x86, vdso: Make the vdso linker script compatible with Gold

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>
Link: http://lkml.kernel.org/r/243fa205098d112ec759c9b1b26785c09f399833.1396547532.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index 2e263f3..9df017a 100644 (file)
--- 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
 }