Re: [PATCH] powerpc/interrupt: Do not call single_step_exception() from other exceptions

From: Nicholas Piggin
Date: Thu Aug 12 2021 - 06:01:18 EST


Excerpts from Christophe Leroy's message of August 11, 2021 2:13 am:
> single_step_exception() is called by emulate_single_step() which
> is called from (at least) alignment exception() handler and
> program_check_exception() handler.
>
> Redefine it as a regular __single_step_exception() which is called
> by both single_step_exception() handler and emulate_single_step()
> function.
>

Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>

> Fixes: 3a96570ffceb ("powerpc: convert interrupt handlers to use wrappers")
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Stan Johnson <userm57@xxxxxxxxx>
> Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> Cc: Finn Thain <fthain@xxxxxxxxxxxxxx>
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> ---
> arch/powerpc/kernel/traps.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index dfbce527c98e..d56254f05e17 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -1104,7 +1104,7 @@ DEFINE_INTERRUPT_HANDLER(RunModeException)
> _exception(SIGTRAP, regs, TRAP_UNK, 0);
> }
>
> -DEFINE_INTERRUPT_HANDLER(single_step_exception)
> +static void __single_step_exception(struct pt_regs *regs)
> {
> clear_single_step(regs);
> clear_br_trace(regs);
> @@ -1121,6 +1121,11 @@ DEFINE_INTERRUPT_HANDLER(single_step_exception)
> _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
> }
>
> +DEFINE_INTERRUPT_HANDLER(single_step_exception)
> +{
> + __single_step_exception(regs);
> +}
> +
> /*
> * After we have successfully emulated an instruction, we have to
> * check if the instruction was being single-stepped, and if so,
> @@ -1130,7 +1135,7 @@ DEFINE_INTERRUPT_HANDLER(single_step_exception)
> static void emulate_single_step(struct pt_regs *regs)
> {
> if (single_stepping(regs))
> - single_step_exception(regs);
> + __single_step_exception(regs);
> }
>
> static inline int __parse_fpscr(unsigned long fpscr)
> --
> 2.25.0
>
>