/* * Low-level exception handling code * * Copyright (C) 2012 ARM Ltd. * Authors: Catalin Marinas * Will Deacon * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Context tracking subsystem. Used to instrument transitions * between user and kernel mode. */ .macro ct_user_exit #ifdef CONFIG_CONTEXT_TRACKING bl context_tracking_user_exit #endif .endm .macro ct_user_enter #ifdef CONFIG_CONTEXT_TRACKING bl context_tracking_user_enter #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 .Lventry_start\@: .if \el == 0 /* * This must be the first instruction of the EL0 vector entries. It is * skipped by the trampoline vectors, to trigger the cleanup. */ b .Lskip_tramp_vectors_cleanup\@ .if \regsize == 64 mrs x30, tpidrro_el0 msr tpidrro_el0, xzr .else mov x30, xzr .endif .Lskip_tramp_vectors_cleanup\@: .endif sub sp, sp, #S_FRAME_SIZE #ifdef CONFIG_VMAP_STACK /* * Test whether the SP has overflowed, without corrupting a GPR. * Task and IRQ stacks are aligned to (1 << THREAD_SHIFT). */ 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 S_FRAME_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 .org .Lventry_start\@ + 128 // Did we overflow the ventry slot? .endm .macro tramp_alias, dst, sym, tmp mov_q \dst, TRAMP_VALIAS adr_l \tmp, \sym add \dst, \dst, \tmp adr_l \tmp, .entry.tramp.text sub \dst, \dst, \tmp .endm // This macro corrupts x0-x3. It is the caller's duty // to save/restore them if required. .macro apply_ssbd, state, tmp1, tmp2 #ifdef CONFIG_ARM64_SSBD alternative_cb arm64_enable_wa2_handling b .L__asm_ssbd_skip\@ 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 arm64_update_smccc_conduit nop // Patched to SMC/HVC #0 alternative_cb_end .L__asm_ssbd_skip\@: #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 // Ensure MDSCR_EL1.SS is clear, ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug disable_step_tsk x19, x20 // exceptions when scheduling. apply_ssbd 1, x22, x23 #ifdef CONFIG_SHADOW_CALL_STACK ldr x18, [tsk, #TSK_TI_SCS] // Restore shadow call stack str xzr, [tsk, #TSK_TI_SCS] // Limit visibility of saved SCS #endif .else add x21, sp, #S_FRAME_SIZE get_thread_info tsk /* Save the task's original addr_limit and set USER_DS */ ldr x20, [tsk, #TSK_TI_ADDR_LIMIT] str x20, [sp, #S_ORIG_ADDR_LIMIT] mov x20, #USER_DS str x20, [tsk, #TSK_TI_ADDR_LIMIT] /* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */ .endif /* \el == 0 */ mrs x22, elr_el1 mrs x23, spsr_el1 stp lr, x21, [sp, #S_LR] /* * In order to be able to dump the contents of struct pt_regs at the * time the exception was taken (in case we attempt to walk the call * stack later), chain it together with the stack frames. */ .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 /* * 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. */ alternative_if ARM64_HAS_PAN b 1f // skip TTBR0 PAN alternative_else_nop_endif .if \el != 0 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 .endif __uaccess_ttbr0_disable x21 1: #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 /* * Set sp_el0 to current thread_info. */ .if \el == 0 msr sp_el0, tsk .endif /* * Registers that may be useful after this macro is invoked: * * x21 - aborted SP * x22 - aborted PC * x23 - aborted PSTATE */ .endm .macro kernel_exit, el .if \el != 0 disable_daif /* Restore the task's original addr_limit. */ ldr x20, [sp, #S_ORIG_ADDR_LIMIT] str x20, [tsk, #TSK_TI_ADDR_LIMIT] /* No need to restore UAO, it will be restored from SPSR_EL1 */ .endif ldp x21, x22, [sp, #S_PC] // load ELR, SPSR .if \el == 0 ct_user_enter .endif #ifdef CONFIG_SHADOW_CALL_STACK .if \el == 0 str x18, [tsk, #TSK_TI_SCS] // Save shadow call stack .endif #endif #ifdef CONFIG_ARM64_SW_TTBR0_PAN /* * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR * PAN bit checking. */ alternative_if ARM64_HAS_PAN b 2f // skip TTBR0 PAN alternative_else_nop_endif .if \el != 0 tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set .endif __uaccess_ttbr0_enable x0, x1 .if \el == 0 /* * 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). */ bl post_ttbr_update_workaround .endif 1: .if \el != 0 and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit .endif 2: #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: 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] /* * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on eret context synchronization * when returning from IPI handler, and when returning to user-space. */ .if \el == 0 alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 ldr lr, [sp, #S_LR] add sp, sp, #S_FRAME_SIZE // restore sp eret alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 bne 4f msr far_el1, x29 tramp_alias x30, tramp_exit_native, x29 br x30 4: tramp_alias x30, tramp_exit_compat, x29 br x30 #endif .else ldr lr, [sp, #S_LR] add sp, sp, #S_FRAME_SIZE // restore sp eret .endif .endm .macro irq_stack_entry mov x19, sp // preserve the original sp #ifdef CONFIG_SHADOW_CALL_STACK mov x20, x18 // 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 x18, 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. */ .macro irq_stack_exit mov sp, x19 #ifdef CONFIG_SHADOW_CALL_STACK mov x18, x20 #endif .endm /* * These are the registers used in the syscall handler, and allow us to * have in theory up to 7 arguments to a function - x0 to x6. * * x7 is reserved for the system call number in 32-bit mode. */ wsc_nr .req w25 // number of system calls xsc_nr .req x25 // number of system calls (zero-extended) wscno .req w26 // syscall number xscno .req x26 // syscall number (zero-extended) stbl .req x27 // syscall table pointer tsk .req x28 // current thread_info /* * Interrupt handling. */ .macro irq_handler ldr_l x1, handle_arch_irq mov x0, sp irq_stack_entry blr x1 irq_stack_exit .endm .text /* * Exception vectors. */ .pushsection ".entry.text", "ax" .align 11 ENTRY(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_invalid // 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_invalid // 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_invalid_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 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 * S_FRAME_SIZE) was stashed in tpidr_el0 by kernel_ventry. */ sub sp, sp, #S_FRAME_SIZE kernel_entry 1 mrs x0, tpidr_el0 add x0, x0, #S_FRAME_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 el0_sync_invalid: inv_entry 0, BAD_SYNC ENDPROC(el0_sync_invalid) el0_irq_invalid: inv_entry 0, BAD_IRQ ENDPROC(el0_irq_invalid) el0_fiq_invalid: inv_entry 0, BAD_FIQ ENDPROC(el0_fiq_invalid) el0_error_invalid: inv_entry 0, BAD_ERROR ENDPROC(el0_error_invalid) #ifdef CONFIG_COMPAT el0_fiq_invalid_compat: inv_entry 0, BAD_FIQ, 32 ENDPROC(el0_fiq_invalid_compat) #endif el1_sync_invalid: inv_entry 1, BAD_SYNC ENDPROC(el1_sync_invalid) el1_irq_invalid: inv_entry 1, BAD_IRQ ENDPROC(el1_irq_invalid) el1_fiq_invalid: inv_entry 1, BAD_FIQ ENDPROC(el1_fiq_invalid) el1_error_invalid: inv_entry 1, BAD_ERROR ENDPROC(el1_error_invalid) /* * EL1 mode handlers. */ .align 6 el1_sync: kernel_entry 1 mrs x1, esr_el1 // read the syndrome register lsr x24, x1, #ESR_ELx_EC_SHIFT // exception class cmp x24, #ESR_ELx_EC_DABT_CUR // data abort in EL1 b.eq el1_da cmp x24, #ESR_ELx_EC_IABT_CUR // instruction abort in EL1 b.eq el1_ia cmp x24, #ESR_ELx_EC_SYS64 // configurable trap b.eq el1_undef cmp x24, #ESR_ELx_EC_SP_ALIGN // stack alignment exception b.eq el1_sp_pc cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception b.eq el1_sp_pc cmp x24, #ESR_ELx_EC_UNKNOWN // unknown exception in EL1 b.eq el1_undef cmp x24, #ESR_ELx_EC_BREAKPT_CUR // debug exception in EL1 b.ge el1_dbg b el1_inv el1_ia: /* * Fall through to the Data abort case */ el1_da: /* * Data abort handling */ mrs x3, far_el1 inherit_daif pstate=x23, tmp=x2 untagged_addr x0, x3 mov x2, sp // struct pt_regs bl do_mem_abort kernel_exit 1 el1_sp_pc: /* * Stack or PC alignment exception handling */ mrs x0, far_el1 inherit_daif pstate=x23, tmp=x2 mov x2, sp bl do_sp_pc_abort ASM_BUG() el1_undef: /* * Undefined instruction */ inherit_daif pstate=x23, tmp=x2 mov x0, sp bl do_undefinstr kernel_exit 1 el1_dbg: /* * Debug exception handling */ cmp x24, #ESR_ELx_EC_BRK64 // if BRK64 cinc x24, x24, eq // set bit '0' tbz x24, #0, el1_inv // EL1 only mrs x0, far_el1 mov x2, sp // struct pt_regs bl do_debug_exception kernel_exit 1 el1_inv: // TODO: add support for undefined instructions in kernel mode inherit_daif pstate=x23, tmp=x2 mov x0, sp mov x2, x1 mov x1, #BAD_SYNC bl bad_mode ASM_BUG() ENDPROC(el1_sync) .align 6 el1_irq: kernel_entry 1 enable_da_f #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_off #endif irq_handler #ifdef CONFIG_PREEMPT ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count cbnz w24, 1f // preempt count != 0 ldr x0, [tsk, #TSK_TI_FLAGS] // get flags tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling? bl el1_preempt 1: #endif #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_on #endif kernel_exit 1 ENDPROC(el1_irq) #ifdef CONFIG_PREEMPT el1_preempt: mov x24, lr 1: bl preempt_schedule_irq // irq en/disable is done inside ldr x0, [tsk, #TSK_TI_FLAGS] // get new tasks TI_FLAGS tbnz x0, #TIF_NEED_RESCHED, 1b // needs rescheduling? ret x24 #endif /* * EL0 mode handlers. */ .align 6 el0_sync: kernel_entry 0 mrs x25, esr_el1 // read the syndrome register lsr x24, x25, #ESR_ELx_EC_SHIFT // exception class cmp x24, #ESR_ELx_EC_SVC64 // SVC in 64-bit state b.eq el0_svc cmp x24, #ESR_ELx_EC_DABT_LOW // data abort in EL0 b.eq el0_da cmp x24, #ESR_ELx_EC_IABT_LOW // instruction abort in EL0 b.eq el0_ia cmp x24, #ESR_ELx_EC_FP_ASIMD // FP/ASIMD access b.eq el0_fpsimd_acc cmp x24, #ESR_ELx_EC_SVE // SVE access b.eq el0_sve_acc cmp x24, #ESR_ELx_EC_FP_EXC64 // FP/ASIMD exception b.eq el0_fpsimd_exc cmp x24, #ESR_ELx_EC_SYS64 // configurable trap b.eq el0_sys cmp x24, #ESR_ELx_EC_SP_ALIGN // stack alignment exception b.eq el0_sp_pc cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception b.eq el0_sp_pc cmp x24, #ESR_ELx_EC_UNKNOWN // unknown exception in EL0 b.eq el0_undef cmp x24, #ESR_ELx_EC_BREAKPT_LOW // debug exception in EL0 b.ge el0_dbg b el0_inv #ifdef CONFIG_COMPAT .align 6 el0_sync_compat: kernel_entry 0, 32 mrs x25, esr_el1 // read the syndrome register lsr x24, x25, #ESR_ELx_EC_SHIFT // exception class cmp x24, #ESR_ELx_EC_SVC32 // SVC in 32-bit state b.eq el0_svc_compat cmp x24, #ESR_ELx_EC_DABT_LOW // data abort in EL0 b.eq el0_da cmp x24, #ESR_ELx_EC_IABT_LOW // instruction abort in EL0 b.eq el0_ia cmp x24, #ESR_ELx_EC_FP_ASIMD // FP/ASIMD access b.eq el0_fpsimd_acc cmp x24, #ESR_ELx_EC_FP_EXC32 // FP/ASIMD exception b.eq el0_fpsimd_exc cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception b.eq el0_sp_pc cmp x24, #ESR_ELx_EC_UNKNOWN // unknown exception in EL0 b.eq el0_undef cmp x24, #ESR_ELx_EC_CP15_32 // CP15 MRC/MCR trap b.eq el0_undef cmp x24, #ESR_ELx_EC_CP15_64 // CP15 MRRC/MCRR trap b.eq el0_undef cmp x24, #ESR_ELx_EC_CP14_MR // CP14 MRC/MCR trap b.eq el0_undef cmp x24, #ESR_ELx_EC_CP14_LS // CP14 LDC/STC trap b.eq el0_undef cmp x24, #ESR_ELx_EC_CP14_64 // CP14 MRRC/MCRR trap b.eq el0_undef cmp x24, #ESR_ELx_EC_BREAKPT_LOW // debug exception in EL0 b.ge el0_dbg b el0_inv el0_svc_compat: mov x0, sp bl el0_svc_compat_handler b ret_to_user .align 6 el0_irq_compat: kernel_entry 0, 32 b el0_irq_naked el0_error_compat: kernel_entry 0, 32 b el0_error_naked #endif el0_da: /* * Data abort handling */ mrs x26, far_el1 enable_daif ct_user_exit untagged_addr x0, x26 mov x1, x25 mov x2, sp bl do_mem_abort b ret_to_user el0_ia: /* * Instruction abort handling */ mrs x26, far_el1 enable_da_f #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_off #endif ct_user_exit mov x0, x26 mov x1, x25 mov x2, sp bl do_el0_ia_bp_hardening b ret_to_user el0_fpsimd_acc: /* * Floating Point or Advanced SIMD access */ enable_daif ct_user_exit mov x0, x25 mov x1, sp bl do_fpsimd_acc b ret_to_user el0_sve_acc: /* * Scalable Vector Extension access */ enable_daif ct_user_exit mov x0, x25 mov x1, sp bl do_sve_acc b ret_to_user el0_fpsimd_exc: /* * Floating Point, Advanced SIMD or SVE exception */ enable_daif ct_user_exit mov x0, x25 mov x1, sp bl do_fpsimd_exc b ret_to_user el0_sp_pc: /* * Stack or PC alignment exception handling */ mrs x26, far_el1 enable_da_f #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_off #endif ct_user_exit mov x0, x26 mov x1, x25 mov x2, sp bl do_sp_pc_abort b ret_to_user el0_undef: /* * Undefined instruction */ enable_daif ct_user_exit mov x0, sp bl do_undefinstr b ret_to_user el0_sys: /* * System instructions, for trapped cache maintenance instructions */ enable_daif ct_user_exit mov x0, x25 mov x1, sp bl do_sysinstr b ret_to_user el0_dbg: /* * Debug exception handling */ tbnz x24, #0, el0_inv // EL0 only mrs x0, far_el1 mov x1, x25 mov x2, sp bl do_debug_exception enable_da_f ct_user_exit b ret_to_user el0_inv: enable_daif ct_user_exit mov x0, sp mov x1, #BAD_SYNC mov x2, x25 bl bad_el0_sync b ret_to_user ENDPROC(el0_sync) .align 6 el0_irq: kernel_entry 0 el0_irq_naked: enable_da_f #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_off #endif ct_user_exit #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR tbz x22, #55, 1f bl do_el0_irq_bp_hardening 1: #endif irq_handler #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_on #endif b ret_to_user ENDPROC(el0_irq) el1_error: kernel_entry 1 mrs x1, esr_el1 enable_dbg mov x0, sp bl do_serror kernel_exit 1 ENDPROC(el1_error) el0_error: kernel_entry 0 el0_error_naked: mrs x1, esr_el1 enable_dbg mov x0, sp bl do_serror enable_da_f ct_user_exit b ret_to_user ENDPROC(el0_error) /* * Ok, we need to do extra processing, enter the slow path. */ work_pending: mov x0, sp // 'regs' bl do_notify_resume #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_on // enabled while in userspace #endif ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step b finish_ret_to_user /* * "slow" syscall return path. */ ret_to_user: disable_daif ldr x1, [tsk, #TSK_TI_FLAGS] and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending finish_ret_to_user: enable_step_tsk x1, x2 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK bl stackleak_erase #endif kernel_exit 0 ENDPROC(ret_to_user) /* * SVC handler. */ .align 6 el0_svc: mov x0, sp bl el0_svc_handler b ret_to_user ENDPROC(el0_svc) .popsection // .entry.text // Move from tramp_pg_dir to swapper_pg_dir .macro tramp_map_kernel, tmp mrs \tmp, ttbr1_el1 add \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE) 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 .macro tramp_unmap_kernel, tmp mrs \tmp, ttbr1_el1 sub \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE) 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_data_page dst adr_l \dst, .entry.tramp.text sub \dst, \dst, PAGE_SIZE .endm .macro tramp_data_read_var dst, var #ifdef CONFIG_RANDOMIZE_BASE tramp_data_page \dst add \dst, \dst, #:lo12:__entry_tramp_data_\var ldr \dst, [\dst] #else ldr \dst, =\var #endif .endm #define BHB_MITIGATION_NONE 0 #define BHB_MITIGATION_LOOP 1 #define BHB_MITIGATION_FW 2 #define BHB_MITIGATION_INSN 3 .macro tramp_ventry, vector_start, regsize, kpti, bhb .align 7 1: .if \regsize == 64 msr tpidrro_el0, x30 // Restored in kernel_ventry .endif .if \bhb == BHB_MITIGATION_LOOP /* * This sequence must appear before the first indirect branch. i.e. the * ret out of tramp_ventry. It appears here because x30 is free. */ __mitigate_spectre_bhb_loop x30 .endif // \bhb == BHB_MITIGATION_LOOP .if \bhb == BHB_MITIGATION_INSN clearbhb isb .endif // \bhb == BHB_MITIGATION_INSN .if \kpti == 1 /* * 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 alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 tramp_data_read_var x30, vectors prfm plil1strm, [x30, #(1b - \vector_start)] msr vbar_el1, x30 isb .else ldr x30, =vectors .endif // \kpti == 1 .if \bhb == BHB_MITIGATION_FW /* * The firmware sequence must appear before the first indirect branch. * i.e. the ret out of tramp_ventry. But it also needs the stack to be * mapped to save/restore the registers the SMC clobbers. */ __mitigate_spectre_bhb_fw .endif // \bhb == BHB_MITIGATION_FW add x30, x30, #(1b - \vector_start + 4) ret .org 1b + 128 // Did we overflow the ventry slot? .endm .macro tramp_exit, regsize = 64 tramp_data_read_var x30, this_cpu_vector alternative_if_not ARM64_HAS_VIRT_HOST_EXTN mrs x29, tpidr_el1 alternative_else mrs x29, tpidr_el2 alternative_endif ldr x30, [x30, x29] msr vbar_el1, x30 ldr lr, [sp, #S_LR] tramp_unmap_kernel x29 .if \regsize == 64 mrs x29, far_el1 .endif add sp, sp, #S_FRAME_SIZE // restore sp eret .endm .macro generate_tramp_vector, kpti, bhb .Lvector_start\@: .space 0x400 .rept 4 tramp_ventry .Lvector_start\@, 64, \kpti, \bhb .endr .rept 4 tramp_ventry .Lvector_start\@, 32, \kpti, \bhb .endr .endm #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 /* * Exception vectors trampoline. * The order must match __bp_harden_el1_vectors and the * arm64_bp_harden_el1_vectors enum. */ .pushsection ".entry.tramp.text", "ax" .align 11 ENTRY(tramp_vectors) #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_INSN #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE END(tramp_vectors) ENTRY(tramp_exit_native) tramp_exit END(tramp_exit_native) ENTRY(tramp_exit_compat) tramp_exit 32 END(tramp_exit_compat) .ltorg .popsection // .entry.tramp.text #ifdef CONFIG_RANDOMIZE_BASE .pushsection ".rodata", "a" .align PAGE_SHIFT .globl __entry_tramp_data_start __entry_tramp_data_start: __entry_tramp_data_vectors: .quad vectors #ifdef CONFIG_ARM_SDE_INTERFACE __entry_tramp_data___sdei_asm_handler: .quad __sdei_asm_handler #endif /* CONFIG_ARM_SDE_INTERFACE */ __entry_tramp_data_this_cpu_vector: .quad this_cpu_vector .popsection // .rodata #endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ /* * Exception vectors for spectre mitigations on entry from EL1 when * kpti is not in use. */ .macro generate_el1_vector, bhb .Lvector_start\@: 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_invalid // FIQ EL1h kernel_ventry 1, error // Error EL1h .rept 4 tramp_ventry .Lvector_start\@, 64, 0, \bhb .endr .rept 4 tramp_ventry .Lvector_start\@, 32, 0, \bhb .endr .endm /* The order must match tramp_vecs and the arm64_bp_harden_el1_vectors enum. */ .pushsection ".entry.text", "ax" .align 11 ENTRY(__bp_harden_el1_vectors) #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY generate_el1_vector bhb=BHB_MITIGATION_LOOP generate_el1_vector bhb=BHB_MITIGATION_FW generate_el1_vector bhb=BHB_MITIGATION_INSN #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ END(__bp_harden_el1_vectors) .popsection /* * 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. * */ ENTRY(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 #ifdef CONFIG_SHADOW_CALL_STACK str x18, [x0, #TSK_TI_SCS] ldr x18, [x1, #TSK_TI_SCS] str xzr, [x1, #TSK_TI_SCS] // limit visibility of saved SCS #endif ret ENDPROC(cpu_switch_to) NOKPROBE(cpu_switch_to) /* * This is how we return from a fork. */ ENTRY(ret_from_fork) bl schedule_tail cbz x19, 1f // not a kernel thread mov x0, x20 blr x19 1: get_thread_info tsk b ret_to_user ENDPROC(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" ENTRY(__sdei_asm_entry_trampoline) mrs x4, ttbr1_el1 tbz x4, #USER_ASID_BIT, 1f tramp_map_kernel tmp=x4 isb mov x4, xzr /* * Use reg->interrupted_regs.addr_limit to remember whether to unmap * the kernel on exit. */ 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] tramp_data_read_var x4, __sdei_asm_handler br x4 ENDPROC(__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. */ ENTRY(__sdei_asm_exit_trampoline) ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] cbnz x4, 1f tramp_unmap_kernel tmp=x4 1: sdei_handler_exit exit_mode=x2 ENDPROC(__sdei_asm_exit_trampoline) NOKPROBE(__sdei_asm_exit_trampoline) .ltorg .popsection // .entry.tramp.text #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. */ ENTRY(__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 #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. */ ldrb w4, [x19, #SDEI_EVENT_PRIORITY] 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 /* * 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, tmp=x3 br x5 #endif ENDPROC(__sdei_asm_handler) NOKPROBE(__sdei_asm_handler) #endif /* CONFIG_ARM_SDE_INTERFACE */