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| author | Al Viro <viro@ZenIV.linux.org.uk> | 2013-09-01 21:35:01 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-09-01 23:16:33 +0200 |
| commit | bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 (patch) | |
| tree | 1ccdf876f778bd986a6238d379ee9e9981ed98dc /virt/kvm/kvm_main.c | |
| parent | x86, smap: Handle csum_partial_copy_*_user() (diff) | |
| download | linux-bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5.tar.xz linux-bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5.zip | |
Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP
For performance reasons, when SMAP is in use, SMAP is left open for an
entire put_user_try { ... } put_user_catch(); block, however, calling
__put_user() in the middle of that block will close SMAP as the
STAC..CLAC constructs intentionally do not nest.
Furthermore, using __put_user() rather than put_user_ex() here is bad
for performance.
Thus, introduce new [compat_]save_altstack_ex() helpers that replace
__[compat_]save_altstack() for x86, being currently the only
architecture which supports put_user_try { ... } put_user_catch().
Reported-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.8+
Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org
Diffstat (limited to 'virt/kvm/kvm_main.c')
0 files changed, 0 insertions, 0 deletions