signal: Deliver all of the siginfo perf data in _perf

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

Note: 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
v3: https://lkml.kernel.org/r/20210505141101.11519-11-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20210517195748.8880-4-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index a4b7ee1..8f215e7 100644 (file)
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -623,7 +623,8 @@ static inline void siginfo_build_tests(void)
        BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x12);
 
        /* _sigfault._perf */
-       BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x10);
+       BUILD_BUG_ON(offsetof(siginfo_t, si_perf_data) != 0x10);
+       BUILD_BUG_ON(offsetof(siginfo_t, si_perf_type) != 0x14);
 
        /* _sigpoll */
        BUILD_BUG_ON(offsetof(siginfo_t, si_band)   != 0x0c);

diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index a9fcabd..06743ec 100644 (file)
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -141,8 +141,10 @@ 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 e87e595..373df2f 100644 (file)
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
                break;
        case SIL_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 6af7bef..a27fffa 100644 (file)
--- 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 e663bf1..5a3c221 100644 (file)
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -91,7 +91,10 @@ union __sifields {
                                __u32 _pkey;
                        } _addr_pkey;
                        /* used when si_code=TRAP_PERF */
-                       unsigned long _perf;
+                       struct {
+                               unsigned long _data;
+                               __u32 _type;
+                       } _perf;
                };
        } _sigfault;
 
@@ -154,7 +157,8 @@ 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/perf_event.h b/include/uapi/linux/perf_event.h
index e54e639..7b14753 100644 (file)
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -464,7 +464,7 @@ struct perf_event_attr {
 
        /*
         * User provided data if sigtrap=1, passed back to user via
-        * siginfo_t::si_perf, e.g. to permit user to identify the event.
+        * siginfo_t::si_perf_data, e.g. to permit user to identify the event.
         */
        __u64   sig_data;
 };

diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 7e33304..e78dddf 100644 (file)
--- 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 3a18d13..dca5351 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1768,11 +1768,13 @@ 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);
 }
 
@@ -3356,7 +3358,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
                break;
        case SIL_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;
@@ -3432,7 +3435,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
                break;
        case SIL_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;
@@ -4615,7 +4619,8 @@ 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 78ddf5e..8e83cf9 100644 (file)
--- a/tools/testing/selftests/perf_events/sigtrap_threads.c
+++ b/tools/testing/selftests/perf_events/sigtrap_threads.c
@@ -43,7 +43,7 @@ static struct {
        siginfo_t first_siginfo;        /* First observed siginfo_t. */
 } ctx;
 
-/* Unique value to check si_perf is correctly set from perf_event_attr::sig_data. */
+/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */
 #define TEST_SIG_DATA(addr) (~(unsigned long)(addr))
 
 static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr)
@@ -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