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powerpc: Send SIGBUS on unaligned copy and paste

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Calling ISA 3.0 instructions copy, copy_first, paste and paste_last
generates an alignment fault when copying or pasting unaligned
data (128 byte). We catch this and send SIGBUS to the userspace
process that caused it.

We do not emulate these because paste may contain additional metadata
when pasting to a co-processor and paste_last is the synchronisation
point for preceding copy/paste sequences.

Thanks to Michael Neuling <mikey@neuling.org> for his help.

Signed-off-by: Chris Smart <chris@distroguy.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Chris Smart
2016-06-17 09:33:45 +10:00
committed by Michael Ellerman
parent 0c63e8b7b9
commit ae26b36f80
2 changed files with 18 additions and 0 deletions
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14
arch/powerpc/kernel/align.c
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@@ -873,6 +873,20 @@ int fix_alignment(struct pt_regs *regs)
return emulate_vsx(addr, reg, areg, regs, flags, nb, elsize);
}
#endif
/*
* ISA 3.0 (such as P9) copy, copy_first, paste and paste_last alignment
* check.
*
* Send a SIGBUS to the process that caused the fault.
*
* We do not emulate these because paste may contain additional metadata
* when pasting to a co-processor. Furthermore, paste_last is the
* synchronisation point for preceding copy/paste sequences.
*/
if ((instruction & 0xfc0006fe) == PPC_INST_COPY)
return -EIO;
/* A size of 0 indicates an instruction we don't support, with
* the exception of DCBZ which is handled as a special case here
*/