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author | Peter Zijlstra <peterz@infradead.org> | 2022-06-15 00:15:48 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-07-25 12:26:40 +0300 |
commit | df748593c55389892902aecb8691080ad5e8cff5 (patch) | |
tree | 03a1cabfc730b02737c916f0517a0e87c193cb51 /include | |
parent | c70d6f82141b89db6c076b0cbf9a7a2edc29e46d (diff) | |
download | linux-df748593c55389892902aecb8691080ad5e8cff5.tar.xz |
x86: Add magic AMD return-thunk
commit a149180fbcf336e97ce4eb2cdc13672727feb94d upstream.
Note: needs to be in a section distinct from Retpolines such that the
Retpoline RET substitution cannot possibly use immediate jumps.
ORC unwinding for zen_untrain_ret() and __x86_return_thunk() is a
little tricky but works due to the fact that zen_untrain_ret() doesn't
have any stack ops and as such will emit a single ORC entry at the
start (+0x3f).
Meanwhile, unwinding an IP, including the __x86_return_thunk() one
(+0x40) will search for the largest ORC entry smaller or equal to the
IP, these will find the one ORC entry (+0x3f) and all works.
[ Alexandre: SVM part. ]
[ bp: Build fix, massages. ]
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: conflicts at arch/x86/entry/entry_64_compat.S]
[cascardo: there is no ANNOTATE_NOENDBR]
[cascardo: objtool commit 34c861e806478ac2ea4032721defbf1d6967df08 missing]
[cascardo: conflict fixup]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
[bwh: Backported to 5.10: SEV-ES is not supported, so drop the change
in arch/x86/kvm/svm/vmenter.S]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions