ARM: 7008/1: alignment: Make SIGBUS sent to userspace POSIXly correct

With the UM_SIGNAL alignment fault mode, no siginfo structure is
passed to userspace.

POSIX specifies how siginfo_t should be populated for alignment
faults, so this patch does just that:

  * si_signo = SIGBUS
  * si_code = BUS_ADRALN
  * si_addr = misaligned data address at which access was attempted

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 11 insertions, 3 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 1df38e833570..cfbcf8b95599 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -22,6 +22,7 @@
 #include <linux/sched.h>
 #include <linux/uaccess.h>
 
+#include <asm/system.h>
 #include <asm/unaligned.h>
 
 #include "fault.h"
@@ -913,9 +914,16 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
         if (ai_usermode & UM_FIXUP)
                 goto fixup;
 
-        if (ai_usermode & UM_SIGNAL)
-                force_sig(SIGBUS, current);
-        else {
+        if (ai_usermode & UM_SIGNAL) {
+                siginfo_t si;
+
+                si.si_signo = SIGBUS;
+                si.si_errno = 0;
+                si.si_code = BUS_ADRALN;
+                si.si_addr = (void __user *)addr;
+
+                force_sig_info(si.si_signo, &si, current);
+        } else {
                 /*
                  * We're about to disable the alignment trap and return to
                  * user space.  But if an interrupt occurs before actually