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powerpc/sstep: Fix incorrect return from analyze_instr()

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commit 718aae916fa6619c57c348beaedd675835cf1aa1 upstream.

We currently just percolate the return value from analyze_instr()
to the caller of emulate_step(), especially if it is a -1.

For one particular case (opcode = 4) for instructions that aren't
currently emulated, we are returning 'should not be single-stepped'
while we should have returned 0 which says 'did not emulate, may
have to single-step'.

Fixes: 930d6288a2 ("powerpc: sstep: Add support for maddhd, maddhdu, maddld instructions")
Signed-off-by: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/161157999039.64773.14950289716779364766.stgit@thinktux.local
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ananth N Mavinakayanahalli 2021-01-25 18:36:43 +05:30 committed by Greg Kroah-Hartman
parent 20d323c8cf
commit 686fa5a0c6
1 changed files with 6 additions and 1 deletions
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7
arch/powerpc/lib/sstep.c
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@ -1382,6 +1382,11 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
#ifdef __powerpc64__
case 4:
/*
* There are very many instructions with this primary opcode
* introduced in the ISA as early as v2.03. However, the ones
* we currently emulate were all introduced with ISA 3.0
*/
if (!cpu_has_feature(CPU_FTR_ARCH_300))
goto unknown_opcode;
@ -1409,7 +1414,7 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
* There are other instructions from ISA 3.0 with the same
* primary opcode which do not have emulation support yet.
*/
return -1;
goto unknown_opcode;
#endif
case 7: /* mulli */