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    Subject[REVIEW][PATCH 19/22] signal/um: Use force_sig_fault in relay_signal.
    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 <jdike@addtoit.com>
    Cc: Richard Weinberger <richard@nod.at>
    Cc: user-mode-linux-devel@lists.sourceforge.net
    Signed-off-by: "Eric W. Biederman" <ebiederm@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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