x86, paravirt: prevent gcc from generating the wrong addressing mode
Impact: fix crash on VMI (VMware) When we generate a call sequence for calling a paravirtualized function, we presume that the generated code is "call *0xXXXXX", which is a 6 byte opcode; this is larger than a normal direct call, and so we can patch a direct call over it. At the moment, however we give gcc enough rope to hang us by putting the address in a register and generating a two byte indirect-via-register call. Prevent this by explicitly dereferencing the function pointer and passing it into the asm as a constant. This prevents crashes in VMI, as it cannot handle unpatchable callsites. Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Alok Kataria <akataria@vmware.com> LKML-Reference: <49BEEDC2.2070809@goop.org> Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
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