asm_ssbd_skip\@ ldr \tmp2, [tsk, #TSK_TI_FLAGS] tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@ mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 mov w1, #\state alternative_cb spectre_v4_patch_fw_mitigation_conduit nop // Patched to SMC/HVC #0 alternative_cb_end .L__asm_ssbd_skip\@: .endm /* Check for MTE asynchronous tag check faults */ .macro check_mte_async_tcf, flgs, tmp #ifdef CONFIG_ARM64_MTE alternative_if_not ARM64_MTE b 1f alternative_else_nop_endif mrs_s \tmp, SYS_TFSRE0_EL1 tbz \tmp, #SYS_TFSR_EL1_TF0_SHIFT, 1f /* Asynchronous TCF occurred for TTBR0 access, set the TI flag */ orr \flgs, \flgs, #_TIF_MTE_ASYNC_FAULT str \flgs, [tsk, #TSK_TI_FLAGS] msr_s SYS_TFSRE0_EL1, xzr 1: #endif .endm /* Clear the MTE asynchronous tag check faults */ .macro clear_mte_async_tcf #ifdef CONFIG_ARM64_MTE alternative_if ARM64_MTE dsb ish msr_s SYS_TFSRE0_EL1, xzr alternative_else_nop_endif #endif .endm .macro mte_set_gcr, tmp, tmp2 #ifdef CONFIG_ARM64_MTE /* * Calculate and set the exclude mask preserving * the RRND (bit[16]) setting. */ mrs_s \tmp2, SYS_GCR_EL1 bfi \tmp2, \tmp, #0, #16 msr_s SYS_GCR_EL1, \tmp2 #endif .endm .macro mte_set_kernel_gcr, tmp, tmp2 #ifdef CONFIG_KASAN_HW_TAGS alternative_if_not ARM64_MTE b 1f alternative_else_nop_endif ldr_l \tmp, gcr_kernel_excl mte_set_gcr \tmp, \tmp2 isb 1: #endif .endm .macro mte_set_user_gcr, tsk, tmp, tmp2 #ifdef CONFIG_ARM64_MTE alternative_if_not ARM64_MTE b 1f alternative_else_nop_endif ldr \tmp, [\tsk, #THREAD_GCR_EL1_USER] mte_set_gcr \tmp, \tmp2 1: #endif .endm .macro kernel_entry, el, regsize = 64 .if \regsize == 32 mov w0, w0 // zero upper 32 bits of x0 .endif stp x0, x1, [sp, #16 * 0] stp x2, x3, [sp, #16 * 1] stp x4, x5, [sp, #16 * 2] stp x6, x7, [sp, #16 * 3] stp x8, x9, [sp, #16 * 4] stp x10, x11, [sp, #16 * 5] stp x12, x13, [sp, #16 * 6] stp x14, x15, [sp, #16 * 7] stp x16, x17, [sp, #16 * 8] stp x18, x19, [sp, #16 * 9] stp x20, x21, [sp, #16 * 10] stp x22, x23, [sp, #16 * 11] stp x24, x25, [sp, #16 * 12] stp x26, x27, [sp, #16 * 13] stp x28, x29, [sp, #16 * 14] .if \el == 0 clear_gp_regs mrs x21, sp_el0 ldr_this_cpu tsk, __entry_task, x20 msr sp_el0, tsk /* * Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions * when scheduling. */ ldr x19, [tsk, #TSK_TI_FLAGS] disable_step_tsk x19, x20 /* Check for asynchronous tag check faults in user space */ check_mte_async_tcf x19, x22 apply_ssbd 1, x22, x23 #ifdef CONFIG_ARM64_PTR_AUTH alternative_if ARM64_HAS_ADDRESS_AUTH /* * Enable IA for in-kernel PAC if the task had it disabled. Although * this could be implemented with an unconditional MRS which would avoid * a load, this was measured to be slower on Cortex-A75 and Cortex-A76. * * Install the kernel IA key only if IA was enabled in the task. If IA * was disabled on kernel exit then we would have left the kernel IA * installed so there is no need to install it again. */ ldr x0, [tsk, THREAD_SCTLR_USER] tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f __ptrauth_keys_install_kernel_nosync tsk, x20, x22, x23 b 2f 1: mrs x0, sctlr_el1 orr x0, x0, SCTLR_ELx_ENIA msr sctlr_el1, x0 2: isb alternative_else_nop_endif #endif mte_set_kernel_gcr x22, x23 scs_load tsk, x20 .else add x21, sp, #PT_REGS_SIZE get_current_task tsk .endif /* \el == 0 */ mrs x22, elr_el1 mrs x23, spsr_el1 stp lr, x21, [sp, #S_LR] /* * For exceptions from EL0, create a terminal frame record. * For exceptions from EL1, create a synthetic frame record so the * interrupted code shows up in the backtrace. */ .if \el == 0 stp xzr, xzr, [sp, #S_STACKFRAME] .else stp x29, x22, [sp, #S_STACKFRAME] .endif add x29, sp, #S_STACKFRAME #ifdef CONFIG_ARM64_SW_TTBR0_PAN alternative_if_not ARM64_HAS_PAN bl __swpan_entry_el\el alternative_else_nop_endif #endif stp x22, x23, [sp, #S_PC] /* Not in a syscall by default (el0_svc overwrites for real syscall) */ .if \el == 0 mov w21, #NO_SYSCALL str w21, [sp, #S_SYSCALLNO] .endif /* Save pmr */ alternative_if ARM64_HAS_IRQ_PRIO_MASKING mrs_s x20, SYS_ICC_PMR_EL1 str x20, [sp, #S_PMR_SAVE] alternative_else_nop_endif /* Re-enable tag checking (TCO set on exception entry) */ #ifdef CONFIG_ARM64_MTE alternative_if ARM64_MTE SET_PSTATE_TCO(0) alternative_else_nop_endif #endif /* * Registers that may be useful after this macro is invoked: * * x20 - ICC_PMR_EL1 * x21 - aborted SP * x22 - aborted PC * x23 - aborted PSTATE */ .endm .macro kernel_exit, el .if \el != 0 disable_daif .endif /* Restore pmr */ alternative_if ARM64_HAS_IRQ_PRIO_MASKING ldr x20, [sp, #S_PMR_SAVE] msr_s SYS_ICC_PMR_EL1, x20 mrs_s x21, SYS_ICC_CTLR_EL1 tbz x21, #6, .L__skip_pmr_sync\@ // Check for ICC_CTLR_EL1.PMHE dsb sy // Ensure priority change is seen by redistributor .L__skip_pmr_sync\@: alternative_else_nop_endif ldp x21, x22, [sp, #S_PC] // load ELR, SPSR #ifdef CONFIG_ARM64_SW_TTBR0_PAN alternative_if_not ARM64_HAS_PAN bl __swpan_exit_el\el alternative_else_nop_endif #endif .if \el == 0 ldr x23, [sp, #S_SP] // load return stack pointer msr sp_el0, x23 tst x22, #PSR_MODE32_BIT // native task? b.eq 3f #ifdef CONFIG_ARM64_ERRATUM_845719 alternative_if ARM64_WORKAROUND_845719 #ifdef CONFIG_PID_IN_CONTEXTIDR mrs x29, contextidr_el1 msr contextidr_el1, x29 #else msr contextidr_el1, xzr #endif alternative_else_nop_endif #endif 3: scs_save tsk, x0 #ifdef CONFIG_ARM64_PTR_AUTH alternative_if ARM64_HAS_ADDRESS_AUTH /* * IA was enabled for in-kernel PAC. Disable it now if needed, or * alternatively install the user's IA. All other per-task keys and * SCTLR bits were updated on task switch. * * No kernel C function calls after this. */ ldr x0, [tsk, THREAD_SCTLR_USER] tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f __ptrauth_keys_install_user tsk, x0, x1, x2 b 2f 1: mrs x0, sctlr_el1 bic x0, x0, SCTLR_ELx_ENIA msr sctlr_el1, x0 2: alternative_else_nop_endif #endif mte_set_user_gcr tsk, x0, x1 apply_ssbd 0, x0, x1 .endif msr elr_el1, x21 // set up the return data msr spsr_el1, x22 ldp x0, x1, [sp, #16 * 0] ldp x2, x3, [sp, #16 * 1] ldp x4, x5, [sp, #16 * 2] ldp x6, x7, [sp, #16 * 3] ldp x8, x9, [sp, #16 * 4] ldp x10, x11, [sp, #16 * 5] ldp x12, x13, [sp, #16 * 6] ldp x14, x15, [sp, #16 * 7] ldp x16, x17, [sp, #16 * 8] ldp x18, x19, [sp, #16 * 9] ldp x20, x21, [sp, #16 * 10] ldp x22, x23, [sp, #16 * 11] ldp x24, x25, [sp, #16 * 12] ldp x26, x27, [sp, #16 * 13] ldp x28, x29, [sp, #16 * 14] ldr lr, [sp, #S_LR] add sp, sp, #PT_REGS_SIZE // restore sp .if \el == 0 alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 bne 4f msr far_el1, x30 tramp_alias x30, tramp_exit_native br x30 4: tramp_alias x30, tramp_exit_compat br x30 #endif .else /* Ensure any device/NC reads complete */ alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 eret .endif sb .endm #ifdef CONFIG_ARM64_SW_TTBR0_PAN /* * Set the TTBR0 PAN bit in SPSR. When the exception is taken from * EL0, there is no need to check the state of TTBR0_EL1 since * accesses are always enabled. * Note that the meaning of this bit differs from the ARMv8.1 PAN * feature as all TTBR0_EL1 accesses are disabled, not just those to * user mappings. */ SYM_CODE_START_LOCAL(__swpan_entry_el1) mrs x21, ttbr0_el1 tst x21, #TTBR_ASID_MASK // Check for the reserved ASID orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR b.eq 1f // TTBR0 access already disabled and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR SYM_INNER_LABEL(__swpan_entry_el0, SYM_L_LOCAL) __uaccess_ttbr0_disable x21 1: ret SYM_CODE_END(__swpan_entry_el1) /* * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR * PAN bit checking. */ SYM_CODE_START_LOCAL(__swpan_exit_el1) tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set __uaccess_ttbr0_enable x0, x1 1: and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit ret SYM_CODE_END(__swpan_exit_el1) SYM_CODE_START_LOCAL(__swpan_exit_el0) __uaccess_ttbr0_enable x0, x1 /* * Enable errata workarounds only if returning to user. The only * workaround currently required for TTBR0_EL1 changes are for the * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache * corruption). */ b post_ttbr_update_workaround SYM_CODE_END(__swpan_exit_el0) #endif .macro irq_stack_entry mov x19, sp // preserve the original sp #ifdef CONFIG_SHADOW_CALL_STACK mov x24, scs_sp // preserve the original shadow stack #endif /* * Compare sp with the base of the task stack. * If the top ~(THREAD_SIZE - 1) bits match, we are on a task stack, * and should switch to the irq stack. */ ldr x25, [tsk, TSK_STACK] eor x25, x25, x19 and x25, x25, #~(THREAD_SIZE - 1) cbnz x25, 9998f ldr_this_cpu x25, irq_stack_ptr, x26 mov x26, #IRQ_STACK_SIZE add x26, x25, x26 /* switch to the irq stack */ mov sp, x26 #ifdef CONFIG_SHADOW_CALL_STACK /* also switch to the irq shadow stack */ ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x26 #endif 9998: .endm /* * The callee-saved regs (x19-x29) should be preserved between * irq_stack_entry and irq_stack_exit, but note that kernel_entry * uses x20-x23 to store data for later use. */ .macro irq_stack_exit mov sp, x19 #ifdef CONFIG_SHADOW_CALL_STACK mov scs_sp, x24 #endif .endm /* GPRs used by entry code */ tsk .req x28 // current thread_info /* * Interrupt handling. */ .macro irq_handler, handler:req ldr_l x1, \handler mov x0, sp irq_stack_entry blr x1 irq_stack_exit .endm .macro gic_prio_kentry_setup, tmp:req #ifdef CONFIG_ARM64_PSEUDO_NMI alternative_if ARM64_HAS_IRQ_PRIO_MASKING mov \tmp, #(GIC_PRIO_PSR_I_SET | GIC_PRIO_IRQON) msr_s SYS_ICC_PMR_EL1, \tmp alternative_else_nop_endif #endif .endm .macro gic_prio_irq_setup, pmr:req, tmp:req #ifdef CONFIG_ARM64_PSEUDO_NMI alternative_if ARM64_HAS_IRQ_PRIO_MASKING orr \tmp, \pmr, #GIC_PRIO_PSR_I_SET msr_s SYS_ICC_PMR_EL1, \tmp alternative_else_nop_endif #endif .endm .macro el1_interrupt_handler, handler:req gic_prio_irq_setup pmr=x20, tmp=x1 enable_da mov x0, sp bl enter_el1_irq_or_nmi irq_handler \handler #ifdef CONFIG_PREEMPTION ldr x24, [tsk, #TSK_TI_PREEMPT] // get preempt count alternative_if ARM64_HAS_IRQ_PRIO_MASKING /* * DA were cleared at start of handling, and IF are cleared by * the GIC irqchip driver using gic_arch_enable_irqs() for * normal IRQs. If anything is set, it means we come back from * an NMI instead of a normal IRQ, so skip preemption */ mrs x0, daif orr x24, x24, x0 alternative_else_nop_endif cbnz x24, 1f // preempt count != 0 || NMI return path bl arm64_preempt_schedule_irq // irq en/disable is done inside 1: #endif mov x0, sp bl exit_el1_irq_or_nmi .endm .macro el0_interrupt_handler, handler:req gic_prio_irq_setup pmr=x20, tmp=x0 user_exit_irqoff enable_da tbz x22, #55, 1f bl do_el0_irq_bp_hardening 1: irq_handler \handler .endm .text /* * Exception vectors. */ .pushsection ".entry.text", "ax" .align 11 SYM_CODE_START(vectors) kernel_ventry 1, sync_invalid // Synchronous EL1t kernel_ventry 1, irq_invalid // IRQ EL1t kernel_ventry 1, fiq_invalid // FIQ EL1t kernel_ventry 1, error_invalid // Error EL1t kernel_ventry 1, sync // Synchronous EL1h kernel_ventry 1, irq // IRQ EL1h kernel_ventry 1, fiq // FIQ EL1h kernel_ventry 1, error // Error EL1h kernel_ventry 0, sync // Synchronous 64-bit EL0 kernel_ventry 0, irq // IRQ 64-bit EL0 kernel_ventry 0, fiq // FIQ 64-bit EL0 kernel_ventry 0, error // Error 64-bit EL0 #ifdef CONFIG_COMPAT kernel_ventry 0, sync_compat, 32 // Synchronous 32-bit EL0 kernel_ventry 0, irq_compat, 32 // IRQ 32-bit EL0 kernel_ventry 0, fiq_compat, 32 // FIQ 32-bit EL0 kernel_ventry 0, error_compat, 32 // Error 32-bit EL0 #else kernel_ventry 0, sync_invalid, 32 // Synchronous 32-bit EL0 kernel_ventry 0, irq_invalid, 32 // IRQ 32-bit EL0 kernel_ventry 0, fiq_invalid, 32 // FIQ 32-bit EL0 kernel_ventry 0, error_invalid, 32 // Error 32-bit EL0 #endif SYM_CODE_END(vectors) #ifdef CONFIG_VMAP_STACK /* * We detected an overflow in kernel_ventry, which switched to the * overflow stack. Stash the exception regs, and head to our overflow * handler. */ __bad_stack: /* Restore the original x0 value */ mrs x0, tpidrro_el0 /* * Store the original GPRs to the new stack. The orginal SP (minus * PT_REGS_SIZE) was stashed in tpidr_el0 by kernel_ventry. */ sub sp, sp, #PT_REGS_SIZE kernel_entry 1 mrs x0, tpidr_el0 add x0, x0, #PT_REGS_SIZE str x0, [sp, #S_SP] /* Stash the regs for handle_bad_stack */ mov x0, sp /* Time to die */ bl handle_bad_stack ASM_BUG() #endif /* CONFIG_VMAP_STACK */ /* * Invalid mode handlers */ .macro inv_entry, el, reason, regsize = 64 kernel_entry \el, \regsize mov x0, sp mov x1, #\reason mrs x2, esr_el1 bl bad_mode ASM_BUG() .endm SYM_CODE_START_LOCAL(el0_sync_invalid) inv_entry 0, BAD_SYNC SYM_CODE_END(el0_sync_invalid) SYM_CODE_START_LOCAL(el0_irq_invalid) inv_entry 0, BAD_IRQ SYM_CODE_END(el0_irq_invalid) SYM_CODE_START_LOCAL(el0_fiq_invalid) inv_entry 0, BAD_FIQ SYM_CODE_END(el0_fiq_invalid) SYM_CODE_START_LOCAL(el0_error_invalid) inv_entry 0, BAD_ERROR SYM_CODE_END(el0_error_invalid) SYM_CODE_START_LOCAL(el1_sync_invalid) inv_entry 1, BAD_SYNC SYM_CODE_END(el1_sync_invalid) SYM_CODE_START_LOCAL(el1_irq_invalid) inv_entry 1, BAD_IRQ SYM_CODE_END(el1_irq_invalid) SYM_CODE_START_LOCAL(el1_fiq_invalid) inv_entry 1, BAD_FIQ SYM_CODE_END(el1_fiq_invalid) SYM_CODE_START_LOCAL(el1_error_invalid) inv_entry 1, BAD_ERROR SYM_CODE_END(el1_error_invalid) /* * EL1 mode handlers. */ .align 6 SYM_CODE_START_LOCAL_NOALIGN(el1_sync) kernel_entry 1 mov x0, sp bl el1_sync_handler kernel_exit 1 SYM_CODE_END(el1_sync) .align 6 SYM_CODE_START_LOCAL_NOALIGN(el1_irq) kernel_entry 1 el1_interrupt_handler handle_arch_irq kernel_exit 1 SYM_CODE_END(el1_irq) SYM_CODE_START_LOCAL_NOALIGN(el1_fiq) kernel_entry 1 el1_interrupt_handler handle_arch_fiq kernel_exit 1 SYM_CODE_END(el1_fiq) /* * EL0 mode handlers. */ .align 6 SYM_CODE_START_LOCAL_NOALIGN(el0_sync) kernel_entry 0 mov x0, sp bl el0_sync_handler b ret_to_user SYM_CODE_END(el0_sync) #ifdef CONFIG_COMPAT .align 6 SYM_CODE_START_LOCAL_NOALIGN(el0_sync_compat) kernel_entry 0, 32 mov x0, sp bl el0_sync_compat_handler b ret_to_user SYM_CODE_END(el0_sync_compat) .align 6 SYM_CODE_START_LOCAL_NOALIGN(el0_irq_compat) kernel_entry 0, 32 b el0_irq_naked SYM_CODE_END(el0_irq_compat) SYM_CODE_START_LOCAL_NOALIGN(el0_fiq_compat) kernel_entry 0, 32 b el0_fiq_naked SYM_CODE_END(el0_fiq_compat) SYM_CODE_START_LOCAL_NOALIGN(el0_error_compat) kernel_entry 0, 32 b el0_error_naked SYM_CODE_END(el0_error_compat) #endif .align 6 SYM_CODE_START_LOCAL_NOALIGN(el0_irq) kernel_entry 0 el0_irq_naked: el0_interrupt_handler handle_arch_irq b ret_to_user SYM_CODE_END(el0_irq) SYM_CODE_START_LOCAL_NOALIGN(el0_fiq) kernel_entry 0 el0_fiq_naked: el0_interrupt_handler handle_arch_fiq b ret_to_user SYM_CODE_END(el0_fiq) SYM_CODE_START_LOCAL(el1_error) kernel_entry 1 mrs x1, esr_el1 gic_prio_kentry_setup tmp=x2 enable_dbg mov x0, sp bl do_serror kernel_exit 1 SYM_CODE_END(el1_error) SYM_CODE_START_LOCAL(el0_error) kernel_entry 0 el0_error_naked: mrs x25, esr_el1 gic_prio_kentry_setup tmp=x2 user_exit_irqoff enable_dbg mov x0, sp mov x1, x25 bl do_serror enable_da b ret_to_user SYM_CODE_END(el0_error) /* * "slow" syscall return path. */ SYM_CODE_START_LOCAL(ret_to_user) disable_daif gic_prio_kentry_setup tmp=x3 #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_off #endif ldr x19, [tsk, #TSK_TI_FLAGS] and x2, x19, #_TIF_WORK_MASK cbnz x2, work_pending finish_ret_to_user: user_enter_irqoff /* Ignore asynchronous tag check faults in the uaccess routines */ clear_mte_async_tcf enable_step_tsk x19, x2 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK bl stackleak_erase #endif kernel_exit 0 /* * Ok, we need to do extra processing, enter the slow path. */ work_pending: mov x0, sp // 'regs' mov x1, x19 bl do_notify_resume ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step b finish_ret_to_user SYM_CODE_END(ret_to_user) .popsection // .entry.text #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 /* * Exception vectors trampoline. */ .pushsection ".entry.tramp.text", "ax" // Move from tramp_pg_dir to swapper_pg_dir .macro tramp_map_kernel, tmp mrs \tmp, ttbr1_el1 add \tmp, \tmp, #TRAMP_SWAPPER_OFFSET bic \tmp, \tmp, #USER_ASID_FLAG msr ttbr1_el1, \tmp #ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003 alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003 /* ASID already in \tmp[63:48] */ movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12) movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12) /* 2MB boundary containing the vectors, so we nobble the walk cache */ movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12) isb tlbi vae1, \tmp dsb nsh alternative_else_nop_endif #endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */ .endm // Move from swapper_pg_dir to tramp_pg_dir .macro tramp_unmap_kernel, tmp mrs \tmp, ttbr1_el1 sub \tmp, \tmp, #TRAMP_SWAPPER_OFFSET orr \tmp, \tmp, #USER_ASID_FLAG msr ttbr1_el1, \tmp /* * We avoid running the post_ttbr_update_workaround here because * it's only needed by Cavium ThunderX, which requires KPTI to be * disabled. */ .endm .macro tramp_ventry, regsize = 64 .align 7 1: .if \regsize == 64 msr tpidrro_el0, x30 // Restored in kernel_ventry .endif /* * Defend against branch aliasing attacks by pushing a dummy * entry onto the return stack and using a RET instruction to * enter the full-fat kernel vectors. */ bl 2f b . 2: tramp_map_kernel x30 #ifdef CONFIG_RANDOMIZE_BASE adr x30, tramp_vectors + PAGE_SIZE alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 ldr x30, [x30] #else ldr x30, =vectors #endif alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM prfm plil1strm, [x30, #(1b - tramp_vectors)] alternative_else_nop_endif msr vbar_el1, x30 add x30, x30, #(1b - tramp_vectors) isb ret .endm .macro tramp_exit, regsize = 64 adr x30, tramp_vectors msr vbar_el1, x30 tramp_unmap_kernel x30 .if \regsize == 64 mrs x30, far_el1 .endif eret sb .endm .align 11 SYM_CODE_START_NOALIGN(tramp_vectors) .space 0x400 tramp_ventry tramp_ventry tramp_ventry tramp_ventry tramp_ventry 32 tramp_ventry 32 tramp_ventry 32 tramp_ventry 32 SYM_CODE_END(tramp_vectors) SYM_CODE_START(tramp_exit_native) tramp_exit SYM_CODE_END(tramp_exit_native) SYM_CODE_START(tramp_exit_compat) tramp_exit 32 SYM_CODE_END(tramp_exit_compat) .ltorg .popsection // .entry.tramp.text #ifdef CONFIG_RANDOMIZE_BASE .pushsection ".rodata", "a" .align PAGE_SHIFT SYM_DATA_START(__entry_tramp_data_start) .quad vectors SYM_DATA_END(__entry_tramp_data_start) .popsection // .rodata #endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ /* * Register switch for AArch64. The callee-saved registers need to be saved * and restored. On entry: * x0 = previous task_struct (must be preserved across the switch) * x1 = next task_struct * Previous and next are guaranteed not to be the same. * */ SYM_FUNC_START(cpu_switch_to) mov x10, #THREAD_CPU_CONTEXT add x8, x0, x10 mov x9, sp stp x19, x20, [x8], #16 // store callee-saved registers stp x21, x22, [x8], #16 stp x23, x24, [x8], #16 stp x25, x26, [x8], #16 stp x27, x28, [x8], #16 stp x29, x9, [x8], #16 str lr, [x8] add x8, x1, x10 ldp x19, x20, [x8], #16 // restore callee-saved registers ldp x21, x22, [x8], #16 ldp x23, x24, [x8], #16 ldp x25, x26, [x8], #16 ldp x27, x28, [x8], #16 ldp x29, x9, [x8], #16 ldr lr, [x8] mov sp, x9 msr sp_el0, x1 ptrauth_keys_install_kernel x1, x8, x9, x10 scs_save x0, x8 scs_load x1, x8 ret SYM_FUNC_END(cpu_switch_to) NOKPROBE(cpu_switch_to) /* * This is how we return from a fork. */ SYM_CODE_START(ret_from_fork) bl schedule_tail cbz x19, 1f // not a kernel thread mov x0, x20 blr x19 1: get_current_task tsk b ret_to_user SYM_CODE_END(ret_from_fork) NOKPROBE(ret_from_fork) #ifdef CONFIG_ARM_SDE_INTERFACE #include #include .macro sdei_handler_exit exit_mode /* On success, this call never returns... */ cmp \exit_mode, #SDEI_EXIT_SMC b.ne 99f smc #0 b . 99: hvc #0 b . .endm #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 /* * The regular SDEI entry point may have been unmapped along with the rest of * the kernel. This trampoline restores the kernel mapping to make the x1 memory * argument accessible. * * This clobbers x4, __sdei_handler() will restore this from firmware's * copy. */ .ltorg .pushsection ".entry.tramp.text", "ax" SYM_CODE_START(__sdei_asm_entry_trampoline) mrs x4, ttbr1_el1 tbz x4, #USER_ASID_BIT, 1f tramp_map_kernel tmp=x4 isb mov x4, xzr /* * Remember whether to unmap the kernel on exit. */ 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] #ifdef CONFIG_RANDOMIZE_BASE adr x4, tramp_vectors + PAGE_SIZE add x4, x4, #:lo12:__sdei_asm_trampoline_next_handler ldr x4, [x4] #else ldr x4, =__sdei_asm_handler #endif br x4 SYM_CODE_END(__sdei_asm_entry_trampoline) NOKPROBE(__sdei_asm_entry_trampoline) /* * Make the exit call and restore the original ttbr1_el1 * * x0 & x1: setup for the exit API call * x2: exit_mode * x4: struct sdei_registered_event argument from registration time. */ SYM_CODE_START(__sdei_asm_exit_trampoline) ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] cbnz x4, 1f tramp_unmap_kernel tmp=x4 1: sdei_handler_exit exit_mode=x2 SYM_CODE_END(__sdei_asm_exit_trampoline) NOKPROBE(__sdei_asm_exit_trampoline) .ltorg .popsection // .entry.tramp.text #ifdef CONFIG_RANDOMIZE_BASE .pushsection ".rodata", "a" SYM_DATA_START(__sdei_asm_trampoline_next_handler) .quad __sdei_asm_handler SYM_DATA_END(__sdei_asm_trampoline_next_handler) .popsection // .rodata #endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ /* * Software Delegated Exception entry point. * * x0: Event number * x1: struct sdei_registered_event argument from registration time. * x2: interrupted PC * x3: interrupted PSTATE * x4: maybe clobbered by the trampoline * * Firmware has preserved x0->x17 for us, we must save/restore the rest to * follow SMC-CC. We save (or retrieve) all the registers as the handler may * want them. */ SYM_CODE_START(__sdei_asm_handler) stp x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC] stp x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2] stp x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3] stp x8, x9, [x1, #SDEI_EVENT_INTREGS + 16 * 4] stp x10, x11, [x1, #SDEI_EVENT_INTREGS + 16 * 5] stp x12, x13, [x1, #SDEI_EVENT_INTREGS + 16 * 6] stp x14, x15, [x1, #SDEI_EVENT_INTREGS + 16 * 7] stp x16, x17, [x1, #SDEI_EVENT_INTREGS + 16 * 8] stp x18, x19, [x1, #SDEI_EVENT_INTREGS + 16 * 9] stp x20, x21, [x1, #SDEI_EVENT_INTREGS + 16 * 10] stp x22, x23, [x1, #SDEI_EVENT_INTREGS + 16 * 11] stp x24, x25, [x1, #SDEI_EVENT_INTREGS + 16 * 12] stp x26, x27, [x1, #SDEI_EVENT_INTREGS + 16 * 13] stp x28, x29, [x1, #SDEI_EVENT_INTREGS + 16 * 14] mov x4, sp stp lr, x4, [x1, #SDEI_EVENT_INTREGS + S_LR] mov x19, x1 #if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK) ldrb w4, [x19, #SDEI_EVENT_PRIORITY] #endif #ifdef CONFIG_VMAP_STACK /* * entry.S may have been using sp as a scratch register, find whether * this is a normal or critical event and switch to the appropriate * stack for this CPU. */ cbnz w4, 1f ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6 b 2f 1: ldr_this_cpu dst=x5, sym=sdei_stack_critical_ptr, tmp=x6 2: mov x6, #SDEI_STACK_SIZE add x5, x5, x6 mov sp, x5 #endif #ifdef CONFIG_SHADOW_CALL_STACK /* Use a separate shadow call stack for normal and critical events */ cbnz w4, 3f ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6 b 4f 3: ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6 4: #endif /* * We may have interrupted userspace, or a guest, or exit-from or * return-to either of these. We can't trust sp_el0, restore it. */ mrs x28, sp_el0 ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1 msr sp_el0, x0 /* If we interrupted the kernel point to the previous stack/frame. */ and x0, x3, #0xc mrs x1, CurrentEL cmp x0, x1 csel x29, x29, xzr, eq // fp, or zero csel x4, x2, xzr, eq // elr, or zero stp x29, x4, [sp, #-16]! mov x29, sp add x0, x19, #SDEI_EVENT_INTREGS mov x1, x19 bl __sdei_handler msr sp_el0, x28 /* restore regs >x17 that we clobbered */ mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14] ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9] ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR] mov sp, x1 mov x1, x0 // address to complete_and_resume /* x0 = (x0 <= 1) ? EVENT_COMPLETE:EVENT_COMPLETE_AND_RESUME */ cmp x0, #1 mov_q x2, SDEI_1_0_FN_SDEI_EVENT_COMPLETE mov_q x3, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME csel x0, x2, x3, ls ldr_l x2, sdei_exit_mode alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 sdei_handler_exit exit_mode=x2 alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline br x5 #endif SYM_CODE_END(__sdei_asm_handler) NOKPROBE(__sdei_asm_handler) #endif /* CONFIG_ARM_SDE_INTERFACE */