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 <dave.hansen@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac@vger.kernel.org
Link: http://lkml.kernel.org/r/20160608172533.F8F05637@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 26 insertions, 0 deletions

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 5a3b2c119ed0..a18806165fe4 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -40,6 +40,7 @@ typedef s32		compat_long_t;
 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;
 
@@ -181,6 +182,16 @@ typedef struct compat_siginfo {
                 /* 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 */
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index dc3c0b1c816f..5335ad96a290 100644
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -32,6 +32,21 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
                                           &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);