signal: Implement SIL_FAULT_TRAPNO

Now that si_trapno is part of the union in _si_fault and available on
all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
return SIL_FAULT_TRAPNO when the code assumes si_trapno is valid.

There is room for future changes to reduce when si_trapno is valid but
this is all that is needed to make si_trapno and the other members of
the the union in _sigfault mutually exclusive.

Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
and have the same code ignore si_trapno in in all other cases.

v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/20210505141101.11519-6-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20210517195748.8880-2-ebiederm@xmission.com
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040a114..e87e595 100644 (file)
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -123,15 +123,13 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
                 */
        case SIL_FAULT:
                new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
+               break;
+       case SIL_FAULT_TRAPNO:
+               new.ssi_addr = (long) kinfo->si_addr;
                new.ssi_trapno = kinfo->si_trapno;
-#endif
                break;
        case SIL_FAULT_MCEERR:
                new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
-               new.ssi_trapno = kinfo->si_trapno;
-#endif
                new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
                break;
        case SIL_PERF_EVENT:

diff --git a/include/linux/signal.h b/include/linux/signal.h
index 1e98548..5160fd4 100644 (file)
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -40,6 +40,7 @@ enum siginfo_layout {
        SIL_TIMER,
        SIL_POLL,
        SIL_FAULT,
+       SIL_FAULT_TRAPNO,
        SIL_FAULT_MCEERR,
        SIL_FAULT_BNDERR,
        SIL_FAULT_PKUERR,

diff --git a/kernel/signal.c b/kernel/signal.c
index 65888ae..597594e 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
        case SIL_TIMER:
        case SIL_POLL:
        case SIL_FAULT:
+       case SIL_FAULT_TRAPNO:
        case SIL_FAULT_MCEERR:
        case SIL_FAULT_BNDERR:
        case SIL_FAULT_PKUERR:
@@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 {
        switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
        case SIL_FAULT:
+       case SIL_FAULT_TRAPNO:
        case SIL_FAULT_MCEERR:
        case SIL_FAULT_BNDERR:
        case SIL_FAULT_PKUERR:
@@ -3214,6 +3216,10 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 #endif
                        else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
                                layout = SIL_PERF_EVENT;
+#ifdef __ARCH_SI_TRAPNO
+                       else if (layout == SIL_FAULT)
+                               layout = SIL_FAULT_TRAPNO;
+#endif
                }
                else if (si_code <= NSIGPOLL)
                        layout = SIL_POLL;
@@ -3317,30 +3323,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
                break;
        case SIL_FAULT:
                to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+               break;
+       case SIL_FAULT_TRAPNO:
+               to->si_addr = ptr_to_compat(from->si_addr);
                to->si_trapno = from->si_trapno;
-#endif
                break;
        case SIL_FAULT_MCEERR:
                to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-               to->si_trapno = from->si_trapno;
-#endif
                to->si_addr_lsb = from->si_addr_lsb;
                break;
        case SIL_FAULT_BNDERR:
                to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-               to->si_trapno = from->si_trapno;
-#endif
                to->si_lower = ptr_to_compat(from->si_lower);
                to->si_upper = ptr_to_compat(from->si_upper);
                break;
        case SIL_FAULT_PKUERR:
                to->si_addr = ptr_to_compat(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-               to->si_trapno = from->si_trapno;
-#endif
                to->si_pkey = from->si_pkey;
                break;
        case SIL_PERF_EVENT:
@@ -3401,30 +3399,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
                break;
        case SIL_FAULT:
                to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
+               break;
+       case SIL_FAULT_TRAPNO:
+               to->si_addr = compat_ptr(from->si_addr);
                to->si_trapno = from->si_trapno;
-#endif
                break;
        case SIL_FAULT_MCEERR:
                to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-               to->si_trapno = from->si_trapno;
-#endif
                to->si_addr_lsb = from->si_addr_lsb;
                break;
        case SIL_FAULT_BNDERR:
                to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-               to->si_trapno = from->si_trapno;
-#endif
                to->si_lower = compat_ptr(from->si_lower);
                to->si_upper = compat_ptr(from->si_upper);
                break;
        case SIL_FAULT_PKUERR:
                to->si_addr = compat_ptr(from->si_addr);
-#ifdef __ARCH_SI_TRAPNO
-               to->si_trapno = from->si_trapno;
-#endif
                to->si_pkey = from->si_pkey;
                break;
        case SIL_PERF_EVENT: