Final si_trapno bits

As a part of a fix for the ABI of the newly added SIGTRAP TRAP_PERF a
si_trapno was reduced to an ordinary extention of the _sigfault case
of struct siginfo.

When Linus saw the complete set of changes come in as a fix he requested
that the set of changes be trimmed down to just what was necessary to
fix the SIGTRAP TRAP_PERF ABI.

I had intended to get the rest of the changes into the merge window for
v5.14 but I dropped the ball.

I have made the changes to stop using __ARCH_SI_TRAPNO be per
architecture so they are easier to review.  In doing so I found one
place on alpha where I used send_sig_fault instead of
send_sig_fault_trapno(... si_trapno = 0).  That would not have changed
the userspace behavior but it did make the kernel code less clear.

My rule in these patches is everywhere that siginfo layout calls
for SIL_FAULT_TRAPNO the code uses either force_sig_fault_trapno
or send_sig_fault_trapno.

And of course I have rebased and compile tested Marco's compile time
assert patches.

v1: https://lkml.kernel.org/r/m1zgxfs7zq.fsf_-_@fess.ebiederm.org
v2: https://lkml.kernel.org/r/m14kfjh8et.fsf_-_@fess.ebiederm.org
v3: https://lkml.kernel.org/r/m1tuni8ano.fsf_-_@fess.ebiederm.org
v4: https://lkml.kernel.org/r/m1a6ot5e2h.fsf_-_@fess.ebiederm.org
Link: https://lkml.kernel.org/r/87a6mnzbx2.fsf_-_@disp2133

Eric W. Biederman (5):
      signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
      signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
      signal: Remove the generic __ARCH_SI_TRAPNO support
      signal: Verify the alignment and size of siginfo_t
      signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

Marco Elver (3):
      sparc64: Add compile-time asserts for siginfo_t offsets
      arm: Add compile-time asserts for siginfo_t offsets
      arm64: Add compile-time asserts for siginfo_t offsets

 arch/alpha/include/uapi/asm/siginfo.h |  2 --
 arch/alpha/kernel/osf_sys.c           |  2 +-
 arch/alpha/kernel/signal.c            |  4 +--
 arch/alpha/kernel/traps.c             | 26 +++++++--------
 arch/alpha/mm/fault.c                 |  4 +--
 arch/arm/kernel/signal.c              | 39 ++++++++++++++++++++++
 arch/arm64/kernel/signal.c            | 39 ++++++++++++++++++++++
 arch/arm64/kernel/signal32.c          | 39 ++++++++++++++++++++++
 arch/mips/include/uapi/asm/siginfo.h  |  2 --
 arch/sparc/include/uapi/asm/siginfo.h |  3 --
 arch/sparc/kernel/process_64.c        |  2 +-
 arch/sparc/kernel/signal32.c          | 37 +++++++++++++++++++++
 arch/sparc/kernel/signal_64.c         | 36 ++++++++++++++++++++
 arch/sparc/kernel/sys_sparc_32.c      |  2 +-
 arch/sparc/kernel/sys_sparc_64.c      |  2 +-
 arch/sparc/kernel/traps_32.c          | 22 ++++++-------
 arch/sparc/kernel/traps_64.c          | 44 +++++++++++--------------
 arch/sparc/kernel/unaligned_32.c      |  2 +-
 arch/sparc/mm/fault_32.c              |  2 +-
 arch/sparc/mm/fault_64.c              |  2 +-
 arch/x86/kernel/signal_compat.c       |  6 ++++
 fs/signalfd.c                         |  4 +--
 include/linux/sched/signal.h          | 11 ++-----
 include/linux/signal.h                |  2 +-
 include/uapi/asm-generic/siginfo.h    |  5 +++
 kernel/signal.c                       | 62 +++++++++++++++++++++++++----------
 26 files changed, 305 insertions(+), 96 deletions(-)

1 files changed, 44 insertions, 18 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index a3229add4455..332b21f2fe72 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1213,7 +1213,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 	case SIL_SYS:
 		ret = false;
 		break;
@@ -1666,7 +1666,6 @@ void force_sigsegv(int sig)
 }
 
 int force_sig_fault_to_task(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1677,9 +1676,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1689,16 +1685,13 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 }
 
 int force_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
 {
 	return force_sig_fault_to_task(sig, code, addr
-				       ___ARCH_SI_TRAPNO(trapno)
 				       ___ARCH_SI_IA64(imm, flags, isr), current);
 }
 
 int send_sig_fault(int sig, int code, void __user *addr
-	___ARCH_SI_TRAPNO(int trapno)
 	___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
 	, struct task_struct *t)
 {
@@ -1709,9 +1702,6 @@ int send_sig_fault(int sig, int code, void __user *addr
 	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
-#ifdef __ARCH_SI_TRAPNO
-	info.si_trapno = trapno;
-#endif
 #ifdef __ia64__
 	info.si_imm = imm;
 	info.si_flags = flags;
@@ -1808,6 +1798,39 @@ int force_sig_ptrace_errno_trap(int errno, void __user *addr)
 	return force_sig_info(&info);
 }
 
+/* For the rare architectures that include trap information using
+ * si_trapno.
+ */
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return force_sig_info(&info);
+}
+
+/* For the rare architectures that include trap information using
+ * si_trapno.
+ */
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			  struct task_struct *t)
+{
+	struct kernel_siginfo info;
+
+	clear_siginfo(&info);
+	info.si_signo = sig;
+	info.si_errno = 0;
+	info.si_code  = code;
+	info.si_addr  = addr;
+	info.si_trapno = trapno;
+	return send_sig_info(info.si_signo, &info, t);
+}
+
 int kill_pgrp(struct pid *pid, int sig, int priv)
 {
 	int ret;
@@ -2557,7 +2580,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
 	case SIL_FAULT_MCEERR:
 	case SIL_FAULT_BNDERR:
 	case SIL_FAULT_PKUERR:
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		ksig->info.si_addr = arch_untagged_si_addr(
 			ksig->info.si_addr, ksig->sig, ksig->info.si_code);
 		break;
@@ -3242,11 +3265,14 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 				layout = SIL_FAULT_PKUERR;
 #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_PERF_EVENT;
+			else if (IS_ENABLED(CONFIG_SPARC) &&
+				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
+				layout = SIL_FAULT_TRAPNO;
+			else if (IS_ENABLED(CONFIG_ALPHA) &&
+				 ((sig == SIGFPE) ||
+				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
 				layout = SIL_FAULT_TRAPNO;
-#endif
 		}
 		else if (si_code <= NSIGPOLL)
 			layout = SIL_POLL;
@@ -3368,7 +3394,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = ptr_to_compat(from->si_addr);
 		to->si_perf_data = from->si_perf_data;
 		to->si_perf_type = from->si_perf_type;
@@ -3445,7 +3471,7 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_pkey = from->si_pkey;
 		break;
-	case SIL_PERF_EVENT:
+	case SIL_FAULT_PERF_EVENT:
 		to->si_addr = compat_ptr(from->si_addr);
 		to->si_perf_data = from->si_perf_data;
 		to->si_perf_type = from->si_perf_type;