Marco Elver [off-list ref] writes:

On Sat, 1 May 2021 at 01:44, Eric W. Biederman [off-list ref] wrote:

quoted

Don't abuse si_errno and deliver all of the perf data in si_perf.

Signed-off-by: "Eric W. Biederman" <redacted>
---

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:

quoted

 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

quoted

 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.

quoted

+                       } _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