Marco Elver [off-list ref] writes:

On Sat, 1 May 2021 at 00:54, Eric W. Biederman [off-list ref] wrote:

quoted

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 si_trapno is actually used.

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.

Signed-off-by: "Eric W. Biederman" <redacted>
---
 fs/signalfd.c          |  7 ++-----
 include/linux/signal.h |  1 +
 kernel/signal.c        | 36 ++++++++++++++----------------------
 3 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index 040a1142915f..126c681a30e7 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c

@@ -123,15 +123,12 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
                 */
        case SIL_FAULT:
                new.ssi_addr = (long) kinfo->si_addr;
-#ifdef __ARCH_SI_TRAPNO
+       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 1e98548d7cf6..5160fd45e5ca 100644
--- 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 c3017aa8024a..7b2d61cb7411 100644
--- 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:

@@ -3206,6 +3208,12 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
                        if ((sig == SIGBUS) &&
                            (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
                                layout = SIL_FAULT_MCEERR;
+                       else if (IS_ENABLED(ALPHA) &&
+                                ((sig == SIGFPE) ||
+                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
+                               layout = SIL_FAULT_TRAPNO;
+                       else if (IS_ENABLED(SPARC) && (sig == SIGILL) && (si_code == ILL_ILLTRP))
+                               layout = SIL_FAULT_TRAPNO;

The breakage isn't apparent here, but in later patches. These need to
become CONFIG_SPARC and CONFIG_ALPHA.

Good catch.  For some reason I thought IS_ENABLED added the CONFIG_
prefix but I looked and it doesn't.

quoted

                        else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
                                layout = SIL_FAULT_BNDERR;
 #ifdef SEGV_PKUERR

@@ -3317,30 +3325,22 @@ 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 +3401,22 @@ 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:
--

2.30.1