| commit | 0863b5e00d32b9adaf93226c893918af297b74f3 | |
| author | Jeremy Fitzhardinge <jeremy@goop.org> | |
| Thu, 3 Sep 2009 19:27:15 +0000 (3 12:27 -0700) | ||
| committer | Greg Kroah-Hartman <gregkh@suse.de> | |
| Thu, 24 Sep 2009 15:27:21 +0000 (24 08:27 -0700) | ||
| tree | df0a8b15ba1e9991e67c5b4a9aa721a634f31e42 | treesnapshot (tar.gz zip) |
| parent | 06849e6aac573df704bcb4889d4696cac6ecf8cd | commitdiff |
x86/i386: Make sure stack-protector segment base is cache aligned
commit 1ea0d14e480c245683927eecc03a70faf06e80c8 upstream.
The Intel Optimization Reference Guide says:
In Intel Atom microarchitecture, the address generation unit
assumes that the segment base will be 0 by default. Non-zero
segment base will cause load and store operations to experience
a delay.
- If the segment base isn't aligned to a cache line
boundary, the max throughput of memory operations is
reduced to one [e]very 9 cycles.
[...]
Assembly/Compiler Coding Rule 15. (H impact, ML generality)
For Intel Atom processors, use segments with base set to 0
whenever possible; avoid non-zero segment base address that is
not aligned to cache line boundary at all cost.
We can't avoid having a non-zero base for the stack-protector
segment, but we can make it cache-aligned.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
LKML-Reference: <4AA01893.6000507@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
commit 1ea0d14e480c245683927eecc03a70faf06e80c8 upstream.
The Intel Optimization Reference Guide says:
In Intel Atom microarchitecture, the address generation unit
assumes that the segment base will be 0 by default. Non-zero
segment base will cause load and store operations to experience
a delay.
- If the segment base isn't aligned to a cache line
boundary, the max throughput of memory operations is
reduced to one [e]very 9 cycles.
[...]
Assembly/Compiler Coding Rule 15. (H impact, ML generality)
For Intel Atom processors, use segments with base set to 0
whenever possible; avoid non-zero segment base address that is
not aligned to cache line boundary at all cost.
We can't avoid having a non-zero base for the stack-protector
segment, but we can make it cache-aligned.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
LKML-Reference: <4AA01893.6000507@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>