diff options
| -rw-r--r-- | arch/arm/mm/Kconfig | 19 | ||||
| -rw-r--r-- | arch/arm/mm/proc-v7.S | 27 |
2 files changed, 46 insertions, 0 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index df6b89170..b0834ac50 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -761,6 +761,25 @@ config CPU_BPREDICT_DISABLE config CPU_SPECTRE bool +config HARDEN_BRANCH_PREDICTOR + bool "Harden the branch predictor against aliasing attacks" if EXPERT + depends on CPU_SPECTRE + default y + help + Speculation attacks against some high-performance processors rely + on being able to manipulate the branch predictor for a victim + context by executing aliasing branches in the attacker context. + Such attacks can be partially mitigated against by clearing + internal branch predictor state and limiting the prediction + logic in some situations. + + This config option will take CPU-specific actions to harden + the branch predictor against aliasing attacks and may rely on + specific instruction sequences or control bits being set by + the system firmware. + + If unsure, say Y. + config TLS_REG_EMUL bool select NEED_KUSER_HELPERS diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 4ac6a9629..dcfb42e11 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -92,6 +92,12 @@ ENTRY(cpu_v7_dcache_clean_area) mov pc, lr ENDPROC(cpu_v7_dcache_clean_area) +ENTRY(cpu_v7_bpiall_switch_mm) + mov r3, #0 + mcr p15, 0, r3, c7, c5, 6 @ flush BTAC/BTB + b cpu_v7_switch_mm +ENDPROC(cpu_v7_bpiall_switch_mm) + string cpu_v7_name, "ARMv7 Processor" .align @@ -471,6 +477,27 @@ __v7_setup_stack: @ define struct processor (see <asm/proc-fns.h> and proc-macros.S) define_processor_functions v7, dabort=v7_early_abort, pabort=v7_pabort, suspend=1 + +#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR + @ generic v7 bpiall on context switch + globl_equ cpu_v7_bpiall_proc_init, cpu_v7_proc_init + globl_equ cpu_v7_bpiall_proc_fin, cpu_v7_proc_fin + globl_equ cpu_v7_bpiall_reset, cpu_v7_reset + globl_equ cpu_v7_bpiall_do_idle, cpu_v7_do_idle + globl_equ cpu_v7_bpiall_dcache_clean_area, cpu_v7_dcache_clean_area + globl_equ cpu_v7_bpiall_set_pte_ext, cpu_v7_set_pte_ext + globl_equ cpu_v7_bpiall_suspend_size, cpu_v7_suspend_size +#ifdef CONFIG_ARM_CPU_SUSPEND + globl_equ cpu_v7_bpiall_do_suspend, cpu_v7_do_suspend + globl_equ cpu_v7_bpiall_do_resume, cpu_v7_do_resume +#endif + define_processor_functions v7_bpiall, dabort=v7_early_abort, pabort=v7_pabort, suspend=1 + +#define HARDENED_BPIALL_PROCESSOR_FUNCTIONS v7_bpiall_processor_functions +#else +#define HARDENED_BPIALL_PROCESSOR_FUNCTIONS v7_processor_functions +#endif + #ifdef CONFIG_CPU_PJ4B define_processor_functions pj4b, dabort=v7_early_abort, pabort=v7_pabort, suspend=1 #endif |