Hi Greg,
On Thu, Nov 05, 2015 at 09:57:12PM -0800, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 4.1-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
The reason for that is a dependency on commit id:
commit af391b15f7b5 ("arm64: kernel: rename __cpu_suspend to keep it
aligned with arm")
that was not sent to stable since it was not a fix.
I applied the commit above and subsequently the $SUBJECT patch on
top of v4.1, tested the resulting tree and everything is fine, so
if you can apply the dependency above and then this patch I think
we are done, please let me know if that's reasonable and you need
more help.
Thank you very much !
Lorenzo
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From e13d918a19a7b6cba62b32884f5e336e764c2cc6 Mon Sep 17 00:00:00 2001
> From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Date: Tue, 27 Oct 2015 17:29:10 +0000
> Subject: [PATCH] arm64: kernel: fix tcr_el1.t0sz restore on systems with
> extended idmap
>
> Commit dd006da21646 ("arm64: mm: increase VA range of identity map")
> introduced a mechanism to extend the virtual memory map range
> to support arm64 systems with system RAM located at very high offset,
> where the identity mapping used to enable/disable the MMU requires
> additional translation levels to map the physical memory at an equal
> virtual offset.
>
> The kernel detects at boot time the tcr_el1.t0sz value required by the
> identity mapping and sets-up the tcr_el1.t0sz register field accordingly,
> any time the identity map is required in the kernel (ie when enabling the
> MMU).
>
> After enabling the MMU, in the cold boot path the kernel resets the
> tcr_el1.t0sz to its default value (ie the actual configuration value for
> the system virtual address space) so that after enabling the MMU the
> memory space translated by ttbr0_el1 is restored as expected.
>
> Commit dd006da21646 ("arm64: mm: increase VA range of identity map")
> also added code to set-up the tcr_el1.t0sz value when the kernel resumes
> from low-power states with the MMU off through cpu_resume() in order to
> effectively use the identity mapping to enable the MMU but failed to add
> the code required to restore the tcr_el1.t0sz to its default value, when
> the core returns to the kernel with the MMU enabled, so that the kernel
> might end up running with tcr_el1.t0sz value set-up for the identity
> mapping which can be lower than the value required by the actual virtual
> address space, resulting in an erroneous set-up.
>
> This patchs adds code in the resume path that restores the tcr_el1.t0sz
> default value upon core resume, mirroring this way the cold boot path
> behaviour therefore fixing the issue.
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Fixes: dd006da21646 ("arm64: mm: increase VA range of identity map")
> Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
>
> diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
> index 8297d502217e..44ca4143b013 100644
> --- a/arch/arm64/kernel/suspend.c
> +++ b/arch/arm64/kernel/suspend.c
> @@ -80,17 +80,21 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
> if (ret == 0) {
> /*
> * 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.
> + * idmap to enable the MMU; set the TTBR0 to the reserved
> + * page tables to prevent speculative TLB allocations, flush
> + * the local tlb and set the default tcr_el1.t0sz so that
> + * the TTBR0 address space set-up is properly restored.
> + * If the current active_mm != &init_mm we entered cpu_suspend
> + * with mappings in TTBR0 that must be restored, so we switch
> + * them back to complete the address space configuration
> + * restoration before returning.
> */
> - if (mm == &init_mm)
> - cpu_set_reserved_ttbr0();
> - else
> - cpu_switch_mm(mm->pgd, mm);
> -
> + cpu_set_reserved_ttbr0();
> flush_tlb_all();
> + cpu_set_default_tcr_t0sz();
> +
> + if (mm != &init_mm)
> + cpu_switch_mm(mm->pgd, mm);
>
> /*
> * Restore per-cpu offset before any kernel
>
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