powerpc/xmon: Add address lookup for percpu symbols

Currently, in xmon, there is no obvious way to get an address for a
percpu symbol for a particular cpu. Having such an ability would be
good for debugging the system when percpu variables got involved.

Therefore, this patch introduces a new xmon command "lp" to lookup the
address for percpu symbols. Usage of "lp" is similar to "ls", except
that we could add a cpu number to choose the variable of which cpu we
want to lookup. If no cpu number is given, lookup for current cpu.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index b7dd683..7c4aa5b 100644 (file)
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -56,6 +56,7 @@
 #include <asm/opal.h>
 #include <asm/firmware.h>
 #include <asm/code-patching.h>
+#include <asm/sections.h>
 
 #ifdef CONFIG_PPC64
 #include <asm/hvcall.h>
@@ -244,6 +245,7 @@ Commands:\n\
   f    flush cache\n\
   la   lookup symbol+offset of specified address\n\
   ls   lookup address of specified symbol\n\
+  lp s [#]     lookup address of percpu symbol s for current cpu, or cpu #\n\
   m    examine/change memory\n\
   mm   move a block of memory\n\
   ms   set a block of memory\n\
@@ -3352,7 +3354,8 @@ static void
 symbol_lookup(void)
 {
        int type = inchar();
-       unsigned long addr;
+       unsigned long addr, cpu;
+       void __percpu *ptr = NULL;
        static char tmp[64];
 
        switch (type) {
@@ -3373,6 +3376,34 @@ symbol_lookup(void)
                                printf("Symbol '%s' not found.\n", tmp);
                        sync();
                }
+               catch_memory_errors = 0;
+               termch = 0;
+               break;
+       case 'p':
+               getstring(tmp, 64);
+               if (setjmp(bus_error_jmp) == 0) {
+                       catch_memory_errors = 1;
+                       sync();
+                       ptr = (void __percpu *)kallsyms_lookup_name(tmp);
+                       sync();
+               }
+
+               if (ptr &&
+                   ptr >= (void __percpu *)__per_cpu_start &&
+                   ptr < (void __percpu *)__per_cpu_end)
+               {
+                       if (scanhex(&cpu) && cpu < num_possible_cpus()) {
+                               addr = (unsigned long)per_cpu_ptr(ptr, cpu);
+                       } else {
+                               cpu = raw_smp_processor_id();
+                               addr = (unsigned long)this_cpu_ptr(ptr);
+                       }
+
+                       printf("%s for cpu 0x%lx: %lx\n", tmp, cpu, addr);
+               } else {
+                       printf("Percpu symbol '%s' not found.\n", tmp);
+               }
+
                catch_memory_errors = 0;
                termch = 0;
                break;