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>

diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 0cc2f29..9cd03f3 100644 (file)
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -34,6 +34,8 @@ struct undef_hook {
 void register_undef_hook(struct undef_hook *hook);
 void unregister_undef_hook(struct undef_hook *hook);
 
+void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr);
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static inline int __in_irqentry_text(unsigned long ptr)
 {

diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index c37202c..fab5603 100644 (file)
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -316,28 +316,6 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table)
  */
 #define TYPE_SWPB (1 << 22)
 
-/*
- * Set up process info to signal segmentation fault - called on access error.
- */
-static void set_segfault(struct pt_regs *regs, unsigned long addr)
-{
-       siginfo_t info;
-
-       down_read(&current->mm->mmap_sem);
-       if (find_vma(current->mm, addr) == NULL)
-               info.si_code = SEGV_MAPERR;
-       else
-               info.si_code = SEGV_ACCERR;
-       up_read(&current->mm->mmap_sem);
-
-       info.si_signo = SIGSEGV;
-       info.si_errno = 0;
-       info.si_addr  = (void *) instruction_pointer(regs);
-
-       pr_debug("SWP{B} emulation: access caused memory abort!\n");
-       arm64_notify_die("Illegal memory access", regs, &info, 0);
-}
-
 static int emulate_swpX(unsigned int address, unsigned int *data,
                        unsigned int type)
 {
@@ -430,7 +408,8 @@ ret:
        return 0;
 
 fault:
-       set_segfault(regs, address);
+       pr_debug("SWP{B} emulation: access caused memory abort!\n");
+       arm64_notify_segfault(regs, address);
 
        return 0;
 }

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index a4250a5..d8a5366 100644 (file)
--- 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);