From 5ab8c6e8879c3eee7d70714b630a4770ff8a2678 Mon Sep 17 00:00:00 2001 From: Russell King Date: Mon, 15 Oct 2018 11:32:02 -0400 Subject: ARM: spectre-v2: harden user aborts in kernel space Commit f5fe12b1eaee220ce62ff9afb8b90929c396595f upstream. In order to prevent aliasing attacks on the branch predictor, invalidate the BTB or instruction cache on CPUs that are known to be affected when taking an abort on a address that is outside of a user task limit: Cortex A8, A9, A12, A17, A73, A75: flush BTB. Cortex A15, Brahma B15: invalidate icache. If the IBE bit is not set, then there is little point to enabling the workaround. Signed-off-by: Russell King Boot-tested-by: Tony Lindgren Reviewed-by: Tony Lindgren Signed-off-by: David A. Long Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/cp15.h | 3 +++ arch/arm/include/asm/system_misc.h | 15 +++++++++++++++ 2 files changed, 18 insertions(+) (limited to 'arch/arm/include') diff --git a/arch/arm/include/asm/cp15.h b/arch/arm/include/asm/cp15.h index 4c9fa72b59f5..07e27f212dc7 100644 --- a/arch/arm/include/asm/cp15.h +++ b/arch/arm/include/asm/cp15.h @@ -65,6 +65,9 @@ #define __write_sysreg(v, r, w, c, t) asm volatile(w " " c : : "r" ((t)(v))) #define write_sysreg(v, ...) __write_sysreg(v, __VA_ARGS__) +#define BPIALL __ACCESS_CP15(c7, 0, c5, 6) +#define ICIALLU __ACCESS_CP15(c7, 0, c5, 0) + extern unsigned long cr_alignment; /* defined in entry-armv.S */ static inline unsigned long get_cr(void) diff --git a/arch/arm/include/asm/system_misc.h b/arch/arm/include/asm/system_misc.h index 78f6db114faf..8e76db83c498 100644 --- a/arch/arm/include/asm/system_misc.h +++ b/arch/arm/include/asm/system_misc.h @@ -8,6 +8,7 @@ #include #include #include +#include extern void cpu_init(void); @@ -15,6 +16,20 @@ void soft_restart(unsigned long); extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd); extern void (*arm_pm_idle)(void); +#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR +typedef void (*harden_branch_predictor_fn_t)(void); +DECLARE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn); +static inline void harden_branch_predictor(void) +{ + harden_branch_predictor_fn_t fn = per_cpu(harden_branch_predictor_fn, + smp_processor_id()); + if (fn) + fn(); +} +#else +#define harden_branch_predictor() do { } while (0) +#endif + #define UDBG_UNDEFINED (1 << 0) #define UDBG_SYSCALL (1 << 1) #define UDBG_BADABORT (1 << 2) -- cgit v1.2.3