* [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64)
[not found] <bug-15931-131@http.sourceware.org/bugzilla/>
@ 2013-09-04 17:06 ` pchang9 at cs dot wisc.edu
2013-09-04 17:07 ` pchang9 at cs dot wisc.edu
` (4 subsequent siblings)
5 siblings, 0 replies; 6+ messages in thread
From: pchang9 at cs dot wisc.edu @ 2013-09-04 17:06 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15931
--- Comment #1 from Po-Chun Chang <pchang9 at cs dot wisc.edu> ---
Created attachment 7187
--> https://sourceware.org/bugzilla/attachment.cgi?id=7187&action=edit
Testing code
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64)
[not found] <bug-15931-131@http.sourceware.org/bugzilla/>
2013-09-04 17:06 ` [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64) pchang9 at cs dot wisc.edu
@ 2013-09-04 17:07 ` pchang9 at cs dot wisc.edu
2013-09-04 17:23 ` pchang9 at cs dot wisc.edu
` (3 subsequent siblings)
5 siblings, 0 replies; 6+ messages in thread
From: pchang9 at cs dot wisc.edu @ 2013-09-04 17:07 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15931
Po-Chun Chang <pchang9 at cs dot wisc.edu> changed:
What |Removed |Added
----------------------------------------------------------------------------
Attachment #7187|0 |1
is obsolete| |
--- Comment #2 from Po-Chun Chang <pchang9 at cs dot wisc.edu> ---
Created attachment 7188
--> https://sourceware.org/bugzilla/attachment.cgi?id=7188&action=edit
Testing code
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64)
[not found] <bug-15931-131@http.sourceware.org/bugzilla/>
2013-09-04 17:06 ` [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64) pchang9 at cs dot wisc.edu
2013-09-04 17:07 ` pchang9 at cs dot wisc.edu
@ 2013-09-04 17:23 ` pchang9 at cs dot wisc.edu
2013-09-04 20:54 ` jsm28 at gcc dot gnu.org
` (2 subsequent siblings)
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From: pchang9 at cs dot wisc.edu @ 2013-09-04 17:23 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15931
--- Comment #3 from Po-Chun Chang <pchang9 at cs dot wisc.edu> ---
Created attachment 7189
--> https://sourceware.org/bugzilla/attachment.cgi?id=7189&action=edit
Suggested patch
This patch simply clear the DF before doing "movsq", and retore after it is
done.
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64)
[not found] <bug-15931-131@http.sourceware.org/bugzilla/>
` (2 preceding siblings ...)
2013-09-04 17:23 ` pchang9 at cs dot wisc.edu
@ 2013-09-04 20:54 ` jsm28 at gcc dot gnu.org
2013-09-06 3:11 ` bugdal at aerifal dot cx
2014-06-13 12:56 ` fweimer at redhat dot com
5 siblings, 0 replies; 6+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2013-09-04 20:54 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15931
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |INVALID
--- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
The x86_64 ABI specifies (section 3.2.1) that 'The direction flag DF in the
%rFLAGS register must be clear (set to "forward" direction) on function entry
and return.'. Thus, it is not valid to call any library function with DF set,
and code that does so has undefined behavior.
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64)
[not found] <bug-15931-131@http.sourceware.org/bugzilla/>
` (3 preceding siblings ...)
2013-09-04 20:54 ` jsm28 at gcc dot gnu.org
@ 2013-09-06 3:11 ` bugdal at aerifal dot cx
2014-06-13 12:56 ` fweimer at redhat dot com
5 siblings, 0 replies; 6+ messages in thread
From: bugdal at aerifal dot cx @ 2013-09-06 3:11 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15931
Rich Felker <bugdal at aerifal dot cx> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugdal at aerifal dot cx
--- Comment #5 from Rich Felker <bugdal at aerifal dot cx> ---
Further, it should be noted that the original program that's failing is invalid
GNU C. The inline assembly block is modifying registers (the flags register)
without informing the compiler via the clobber list. Even without ANY
involvement of glibc, it could break; for example, the compiler itself could
generate "rep stosq" or "rep movsq" and have them run in the wrong direction
due to the direction flag having been changed out from under the compiler's
knowledge.
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^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug libc/15931] memcpy() has different behavior when statically linked (x86_64)
[not found] <bug-15931-131@http.sourceware.org/bugzilla/>
` (4 preceding siblings ...)
2013-09-06 3:11 ` bugdal at aerifal dot cx
@ 2014-06-13 12:56 ` fweimer at redhat dot com
5 siblings, 0 replies; 6+ messages in thread
From: fweimer at redhat dot com @ 2014-06-13 12:56 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15931
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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