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Date:   Tue, 8 Dec 2020 23:01:57 +1100
From:   Stephen Rothwell <sfr@canb.auug.org.au>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        PowerPC <linuxppc-dev@lists.ozlabs.org>,
        Mathieu Malaterre <malat@debian.org>,
        Nicholas Piggin <npiggin@gmail.com>
Subject: Re: linux-next: build warning after merge of the akpm tree
Message-ID: <20201208230157.42c42789@canb.auug.org.au>
In-Reply-To: <20201204210000.660293c6@canb.auug.org.au>
References: <20201204210000.660293c6@canb.auug.org.au>
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Hi Stephen,

On Fri, 4 Dec 2020 21:00:00 +1100 Stephen Rothwell <sfr@canb.auug.org.au> w=
rote:
>
> Hi all,
>=20
> After merging the akpm tree, today's linux-next build (powerpc
> allyesconfig) produced warnings like this:
>=20
> ld: warning: orphan section `.data..Lubsan_data177' from `arch/powerpc/op=
rofile/op_model_pa6t.o' being placed in section `.data..Lubsan_data177'
>=20
> (lots of these latter ones)

781584 of them today!

> I don't know what produced these, but it is in the akpm-current or
> akpm trees.

Presumably the result of commit

  186c3e18dba3 ("ubsan: enable for all*config builds")

from the akpm-current tree.

arch/powerpc/kernel/vmlinux.lds.S has:

#ifdef CONFIG_PPC32
        .data : AT(ADDR(.data) - LOAD_OFFSET) {
                DATA_DATA
#ifdef CONFIG_UBSAN
                *(.data..Lubsan_data*)
                *(.data..Lubsan_type*)
#endif
                *(.data.rel*)
                *(SDATA_MAIN)

added by commit

  beba24ac5913 ("powerpc/32: Add .data..Lubsan_data*/.data..Lubsan_type* se=
ctions explicitly")

in 2018, but no equivalent for 64 bit.

I will try the following patch tomorrow:

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Tue, 8 Dec 2020 22:58:24 +1100
Subject: [PATCH] powerpc: Add .data..Lubsan_data*/.data..Lubsan_type* secti=
ons explicitly

Similarly to commit

  beba24ac5913 ("powerpc/32: Add .data..Lubsan_data*/.data..Lubsan_type* se=
ctions explicitly")

since CONFIG_UBSAN bits can now be enabled for all*config.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
 arch/powerpc/kernel/vmlinux.lds.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinu=
x.lds.S
index 3b4c26e94328..0318ba436f34 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -296,6 +296,10 @@ SECTIONS
 #else
 	.data : AT(ADDR(.data) - LOAD_OFFSET) {
 		DATA_DATA
+#ifdef CONFIG_UBSAN
+		*(.data..Lubsan_data*)
+		*(.data..Lubsan_type*)
+#endif
 		*(.data.rel*)
 		*(.toc1)
 		*(.branch_lt)
--=20
2.29.2

--=20
Cheers,
Stephen Rothwell

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