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 <[email protected]>
---
arch/powerpc/xmon/xmon.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 760545519a0b..3556966a29a5 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -229,6 +229,7 @@ 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\
@@ -2943,7 +2944,7 @@ static void
symbol_lookup(void)
{
int type = inchar();
- unsigned long addr;
+ unsigned long addr, cpu, offset;
static char tmp[64];
switch (type) {
@@ -2967,6 +2968,31 @@ symbol_lookup(void)
catch_memory_errors = 0;
termch = 0;
break;
+ case 'p':
+ getstring(tmp, 64);
+ if (setjmp(bus_error_jmp) == 0) {
+ catch_memory_errors = 1;
+ sync();
+ addr = kallsyms_lookup_name(tmp);
+ sync();
+ }
+
+ if (scanhex(&cpu) && cpu < num_possible_cpus())
+ offset = per_cpu_offset(cpu);
+ else {
+ offset = my_cpu_offset;
+ cpu = raw_smp_processor_id();
+ }
+
+ if (addr)
+ printf("%s for cpu 0x%lx: %lx\n", tmp, cpu,
+ addr + offset);
+ else
+ printf("Percpu symbol '%s' not found.\n", tmp);
+
+ catch_memory_errors = 0;
+ termch = 0;
+ break;
}
}
--
2.10.1
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 <[email protected]>
---
v1 --> v2:
o Using per_cpu_ptr() and this_cpu_ptr() instead of
per_cpu_offset() and my_cpu_offset, because the latter
are undefined on !SMP kernel.
o Only print the address of percpu symbols, i.e. symbols
in [__per_cpu_start, __per_cpu_end)
arch/powerpc/xmon/xmon.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 760545519a0b..2747c94400a2 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -49,6 +49,7 @@
#include <asm/opal.h>
#include <asm/firmware.h>
+#include <asm/sections.h>
#ifdef CONFIG_PPC64
#include <asm/hvcall.h>
@@ -229,6 +230,7 @@ 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\
@@ -2943,7 +2945,8 @@ 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) {
@@ -2967,6 +2970,36 @@ symbol_lookup(void)
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;
}
}
--
2.10.1
On Tue, 2016-11-22 at 09:20:09 UTC, Boqun Feng wrote:
> 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 <[email protected]>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/302c7b0c4ff5aed585419603f835de
cheers