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fix(errata): workaround for Neoverse-N2 erratum 2280757

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Neoverse-N2 erratum 2280757 is a Cat B erratum that applies to
revision r0p0 of CPU. It is still open. The workaround
is to set CPUACTLR_EL1[22] to 1'b1. Setting CPUACTLR_EL1[22]
will cause CFP instruction to invalidate all branch predictor
resources regardless of context.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1982442/latest

Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: I615bcc1f993c45659b8b6f1a34fca0eb490f8add
This commit is contained in:
nayanpatel-arm 2021-10-20 17:30:46 -07:00
parent 603806d137
commit 0d2d99924e
3 changed files with 45 additions and 0 deletions

3
docs/design/cpu-specific-build-macros.rst
View file

@ -429,6 +429,9 @@ For Neoverse N2, the following errata build flags are defined :
- ``ERRATA_N2_2242400``: This applies errata 2242400 workaround to Neoverse-N2
CPU. This needs to be enabled for revision r0p0 of the CPU and is still open.
- ``ERRATA_N2_2280757``: This applies errata 2280757 workaround to Neoverse-N2
CPU. This needs to be enabled for revision r0p0 of the CPU and is still open.
DSU Errata Workarounds
----------------------

34
lib/cpus/aarch64/neoverse_n2.S
View file

@ -305,6 +305,34 @@ func check_errata_2242400
b cpu_rev_var_ls
endfunc check_errata_2242400
/* --------------------------------------------------
* Errata Workaround for Neoverse N2 Erratum 2280757.
* This applies to revision r0p0 of Neoverse N2. it is still open.
* Inputs:
* x0: variant[4:7] and revision[0:3] of current cpu.
* Shall clobber: x0-x1, x17
* --------------------------------------------------
*/
func errata_n2_2280757_wa
/* Check revision. */
mov x17, x30
bl check_errata_2280757
cbz x0, 1f
/* Apply instruction patching sequence */
mrs x1, NEOVERSE_N2_CPUACTLR_EL1
orr x1, x1, NEOVERSE_N2_CPUACTLR_EL1_BIT_22
msr NEOVERSE_N2_CPUACTLR_EL1, x1
1:
ret x17
endfunc errata_n2_2280757_wa
func check_errata_2280757
/* Applies to r0p0 */
mov x1, #0x00
b cpu_rev_var_ls
endfunc check_errata_2280757
/* -------------------------------------------
* The CPU Ops reset function for Neoverse N2.
* -------------------------------------------
@ -366,6 +394,11 @@ func neoverse_n2_reset_func
bl errata_n2_2242400_wa
#endif
#if ERRATA_N2_2280757
mov x0, x18
bl errata_n2_2280757_wa
#endif
#if ENABLE_AMU
/* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
mrs x0, cptr_el3
@ -435,6 +468,7 @@ func neoverse_n2_errata_report
report_errata ERRATA_N2_2242415, neoverse_n2, 2242415
report_errata ERRATA_N2_2138958, neoverse_n2, 2138958
report_errata ERRATA_N2_2242400, neoverse_n2, 2242400
report_errata ERRATA_N2_2280757, neoverse_n2, 2280757
ldp x8, x30, [sp], #16
ret

8
lib/cpus/cpu-ops.mk
View file

@ -473,6 +473,10 @@ ERRATA_N2_2138958 ?=0
# to revision r0p0 of the Neoverse N2 cpu and is still open.
ERRATA_N2_2242400 ?=0
# Flag to apply erratum 2280757 workaround during reset. This erratum applies
# to revision r0p0 of the Neoverse N2 cpu and is still open.
ERRATA_N2_2280757 ?=0
# Flag to apply erratum 2055002 workaround during reset. This erratum applies
# to revision r1p0, r2p0 of the Cortex-A710 cpu and is still open.
ERRATA_A710_2055002 ?=0
@ -886,6 +890,10 @@ $(eval $(call add_define,ERRATA_N2_2138958))
$(eval $(call assert_boolean,ERRATA_N2_2242400))
$(eval $(call add_define,ERRATA_N2_2242400))
# Process ERRATA_N2_2280757 flag
$(eval $(call assert_boolean,ERRATA_N2_2280757))
$(eval $(call add_define,ERRATA_N2_2280757))
# Process ERRATA_A710_2055002 flag
$(eval $(call assert_boolean,ERRATA_A710_2055002))
$(eval $(call add_define,ERRATA_A710_2055002))