Re: [PATCH v3 06/12] signal: Implement SIL_FAULT_TRAPNO

[Marco Elver]

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xxxxxxxxxxxx> wrote:
> From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
>
> Now that si_trapno is part of the union in _si_fault and available on
> all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
> return SIL_FAULT_TRAPNO when si_trapno is actually used.
>
> Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
> and have the same code ignore si_trapno in in all other cases.
>
> v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@xxxxxxxxxxxxxxxxx
> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>

Reviewed-by: Marco Elver <elver@xxxxxxxxxx>


> ---
>  fs/signalfd.c          |  8 +++-----
>  include/linux/signal.h |  1 +
>  kernel/signal.c        | 37 +++++++++++++++----------------------
>  3 files changed, 19 insertions(+), 27 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 040a1142915f..e87e59581653 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -123,15 +123,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                  */
>         case SIL_FAULT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_trapno = kinfo->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 new.ssi_addr = (long) kinfo->si_addr;
> -#ifdef __ARCH_SI_TRAPNO
> -               new.ssi_trapno = kinfo->si_trapno;
> -#endif
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
>         case SIL_PERF_EVENT:
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 1e98548d7cf6..5160fd45e5ca 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -40,6 +40,7 @@ enum siginfo_layout {
>         SIL_TIMER,
>         SIL_POLL,
>         SIL_FAULT,
> +       SIL_FAULT_TRAPNO,
>         SIL_FAULT_MCEERR,
>         SIL_FAULT_BNDERR,
>         SIL_FAULT_PKUERR,
> diff --git a/kernel/signal.c b/kernel/signal.c
> index 65888aec65a0..3d3ba7949788 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>         case SIL_TIMER:
>         case SIL_POLL:
>         case SIL_FAULT:
> +       case SIL_FAULT_TRAPNO:
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>  {
>         switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
>         case SIL_FAULT:
> +       case SIL_FAULT_TRAPNO:
>         case SIL_FAULT_MCEERR:
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> @@ -3206,6 +3208,13 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                         if ((sig == SIGBUS) &&
>                             (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
>                                 layout = SIL_FAULT_MCEERR;
> +                       else if (IS_ENABLED(CONFIG_ALPHA) &&
> +                                ((sig == SIGFPE) ||
> +                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
> +                               layout = SIL_FAULT_TRAPNO;
> +                       else if (IS_ENABLED(CONFIG_SPARC) &&
> +                                (sig == SIGILL) && (si_code == ILL_ILLTRP))
> +                               layout = SIL_FAULT_TRAPNO;
>                         else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
>                                 layout = SIL_FAULT_BNDERR;
>  #ifdef SEGV_PKUERR
> @@ -3317,30 +3326,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>                 break;
>         case SIL_FAULT:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               to->si_addr = ptr_to_compat(from->si_addr);
>                 to->si_trapno = from->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_addr_lsb = from->si_addr_lsb;
>                 break;
>         case SIL_FAULT_BNDERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_lower = ptr_to_compat(from->si_lower);
>                 to->si_upper = ptr_to_compat(from->si_upper);
>                 break;
>         case SIL_FAULT_PKUERR:
>                 to->si_addr = ptr_to_compat(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_pkey = from->si_pkey;
>                 break;
>         case SIL_PERF_EVENT:
> @@ -3401,30 +3402,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>                 break;
>         case SIL_FAULT:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> +               break;
> +       case SIL_FAULT_TRAPNO:
> +               to->si_addr = compat_ptr(from->si_addr);
>                 to->si_trapno = from->si_trapno;
> -#endif
>                 break;
>         case SIL_FAULT_MCEERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_addr_lsb = from->si_addr_lsb;
>                 break;
>         case SIL_FAULT_BNDERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_lower = compat_ptr(from->si_lower);
>                 to->si_upper = compat_ptr(from->si_upper);
>                 break;
>         case SIL_FAULT_PKUERR:
>                 to->si_addr = compat_ptr(from->si_addr);
> -#ifdef __ARCH_SI_TRAPNO
> -               to->si_trapno = from->si_trapno;
> -#endif
>                 to->si_pkey = from->si_pkey;
>                 break;
>         case SIL_PERF_EVENT:
> --
> 2.30.1