linux-kernel - [PATCH 2/3] signal: Implement SIL_FAULT

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Date:   Fri, 30 Apr 2021 17:54:16 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Marco Elver <elver@...gle.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Florian Weimer <fweimer@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Collingbourne <pcc@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        sparclinux <sparclinux@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: [PATCH 2/3] 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 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" <ebiederm@...ssion.com>
---
 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;
 			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