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Commit c69cccc9 authored by Segher Boessenkool's avatar Segher Boessenkool Committed by Benjamin Herrenschmidt
Browse files

powerpc: Fix build bug with binutils < 2.18 and GCC < 4.2 



binutils < 2.18 has a bug that makes it misbehave when taking an
ELF file with all segments at load address 0 as input.  This
happens when running "strip" on vmlinux, because of the AT() magic
in this linker script.  People using GCC >= 4.2 won't run into
this problem, because the "build-id" support will put some data
into the "notes" segment (at a non-zero load address).

To work around this, we force some data into both the "dummy"
segment and the kernel segment, so the dummy segment will get a
non-zero load address.  It's not enough to always create the
"notes" segment, since if nothing gets assigned to it, its load
address will be zero.

Signed-off-by: default avatarSegher Boessenkool <segher@kernel.crashing.org>
Tested-By: default avatarMilton Miller <miltonm@bga.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent f36c5227

arch/powerpc/kernel/vmlinux.lds.S

+28 −3
Original line number Diff line number Diff line
@@ -9,6 +9,25 @@ 


ENTRY(_stext)



PHDRS {

	kernel PT_LOAD FLAGS(7); /* RWX */

	notes PT_NOTE FLAGS(0);

	dummy PT_NOTE FLAGS(0);



	/* binutils < 2.18 has a bug that makes it misbehave when taking an

	   ELF file with all segments at load address 0 as input.  This

	   happens when running "strip" on vmlinux, because of the AT() magic

	   in this linker script.  People using GCC >= 4.2 won't run into

	   this problem, because the "build-id" support will put some data

	   into the "notes" segment (at a non-zero load address).



	   To work around this, we force some data into both the "dummy"

	   segment and the kernel segment, so the dummy segment will get a

	   non-zero load address.  It's not enough to always create the

	   "notes" segment, since if nothing gets assigned to it, its load

	   address will be zero.  */

}



#ifdef CONFIG_PPC64

OUTPUT_ARCH(powerpc:common64)

jiffies = jiffies_64;
@@ -50,7 +69,7 @@ SECTIONS 
		. = ALIGN(PAGE_SIZE);

		_etext = .;

		PROVIDE32 (etext = .);

	}

	} :kernel



	/* Read-only data */

	RODATA
@@ -62,7 +81,13 @@ SECTIONS 
		__stop___ex_table = .;

	}



	NOTES

	NOTES :kernel :notes



	/* The dummy segment contents for the bug workaround mentioned above

	   near PHDRS.  */

	.dummy : {

		LONG(0xf177)

	} :kernel :dummy



/*

 * Init sections discarded at runtime
@@ -74,7 +99,7 @@ SECTIONS 
		_sinittext = .;

		INIT_TEXT

		_einittext = .;

	}

	} :kernel



	/* .exit.text is discarded at runtime, not link time,

	 * to deal with references from __bug_table