[PATCH v5 1/5] powerpc/sstep: Emulate prefixed instructions only when CPU_FTR_ARCH_31 is set

[Ravi Bangoria]

From: Balamuruhan S <bal...@linux.ibm.com>

Unconditional emulation of prefixed instructions will allow
emulation of them on Power10 predecessors which might cause
issues. Restrict that.

Fixes: 3920742b92f5 ("powerpc sstep: Add support for prefixed fixed-point 
arithmetic")
Fixes: 50b80a12e4cc ("powerpc sstep: Add support for prefixed load/stores")
Signed-off-by: Balamuruhan S <bal...@linux.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
---
 arch/powerpc/lib/sstep.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index e9dcaba9a4f8..e6242744c71b 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1346,6 +1346,9 @@ int analyse_instr(struct instruction_op *op, const struct 
pt_regs *regs,
        switch (opcode) {
 #ifdef __powerpc64__
        case 1:
+               if (!cpu_has_feature(CPU_FTR_ARCH_31))
+                       return -1;
+
                prefix_r = GET_PREFIX_R(word);
                ra = GET_PREFIX_RA(suffix);
                rd = (suffix >> 21) & 0x1f;
@@ -2733,6 +2736,9 @@ int analyse_instr(struct instruction_op *op, const struct 
pt_regs *regs,
                }
                break;
        case 1: /* Prefixed instructions */
+               if (!cpu_has_feature(CPU_FTR_ARCH_31))
+                       return -1;
+
                prefix_r = GET_PREFIX_R(word);
                ra = GET_PREFIX_RA(suffix);
                op->update_reg = ra;
-- 
2.26.2