LoongArch: Fix oops during single-step debugging

When entering KDB via a breakpoint and then performing single-step
debugging, an oops is triggered. Now during single-step debugging,
kdb_local() expects the reason to be KDB_REASON_SSTEP, but it is
actually KDB_REASON_OOPS. In kdb_stub(), when determining the reason,
the ex_vector for single-step should be 0, as already implemented on
other architectures such as arm64 and riscv.

Before the patch:
[112]kdb> ss

Entering kdb (current=0x900020009f520000, pid 10661) on
processor 112 Oops: (null)
due to oops @ 0x90000000005b57a4

Cc: stable@vger.kernel.org
Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/kernel/kgdb.c b/arch/loongarch/kernel/kgdb.c
index 17664a6043b1e0f092798b523c27e4f57957b2b3..e7b59f8a4b05bb1b8ec15fba1100fa03ea28e712 100644 (file)
--- a/arch/loongarch/kernel/kgdb.c
+++ b/arch/loongarch/kernel/kgdb.c
@@ -252,7 +252,8 @@ static int kgdb_loongarch_notify(struct notifier_block *self, unsigned long cmd,
        if (atomic_read(&kgdb_active) != -1)
                kgdb_nmicallback(smp_processor_id(), regs);
 
-       if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
+       if (kgdb_handle_exception(regs->csr_era == stepped_address ? 0 : args->trapnr,
+                                 args->signr, cmd, regs))
                return NOTIFY_DONE;
 
        if (atomic_read(&kgdb_setting_breakpoint))