diff options
Diffstat (limited to 'bl31/aarch64/runtime_exceptions.S')
| -rw-r--r-- | bl31/aarch64/runtime_exceptions.S | 94 |
1 files changed, 91 insertions, 3 deletions
diff --git a/bl31/aarch64/runtime_exceptions.S b/bl31/aarch64/runtime_exceptions.S index bfe13f312..51eb2bd47 100644 --- a/bl31/aarch64/runtime_exceptions.S +++ b/bl31/aarch64/runtime_exceptions.S @@ -1,5 +1,5 @@ /* - * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved. + * Copyright (c) 2013-2021, ARM Limited and Contributors. All rights reserved. * * SPDX-License-Identifier: BSD-3-Clause */ @@ -45,8 +45,9 @@ * instruction. When an error is thus synchronized, the handling is * delegated to platform EA handler. * - * Without RAS_EXTENSION, this macro just saves x30, and unmasks - * Asynchronous External Aborts. + * Without RAS_EXTENSION, this macro synchronizes pending errors using + * a DSB, unmasks Asynchronous External Aborts and saves X30 before + * setting the flag CTX_IS_IN_EL3. */ .macro check_and_unmask_ea #if RAS_EXTENSION @@ -79,13 +80,89 @@ bl restore_gp_pmcr_pauth_regs 1: #else + /* + * For SoCs which do not implement RAS, use DSB as a barrier to + * synchronize pending external aborts. + */ + dsb sy + /* Unmask the SError interrupt */ msr daifclr, #DAIF_ABT_BIT + /* Use ISB for the above unmask operation to take effect immediately */ + isb + + /* + * Refer Note 1. No need to restore X30 as both handle_sync_exception + * and handle_interrupt_exception macro which follow this macro modify + * X30 anyway. + */ str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] + mov x30, #1 + str x30, [sp, #CTX_EL3STATE_OFFSET + CTX_IS_IN_EL3] + dmb sy #endif .endm +#if !RAS_EXTENSION + /* + * Note 1: The explicit DSB at the entry of various exception vectors + * for handling exceptions from lower ELs can inadvertently trigger an + * SError exception in EL3 due to pending asynchronous aborts in lower + * ELs. This will end up being handled by serror_sp_elx which will + * ultimately panic and die. + * The way to workaround is to update a flag to indicate if the exception + * truly came from EL3. This flag is allocated in the cpu_context + * structure and located at offset "CTX_EL3STATE_OFFSET + CTX_IS_IN_EL3" + * This is not a bullet proof solution to the problem at hand because + * we assume the instructions following "isb" that help to update the + * flag execute without causing further exceptions. + */ + + /* --------------------------------------------------------------------- + * This macro handles Asynchronous External Aborts. + * --------------------------------------------------------------------- + */ + .macro handle_async_ea + /* + * Use a barrier to synchronize pending external aborts. + */ + dsb sy + + /* Unmask the SError interrupt */ + msr daifclr, #DAIF_ABT_BIT + + /* Use ISB for the above unmask operation to take effect immediately */ + isb + + /* Refer Note 1 */ + str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] + mov x30, #1 + str x30, [sp, #CTX_EL3STATE_OFFSET + CTX_IS_IN_EL3] + dmb sy + + b handle_lower_el_async_ea + .endm + + /* + * This macro checks if the exception was taken due to SError in EL3 or + * because of pending asynchronous external aborts from lower EL that got + * triggered due to explicit synchronization in EL3. Refer Note 1. + */ + .macro check_if_serror_from_EL3 + /* Assumes SP_EL3 on entry */ + str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] + ldr x30, [sp, #CTX_EL3STATE_OFFSET + CTX_IS_IN_EL3] + cbnz x30, exp_from_EL3 + + /* Handle asynchronous external abort from lower EL */ + b handle_lower_el_async_ea + +exp_from_EL3: + /* Jump to plat_handle_el3_ea which does not return */ + .endm +#endif + /* --------------------------------------------------------------------- * This macro handles Synchronous exceptions. * Only SMC exceptions are supported. @@ -272,6 +349,9 @@ vector_entry fiq_sp_elx end_vector_entry fiq_sp_elx vector_entry serror_sp_elx +#if !RAS_EXTENSION + check_if_serror_from_EL3 +#endif no_ret plat_handle_el3_ea end_vector_entry serror_sp_elx @@ -305,8 +385,12 @@ end_vector_entry fiq_aarch64 vector_entry serror_aarch64 apply_at_speculative_wa +#if RAS_EXTENSION msr daifclr, #DAIF_ABT_BIT b enter_lower_el_async_ea +#else + handle_async_ea +#endif end_vector_entry serror_aarch64 /* --------------------------------------------------------------------- @@ -339,8 +423,12 @@ end_vector_entry fiq_aarch32 vector_entry serror_aarch32 apply_at_speculative_wa +#if RAS_EXTENSION msr daifclr, #DAIF_ABT_BIT b enter_lower_el_async_ea +#else + handle_async_ea +#endif end_vector_entry serror_aarch32 #ifdef MONITOR_TRAPS |