arm64: consolidate signal injection on emulation errors

The code for injecting a signal into userland if a trapped instruction
fails emulation due to a _userland_ error (like an illegal address)
will be used more often with the next patch.
Factor out the core functionality into a separate function and use
that both for the existing trap handler and for the deprecated
instructions emulation.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
[catalin.marinas@arm.com: s/set_segfault/arm64_notify_segfault/]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 50 insertions, 13 deletions

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index a4250a59f2b9..d8a5366dcc24 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -364,30 +364,67 @@ exit:
         return fn ? fn(regs, instr) : 1;
 }
 
-asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
+static void force_signal_inject(int signal, int code, struct pt_regs *regs,
+                                unsigned long address)
 {
         siginfo_t info;
         void __user *pc = (void __user *)instruction_pointer(regs);
+        const char *desc;
 
-        /* check for AArch32 breakpoint instructions */
-        if (!aarch32_break_handler(regs))
-                return;
-
-        if (call_undef_hook(regs) == 0)
-                return;
+        switch (signal) {
+        case SIGILL:
+                desc = "undefined instruction";
+                break;
+        case SIGSEGV:
+                desc = "illegal memory access";
+                break;
+        default:
+                desc = "bad mode";
+                break;
+        }
 
-        if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
-                pr_info("%s[%d]: undefined instruction: pc=%p\n",
-                        current->comm, task_pid_nr(current), pc);
+        if (unhandled_signal(current, signal) &&
+            show_unhandled_signals_ratelimited()) {
+                pr_info("%s[%d]: %s: pc=%p\n",
+                        current->comm, task_pid_nr(current), desc, pc);
                 dump_instr(KERN_INFO, regs);
         }
 
-        info.si_signo = SIGILL;
+        info.si_signo = signal;
         info.si_errno = 0;
-        info.si_code  = ILL_ILLOPC;
+        info.si_code  = code;
         info.si_addr  = pc;
 
-        arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
+        arm64_notify_die(desc, regs, &info, 0);
+}
+
+/*
+ * Set up process info to signal segmentation fault - called on access error.
+ */
+void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr)
+{
+        int code;
+
+        down_read(&current->mm->mmap_sem);
+        if (find_vma(current->mm, addr) == NULL)
+                code = SEGV_MAPERR;
+        else
+                code = SEGV_ACCERR;
+        up_read(&current->mm->mmap_sem);
+
+        force_signal_inject(SIGSEGV, code, regs, addr);
+}
+
+asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
+{
+        /* check for AArch32 breakpoint instructions */
+        if (!aarch32_break_handler(regs))
+                return;
+
+        if (call_undef_hook(regs) == 0)
+                return;
+
+        force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
 }
 
 long compat_arm_syscall(struct pt_regs *regs);