linux-kernel - Re: [PATCH 6/6] of: Add KUnit test to confirm DTB is loaded

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Message-ID: <CABVgOSkFY_c5-=g2HeND4J4Fyxnx+_m0EtW8E=5JgJSRmXFdtg@mail.gmail.com>
Date: Wed, 24 Jan 2024 15:25:34 +0800
From: David Gow <davidgow@...gle.com>
To: Stephen Boyd <sboyd@...nel.org>
Cc: Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org, 
	patches@...ts.linux.dev, linux-um@...ts.infradead.org, 
	linux-arm-kernel@...ts.infradead.org, kunit-dev@...glegroups.com, 
	linux-kselftest@...r.kernel.org, devicetree@...r.kernel.org, 
	Frank Rowand <frowand.list@...il.com>, Brendan Higgins <brendan.higgins@...ux.dev>
Subject: Re: [PATCH 6/6] of: Add KUnit test to confirm DTB is loaded

On Tue, 23 Jan 2024 at 06:48, Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting David Gow (2024-01-15 21:03:12)
> > On Sat, 13 Jan 2024 at 04:07, Stephen Boyd <sboyd@...nel.org> wrote:
> > >
> > > Add a KUnit test that confirms a DTB has been loaded, i.e. there is a
> > > root node, and that the of_have_populated_dt() API works properly.
> > >
> > > Cc: Rob Herring <robh+dt@...nel.org>
> > > Cc: Frank Rowand <frowand.list@...il.com>
> > > Cc: David Gow <davidgow@...gle.com>
> > > Cc: Brendan Higgins <brendan.higgins@...ux.dev>
> > > Signed-off-by: Stephen Boyd <sboyd@...nel.org>
> > > ---
> >
> > I won't pretend to be a devicetree expert, but this looks good to me
> > from a KUnit point of view, and passes comfortably here.
> >
> > checkpatch seems to have one complaint about the kconfig help text.
> > Personally, I think the brief description is fine.
> >
> > Reviewed-by: David Gow <davidgow@...gle.com>
> >
>
> Thanks! I noticed that x86 has some devicetree init code. Did you happen
> to try on an x86 kvm instance? Or only run on UML?
>

I admit, I only tested on UML, plus a quick check that the default
kunitconfig wasn't broken on anything else.

A further look is showing:
aarch64: PASSED
UML: PASSED
UML LLVM: PASSED
powerpc64: PASSED
m68k: FAILED
i386: FAILED
x86_64: FAILED
x86_64 KASAN: FAILED

The failures are all of the form:
> [15:18:34] ============ of_have_populated_dt (2 subtests) =============
> [15:18:34] # of_have_populated_dt_false_when_flag_set: ASSERTION FAILED at drivers/of/of_test.c:53
> [15:18:34] Expected of_root is not null, but is
> [15:18:34] [FAILED] of_have_populated_dt_false_when_flag_set
> [15:18:34] # of_have_populated_dt_true_when_flag_clear: ASSERTION FAILED at drivers/of/of_test.c:70
> [15:18:34] Expected of_root is not null, but is
> [15:18:34] [FAILED] of_have_populated_dt_true_when_flag_clear
> [15:18:34]     # module: of_test
> [15:18:34] # of_have_populated_dt: pass:0 fail:2 skip:0 total:2
> [15:18:34] # Totals: pass:0 fail:2 skip:0 total:2
> [15:18:34] ============== [FAILED] of_have_populated_dt ===============

-- David

> ----8<----
> diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
> index afd09924094e..650752d112a6 100644
> --- a/arch/x86/kernel/devicetree.c
> +++ b/arch/x86/kernel/devicetree.c
> @@ -283,22 +283,24 @@ void __init x86_flattree_get_config(void)
>         u32 size, map_len;
>         void *dt;
>
> -       if (!initial_dtb)
> -               return;
> +       if (initial_dtb) {
> +               map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
>
> -       map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK), (u64)128);
> +               dt = early_memremap(initial_dtb, map_len);
> +               size = fdt_totalsize(dt);
> +               if (map_len < size) {
> +                       early_memunmap(dt, map_len);
> +                       dt = early_memremap(initial_dtb, size);
> +                       map_len = size;
> +               }
>
> -       dt = early_memremap(initial_dtb, map_len);
> -       size = fdt_totalsize(dt);
> -       if (map_len < size) {
> -               early_memunmap(dt, map_len);
> -               dt = early_memremap(initial_dtb, size);
> -               map_len = size;
> +               early_init_dt_verify(dt);
>         }
>
> -       early_init_dt_verify(dt);
>         unflatten_and_copy_device_tree();
> -       early_memunmap(dt, map_len);
> +
> +       if (initial_dtb)
> +               early_memunmap(dt, map_len);
>  }
>  #endif

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