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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>
Date:   Wed,  5 May 2021 09:11:00 -0500
Message-Id: <20210505141101.11519-11-ebiederm@xmission.com>
In-Reply-To: <20210505141101.11519-1-ebiederm@xmission.com>
References: <m1tuni8ano.fsf_-_@fess.ebiederm.org>
 <20210505141101.11519-1-ebiederm@xmission.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: [PATCH v3 11/12] signal: Deliver all of the siginfo perf data in _perf
Precedence: bulk

From: "Eric W. Biederman" <ebiederm@xmission.com>

Don't abuse si_errno and deliver all of the perf data in _perf member
of siginfo_t.

The data field in the perf data structures in a u64 to allow a pointer
to be encoded without needed to implement a 32bit and 64bit version of
the same structure.  There already exists a 32bit and 64bit versions
siginfo_t, and the 32bit version can not include a 64bit member as it
only has 32bit alignment.  So unsigned long is used in siginfo_t
instead of a u64 as unsigned long can encode a pointer on all
architectures linux supports.

v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 arch/arm/kernel/signal.c                      |  3 ++-
 arch/arm64/kernel/signal.c                    |  3 ++-
 arch/arm64/kernel/signal32.c                  |  3 ++-
 arch/sparc/kernel/signal32.c                  |  3 ++-
 arch/sparc/kernel/signal_64.c                 |  3 ++-
 arch/x86/kernel/signal_compat.c               |  6 ++++--
 fs/signalfd.c                                 |  3 ++-
 include/linux/compat.h                        |  5 ++++-
 include/uapi/asm-generic/siginfo.h            |  8 +++++--
 include/uapi/linux/signalfd.h                 |  4 ++--
 kernel/signal.c                               | 21 ++++++++++++-------
 .../selftests/perf_events/sigtrap_threads.c   | 12 +++++------
 12 files changed, 47 insertions(+), 27 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 643bcb0f091b..f3800c0f428b 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -757,7 +757,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x14);
 static_assert(offsetof(siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x10);
 static_assert(offsetof(siginfo_t, si_call_addr)	== 0x0c);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index ad4bd27fc044..b3978b468bd4 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -1005,7 +1005,8 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x18);
 static_assert(offsetof(siginfo_t, si_call_addr)	== 0x10);
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index ee6c7484e130..d3be01c46bec 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -489,7 +489,8 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_call_addr)	== 0x0c);
diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c
index 5573722e34ad..4276b9e003ca 100644
--- a/arch/sparc/kernel/signal32.c
+++ b/arch/sparc/kernel/signal32.c
@@ -778,6 +778,7 @@ static_assert(offsetof(compat_siginfo_t, si_addr_lsb)	== 0x10);
 static_assert(offsetof(compat_siginfo_t, si_lower)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_upper)	== 0x18);
 static_assert(offsetof(compat_siginfo_t, si_pkey)	== 0x14);
-static_assert(offsetof(compat_siginfo_t, si_perf)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_data)	== 0x10);
+static_assert(offsetof(compat_siginfo_t, si_perf_type)	== 0x14);
 static_assert(offsetof(compat_siginfo_t, si_band)	== 0x0c);
 static_assert(offsetof(compat_siginfo_t, si_fd)		== 0x10);
diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index a69a78984c36..cea23cf95600 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -588,6 +588,7 @@ static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
 static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
 static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
 static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
-static_assert(offsetof(siginfo_t, si_perf)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_data)	== 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	== 0x20);
 static_assert(offsetof(siginfo_t, si_band)	== 0x10);
 static_assert(offsetof(siginfo_t, si_fd)	== 0x14);
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index c9601f092a1e..b52407c56000 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -147,8 +147,10 @@ static inline void signal_compat_build_tests(void)
 	BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
 	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
 
-	BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
-	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x18);
+	BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x20);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_data) != 0x10);
+	BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf_type) != 0x14);
 
 	CHECK_CSI_OFFSET(_sigpoll);
 	CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));
diff --git a/fs/signalfd.c b/fs/signalfd.c
index 83130244f653..335ad39f3900 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 6af7bef15e94..a27fffaae121 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -236,7 +236,10 @@ 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 3503282021aa..3ba180f550d7 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -96,7 +96,10 @@ union __sifields {
 				__u32 _pkey;
 			} _addr_pkey;
 			/* used when si_code=TRAP_PERF */
-			unsigned long _perf;
+			struct {
+				unsigned long _data;
+				__u32 _type;
+			} _perf;
 		};
 	} _sigfault;
 
@@ -159,7 +162,8 @@ typedef struct siginfo {
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
 #define si_pkey		_sifields._sigfault._addr_pkey._pkey
-#define si_perf		_sifields._sigfault._perf
+#define si_perf_data	_sifields._sigfault._perf._data
+#define si_perf_type	_sifields._sigfault._perf._type
 #define si_band		_sifields._sigpoll._band
 #define si_fd		_sifields._sigpoll._fd
 #define si_call_addr	_sifields._sigsys._call_addr
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 49560ceac048..7fec9d1c5b11 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *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  = addr;
-	info.si_perf  = sig_data;
+	info.si_signo     = SIGTRAP;
+	info.si_errno     = 0;
+	info.si_code      = TRAP_PERF;
+	info.si_addr      = addr;
+	info.si_perf_data = sig_data;
+	info.si_perf_type = type;
+
 	return force_sig_info(&info);
 }
 
@@ -3380,7 +3382,8 @@ 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;
@@ -3456,7 +3459,8 @@ 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;
@@ -4639,7 +4643,8 @@ static inline void siginfo_buildtime_checks(void)
 	CHECK_OFFSET(si_lower);
 	CHECK_OFFSET(si_upper);
 	CHECK_OFFSET(si_pkey);
-	CHECK_OFFSET(si_perf);
+	CHECK_OFFSET(si_perf_data);
+	CHECK_OFFSET(si_perf_type);
 
 	/* sigpoll */
 	CHECK_OFFSET(si_band);
diff --git a/tools/testing/selftests/perf_events/sigtrap_threads.c b/tools/testing/selftests/perf_events/sigtrap_threads.c
index 78ddf5e11625..fde123066a8c 100644
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -164,8 +164,8 @@ TEST_F(sigtrap_threads, enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -183,8 +183,8 @@ TEST_F(sigtrap_threads, modify_and_enable_event)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 
 	/* Check enabled for parent. */
 	ctx.iterate_on = 0;
@@ -203,8 +203,8 @@ TEST_F(sigtrap_threads, signal_stress)
 	EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
 	EXPECT_EQ(ctx.tids_want_signal, 0);
 	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
-	EXPECT_EQ(ctx.first_siginfo.si_errno, PERF_TYPE_BREAKPOINT);
-	EXPECT_EQ(ctx.first_siginfo.si_perf, TEST_SIG_DATA(&ctx.iterate_on));
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on));
 }
 
 TEST_HARNESS_MAIN
-- 
2.30.1