[PATCH v3 2/3] x86/traps: split code to dump execution state to a separate helper

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Split the code that triggers remote CPUs to dump stacks into a separate
function.  Also introduce a parameter that can be set by the caller of the
newly introduced function to force CPUs to dump the full stack, rather than
just dumping the current function name.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v2:
 - Use parameter opt_show_all variable.
---
 xen/arch/x86/include/asm/processor.h |  1 +
 xen/arch/x86/traps.c                 | 63 ++++++++++++++++++----------
 2 files changed, 41 insertions(+), 23 deletions(-)

diff --git a/xen/arch/x86/include/asm/processor.h 
b/xen/arch/x86/include/asm/processor.h
index eacd425c5350..10d8078cc1ca 100644
--- a/xen/arch/x86/include/asm/processor.h
+++ b/xen/arch/x86/include/asm/processor.h
@@ -371,6 +371,7 @@ void show_registers(const struct cpu_user_regs *regs);
 #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);
+void show_execution_state_nmi(const cpumask_t *mask, bool show_all);
 
 extern void mtrr_ap_init(void);
 extern void mtrr_bp_init(void);
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 22f20629327d..559bb1d2029b 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -734,6 +734,43 @@ static int cf_check nmi_show_execution_state(
     return 1;
 }
 
+void show_execution_state_nmi(const cpumask_t *mask, bool show_all)
+{
+    unsigned int msecs, pending;
+
+    /*
+     * Overwrite the global variable, caller is expected to panic after having
+     * dumped the execution state.
+     */
+    if ( show_all )
+        opt_show_all = true;
+
+    watchdog_disable();
+    console_start_sync();
+
+    cpumask_copy(&show_state_mask, mask);
+    set_nmi_callback(nmi_show_execution_state);
+    send_IPI_mask(mask, APIC_DM_NMI);
+
+    /* Wait at most 10ms for some other CPU to respond. */
+    msecs = 10;
+    pending = cpumask_weight(&show_state_mask);
+    while ( pending && msecs-- )
+    {
+        unsigned int left;
+
+        mdelay(1);
+        left = cpumask_weight(&show_state_mask);
+        if ( left < pending )
+        {
+            pending = left;
+            msecs = 10;
+        }
+    }
+    if ( pending )
+        printk("Non-responding CPUs: {%*pbl}\n", CPUMASK_PR(&show_state_mask));
+}
+
 const char *vector_name(unsigned int vec)
 {
     static const char names[][4] = {
@@ -780,31 +817,11 @@ void fatal_trap(const struct cpu_user_regs *regs, bool 
show_remote)
 
         if ( show_remote )
         {
-            unsigned int msecs, pending;
+            cpumask_t *scratch = this_cpu(scratch_cpumask);
 
-            cpumask_andnot(&show_state_mask, &cpu_online_map,
+            cpumask_andnot(scratch, &cpu_online_map,
                            cpumask_of(smp_processor_id()));
-            set_nmi_callback(nmi_show_execution_state);
-            smp_send_nmi_allbutself();
-
-            /* Wait at most 10ms for some other CPU to respond. */
-            msecs = 10;
-            pending = cpumask_weight(&show_state_mask);
-            while ( pending && msecs-- )
-            {
-                unsigned int left;
-
-                mdelay(1);
-                left = cpumask_weight(&show_state_mask);
-                if ( left < pending )
-                {
-                    pending = left;
-                    msecs = 10;
-                }
-            }
-            if ( pending )
-                printk("Non-responding CPUs: {%*pbl}\n",
-                       CPUMASK_PR(&show_state_mask));
+            show_execution_state_nmi(scratch, false);
         }
     }
 
-- 
2.49.0