Re: [PATCH 1/2] arm64: Reduce add_map() complexity

Fabio Estevam
2024-03-08T20:23:12Z

Hi Paul and Tom,

On Tue, Feb 14, 2023 at 10:38 AM Ying-Chun Liu (PaulLiu)
<paul.liu@linaro.org> wrote:
>
> From: Marc Zyngier <maz@kernel.org>
>
> In the add_map() function, for each level it populates, it iterates from
> the root of the PT tree, making it ineficient if a mapping needs to occur
> past level 1.
>
> Instead, replace it with a recursive (and much simpler) algorithm
> that keeps the complexity as low as possible. With this, mapping
> 512GB at level 2 goes from several seconds down to not measurable
> on an A55 machine.
>
> We keep the block mappings at level 1 for now though.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
> [ Paul: pick from the Android tree. Fixup Pierre's commit. Rebase to the
> upstream ]
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
> Cc: Tom Rini <trini@konsulko.com>
> Link: https://android.googlesource.com/platform/external/u-boot/+/96ad729cf4cab53bdff8222bb3eb256f38b5c3a6
> Link: https://android.googlesource.com/platform/external/u-boot/+/6be9330601d81545c7c941e3609f35bf68a09059

I know this is an old thread, but this commit causes the following
boot regression on a colibri-imx8qxp board:

U-Boot 2024.04-rc3-00070-gecc9298a893b (Mar 08 2024 - 17:15:31 -0300)

CPU: NXP i.MX8QXP RevC A35 at 1200 MHz at 51C

DRAM: 2 GiB
"Error" handler, esr 0xbf000000
elr: 0000000080020914 lr : 00000000800209c0 (reloc)
elr: 00000000ffec4914 lr : 00000000ffec49c0
x0 : 0060000070800401 x1 : 0000000070000000
x2 : 0000000010000000 x3 : 0000000000000002
x4 : 0000000040000000 x5 : 0060000000000401
x6 : 0000000000000c00 x7 : 00000000fff45140
x8 : 0060000000000000 x9 : 00000000fff45100
x10: 000000000a200023 x11: 0000000000000002
x12: 0000000000000002 x13: 00000000800a10e8
x14: 00000000ffffffff x15: 00000000ffec4cb8
x16: 0000000080056a88 x17: 0000000000000000
x18: 00000000fd6c1d70 x19: 000000000f600000
x20: 0000000000000000 x21: 0060000000000401
x22: 0000000070a00000 x23: 0000000000200000
x24: 0000000040000c28 x25: 00000000001fffff
x26: 0000000000000003 x27: 0000000070a00000
x28: 0000000000000002 x29: 00000000fd6bbfd0

Code: 1100047a a90573fb aa0103fb 2a0303fc (b5000113)
Resetting CPU ...

resetting ...

Reverting this commit on top of master fixes the boot regression.

Any ideas?

Thanks