signal/arm64: Add and use arm64_force_sig_mceerr as appropriate

Add arm64_force_sig_mceerr for consistency with arm64_force_sig_fault,
and use it in the one location that can take advantage of it.

This removes the fiddly filling out of siginfo before sending a signal
reporting an memory error to userspace.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

arch/arm64/include/asm/traps.h

@@ -38,6 +38,7 @@ void unregister_undef_hook(struct undef_hook *hook);
 void force_signal_inject(int signal, int code, unsigned long address);
 void arm64_notify_segfault(unsigned long addr);
 void arm64_force_sig_fault(int signo, int code, void __user *addr, const char *str);
+void arm64_force_sig_mceerr(int code, void __user *addr, short lsb, const char *str);
 void arm64_force_sig_info(struct siginfo *info, const char *str);
 
 /*

arch/arm64/kernel/traps.c

@@ -255,6 +255,13 @@ void arm64_force_sig_fault(int signo, int code, void __user *addr,
 	force_sig_fault(signo, code, addr, current);
 }
 
+void arm64_force_sig_mceerr(int code, void __user *addr, short lsb,
+			    const char *str)
+{
+	arm64_show_signal(SIGBUS, str);
+	force_sig_mceerr(code, addr, lsb, current);
+}
+
 void arm64_force_sig_info(struct siginfo *info, const char *str)
 {
 	arm64_show_signal(info->si_signo, str);

arch/arm64/mm/fault.c

@@ -422,7 +422,6 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 	const struct fault_info *inf;
 	struct task_struct *tsk;
 	struct mm_struct *mm;
-	struct siginfo si;
 	vm_fault_t fault, major = 0;
 	unsigned long vm_flags = VM_READ | VM_WRITE;
 	unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
@@ -574,12 +573,8 @@ retry:
 		if (fault & VM_FAULT_HWPOISON_LARGE)
 			lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
 
-		clear_siginfo(&si);
-		si.si_signo	= SIGBUS;
-		si.si_code	= BUS_MCEERR_AR;
-		si.si_addr = (void __user *)addr;
-		si.si_addr_lsb	= lsb;
-		arm64_force_sig_info(&si, inf->name);
+		arm64_force_sig_mceerr(BUS_MCEERR_AR, (void __user *)addr, lsb,
+				       inf->name);
 	} else {
 		/*
 		 * Something tried to access memory that isn't in our memory