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Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 1360 |
1 files changed, 1360 insertions, 0 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S new file mode 100644 index 000000000..85433a847 --- /dev/null +++ b/arch/arm64/kernel/entry.S @@ -0,0 +1,1360 @@ +/* + * Low-level exception handling code + * + * Copyright (C) 2012 ARM Ltd. + * Authors: Catalin Marinas <catalin.marinas@arm.com> + * Will Deacon <will.deacon@arm.com> + * + * 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 <http://www.gnu.org/licenses/>. + */ + +#include <linux/arm-smccc.h> +#include <linux/init.h> +#include <linux/linkage.h> + +#include <asm/alternative.h> +#include <asm/assembler.h> +#include <asm/asm-offsets.h> +#include <asm/cpufeature.h> +#include <asm/errno.h> +#include <asm/esr.h> +#include <asm/irq.h> +#include <asm/memory.h> +#include <asm/mmu.h> +#include <asm/processor.h> +#include <asm/ptrace.h> +#include <asm/thread_info.h> +#include <asm/asm-uaccess.h> +#include <asm/unistd.h> + +/* + * 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 + + .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_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 + + /* + * 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 +9998: + .endm + + /* + * x19 should be preserved between irq_stack_entry and + * irq_stack_exit. + */ + .macro irq_stack_exit + mov sp, x19 + .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 + clear_address_tag 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 + clear_address_tag 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 + 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 <asm/sdei.h> +#include <uapi/linux/arm_sdei.h> + +.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 */ |