Commit 92b4dc16 authored May 28, 2005 by Kumar Gala Committed by Linus Torvalds May 28, 2005

[PATCH] ppc32: Simplified load string emulation error checking



The error checking for emulation of load string instructions was overly
generous and would cause certain valid forms of the instructions to be
treated as illegal.  We drop the range checking since the architecture
allows this to be boundedly undefined.  Tests on CPUs that support these
instructions appear not do cause illegal instruction traps on range errors
and just allow the execution to occur.

Thanks to Kim Phillips for debugging this and figuring out what real HW was
doing.

Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 91f9855a

arch/ppc/kernel/traps.c

+1 −6

Original line number	Diff line number	Diff line
		@@ -408,12 +408,7 @@ static int emulate_string_inst(struct pt_regs *regs, u32 instword)

		/* Early out if we are an invalid form of lswx */
		if ((instword & INST_STRING_MASK) == INST_LSWX)
		if ((rA >= rT) \|\| (NB_RB >= rT) \|\| (rT == rA) \|\| (rT == NB_RB))
		return -EINVAL;

		/* Early out if we are an invalid form of lswi */
		if ((instword & INST_STRING_MASK) == INST_LSWI)
		if ((rA >= rT) \|\| (rT == rA))
		if ((rT == rA) \|\| (rT == NB_RB))
		return -EINVAL;

		EA = (rA == 0) ? 0 : regs->gpr[rA];

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