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Workaround for Neoverse N1 erratum 1275112

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Neoverse N1 erratum 1275112 is a Cat B erratum [1],
present in older revisions of the Neoverse N1 processor core.
The workaround is to set a bit in the implementation defined
CPUACTLR_EL1 system register, which delays instruction fetch after
branch misprediction.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdoc-466751330-10325/index.html

Change-Id: If7fe55fe92e656fa6aea12327ab297f2e6119833
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
This commit is contained in:
lauwal01 2019-06-24 11:49:01 -05:00
parent 11c48370bd
commit 4d8801fe5a
3 changed files with 44 additions and 0 deletions
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3
docs/design/cpu-specific-build-macros.rst
View file

@ -252,6 +252,9 @@ For Neoverse N1, the following errata build flags are defined :
- ``ERRATA_N1_1262888``: This applies errata 1262888 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
- ``ERRATA_N1_1275112``: This applies errata 1275112 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
- ``ERRATA_N1_1315703``: This applies errata 1315703 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r3p0 of the CPU.

33
lib/cpus/aarch64/neoverse_n1.S
View file

@ -292,6 +292,33 @@ func check_errata_1262888
b cpu_rev_var_ls
endfunc check_errata_1262888
/* --------------------------------------------------
* Errata Workaround for Neoverse N1 Errata #1275112
* This applies to revision <=r3p0 of Neoverse N1.
* Inputs:
* x0: variant[4:7] and revision[0:3] of current cpu.
* Shall clobber: x0-x17
* --------------------------------------------------
*/
func errata_n1_1275112_wa
/* Compare x0 against revision r3p0 */
mov x17, x30
bl check_errata_1275112
cbz x0, 1f
mrs x1, NEOVERSE_N1_CPUACTLR_EL1
orr x1, x1, NEOVERSE_N1_CPUACTLR_EL1_BIT_13
msr NEOVERSE_N1_CPUACTLR_EL1, x1
isb
1:
ret x17
endfunc errata_n1_1275112_wa
func check_errata_1275112
/* Applies to <=r3p0 */
mov x1, #0x30
b cpu_rev_var_ls
endfunc check_errata_1275112
/* --------------------------------------------------
* Errata Workaround for Neoverse N1 Erratum 1315703.
* This applies to revision <= r3p0 of Neoverse N1.
@ -380,6 +407,11 @@ func neoverse_n1_reset_func
bl errata_n1_1262888_wa
#endif
#if ERRATA_N1_1275112
mov x0, x18
bl errata_n1_1275112_wa
#endif
#if ERRATA_N1_1315703
mov x0, x18
bl errata_n1_1315703_wa
@ -450,6 +482,7 @@ func neoverse_n1_errata_report
report_errata ERRATA_N1_1257314, neoverse_n1, 1257314
report_errata ERRATA_N1_1262606, neoverse_n1, 1262606
report_errata ERRATA_N1_1262888, neoverse_n1, 1262888
report_errata ERRATA_N1_1275112, neoverse_n1, 1275112
report_errata ERRATA_N1_1315703, neoverse_n1, 1315703
report_errata ERRATA_DSU_936184, neoverse_n1, dsu_936184

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

@ -270,6 +270,10 @@ ERRATA_N1_1262606 ?=0
# only to revision <= r3p0 of the Neoverse N1 cpu.
ERRATA_N1_1262888 ?=0
# Flag to apply erratum 1275112 workaround during reset. This erratum applies
# only to revision <= r3p0 of the Neoverse N1 cpu.
ERRATA_N1_1275112 ?=0
# Flag to apply erratum 1315703 workaround during reset. This erratum applies
# to revisions before r3p1 of the Neoverse N1 cpu.
ERRATA_N1_1315703 ?=1
@ -495,6 +499,10 @@ $(eval $(call add_define,ERRATA_N1_1262606))
$(eval $(call assert_boolean,ERRATA_N1_1262888))
$(eval $(call add_define,ERRATA_N1_1262888))
# Process ERRATA_N1_1275112 flag
$(eval $(call assert_boolean,ERRATA_N1_1275112))
$(eval $(call add_define,ERRATA_N1_1275112))
# Process ERRATA_N1_1315703 flag
$(eval $(call assert_boolean,ERRATA_N1_1315703))
$(eval $(call add_define,ERRATA_N1_1315703))