x86/signals: Add missing signal_compat code for x86 features

The 32-bit siginfo is a different binary format than the 64-bit
one. So, when running 32-bit binaries on 64-bit kernels, we have
to convert the kernel's 64-bit version to a 32-bit version that
userspace can grok.

We've added a few features to siginfo over the past few years and
neglected to add them to arch/x86/kernel/signal_compat.c:

1. The si_addr_lsb used in SIGBUS's sent for machine checks
2. The upper/lower bounds for MPX SIGSEGV faults
3. The protection key for pkey faults

I caught this with some protection keys unit tests and realized
it affected a few more features.

This was tested only with my protection keys patch that looks
for a proper value in si_pkey. I didn't actually test the machine
check or MPX code.

Signed-off-by: Dave Hansen <[e-mail]>
Cc: Al Viro <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Brian Gerst <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: Denys Vlasenko <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Oleg Nesterov <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/compat.h

···
 typedef s64 __attribute__((aligned(4))) compat_s64;
 typedef u32		compat_uint_t;
 typedef u32		compat_ulong_t;
+typedef u32		compat_u32;
 typedef u64 __attribute__((aligned(4))) compat_u64;
 typedef u32		compat_uptr_t;
 
···
 		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS */
 		struct {
 			unsigned int _addr;	/* faulting insn/memory ref. */
+			short int _addr_lsb;	/* Valid LSB of the reported address. */
+			union {
+				/* used when si_code=SEGV_BNDERR */
+				struct {
+					compat_uptr_t _lower;
+					compat_uptr_t _upper;
+				} _addr_bnd;
+				/* used when si_code=SEGV_PKUERR */
+				compat_u32 _pkey;
+			};
 		} _sigfault;
 
 		/* SIGPOLL */

arch/x86/kernel/signal_compat.c

···
 					  &to->_sifields._pad[0]);
 			switch (from->si_code >> 16) {
 			case __SI_FAULT >> 16:
+				if (from->si_signo == SIGBUS &&
+				    (from->si_code == BUS_MCEERR_AR ||
+				     from->si_code == BUS_MCEERR_AO))
+					put_user_ex(from->si_addr_lsb, &to->si_addr_lsb);
+
+				if (from->si_signo == SIGSEGV) {
+					if (from->si_code == SEGV_BNDERR) {
+						compat_uptr_t lower = (unsigned long)&to->si_lower;
+						compat_uptr_t upper = (unsigned long)&to->si_upper;
+						put_user_ex(lower, &to->si_lower);
+						put_user_ex(upper, &to->si_upper);
+					}
+					if (from->si_code == SEGV_PKUERR)
+						put_user_ex(from->si_pkey, &to->si_pkey);
+				}
 				break;
 			case __SI_SYS >> 16:
 				put_user_ex(from->si_syscall, &to->si_syscall);