signal: Factor force_sig_perf out of perf_sigtrap

Separate filling in siginfo for TRAP_PERF from deciding that
siginal needs to be sent.

There are enough little details that need to be correct when
properly filling in siginfo_t that it is easy to make mistakes
if filling in the siginfo_t is in the same function with other
logic.  So factor out force_sig_perf to reduce the cognative
load of on reviewers, maintainers and implementors.

v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-10-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20210517195748.8880-3-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 3f6a0fcaa10cf47050a79f366a1371613178c8df..7f4278fa21fef7e2de8d832ed46461f1de9aba7d 100644 (file)
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -326,6 +326,7 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
 
 int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
 int force_sig_pkuerr(void __user *addr, u32 pkey);
+int force_sig_perf(void __user *addr, u32 type, u64 sig_data);
 
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 928b166d888e3e017c98533b702e8150e1f57324..48ea8863183bf66f64b77ae2bfbcbc76814f5bac 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6394,8 +6394,6 @@ void perf_event_wakeup(struct perf_event *event)
 
 static void perf_sigtrap(struct perf_event *event)
 {
-       struct kernel_siginfo info;
-
        /*
         * We'd expect this to only occur if the irq_work is delayed and either
         * ctx->task or current has changed in the meantime. This can be the
@@ -6410,13 +6408,8 @@ static void perf_sigtrap(struct perf_event *event)
        if (current->flags & PF_EXITING)
                return;
 
-       clear_siginfo(&info);
-       info.si_signo = SIGTRAP;
-       info.si_code = TRAP_PERF;
-       info.si_errno = event->attr.type;
-       info.si_perf = event->attr.sig_data;
-       info.si_addr = (void __user *)event->pending_addr;
-       force_sig_info(&info);
+       force_sig_perf((void __user *)event->pending_addr,
+                      event->attr.type, event->attr.sig_data);
 }
 
 static void perf_pending_event_disable(struct perf_event *event)

diff --git a/kernel/signal.c b/kernel/signal.c
index 597594ee72de151502e42c5b55af9d38a77281fd..3a18d13c39b2efc395c159e97d4339a4ce7efa2e 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1763,6 +1763,19 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 }
 #endif
 
+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;
+       return force_sig_info(&info);
+}
+
 /* For the crazy architectures that include trap information in
  * the errno field, instead of an actual errno value.
  */