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| author |   Borislav Petkov <bp@suse.de> | 2020-08-20 11:10:15 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-08-24 10:23:40 +0200 |
| commit | 0b2c605fa4ee3117c00b97b7af67791576b28f88 (patch) | |
| tree | f9b6b5708f309aac92d8106ddd918662703cafce /arch/x86/entry/entry_64.S | |
| parent | Linux 5.9-rc2 (diff) | |
| download | wireguard-linux-0b2c605fa4ee3117c00b97b7af67791576b28f88.tar.xz wireguard-linux-0b2c605fa4ee3117c00b97b7af67791576b28f88.zip | |
x86/entry/64: Correct the comment over SAVE_AND_SET_GSBASE
Add the proper explanation why an LFENCE is not needed in the FSGSBASE
case.
Fixes: c82965f9e530 ("x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit")
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200821090710.GE12181@zn.tnic
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 70dea9337816..bf78de4de7f0 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -840,8 +840,9 @@ SYM_CODE_START_LOCAL(paranoid_entry) * retrieve and set the current CPUs kernel GSBASE. The stored value * has to be restored in paranoid_exit unconditionally. * - * The MSR write ensures that no subsequent load is based on a - * mispredicted GSBASE. No extra FENCE required. + * The unconditional write to GS base below ensures that no subsequent + * loads based on a mispredicted GS base can happen, therefore no LFENCE + * is needed here. */ SAVE_AND_SET_GSBASE scratch_reg=%rax save_reg=%rbx ret |