[PATCH] x86, vdso: Fix vdso-layout linker script

[PATCH] x86, vdso: Fix vdso-layout linker script

[Markus Trippelsdorf]

Commit 26f5ef2e3c3 added a /DISCARD/ section to the vdso-layout.lds.S
linker script. This broke the build when using the gold linker:

 ld: error: arch/x86/vdso/vdso.lds:79:12: syntax error, unexpected ':'
 ld: fatal error: unable to parse script file arch/x86/vdso/vdso.lds

As Cary Coutant pointed out on the sourceware bugzilla: 
https://sourceware.org/bugzilla/show_bug.cgi?id=16804  
the problem is that the .text section directly above the /DISCARD/
section should be terminated with an comma.

Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>

diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index 2e263f367b13..313bca59ddea 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -61,7 +61,7 @@ SECTIONS
 	 */
 	. = ALIGN(0x100);
 
-	.text		: { *(.text*) }			:text	=0x90909090
+	.text		: { *(.text*) }			:text	=0x90909090,
 
 	/DISCARD/ : {
 		*(.discard)
-- 
Markus

Re: [PATCH] x86, vdso: Fix vdso-layout linker script

[Andy Lutomirski]

On Thu, Apr 3, 2014 at 10:43 AM, Markus Trippelsdorf
<markus@trippelsdorf.de> wrote:
> Commit 26f5ef2e3c3 added a /DISCARD/ section to the vdso-layout.lds.S
> linker script. This broke the build when using the gold linker:
>
>  ld: error: arch/x86/vdso/vdso.lds:79:12: syntax error, unexpected ':'
>  ld: fatal error: unable to parse script file arch/x86/vdso/vdso.lds
>
> As Cary Coutant pointed out on the sourceware bugzilla:
> https://sourceware.org/bugzilla/show_bug.cgi?id=16804
> the problem is that the .text section directly above the /DISCARD/
> section should be terminated with an comma.
>
> Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>

This patch triggers an internal error in whatever version of gold I'm
using.  I'll send a variant of the patch when I finish testing it.

>
> diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
> index 2e263f367b13..313bca59ddea 100644
> --- a/arch/x86/vdso/vdso-layout.lds.S
> +++ b/arch/x86/vdso/vdso-layout.lds.S
> @@ -61,7 +61,7 @@ SECTIONS
>          */
>         . = ALIGN(0x100);
>
> -       .text           : { *(.text*) }                 :text   =0x90909090
> +       .text           : { *(.text*) }                 :text   =0x90909090,
>
>         /DISCARD/ : {
>                 *(.discard)
> --
> Markus



-- 
Andy Lutomirski
AMA Capital Management, LLC

[PATCH] x86, vdso: Make the vdso linker script compatible with Gold

[Andy Lutomirski]

Gold can't parse the script due to:
https://sourceware.org/bugzilla/show_bug.cgi?id=16804

With a workaround in place for that issue, Gold 2.23 crashes due to:
https://sourceware.org/bugzilla/show_bug.cgi?id=15355

This works around the former bug and avoids the second by removing
the unnecessary vvar and hpet sections and segments.  The vdso and
hpet symbols are still there, and nothing needed the sections or
segments.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
 arch/x86/vdso/vdso-layout.lds.S | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index 2e263f3..9df017a 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -9,12 +9,9 @@ SECTIONS
 #ifdef BUILD_VDSO32
 #include <asm/vdso32.h>
 
-	.hpet_sect : {
-		hpet_page = . - VDSO_OFFSET(VDSO_HPET_PAGE);
-	} :text :hpet_sect
+	hpet_page = . - VDSO_OFFSET(VDSO_HPET_PAGE);
 
-	.vvar_sect : {
-		vvar = . - VDSO_OFFSET(VDSO_VVAR_PAGE);
+	vvar = . - VDSO_OFFSET(VDSO_VVAR_PAGE);
 
 	/* Place all vvars at the offsets in asm/vvar.h. */
 #define EMIT_VVAR(name, offset) vvar_ ## name = vvar + offset;
@@ -22,7 +19,6 @@ SECTIONS
 #include <asm/vvar.h>
 #undef __VVAR_KERNEL_LDS
 #undef EMIT_VVAR
-	} :text :vvar_sect
 #endif
 	. = SIZEOF_HEADERS;
 
@@ -61,7 +57,12 @@ SECTIONS
 	 */
 	. = ALIGN(0x100);
 
-	.text		: { *(.text*) }			:text	=0x90909090
+	.text		: { *(.text*) }			:text	=0x90909090,
+
+	/*
+	 * The comma above works around a bug in gold:
+	 * https://sourceware.org/bugzilla/show_bug.cgi?id=16804
+	 */
 
 	/DISCARD/ : {
 		*(.discard)
@@ -84,8 +85,4 @@ PHDRS
 	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */
 	note		PT_NOTE		FLAGS(4);		/* PF_R */
 	eh_frame_hdr	PT_GNU_EH_FRAME;
-#ifdef BUILD_VDSO32
-	vvar_sect	PT_NULL		FLAGS(4);		/* PF_R */
-	hpet_sect	PT_NULL		FLAGS(4);		/* PF_R */
-#endif
 }
-- 
1.9.0