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author | Peter Zijlstra <peterz@infradead.org> | 2022-03-18 21:24:38 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-13 20:59:27 +0200 |
commit | f4f8b6d8490e1824e99b461dc869e4f46bc734ea (patch) | |
tree | 2d233460b97f3f2b044acb2e409a989883dc7078 /drivers/irqchip | |
parent | ff6505766565616deb65a203e62d4ca63c6c277b (diff) |
x86,static_call: Fix __static_call_return0 for i386
commit 1cd5f059d956e6f614ba6666ecdbcf95db05d5f5 upstream.
Paolo reported that the instruction sequence that is used to replace:
call __static_call_return0
namely:
66 66 48 31 c0 data16 data16 xor %rax,%rax
decodes to something else on i386, namely:
66 66 48 data16 dec %ax
31 c0 xor %eax,%eax
Which is a nonsensical sequence that happens to have the same outcome.
*However* an important distinction is that it consists of 2
instructions which is a problem when the thing needs to be overwriten
with a regular call instruction again.
As such, replace the instruction with something that decodes the same
on both i386 and x86_64.
Fixes: 3f2a8fc4b15d ("static_call/x86: Add __static_call_return0()")
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220318204419.GT8939@worktop.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/irqchip')
0 files changed, 0 insertions, 0 deletions