| Date | Thu, 18 Jan 2018 14:48:30 +0100 | From | Peter Zijlstra <> | From | Peter Zijlstra <> | Subject | [PATCH 30/35] x86/speculation: Use Indirect Branch Prediction Barrier in context switch |
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From: Thomas Gleixner <tglx@linutronix.de>
[peterz: comment]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/mm/tlb.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -6,13 +6,14 @@ #include <linux/interrupt.h> #include <linux/export.h> #include <linux/cpu.h> +#include <linux/debugfs.h> #include <asm/tlbflush.h> #include <asm/mmu_context.h> +#include <asm/nospec-branch.h> #include <asm/cache.h> #include <asm/apic.h> #include <asm/uv/uv.h> -#include <linux/debugfs.h> /* * TLB flushing, formerly SMP-only @@ -220,6 +221,13 @@ void switch_mm_irqs_off(struct mm_struct u16 new_asid; bool need_flush; + /* + * Avoid user/user BTB poisoning by flushing the branch predictor + * when switching between processes. This stops one process from + * doing spectre-v2 attacks on another process's data. + */ + indirect_branch_prediction_barrier(); + if (IS_ENABLED(CONFIG_VMAP_STACK)) { /* * If our current stack is in vmalloc space and isn't
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