Today user mode linux only works on x86 and x86_64 and this allows
simplifications of relay_signal.

- x86 always set si_errno to 0 in fault handlers.
- x86 does not implement si_trapno.
- Only si_codes between SI_USER and SI_KERNEL have a fault address.

Therefore warn if si_errno is set (it should never be).
Use force_sig_info in the case where we know we have a good fault.

For signals whose content it is not clear how to relay use plain
force_sig and let the signal sending code come up with an
appropriate generic siginfo.

Cc: Jeff Dike <jd...@addtoit.com>
Cc: Richard Weinberger <rich...@nod.at>
Cc: user-mode-linux-devel@lists.sourceforge.net
Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
---
 arch/um/kernel/trap.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index d4d38520c4c6..5f0ff17cd790 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -296,9 +296,6 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, 
int is_user,
 
 void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs)
 {
-       struct faultinfo *fi;
-       struct siginfo clean_si;
-
        if (!UPT_IS_USER(regs)) {
                if (sig == SIGBUS)
                        printk(KERN_ERR "Bus error - the host /dev/shm or /tmp "
@@ -308,29 +305,30 @@ void relay_signal(int sig, struct siginfo *si, struct 
uml_pt_regs *regs)
 
        arch_examine_signal(sig, regs);
 
-       clear_siginfo(&clean_si);
-       clean_si.si_signo = si->si_signo;
-       clean_si.si_errno = si->si_errno;
-       clean_si.si_code = si->si_code;
+       if (unlikely(si->si_errno)) {
+               printk(KERN_ERR "Attempted to relay signal %d (si_code = %d) 
with errno %d\n",
+                      sig, si->si_code, si->si_errno);
+       }
        switch (sig) {
        case SIGILL:
        case SIGFPE:
        case SIGSEGV:
        case SIGBUS:
        case SIGTRAP:
-               fi = UPT_FAULTINFO(regs);
-               clean_si.si_addr = (void __user *) FAULT_ADDRESS(*fi);
-               current->thread.arch.faultinfo = *fi;
-#ifdef __ARCH_SI_TRAPNO
-               clean_si.si_trapno = si->si_trapno;
-#endif
-               break;
+               if ((si->si_code > SI_USER) && (si->si_code < SI_KERNEL)) {
+                       struct faultinfo *fi = UPT_FAULTINFO(regs);
+                       current->thread.arch.faultinfo = *fi;
+                       force_sig_fault(sig, si->si_code,
+                                       (void __user *)FAULT_ADDRESS(*fi),
+                                       current);
+                       break;
+               }
        default:
                printk(KERN_ERR "Attempted to relay unknown signal %d (si_code 
= %d)\n",
                        sig, si->si_code);
        }
 
-       force_sig_info(sig, &clean_si, current);
+       force_sig(sig, current);
 }
 
 void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs)
-- 
2.14.1


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