Re: [PATCH 6/6] signal: Remove the generic __ARCH_SI_TRAPNO support

From: Marco Elver <elver@google.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Florian Weimer <fweimer@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Collingbourne <pcc@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Alexander Potapenko <glider@google.com>,
	sparclinux <sparclinux@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: [PATCH 6/6] signal: Remove the generic __ARCH_SI_TRAPNO support
Date: Fri, 16 Jul 2021 13:48:18 +0200	[thread overview]
Message-ID: <CANpmjNOv4mf3PiEVvAUFAXkRaA3V37UBYoB2j2P7_qF868B6mA@mail.gmail.com> (raw)
In-Reply-To: <87bl73xx6x.fsf_-_@disp2133>

On Thu, 15 Jul 2021 at 20:13, Eric W. Biederman <ebiederm@xmission.com> wrote:
> Now that __ARCH_SI_TRAPNO is no longer set by any architecture remove
> all of the code it enabled from the kernel.
>
> On alpha and sparc a more explict approach of using
> send_sig_fault_trapno or force_sig_fault_trapno in the very limited
> circumstances where si_trapno was set to a non-zero value.
>
> The generic support that is being removed always set si_trapno on all
> fault signals.  With only SIGILL ILL_ILLTRAP on sparc and SIGFPE and
> SIGTRAP TRAP_UNK on alpla providing si_trapno values asking all senders
> of fault signals to provide an si_trapno value does not make sense.
>
> Making si_trapno an ordinary extension of the fault siginfo layout has
> enabled the architecture generic implementation of SIGTRAP TRAP_PERF,
> and enables other faulting signals to grow architecture generic
> senders as well.
>
> v1: https://lkml.kernel.org/r/m18s4zs7nu.fsf_-_@fess.ebiederm.org
> v2: https://lkml.kernel.org/r/20210505141101.11519-8-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  arch/mips/include/uapi/asm/siginfo.h |  2 --
>  include/linux/sched/signal.h         |  8 --------
>  kernel/signal.c                      | 14 --------------
>  3 files changed, 24 deletions(-)
>
> diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
> index c34c7eef0a1c..8cb8bd061a68 100644
> --- a/arch/mips/include/uapi/asm/siginfo.h
> +++ b/arch/mips/include/uapi/asm/siginfo.h
> @@ -10,9 +10,7 @@
>  #ifndef _UAPI_ASM_SIGINFO_H
>  #define _UAPI_ASM_SIGINFO_H
>
> -
>  #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(long) + 2*sizeof(int))
> -#undef __ARCH_SI_TRAPNO /* exception code needs to fill this ...  */
>
>  #define __ARCH_HAS_SWAPPED_SIGINFO
>
> diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
> index 6657184cef07..928e0025d358 100644
> --- a/include/linux/sched/signal.h
> +++ b/include/linux/sched/signal.h
> @@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
>
>         schedule();
>  }
> -#ifdef __ARCH_SI_TRAPNO
> -# define ___ARCH_SI_TRAPNO(_a1) , _a1
> -#else
> -# define ___ARCH_SI_TRAPNO(_a1)
> -#endif
>  #ifdef __ia64__
>  # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
>  #else
> @@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
>  #endif
>
>  int force_sig_fault_to_task(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t);
>  int force_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr));
>  int send_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t);
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index ae06a424aa72..2181423e562a 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1666,7 +1666,6 @@ void force_sigsegv(int sig)
>  }
>
>  int force_sig_fault_to_task(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t)
>  {
> @@ -1677,9 +1676,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
>         info.si_errno = 0;
>         info.si_code  = code;
>         info.si_addr  = addr;
> -#ifdef __ARCH_SI_TRAPNO
> -       info.si_trapno = trapno;
> -#endif
>  #ifdef __ia64__
>         info.si_imm = imm;
>         info.si_flags = flags;
> @@ -1689,16 +1685,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
>  }
>
>  int force_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
>  {
>         return force_sig_fault_to_task(sig, code, addr
> -                                      ___ARCH_SI_TRAPNO(trapno)
>                                        ___ARCH_SI_IA64(imm, flags, isr), current);
>  }
>
>  int send_sig_fault(int sig, int code, void __user *addr
> -       ___ARCH_SI_TRAPNO(int trapno)
>         ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
>         , struct task_struct *t)
>  {
> @@ -1709,9 +1702,6 @@ int send_sig_fault(int sig, int code, void __user *addr
>         info.si_errno = 0;
>         info.si_code  = code;
>         info.si_addr  = addr;
> -#ifdef __ARCH_SI_TRAPNO
> -       info.si_trapno = trapno;
> -#endif
>  #ifdef __ia64__
>         info.si_imm = imm;
>         info.si_flags = flags;
> @@ -3283,10 +3273,6 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>                                  ((sig == SIGFPE) ||
>                                   ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
>                                 layout = SIL_FAULT_TRAPNO;
> -#ifdef __ARCH_SI_TRAPNO
> -                       else if (layout == SIL_FAULT)
> -                               layout = SIL_FAULT_TRAPNO;
> -#endif
>                 }
>                 else if (si_code <= NSIGPOLL)
>                         layout = SIL_POLL;
> --
> 2.20.1
>