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From: Marco Elver <elver@google.com>
To: "Eric W. Beiderman" <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 v3 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo
Date: Wed, 5 May 2021 19:27:00 +0200
Message-ID: <CANpmjNPcYS9F+mgFP_DnO5c7kmMs28cdMBWN+ZxE7YNe_oK=_w@mail.gmail.com> (raw)
In-Reply-To: <20210505141101.11519-12-ebiederm@xmission.com>

On Wed, 5 May 2021 at 16:11, Eric W. Beiderman <ebiederm@xmission.com> wrote:
> From: "Eric W. Biederman" <ebiederm@xmission.com>
>
> With the addition of ssi_perf_data and ssi_perf_type struct signalfd_siginfo
> is dangerously close to running out of space.  All that remains is just
> enough space for two additional 64bit fields.  A practice of adding all
> possible siginfo_t fields into struct singalfd_siginfo can not be supported
> as adding the missing fields ssi_lower, ssi_upper, and ssi_pkey would
> require two 64bit fields and one 32bit fields.  In practice the fields
> ssi_perf_data and ssi_perf_type can never be used by signalfd as the signal
> that generates them always delivers them synchronously to the thread that
> triggers them.
>
> Therefore until someone actually needs the fields ssi_perf_data and
> ssi_perf_type in signalfd_siginfo remove them.  This leaves a bit more room
> for future expansion.
>
> v1: https://lkml.kernel.org/r/20210503203814.25487-12-ebiederm@xmission.com
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

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


> ---
>  fs/signalfd.c                 | 16 ++++++----------
>  include/uapi/linux/signalfd.h |  4 +---
>  2 files changed, 7 insertions(+), 13 deletions(-)
>
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 335ad39f3900..040e1cf90528 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -114,12 +114,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 break;
>         case SIL_FAULT_BNDERR:
>         case SIL_FAULT_PKUERR:
> +       case SIL_FAULT_PERF_EVENT:
>                 /*
> -                * Fall through to the SIL_FAULT case.  Both SIL_FAULT_BNDERR
> -                * and SIL_FAULT_PKUERR are only generated by faults that
> -                * deliver them synchronously to userspace.  In case someone
> -                * injects one of these signals and signalfd catches it treat
> -                * it as SIL_FAULT.
> +                * Fall through to the SIL_FAULT case.  SIL_FAULT_BNDERR,
> +                * SIL_FAULT_PKUERR, and SIL_FAULT_PERF_EVENT are only
> +                * generated by faults that deliver them synchronously to
> +                * userspace.  In case someone injects one of these signals
> +                * and signalfd catches it treat it as SIL_FAULT.
>                  */
>         case SIL_FAULT:
>                 new.ssi_addr = (long) kinfo->si_addr;
> @@ -132,11 +133,6 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>                 new.ssi_addr = (long) kinfo->si_addr;
>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>                 break;
> -       case SIL_FAULT_PERF_EVENT:
> -               new.ssi_addr = (long) kinfo->si_addr;
> -               new.ssi_perf_type = kinfo->si_perf_type;
> -               new.ssi_perf_data = kinfo->si_perf_data;
> -               break;
>         case SIL_CHLD:
>                 new.ssi_pid    = kinfo->si_pid;
>                 new.ssi_uid    = kinfo->si_uid;
> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
> index e78dddf433fc..83429a05b698 100644
> --- a/include/uapi/linux/signalfd.h
> +++ b/include/uapi/linux/signalfd.h
> @@ -39,8 +39,6 @@ struct signalfd_siginfo {
>         __s32 ssi_syscall;
>         __u64 ssi_call_addr;
>         __u32 ssi_arch;
> -       __u32 ssi_perf_type;
> -       __u64 ssi_perf_data;
>
>         /*
>          * Pad strcture to 128 bytes. Remember to update the
> @@ -51,7 +49,7 @@ struct signalfd_siginfo {
>          * comes out of a read(2) and we really don't want to have
>          * a compat on read(2).
>          */
> -       __u8 __pad[16];
> +       __u8 __pad[28];
>  };
>
>
> --
> 2.30.1

  reply index

Thread overview: 103+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-29  7:48 siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago Marco Elver
2021-04-29 17:23 ` Eric W. Biederman
2021-04-29 18:46   ` Marco Elver
2021-04-29 20:48   ` Arnd Bergmann
2021-04-30 17:08     ` Eric W. Biederman
2021-04-30 19:07       ` Marco Elver
2021-04-30 20:15         ` Eric W. Biederman
2021-04-30 23:50           ` Marco Elver
2021-04-30 22:49         ` [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union Eric W. Biederman
2021-04-30 22:50           ` [PATCH 1/3] siginfo: Move si_trapno inside the union inside _si_fault Eric W. Biederman
2021-05-01 10:31             ` Marco Elver
2021-05-02 18:27               ` Eric W. Biederman
2021-04-30 22:54           ` [PATCH 2/3] signal: Implement SIL_FAULT_TRAPNO Eric W. Biederman
2021-04-30 23:19             ` Eric W. Biederman
2021-05-01 10:33             ` Marco Elver
2021-05-02 18:24               ` Eric W. Biederman
2021-04-30 22:55           ` [PATCH 3/3] signal: Use dedicated helpers to send signals with si_trapno set Eric W. Biederman
2021-05-01 10:33             ` Marco Elver
2021-04-30 22:56           ` [PATCH 4/3] signal: Remove __ARCH_SI_TRAPNO Eric W. Biederman
2021-04-30 23:23           ` Is perf_sigtrap synchronous? Eric W. Biederman
2021-05-01  0:28             ` Marco Elver
2021-04-30 23:42           ` [PATCH 5/3] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency Eric W. Biederman
2021-05-01 10:35             ` Marco Elver
2021-04-30 23:43           ` [PATCH 6/3] signal: Factor force_sig_perf out of perf_sigtrap Eric W. Biederman
2021-05-01 10:45             ` Marco Elver
2021-04-30 23:43           ` [PATCH 7/3] signal: Deliver all of the perf_data in si_perf Eric W. Biederman
2021-05-01 10:47             ` Marco Elver
2021-05-02 18:39               ` Eric W. Biederman
2021-05-02 19:13                 ` Marco Elver
2021-05-03 12:44                 ` Peter Zijlstra
2021-05-03 19:38                   ` Eric W. Biederman
2021-05-03 19:53                     ` Marco Elver
2021-04-30 23:47           ` [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union Eric W. Biederman
2021-05-01  0:37             ` Marco Elver
2021-05-01 15:16               ` Eric W. Biederman
2021-05-01 16:24                 ` Marco Elver
2021-05-03 20:25                   ` [PATCH 00/12] signal: sort out si_trapno and si_perf Eric W. Biederman
2021-05-03 20:38                     ` [PATCH 01/12] sparc64: Add compile-time asserts for siginfo_t offsets Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 02/12] arm: " Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 03/12] arm64: " Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 04/12] siginfo: Move si_trapno inside the union inside _si_fault Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 05/12] signal: Implement SIL_FAULT_TRAPNO Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 06/12] signal: Use dedicated helpers to send signals with si_trapno set Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 07/12] signal: Remove __ARCH_SI_TRAPNO Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 08/12] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 09/12] signal: Factor force_sig_perf out of perf_sigtrap Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 10/12] signal: Redefine signinfo so 64bit fields are possible Eric W. Beiderman
2021-05-03 21:04                         ` Eric W. Biederman
2021-05-03 22:47                           ` Marco Elver
2021-05-04  3:42                             ` Eric W. Biederman
2021-05-04  4:03                               ` Peter Collingbourne
2021-05-04  9:52                                 ` Marco Elver
2021-05-04 16:16                                   ` Eric W. Biederman
2021-05-03 20:38                       ` [PATCH 11/12] signal: Deliver all of the siginfo perf data in _perf Eric W. Beiderman
2021-05-03 20:38                       ` [PATCH 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo Eric W. Beiderman
2021-05-04 21:13                     ` [PATCH v3 00/12] signal: sort out si_trapno and si_perf Eric W. Biederman
2021-05-04 22:05                       ` Marco Elver
2021-05-05 14:12                         ` Eric W. Biederman
2021-05-05 14:10                       ` [PATCH v3 01/12] sparc64: Add compile-time asserts for siginfo_t offsets Eric W. Beiderman
2021-05-05 14:10                         ` [PATCH v3 02/12] arm: " Eric W. Beiderman
2021-05-05 14:10                         ` [PATCH v3 03/12] arm64: " Eric W. Beiderman
2021-05-05 14:10                         ` [PATCH v3 04/12] signal: Verify the alignment and size of siginfo_t Eric W. Beiderman
2021-05-05 17:24                           ` Marco Elver
2021-05-05 14:10                         ` [PATCH v3 05/12] siginfo: Move si_trapno inside the union inside _si_fault Eric W. Beiderman
2021-05-05 14:10                         ` [PATCH v3 06/12] signal: Implement SIL_FAULT_TRAPNO Eric W. Beiderman
2021-05-05 17:25                           ` Marco Elver
2021-05-05 14:10                         ` [PATCH v3 07/12] signal: Use dedicated helpers to send signals with si_trapno set Eric W. Beiderman
2021-05-05 17:25                           ` Marco Elver
2021-05-05 14:10                         ` [PATCH v3 08/12] signal: Remove __ARCH_SI_TRAPNO Eric W. Beiderman
2021-05-05 17:25                           ` Marco Elver
2021-05-05 14:10                         ` [PATCH v3 09/12] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency Eric W. Beiderman
2021-05-05 17:26                           ` Marco Elver
2021-05-05 14:10                         ` [PATCH v3 10/12] signal: Factor force_sig_perf out of perf_sigtrap Eric W. Beiderman
2021-05-05 17:26                           ` Marco Elver
2021-05-06 10:54                           ` Peter Zijlstra
2021-05-05 14:11                         ` [PATCH v3 11/12] signal: Deliver all of the siginfo perf data in _perf Eric W. Beiderman
2021-05-05 17:27                           ` Marco Elver
2021-05-05 14:11                         ` [PATCH v3 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo Eric W. Beiderman
2021-05-05 17:27                           ` Marco Elver [this message]
2021-05-05 17:28                       ` [PATCH v3 00/12] signal: sort out si_trapno and si_perf Marco Elver
2021-05-06  7:00                       ` Geert Uytterhoeven
2021-05-06 10:43                         ` Marco Elver
2021-05-06 15:28                           ` Eric W. Biederman
2021-05-06 15:14                         ` Eric W. Biederman
2021-05-14  4:54                       ` [GIT PULL] siginfo: ABI fixes for v5.13-rc2 Eric W. Biederman
2021-05-14 19:14                         ` Linus Torvalds
2021-05-14 21:15                           ` Eric W. Biederman
2021-05-14 22:38                             ` Eric W. Biederman
2021-05-16  7:40                         ` Ingo Molnar
2021-05-17 15:29                           ` Eric W. Biederman
2021-05-21 14:59                         ` [GIT PULL] siginfo: ABI fixes for v5.13-rc3 Eric W. Biederman
2021-05-21 16:34                           ` pr-tracker-bot
2021-05-17 19:56                       ` [PATCH v4 0/5] siginfo: ABI fixes for TRAP_PERF Eric W. Biederman
2021-05-17 19:57                         ` [PATCH v4 1/5] siginfo: Move si_trapno inside the union inside _si_fault Eric W. Beiderman
2021-05-17 19:57                           ` [PATCH v4 2/5] signal: Implement SIL_FAULT_TRAPNO Eric W. Beiderman
2021-05-17 19:57                           ` [PATCH v4 3/5] signal: Factor force_sig_perf out of perf_sigtrap Eric W. Beiderman
2021-05-17 19:57                           ` [PATCH v4 4/5] signal: Deliver all of the siginfo perf data in _perf Eric W. Beiderman
2021-05-17 19:57                           ` [PATCH v4 5/5] signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo Eric W. Beiderman
2021-05-17 20:53                         ` [PATCH v4 0/5] siginfo: ABI fixes for TRAP_PERF Marco Elver
2021-05-18  3:46                           ` Eric W. Biederman
2021-05-18  6:44                             ` Marco Elver
2021-05-01 16:26               ` [RFC][PATCH 0/3] signal: Move si_trapno into the _si_fault union Marco Elver
2021-04-30 20:43       ` siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago Arnd Bergmann

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