| From e893286918d2cde3a94850d8f7101cd1039e0c62 Mon Sep 17 00:00:00 2001 |
| From: Jiri Slaby <jslaby@suse.cz> |
| Date: Thu, 5 Mar 2015 09:13:31 +0100 |
| Subject: x86/vdso: Fix the build on GCC5 |
| |
| From: Jiri Slaby <jslaby@suse.cz> |
| |
| commit e893286918d2cde3a94850d8f7101cd1039e0c62 upstream. |
| |
| On gcc5 the kernel does not link: |
| |
| ld: .eh_frame_hdr table[4] FDE at 0000000000000648 overlaps table[5] FDE at 0000000000000670. |
| |
| Because prior GCC versions always emitted NOPs on ALIGN directives, but |
| gcc5 started omitting them. |
| |
| .LSTARTFDEDLSI1 says: |
| |
| /* HACK: The dwarf2 unwind routines will subtract 1 from the |
| return address to get an address in the middle of the |
| presumed call instruction. Since we didn't get here via |
| a call, we need to include the nop before the real start |
| to make up for it. */ |
| .long .LSTART_sigreturn-1-. /* PC-relative start address */ |
| |
| But commit 69d0627a7f6e ("x86 vDSO: reorder vdso32 code") from 2.6.25 |
| replaced .org __kernel_vsyscall+32,0x90 by ALIGN right before |
| __kernel_sigreturn. |
| |
| Of course, ALIGN need not generate any NOP in there. Esp. gcc5 collapses |
| vclock_gettime.o and int80.o together with no generated NOPs as "ALIGN". |
| |
| So fix this by adding to that point at least a single NOP and make the |
| function ALIGN possibly with more NOPs then. |
| |
| Kudos for reporting and diagnosing should go to Richard. |
| |
| Reported-by: Richard Biener <rguenther@suse.de> |
| Signed-off-by: Jiri Slaby <jslaby@suse.cz> |
| Acked-by: Andy Lutomirski <luto@amacapital.net> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: H. Peter Anvin <hpa@zytor.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Link: http://lkml.kernel.org/r/1425543211-12542-1-git-send-email-jslaby@suse.cz |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/vdso/vdso32/sigreturn.S | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/arch/x86/vdso/vdso32/sigreturn.S |
| +++ b/arch/x86/vdso/vdso32/sigreturn.S |
| @@ -17,6 +17,7 @@ |
| .text |
| .globl __kernel_sigreturn |
| .type __kernel_sigreturn,@function |
| + nop /* this guy is needed for .LSTARTFDEDLSI1 below (watch for HACK) */ |
| ALIGN |
| __kernel_sigreturn: |
| .LSTART_sigreturn: |
