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From: ebiederm@xmission.com (Eric W. Biederman)
To: Marco Elver <elver@google.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 7/3] signal: Deliver all of the perf_data in si_perf
Date: Sun, 02 May 2021 13:39:16 -0500
Message-ID: <m1wnshm14b.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <CANpmjNNJ_MnNyD4R2+9i24E=9xPHKnwTh6zwWtBYkuAq1Xo6-w@mail.gmail.com> (Marco Elver's message of "Sat, 1 May 2021 12:47:21 +0200")

Marco Elver <elver@google.com> writes:

> On Sat, 1 May 2021 at 01:44, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> Don't abuse si_errno and deliver all of the perf data in si_perf.
>>
>> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>> ---
>
> Thank you for the fix, this looks cleaner.
>
> Just note that this patch needs to include updates to
> tools/testing/selftests/perf_events. This should do it:
>>  sed -i 's/si_perf/si_perf.data/g; s/si_errno/si_perf.type/g' tools/testing/selftests/perf_events/*.c
>
> Subject: s/perf_data/perf data/ ?
>
> For uapi, need to switch to __u32, see below.

Good point.

The one thing that this doesn't do is give you a 64bit field
on 32bit architectures.

On 32bit builds the layout is:

	int si_signo;
	int si_errno;
	int si_code;
	void __user *_addr;
        
So I believe if the first 3 fields were moved into the _sifields union
si_perf could define a 64bit field as it's first member and it would not
break anything else.

Given that the data field is 64bit that seems desirable.

Eric


>>  fs/signalfd.c                      |  3 ++-
>>  include/linux/compat.h             |  5 ++++-
>>  include/uapi/asm-generic/siginfo.h |  5 ++++-
>>  include/uapi/linux/signalfd.h      |  4 ++--
>>  kernel/signal.c                    | 18 +++++++++++-------
>>  5 files changed, 23 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/signalfd.c b/fs/signalfd.c
>> index 83130244f653..9686af56f073 100644
>> --- a/fs/signalfd.c
>> +++ b/fs/signalfd.c
>> @@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>>                 break;
>>         case SIL_FAULT_PERF_EVENT:
>>                 new.ssi_addr = (long) kinfo->si_addr;
>> -               new.ssi_perf = kinfo->si_perf;
>> +               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;
>> diff --git a/include/linux/compat.h b/include/linux/compat.h
>> index 24462ed63af4..0726f9b3a57c 100644
>> --- a/include/linux/compat.h
>> +++ b/include/linux/compat.h
>> @@ -235,7 +235,10 @@ typedef struct compat_siginfo {
>>                                         u32 _pkey;
>>                                 } _addr_pkey;
>>                                 /* used when si_code=TRAP_PERF */
>> -                               compat_ulong_t _perf;
>> +                               struct {
>> +                                       compat_ulong_t data;
>> +                                       u32 type;
>> +                               } _perf;
>>                         };
>>                 } _sigfault;
>>
>> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
>> index 2abdf1d19aad..19b6310021a3 100644
>> --- a/include/uapi/asm-generic/siginfo.h
>> +++ b/include/uapi/asm-generic/siginfo.h
>> @@ -90,7 +90,10 @@ union __sifields {
>>                                 __u32 _pkey;
>>                         } _addr_pkey;
>>                         /* used when si_code=TRAP_PERF */
>> -                       unsigned long _perf;
>> +                       struct {
>> +                               unsigned long data;
>> +                               u32 type;
>
> This needs to be __u32.
>
>
>> +                       } _perf;
>>                 };
>>         } _sigfault;
>>
>> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
>> index 7e333042c7e3..e78dddf433fc 100644
>> --- a/include/uapi/linux/signalfd.h
>> +++ b/include/uapi/linux/signalfd.h
>> @@ -39,8 +39,8 @@ struct signalfd_siginfo {
>>         __s32 ssi_syscall;
>>         __u64 ssi_call_addr;
>>         __u32 ssi_arch;
>> -       __u32 __pad3;
>> -       __u64 ssi_perf;
>> +       __u32 ssi_perf_type;
>> +       __u64 ssi_perf_data;
>>
>>         /*
>>          * Pad strcture to 128 bytes. Remember to update the
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index 5b1ad7f080ab..cb3574b7319c 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)
>>         struct kernel_siginfo info;
>>
>>         clear_siginfo(&info);
>> -       info.si_signo = SIGTRAP;
>> -       info.si_errno = type;
>> -       info.si_code  = TRAP_PERF;
>> -       info.si_addr  = pending_addr;
>> -       info.si_perf  = sig_data;
>> +       info.si_signo     = SIGTRAP;
>> +       info.si_errno     = 0;
>> +       info.si_code      = TRAP_PERF;
>> +       info.si_addr      = pending_addr;
>> +       info.si_perf.data = sig_data;
>> +       info.si_perf.type = type;
>> +
>>         return force_sig_info(&info);
>>  }
>>
>> @@ -3379,7 +3381,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>>                 break;
>>         case SIL_FAULT_PERF_EVENT:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -               to->si_perf = from->si_perf;
>> +               to->si_perf.data = from->si_perf.data;
>> +               to->si_perf.type = from->si_perf.type;
>>                 break;
>>         case SIL_CHLD:
>>                 to->si_pid = from->si_pid;
>> @@ -3455,7 +3458,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>>                 break;
>>         case SIL_FAULT_PERF_EVENT:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -               to->si_perf = from->si_perf;
>> +               to->si_perf.data = from->si_perf.data;
>> +               to->si_perf.type = from->si_perf.type;
>>                 break;
>>         case SIL_CHLD:
>>                 to->si_pid    = from->si_pid;
>> --
>> 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 [this message]
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
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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