consolidate do_bug_frame() / bug_fn_t

The type not being used in do_bug_frame() is suspicious. Apparently
that's solely because the type uses a pointer-to-const parameter,
when so far run_in_exception_handler() wanted functions taking pointer-
to-non-const. Expand use of const, in turn requiring common code's
do_bug_frame() as well as [gs]et_irq_regs() to also gain const. This
then brings the former function also closer to the common one, with
Arm's use of vaddr_t remaining as a difference.

While there also replace the bogus use of hard tabs in [gs]et_irq_regs()
(I clearly didn't mean to put it in like this).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/arm/irq.c

@@ -220,7 +220,7 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq)
 {
     struct irq_desc *desc = irq_to_desc(irq);
     struct irqaction *action;
-    struct cpu_user_regs *old_regs = set_irq_regs(regs);
+    const struct cpu_user_regs *old_regs = set_irq_regs(regs);
 
     perfc_incr(irqs);
 

xen/arch/x86/include/asm/processor.h

@@ -409,8 +409,7 @@ static always_inline void rep_nop(void)
 void show_code(const struct cpu_user_regs *regs);
 void show_stack_overflow(unsigned int cpu, const struct cpu_user_regs *regs);
 void show_registers(const struct cpu_user_regs *regs);
-#define dump_execution_state() \
-    run_in_exception_handler(show_execution_state_nonconst)
+#define dump_execution_state() run_in_exception_handler(show_execution_state)
 void show_page_walk(unsigned long addr);
 void noreturn fatal_trap(const struct cpu_user_regs *regs, bool show_remote);
 

xen/arch/x86/irq.c

@@ -1896,7 +1896,7 @@ void do_IRQ(struct cpu_user_regs *regs)
     struct irq_desc  *desc;
     unsigned int      vector = (uint8_t)regs->entry_vector;
     int               irq = this_cpu(vector_irq)[vector];
-    struct cpu_user_regs *old_regs = set_irq_regs(regs);
+    const struct cpu_user_regs *old_regs = set_irq_regs(regs);
 
     perfc_incr(irqs);
     this_cpu(irq_count)++;

xen/arch/x86/traps.c

@@ -643,7 +643,7 @@ void show_stack_overflow(unsigned int cpu, const struct cpu_user_regs *regs)
     printk("\n");
 }
 
-void show_execution_state(const struct cpu_user_regs *regs)
+void cf_check show_execution_state(const struct cpu_user_regs *regs)
 {
     /* Prevent interleaving of output. */
     unsigned long flags = console_lock_recursive_irqsave();
@@ -655,11 +655,6 @@ void show_execution_state(const struct cpu_user_regs *regs)
     console_unlock_recursive_irqrestore(flags);
 }
 
-void cf_check show_execution_state_nonconst(struct cpu_user_regs *regs)
-{
-    show_execution_state(regs);
-}
-
 void vcpu_show_execution_state(struct vcpu *v)
 {
     unsigned long flags = 0;

xen/common/bug.c

@@ -10,7 +10,7 @@
  * Returns a negative value in case of an error otherwise
  * BUGFRAME_{run_fn, warn, bug, assert}
  */
-int do_bug_frame(struct cpu_user_regs *regs, unsigned long pc)
+int do_bug_frame(const struct cpu_user_regs *regs, unsigned long pc)
 {
     const struct bug_frame *bug = NULL;
     const struct virtual_region *region;
@@ -44,14 +44,10 @@ int do_bug_frame(struct cpu_user_regs *regs, unsigned long pc)
 
     if ( id == BUGFRAME_run_fn )
     {
-        void (*fn)(struct cpu_user_regs *) = bug_ptr(bug);
+        bug_fn_t *fn = bug_ptr(bug);
 
         fn(regs);
 
-        /* Re-enforce consistent types, because of the casts involved. */
-        if ( false )
-            run_in_exception_handler(fn);
-
         return id;
     }
 

xen/common/irq.c

@@ -1,7 +1,7 @@
 #include <xen/irq.h>
 #include <xen/errno.h>
 
-DEFINE_PER_CPU(struct cpu_user_regs *, irq_regs);
+DEFINE_PER_CPU(const struct cpu_user_regs *, irq_regs);
 
 int init_one_irq_desc(struct irq_desc *desc)
 {

xen/common/keyhandler.c

@@ -135,7 +135,7 @@ static void cf_check show_handlers(unsigned char key)
 
 static cpumask_t dump_execstate_mask;
 
-void cf_check dump_execstate(struct cpu_user_regs *regs)
+void cf_check dump_execstate(const struct cpu_user_regs *regs)
 {
     unsigned int cpu = smp_processor_id();
 

xen/drivers/char/ehci-dbgp.c

@@ -1246,14 +1246,14 @@ static int cf_check ehci_dbgp_getc(struct serial_port *port, char *pc)
 /* Safe: ehci_dbgp_poll() runs as timer handler, so not reentrant. */
 static struct serial_port *poll_port;
 
-static void cf_check _ehci_dbgp_poll(struct cpu_user_regs *regs)
+static void cf_check _ehci_dbgp_poll(const struct cpu_user_regs *regs)
 {
     struct serial_port *port = poll_port;
     struct ehci_dbgp *dbgp = port->uart;
     unsigned long flags;
     unsigned int timeout = MICROSECS(DBGP_CHECK_INTERVAL);
     bool empty = false;
-    struct cpu_user_regs *old_regs;
+    const struct cpu_user_regs *old_regs;
 
     if ( !dbgp->ehci_debug )
         return;

xen/drivers/char/ns16550.c

@@ -206,11 +206,11 @@ static void cf_check ns16550_interrupt(int irq, void *dev_id)
 /* Safe: ns16550_poll() runs as softirq so not reentrant on a given CPU. */
 static DEFINE_PER_CPU(struct serial_port *, poll_port);
 
-static void cf_check __ns16550_poll(struct cpu_user_regs *regs)
+static void cf_check __ns16550_poll(const struct cpu_user_regs *regs)
 {
     struct serial_port *port = this_cpu(poll_port);
     struct ns16550 *uart = port->uart;
-    struct cpu_user_regs *old_regs;
+    const struct cpu_user_regs *old_regs;
 
     if ( uart->intr_works )
         return; /* Interrupts work - no more polling */

xen/include/xen/bug.h

@@ -101,8 +101,7 @@ typedef void bug_fn_t(const struct cpu_user_regs *regs);
 
 #ifndef run_in_exception_handler
 
-static void always_inline run_in_exception_handler(
-    void (*fn)(struct cpu_user_regs *regs))
+static void always_inline run_in_exception_handler(bug_fn_t *fn)
 {
     BUG_FRAME(BUGFRAME_run_fn, 0, fn, 0, NULL);
 }
@@ -133,7 +132,7 @@ static void always_inline run_in_exception_handler(
  * Returns a negative value in case of an error otherwise
  * BUGFRAME_{run_fn, warn, bug, assert}
  */
-int do_bug_frame(struct cpu_user_regs *regs, unsigned long pc);
+int do_bug_frame(const struct cpu_user_regs *regs, unsigned long pc);
 
 #endif /* CONFIG_GENERIC_BUG_FRAME */
 

xen/include/xen/irq.h

@@ -134,21 +134,22 @@ void cf_check irq_actor_none(struct irq_desc *desc);
  * Per-cpu interrupted context register state - the inner-most interrupt frame
  * on the stack.
  */
-DECLARE_PER_CPU(struct cpu_user_regs *, irq_regs);
+DECLARE_PER_CPU(const struct cpu_user_regs *, irq_regs);
 
-static inline struct cpu_user_regs *get_irq_regs(void)
+static inline const struct cpu_user_regs *get_irq_regs(void)
 {
-	return this_cpu(irq_regs);
+    return this_cpu(irq_regs);
 }
 
-static inline struct cpu_user_regs *set_irq_regs(struct cpu_user_regs *new_regs)
+static inline const struct cpu_user_regs *set_irq_regs(
+    const struct cpu_user_regs *new_regs)
 {
-	struct cpu_user_regs *old_regs, **pp_regs = &this_cpu(irq_regs);
+    const struct cpu_user_regs *old_regs, **pp_regs = &this_cpu(irq_regs);
 
-	old_regs = *pp_regs;
-	*pp_regs = new_regs;
+    old_regs = *pp_regs;
+    *pp_regs = new_regs;
 
-	return old_regs;
+    return old_regs;
 }
 
 struct domain;

xen/include/xen/kernel.h

@@ -110,8 +110,7 @@ extern const unsigned int xen_config_data_size;
 struct cpu_user_regs;
 struct vcpu;
 
-void show_execution_state(const struct cpu_user_regs *regs);
-void cf_check show_execution_state_nonconst(struct cpu_user_regs *regs);
+void cf_check show_execution_state(const struct cpu_user_regs *regs);
 void vcpu_show_execution_state(struct vcpu *v);
 
 #endif /* _LINUX_KERNEL_H */

xen/include/xen/lib.h

@@ -173,7 +173,7 @@ extern char *print_tainted(char *str);
 extern void add_taint(unsigned int taint);
 
 struct cpu_user_regs;
-void cf_check dump_execstate(struct cpu_user_regs *regs);
+void cf_check dump_execstate(const struct cpu_user_regs *regs);
 
 void init_constructors(void);