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CONFIG_DISABLE_SSBD
¶
Disable Speculative Store Bypass
Type: bool
Help¶
This option will disable Speculative Store Bypass in order to mitigate against certain kinds of side channel attacks. Quoting the “Speculative Execution Side Channels” document, version 2.0:
When SSBD is set, loads will not execute speculatively until the addresses of all older stores are known. This ensure s that a load does not speculatively consume stale data values due to bypassing an older store on the same logical processor.
If enabled, this applies to all threads in the system.
Even if enabled, will have no effect on CPUs that do not require this feature.
Default¶
y if !
X86_NO_SPECTRE_V4
Kconfig definition¶
At <Zephyr>/arch/x86/Kconfig:276
Included via <Zephyr>/Kconfig:8
→ <Zephyr>/Kconfig.zephyr:29
→ <Zephyr>/arch/Kconfig:12
Menu path: (Top) → X86 Architecture Options
config DISABLE_SSBD bool "Disable Speculative Store Bypass" default y if !X86_NO_SPECTRE_V4
depends onUSERSPACE
&&X86
help This option will disable Speculative Store Bypass in order to mitigate against certain kinds of side channel attacks. Quoting the "Speculative Execution Side Channels" document, version 2.0: When SSBD is set, loads will not execute speculatively until the addresses of all older stores are known. This ensure s that a load does not speculatively consume stale data values due to bypassing an older store on the same logical processor. If enabled, this applies to all threads in the system. Even if enabled, will have no effect on CPUs that do not require this feature.
(The ‘depends on’ condition includes propagated dependencies from ifs and menus.)