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ARM: spectre-v2: harden branch predictor on context switches

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Harden the branch predictor against Spectre v2 attacks on context
switches for ARMv7 and later CPUs.  We do this by:

Cortex A9, A12, A17, A73, A75: invalidating the BTB.
Cortex A15, Brahma B15: invalidating the instruction cache.

Cortex A57 and Cortex A72 are not addressed in this patch.

Cortex R7 and Cortex R8 are also not addressed as we do not enforce
memory protection on these cores.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Boot-tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Russell King
2018-04-20 10:06:27 +01:00
parent c58d237d08
commit 06c23f5ffe
3 changed files with 115 additions and 35 deletions
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6
arch/arm/mm/proc-v7-2level.S
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@@ -41,11 +41,6 @@
* even on Cortex-A8 revisions not affected by 430973.
* If IBE is not set, the flush BTAC/BTB won't do anything.
*/
ENTRY(cpu_ca8_switch_mm)
#ifdef CONFIG_MMU
mov r2, #0
mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB
#endif
ENTRY(cpu_v7_switch_mm)
#ifdef CONFIG_MMU
mmid r1, r1 @ get mm->context.id
@@ -66,7 +61,6 @@ ENTRY(cpu_v7_switch_mm)
#endif
bx lr
ENDPROC(cpu_v7_switch_mm)
ENDPROC(cpu_ca8_switch_mm)
/*
* cpu_v7_set_pte_ext(ptep, pte)