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| author | Peter Zijlstra <peterz@infradead.org> | 2022-03-18 21:24:38 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-04-05 09:59:37 +0200 |
| commit | 1cd5f059d956e6f614ba6666ecdbcf95db05d5f5 (patch) | |
| tree | 67088bbdb10a57988b8cc323e65abb0cb20c865e /kernel/static_call_inline.c | |
| parent | 3123109284176b1532874591f7c81f3837bbdc17 (diff) | |
x86,static_call: Fix __static_call_return0 for i386
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
Diffstat (limited to 'kernel/static_call_inline.c')
0 files changed, 0 insertions, 0 deletions