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From: "Eric W. Beiderman" <ebiederm@xmission.com>
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>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 12/12] signalfd: Remove SIL_FAULT_PERF_EVENT fields from signalfd_siginfo
Date: Mon,  3 May 2021 15:38:14 -0500
Message-ID: <20210503203814.25487-12-ebiederm@xmission.com> (raw)
In-Reply-To: <20210503203814.25487-1-ebiederm@xmission.com>

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.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.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


  parent reply index

Thread overview: 118+ 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                       ` Eric W. Beiderman [this message]
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
2021-07-15 18:09           ` [PATCH 0/6] Final si_trapno bits Eric W. Biederman
2021-07-15 18:11             ` [PATCH 1/6] sparc64: Add compile-time asserts for siginfo_t offsets Eric W. Biederman
2021-07-15 18:11             ` [PATCH 2/6] arm: " Eric W. Biederman
2021-07-15 18:11             ` [PATCH 3/6] arm64: " Eric W. Biederman
2021-07-15 18:12             ` [PATCH 4/6] signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP Eric W. Biederman
2021-07-16 11:49               ` Marco Elver
2021-07-15 18:12             ` [PATCH 5/6] signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK Eric W. Biederman
2021-07-16 11:48               ` Marco Elver
2021-07-15 18:13             ` [PATCH 6/6] signal: Remove the generic __ARCH_SI_TRAPNO support Eric W. Biederman
2021-07-16 11:48               ` Marco Elver
2021-07-16 11:50             ` [PATCH 0/6] Final si_trapno bits Marco Elver
2021-07-16 16:08               ` Eric W. Biederman
2021-07-16 17:15                 ` Marco Elver
2021-07-16 16:06             ` [PATCH 7/7] signal: Verify the alignment and size of siginfo_t Eric W. Biederman
2021-07-16 16:07             ` [PATCH 8/6] signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency Eric W. Biederman
2021-04-30 20:43       ` siginfo_t ABI break on sparc64 from si_addr_lsb move 3y ago Arnd Bergmann

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