arm-trusted-firmware/lib/cpus/aarch64/cortex_x1.S
Boyan Karatotev 89dba82dfa perf(cpus): make reset errata do fewer branches
Errata application is painful for performance. For a start, it's done
when the core has just come out of reset, which means branch predictors
and caches will be empty so a branch to a workaround function must be
fetched from memory and that round trip is very slow. Then it also runs
with the I-cache off, which means that the loop to iterate over the
workarounds must also be fetched from memory on each iteration.

We can remove both branches. First, we can simply apply every erratum
directly instead of defining a workaround function and jumping to it.
Currently, no errata that need to be applied at both reset and runtime,
with the same workaround function, exist. If the need arose in future,
this should be achievable with a reset + runtime wrapper combo.

Then, we can construct a function that applies each erratum linearly
instead of looping over the list. If this function is part of the reset
function, then the only "far" branches at reset will be for the checker
functions. Importantly, this mitigates the slowdown even when an erratum
is disabled.

The result is ~50% speedup on N1SDP and ~20% on AArch64 Juno on wakeup
from PSCI calls that end in powerdown. This is roughly back to the
baseline of v2.9, before the errata framework regressed on performance
(or a little better). It is important to note that there are other
slowdowns since then that remain unknown.

Change-Id: Ie4d5288a331b11fd648e5c4a0b652b74160b07b9
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
2025-02-24 09:36:11 +00:00

99 lines
3.1 KiB
ArmAsm

/*
* Copyright (c) 2022-2024, Google LLC. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <asm_macros.S>
#include <cortex_x1.h>
#include <cpu_macros.S>
#include "wa_cve_2022_23960_bhb_vector.S"
/* Hardware handled coherency */
#if HW_ASSISTED_COHERENCY == 0
#error "Cortex-X1 must be compiled with HW_ASSISTED_COHERENCY enabled"
#endif
/* 64-bit only core */
#if CTX_INCLUDE_AARCH32_REGS == 1
#error "Cortex-X1 supports only AArch64. Compile with CTX_INCLUDE_AARCH32_REGS=0"
#endif
#if WORKAROUND_CVE_2022_23960
wa_cve_2022_23960_bhb_vector_table CORTEX_X1_BHB_LOOP_COUNT, cortex_x1
#endif /* WORKAROUND_CVE_2022_23960 */
cpu_reset_prologue cortex_x1
/* Disable hardware page aggregation. Enables mitigation for `CVE-2024-5660` */
workaround_reset_start cortex_x1, CVE(2024, 5660), WORKAROUND_CVE_2024_5660
sysreg_bit_set CORTEX_X1_CPUECTLR_EL1, BIT(46)
workaround_reset_end cortex_x1, CVE(2024, 5660)
check_erratum_ls cortex_x1, CVE(2024, 5660), CPU_REV(1, 2)
workaround_reset_start cortex_x1, ERRATUM(1688305), ERRATA_X1_1688305
sysreg_bit_set CORTEX_X1_ACTLR2_EL1, BIT(1)
workaround_reset_end cortex_x1, ERRATUM(1688305)
check_erratum_ls cortex_x1, ERRATUM(1688305), CPU_REV(1, 0)
workaround_reset_start cortex_x1, ERRATUM(1821534), ERRATA_X1_1821534
sysreg_bit_set CORTEX_X1_ACTLR2_EL1, BIT(2)
workaround_reset_end cortex_x1, ERRATUM(1821534)
check_erratum_ls cortex_x1, ERRATUM(1821534), CPU_REV(1, 0)
workaround_reset_start cortex_x1, ERRATUM(1827429), ERRATA_X1_1827429
sysreg_bit_set CORTEX_X1_CPUECTLR_EL1, BIT(53)
workaround_reset_end cortex_x1, ERRATUM(1827429)
check_erratum_ls cortex_x1, ERRATUM(1827429), CPU_REV(1, 0)
check_erratum_chosen cortex_x1, CVE(2022, 23960), WORKAROUND_CVE_2022_23960
workaround_reset_start cortex_x1, CVE(2022, 23960), WORKAROUND_CVE_2022_23960
#if IMAGE_BL31
/*
* The Cortex-X1 generic vectors are overridden to apply errata
* mitigation on exception entry from lower ELs.
*/
override_vector_table wa_cve_vbar_cortex_x1
#endif /* IMAGE_BL31 */
workaround_reset_end cortex_x1, CVE(2022, 23960)
cpu_reset_func_start cortex_x1
cpu_reset_func_end cortex_x1
/* ---------------------------------------------
* HW will do the cache maintenance while powering down
* ---------------------------------------------
*/
func cortex_x1_core_pwr_dwn
sysreg_bit_set CORTEX_X1_CPUPWRCTLR_EL1, CORTEX_X1_CORE_PWRDN_EN_MASK
isb
ret
endfunc cortex_x1_core_pwr_dwn
/* ---------------------------------------------
* This function provides Cortex X1 specific
* register information for crash reporting.
* It needs to return with x6 pointing to
* a list of register names in ascii and
* x8 - x15 having values of registers to be
* reported.
* ---------------------------------------------
*/
.section .rodata.cortex_x1_regs, "aS"
cortex_x1_regs: /* The ascii list of register names to be reported */
.asciz "cpuectlr_el1", ""
func cortex_x1_cpu_reg_dump
adr x6, cortex_x1_regs
mrs x8, CORTEX_X1_CPUECTLR_EL1
ret
endfunc cortex_x1_cpu_reg_dump
declare_cpu_ops cortex_x1, CORTEX_X1_MIDR, \
cortex_x1_reset_func, \
cortex_x1_core_pwr_dwn