[PATCH 1/3] siginfo: Move si_trapno inside the union inside _si_fault

[Eric W. Biederman]

It turns out that linux uses si_trapno very sparingly, and as such it
can be considered extra information for a very narrow selection of
signals, rather than information that is present with every fault
reported in siginfo.

As such move si_trapno inside the union inside of _si_fault.  This
results in no change in placement, and makes it eaiser to extend
_si_fault in the future as this reduces the number of special cases.
In particular with si_trapno included in the union it is no longer a
concern that the union must be pointer alligned on most architectures
because the union followes immediately after si_addr which is a
pointer.

Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
 include/linux/compat.h             | 4 +---
 include/uapi/asm-generic/siginfo.h | 6 +-----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index f0d2dd35d408..24462ed63af4 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -214,12 +214,10 @@ typedef struct compat_siginfo {
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 		struct {
 			compat_uptr_t _addr;	/* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-			int _trapno;	/* TRAP # which caused the signal */
-#endif
 #define __COMPAT_ADDR_BND_PKEY_PAD  (__alignof__(compat_uptr_t) < sizeof(short) ? \
 				     sizeof(short) : __alignof__(compat_uptr_t))
 			union {
+				int _trapno;	/* TRAP # which caused the signal */
 				/*
 				 * used when si_code=BUS_MCEERR_AR or
 				 * used when si_code=BUS_MCEERR_AO
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 03d6f6d2c1fe..2abdf1d19aad 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -63,9 +63,6 @@ union __sifields {
 	/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
 	struct {
 		void __user *_addr; /* faulting insn/memory ref. */
-#ifdef __ARCH_SI_TRAPNO
-		int _trapno;	/* TRAP # which caused the signal */
-#endif
 #ifdef __ia64__
 		int _imm;		/* immediate value for "break" */
 		unsigned int _flags;	/* see ia64 si_flags */
@@ -75,6 +72,7 @@ union __sifields {
 #define __ADDR_BND_PKEY_PAD  (__alignof__(void *) < sizeof(short) ? \
 			      sizeof(short) : __alignof__(void *))
 		union {
+			int _trapno;	/* TRAP # which caused the signal */
 			/*
 			 * used when si_code=BUS_MCEERR_AR or
 			 * used when si_code=BUS_MCEERR_AO
@@ -150,9 +148,7 @@ typedef struct siginfo {
 #define si_int		_sifields._rt._sigval.sival_int
 #define si_ptr		_sifields._rt._sigval.sival_ptr
 #define si_addr		_sifields._sigfault._addr
-#ifdef __ARCH_SI_TRAPNO
 #define si_trapno	_sifields._sigfault._trapno
-#endif
 #define si_addr_lsb	_sifields._sigfault._addr_lsb
 #define si_lower	_sifields._sigfault._addr_bnd._lower
 #define si_upper	_sifields._sigfault._addr_bnd._upper
-- 
2.30.1