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powerpc: Send SIGBUS on unaligned copy and paste 

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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4
arch/powerpc/include/asm/ppc-opcode.h
View File

@ -131,6 +131,8 @@
/* sorted alphabetically */
#define PPC_INST_BHRBE 0x7c00025c
#define PPC_INST_CLRBHRB 0x7c00035c
#define PPC_INST_COPY 0x7c00060c
#define PPC_INST_COPY_FIRST 0x7c20060c
#define PPC_INST_CP_ABORT 0x7c00068c
#define PPC_INST_DCBA 0x7c0005ec
#define PPC_INST_DCBA_MASK 0xfc0007fe
@ -161,6 +163,8 @@
#define PPC_INST_MSGSNDP 0x7c00011c
#define PPC_INST_MTTMR 0x7c0003dc
#define PPC_INST_NOP 0x60000000
#define PPC_INST_PASTE 0x7c00070c
#define PPC_INST_PASTE_LAST 0x7c20070d
#define PPC_INST_POPCNTB 0x7c0000f4
#define PPC_INST_POPCNTB_MASK 0xfc0007fe
#define PPC_INST_POPCNTD 0x7c0003f4

14
arch/powerpc/kernel/align.c
View File

@ -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
*/