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From: Joel Stanley <joel@jms.id.au>
To: linuxppc-dev@lists.ozlabs.org
Cc: Stephen Rothwell <sfr@canb.auug.org.au>, Alan Modra <amodra@gmail.com>
Subject: [PATCH v3 3/3] powerpc: Discard .branch_lt section
Date: Tue, 11 Dec 2018 08:58:54 +1030	[thread overview]
Message-ID: <20181210222854.21156-4-joel@jms.id.au> (raw)
In-Reply-To: <20181210222854.21156-1-joel@jms.id.au>

When building a 32 bit powerpc kernel with Binutils 2.31.1 this warning
is emitted:

 powerpc-linux-gnu-ld: warning: orphan section `.branch_lt' from
 `arch/powerpc/kernel/head_44x.o' being placed in section `.branch_lt'

As of binutils commit 2d7ad24e8726 ("Support PLT16 relocs against local
symbols")[1], 32 bit targets can produce .branch_lt sections in their
output.

These sections should be empty for the kernel build so discard them for
both PPC64 and PPC32.

[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commitdiff;h=2d7ad24e8726ba4c45c9e67be08223a146a837ce
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
v2: Discard instead of keep. Alan said "[discarding] can be a recipe for
finding linker bugs", so lets go with that.
---
 arch/powerpc/kernel/vmlinux.lds.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 2c93a420f456..af0f81df8bb9 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -316,7 +316,6 @@ SECTIONS
 		DATA_DATA
 		*(.data.rel*)
 		*(.toc1)
-		*(.branch_lt)
 	}
 
 	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
@@ -388,6 +387,7 @@ SECTIONS
 		*(.hash .gnu.hash)
 		*(.interp)
 		*(.dynstr)
+		*(.branch_lt)
 #ifndef CONFIG_PPC32
 		*(.dynsym)
 #endif
-- 
2.19.1


      parent reply	other threads:[~2018-12-10 22:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-10 22:28 [PATCH v3 0/3] powerpc: Add to linker script discards Joel Stanley
2018-12-10 22:28 ` [PATCH v3 1/3] powerpc: Discard more sections in linker script Joel Stanley
2018-12-20 11:18   ` Michael Ellerman
2018-12-10 22:28 ` [PATCH v3 2/3] powerpc: Discard dynsym section for !PPC32 Joel Stanley
2018-12-20 11:20   ` Michael Ellerman
2018-12-10 22:28 ` Joel Stanley [this message]

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