The patch below does not apply to the 5.10-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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 718aae916fa6619c57c348beaedd675835cf1aa1 Mon Sep 17 00:00:00 2001
From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Tested-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Sandipan Das <sandipan@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/161157999039.64773.14950289716779364766.stgit@thinktux.local
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 */
