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| author | Andy Lutomirski <luto@kernel.org> | 2015-04-26 16:47:59 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-26 17:57:38 -0700 |
| commit | 61f01dd941ba9e06d2bf05994450ecc3d61b6b8b (patch) | |
| tree | 3a4a4ef2d5e4d44bb4cb1708f9fc4749e9c9824a /Documentation/RCU/UP.txt | |
| parent | 1190944f4b12203330ac5ed8784f6c181bf26f2d (diff) | |
| download | linux-61f01dd941ba9e06d2bf05994450ecc3d61b6b8b.tar.bz2 | |
x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue
AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with
SS == 0 results in an invalid usermode state in which SS is apparently
equal to __USER_DS but causes #SS if used.
Work around the issue by setting SS to __KERNEL_DS __switch_to, thus
ensuring that SYSRET never happens with SS set to NULL.
This was exposed by a recent vDSO cleanup.
Fixes: e7d6eefaaa44 x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/RCU/UP.txt')
0 files changed, 0 insertions, 0 deletions