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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: 3f2a8fc ("static_call/x86: Add __static_call_return0()") Reported-by: Paolo Bonzini <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
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