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(-)

3 files changed, 9 insertions, 9 deletions

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index b9126fe06c3f..928e0025d358 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -298,11 +298,6 @@ static inline void kernel_signal_stop(void)
 
 	schedule();
 }
-#ifdef __ARCH_SI_TRAPNO
-# define ___ARCH_SI_TRAPNO(_a1) , _a1
-#else
-# define ___ARCH_SI_TRAPNO(_a1)
-#endif
 #ifdef __ia64__
 # define ___ARCH_SI_IA64(_a1, _a2, _a3) , _a1, _a2, _a3
 #else
@@ -310,14 +305,11 @@ static inline void kernel_signal_stop(void)
 #endif
 
 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);
 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));
 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);
 
@@ -329,6 +321,9 @@ 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);
+int force_sig_fault_trapno(int sig, int code, void __user *addr, int trapno);
+int send_sig_fault_trapno(int sig, int code, void __user *addr, int trapno,
+			struct task_struct *t);
 
 extern int send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
 extern void force_sigsegv(int sig);
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 3454c7ff0778..3f96a6374e4f 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -44,7 +44,7 @@ enum siginfo_layout {
 	SIL_FAULT_MCEERR,
 	SIL_FAULT_BNDERR,
 	SIL_FAULT_PKUERR,
-	SIL_PERF_EVENT,
+	SIL_FAULT_PERF_EVENT,
 	SIL_CHLD,
 	SIL_RT,
 	SIL_SYS,
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 5a3c221f4c9d..3ba180f550d7 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -29,6 +29,11 @@ typedef union sigval {
 #define __ARCH_SI_ATTRIBUTES
 #endif
 
+/*
+ * Be careful when extending this union.  On 32bit siginfo_t is 32bit
+ * aligned.  Which means that a 64bit field or any other field that
+ * would increase the alignment of siginfo_t will break the ABI.
+ */
 union __sifields {
 	/* kill() */
 	struct {