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| author | Jiri Slaby <jslaby@suse.cz> | 2015-03-05 09:13:31 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-26 15:01:00 +0100 |
| commit | 99a9adcaf4b58031d8802c266b9166d558415c38 (patch) | |
| tree | c53c991e2aeadb1c24963df2a5f03e697fa09518 | |
| parent | 16329d3d06836a47ac9bc66867b0bd09dfb76ad9 (diff) | |
| download | lwn-99a9adcaf4b58031d8802c266b9166d558415c38.tar.gz lwn-99a9adcaf4b58031d8802c266b9166d558415c38.zip | |
x86/vdso: Fix the build on GCC5
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>
| -rw-r--r-- | arch/x86/vdso/vdso32/sigreturn.S | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/vdso/vdso32/sigreturn.S b/arch/x86/vdso/vdso32/sigreturn.S index 31776d0efc8c..d7ec4e251c0a 100644 --- 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: |