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Disable speculative loads only if SSBS is supported

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Examine the ID_AA64PFR1_EL1 bits 7:4 to see if speculative
loads (SSBS) is implemented, before disabling speculative
loads.

Change-Id: I7607c45ed2889260d22a94f6fd9af804520acf67
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
This commit is contained in:
Sami Mujawar 2019-05-10 14:28:37 +01:00
parent c33aa45f44
commit eca6e45336
1 changed files with 22 additions and 2 deletions
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24
lib/cpus/aarch64/neoverse_n1.S
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@ -49,11 +49,31 @@ func check_errata_1043202
b cpu_rev_var_ls
endfunc check_errata_1043202
/* --------------------------------------------------
* Disable speculative loads if Neoverse N1 supports
* SSBS.
*
* Shall clobber: x0.
* --------------------------------------------------
*/
func neoverse_n1_disable_speculative_loads
/* Check if the PE implements SSBS */
mrs x0, id_aa64pfr1_el1
tst x0, #(ID_AA64PFR1_EL1_SSBS_MASK << ID_AA64PFR1_EL1_SSBS_SHIFT)
b.eq 1f
/* Disable speculative loads */
msr SSBS, xzr
isb
1:
ret
endfunc neoverse_n1_disable_speculative_loads
func neoverse_n1_reset_func
mov x19, x30
/* Disables speculative loads */
msr SSBS, xzr
bl neoverse_n1_disable_speculative_loads
/* Forces all cacheable atomic instructions to be near */
mrs x0, NEOVERSE_N1_CPUACTLR2_EL1