3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> commit f43c27188a49111b58e9611afa2f0365b0b55625 upstream. On arm64 the TTBR0_EL1 register is set to either the reserved TTBR0 page tables on boot or to the active_mm mappings belonging to user space processes, it must never be set to swapper_pg_dir page tables mappings. When a CPU is booted its active_mm is set to init_mm even though its TTBR0_EL1 points at the reserved TTBR0 page mappings. This implies that when __cpu_suspend is triggered the active_mm can point at init_mm even if the current TTBR0_EL1 register contains the reserved TTBR0_EL1 mappings. Therefore, the mm save and restore executed in __cpu_suspend might turn out to be erroneous in that, if the current->active_mm corresponds to init_mm, on resume from low power it ends up restoring in the TTBR0_EL1 the init_mm mappings that are global and can cause speculation of TLB entries which end up being propagated to user space. This patch fixes the issue by checking the active_mm pointer before restoring the TTBR0 mappings. If the current active_mm == &init_mm, the code sets the TTBR0_EL1 to the reserved TTBR0 mapping instead of switching back to the active_mm, which is the expected behaviour corresponding to the TTBR0_EL1 settings when __cpu_suspend was entered. Fixes: 95322526ef62 ("arm64: kernel: cpu_{suspend/resume} implementation") Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/kernel/suspend.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/arch/arm64/kernel/suspend.c +++ b/arch/arm64/kernel/suspend.c @@ -5,6 +5,7 @@ #include <asm/debug-monitors.h> #include <asm/pgtable.h> #include <asm/memory.h> +#include <asm/mmu_context.h> #include <asm/smp_plat.h> #include <asm/suspend.h> #include <asm/tlbflush.h> @@ -98,7 +99,18 @@ int __cpu_suspend(unsigned long arg, int */ ret = __cpu_suspend_enter(arg, fn); if (ret == 0) { - cpu_switch_mm(mm->pgd, mm); + /* + * We are resuming from reset with TTBR0_EL1 set to the + * idmap to enable the MMU; restore the active_mm mappings in + * TTBR0_EL1 unless the active_mm == &init_mm, in which case + * the thread entered __cpu_suspend with TTBR0_EL1 set to + * reserved TTBR0 page tables and should be restored as such. + */ + if (mm == &init_mm) + cpu_set_reserved_ttbr0(); + else + cpu_switch_mm(mm->pgd, mm); + flush_tlb_all(); /* -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html