The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 718aae916fa6619c57c348beaedd675835cf1aa1 Mon Sep 17 00:00:00 2001
From: Ananth N Mavinakayanahalli ananth@linux.ibm.com Date: Mon, 25 Jan 2021 18:36:43 +0530 Subject: [PATCH] powerpc/sstep: Fix incorrect return from analyze_instr()
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: 930d6288a26787 ("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@thin...
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index f859cbbb6375..e96cff845ef7 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -1445,6 +1445,11 @@ 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;
@@ -1472,7 +1477,7 @@ 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 */