linux_dsm_epyc7002/arch/arm64
Lorenzo Pieralisi f43c27188a arm64: kernel: fix __cpu_suspend mm switch on warm-boot
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: 95322526ef ("arm64: kernel: cpu_{suspend/resume} implementation")
Cc: <stable@vger.kernel.org> # 3.14+: 18ab7db
Cc: <stable@vger.kernel.org> # 3.14+: 714f599
Cc: <stable@vger.kernel.org> # 3.14+: c3684fb
Cc: <stable@vger.kernel.org> # 3.14+
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-12-23 16:38:50 +00:00
..
boot ARM64: SoC changes for 3.19 2014-12-09 17:17:47 -08:00
configs arm64: defconfig: update defconfig for 3.18 2014-11-05 17:07:58 +00:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2014-12-13 13:33:26 -08:00
include arm64: Replace set_arch_dma_coherent_ops with arch_setup_dma_ops 2014-12-22 09:26:32 +00:00
kernel arm64: kernel: fix __cpu_suspend mm switch on warm-boot 2014-12-23 16:38:50 +00:00
kvm 3.19 changes for KVM: 2014-12-18 16:05:28 -08:00
lib arm64: __clear_user: handle exceptions on strb 2014-11-13 15:21:26 +00:00
mm arm64: mm: dump: don't skip final region 2014-12-11 12:08:07 +00:00
net arm64: bpf: lift restriction on last instruction 2014-12-03 18:04:09 +00:00
xen arm: xen: implement multicall hypercall support. 2014-04-24 13:09:46 +01:00
Kconfig Merge branch 'irq-irqdomain-arm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-15 17:30:09 -08:00
Kconfig.debug arm64: add support to dump the kernel page tables 2014-11-26 17:19:18 +00:00
Makefile dts, arm/arm64: Remove dtbs build rules in sub-makes 2014-10-21 18:06:58 +02:00