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5283962eba
ARMv8.3-PAuth adds functionality that supports address authentication of the contents of a register before that register is used as the target of an indirect branch, or as a load. This feature is supported only in AArch64 state. This feature is mandatory in ARMv8.3 implementations. This feature adds several registers to EL1. A new option called CTX_INCLUDE_PAUTH_REGS has been added to select if the TF needs to save them during Non-secure <-> Secure world switches. This option must be enabled if the hardware has the registers or the values will be leaked during world switches. To prevent leaks, this patch also disables pointer authentication in the Secure world if CTX_INCLUDE_PAUTH_REGS is 0. Any attempt to use it will be trapped in EL3. Change-Id: I27beba9907b9a86c6df1d0c5bf6180c972830855 Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
271 lines
6.5 KiB
ArmAsm
271 lines
6.5 KiB
ArmAsm
/*
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* Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <assert_macros.S>
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#include <asm_macros.S>
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#include <assert_macros.S>
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#include <bl31/ea_handle.h>
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#include <context.h>
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#include <lib/extensions/ras_arch.h>
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.globl handle_lower_el_ea_esb
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.globl enter_lower_el_sync_ea
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.globl enter_lower_el_async_ea
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/*
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* Function to delegate External Aborts synchronized by ESB instruction at EL3
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* vector entry. This function assumes GP registers x0-x29 have been saved, and
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* are available for use. It delegates the handling of the EA to platform
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* handler, and returns only upon successfully handling the EA; otherwise
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* panics. On return from this function, the original exception handler is
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* expected to resume.
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*/
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func handle_lower_el_ea_esb
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mov x0, #ERROR_EA_ESB
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mrs x1, DISR_EL1
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b ea_proceed
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endfunc handle_lower_el_ea_esb
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/*
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* This function forms the tail end of Synchronous Exception entry from lower
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* EL, and expects to handle only Synchronous External Aborts from lower EL. If
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* any other kind of exception is detected, then this function reports unhandled
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* exception.
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*
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* Since it's part of exception vector, this function doesn't expect any GP
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* registers to have been saved. It delegates the handling of the EA to platform
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* handler, and upon successfully handling the EA, exits EL3; otherwise panics.
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*/
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func enter_lower_el_sync_ea
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/*
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* Explicitly save x30 so as to free up a register and to enable
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* branching.
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*/
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str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
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mrs x30, esr_el3
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ubfx x30, x30, #ESR_EC_SHIFT, #ESR_EC_LENGTH
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/* Check for I/D aborts from lower EL */
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cmp x30, #EC_IABORT_LOWER_EL
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b.eq 1f
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cmp x30, #EC_DABORT_LOWER_EL
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b.ne 2f
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1:
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/* Test for EA bit in the instruction syndrome */
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mrs x30, esr_el3
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tbz x30, #ESR_ISS_EABORT_EA_BIT, 2f
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/* Save GP registers */
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bl save_gp_registers
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#if CTX_INCLUDE_PAUTH_REGS
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bl pauth_context_save
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#endif
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/* Setup exception class and syndrome arguments for platform handler */
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mov x0, #ERROR_EA_SYNC
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mrs x1, esr_el3
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adr x30, el3_exit
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b delegate_sync_ea
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2:
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/* Synchronous exceptions other than the above are assumed to be EA */
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ldr x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
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no_ret report_unhandled_exception
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endfunc enter_lower_el_sync_ea
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/*
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* This function handles SErrors from lower ELs.
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*
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* Since it's part of exception vector, this function doesn't expect any GP
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* registers to have been saved. It delegates the handling of the EA to platform
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* handler, and upon successfully handling the EA, exits EL3; otherwise panics.
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*/
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func enter_lower_el_async_ea
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/*
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* Explicitly save x30 so as to free up a register and to enable
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* branching
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*/
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str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
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/* Save GP registers */
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bl save_gp_registers
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#if CTX_INCLUDE_PAUTH_REGS
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bl pauth_context_save
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#endif
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/* Setup exception class and syndrome arguments for platform handler */
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mov x0, #ERROR_EA_ASYNC
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mrs x1, esr_el3
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adr x30, el3_exit
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b delegate_async_ea
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endfunc enter_lower_el_async_ea
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/*
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* Prelude for Synchronous External Abort handling. This function assumes that
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* all GP registers have been saved by the caller.
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*
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* x0: EA reason
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* x1: EA syndrome
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*/
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func delegate_sync_ea
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#if RAS_EXTENSION
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/*
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* Check for Uncontainable error type. If so, route to the platform
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* fatal error handler rather than the generic EA one.
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*/
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ubfx x2, x1, #EABORT_SET_SHIFT, #EABORT_SET_WIDTH
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cmp x2, #ERROR_STATUS_SET_UC
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b.ne 1f
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/* Check fault status code */
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ubfx x3, x1, #EABORT_DFSC_SHIFT, #EABORT_DFSC_WIDTH
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cmp x3, #SYNC_EA_FSC
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b.ne 1f
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no_ret plat_handle_uncontainable_ea
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1:
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#endif
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b ea_proceed
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endfunc delegate_sync_ea
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/*
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* Prelude for Asynchronous External Abort handling. This function assumes that
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* all GP registers have been saved by the caller.
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*
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* x0: EA reason
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* x1: EA syndrome
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*/
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func delegate_async_ea
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#if RAS_EXTENSION
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/*
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* Check for Implementation Defined Syndrome. If so, skip checking
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* Uncontainable error type from the syndrome as the format is unknown.
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*/
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tbnz x1, #SERROR_IDS_BIT, 1f
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/*
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* Check for Uncontainable error type. If so, route to the platform
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* fatal error handler rather than the generic EA one.
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*/
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ubfx x2, x1, #EABORT_AET_SHIFT, #EABORT_AET_WIDTH
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cmp x2, #ERROR_STATUS_UET_UC
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b.ne 1f
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/* Check DFSC for SError type */
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ubfx x3, x1, #EABORT_DFSC_SHIFT, #EABORT_DFSC_WIDTH
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cmp x3, #DFSC_SERROR
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b.ne 1f
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no_ret plat_handle_uncontainable_ea
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1:
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#endif
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b ea_proceed
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endfunc delegate_async_ea
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/*
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* Delegate External Abort handling to platform's EA handler. This function
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* assumes that all GP registers have been saved by the caller.
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*
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* x0: EA reason
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* x1: EA syndrome
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*/
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func ea_proceed
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/*
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* If the ESR loaded earlier is not zero, we were processing an EA
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* already, and this is a double fault.
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*/
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ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_ESR_EL3]
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cbz x5, 1f
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no_ret plat_handle_double_fault
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1:
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/* Save EL3 state */
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mrs x2, spsr_el3
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mrs x3, elr_el3
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stp x2, x3, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
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/*
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* Save ESR as handling might involve lower ELs, and returning back to
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* EL3 from there would trample the original ESR.
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*/
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mrs x4, scr_el3
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mrs x5, esr_el3
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stp x4, x5, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
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/*
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* Setup rest of arguments, and call platform External Abort handler.
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*
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* x0: EA reason (already in place)
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* x1: Exception syndrome (already in place).
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* x2: Cookie (unused for now).
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* x3: Context pointer.
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* x4: Flags (security state from SCR for now).
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*/
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mov x2, xzr
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mov x3, sp
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ubfx x4, x4, #0, #1
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/* Switch to runtime stack */
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ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_RUNTIME_SP]
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msr spsel, #0
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mov sp, x5
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mov x29, x30
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#if ENABLE_ASSERTIONS
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/* Stash the stack pointer */
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mov x28, sp
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#endif
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bl plat_ea_handler
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#if ENABLE_ASSERTIONS
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/*
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* Error handling flows might involve long jumps; so upon returning from
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* the platform error handler, validate that the we've completely
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* unwound the stack.
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*/
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mov x27, sp
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cmp x28, x27
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ASM_ASSERT(eq)
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#endif
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/* Make SP point to context */
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msr spsel, #1
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/* Restore EL3 state and ESR */
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ldp x1, x2, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3]
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msr spsr_el3, x1
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msr elr_el3, x2
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/* Restore ESR_EL3 and SCR_EL3 */
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ldp x3, x4, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3]
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msr scr_el3, x3
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msr esr_el3, x4
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#if ENABLE_ASSERTIONS
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cmp x4, xzr
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ASM_ASSERT(ne)
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#endif
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/* Clear ESR storage */
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str xzr, [sp, #CTX_EL3STATE_OFFSET + CTX_ESR_EL3]
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ret x29
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endfunc ea_proceed
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