Provide a means to discover usages of per_cpu map variables before
they are setup. Define CONFIG_DEBUG_PER_CPU_MAPS to activate.
Based on 2.6.24-rc8-mm1
Signed-off-by: Mike Travis <[EMAIL PROTECTED]>
---
Fixup:
- for cpu_to_node() instead of panic'ing with BUG() use
dump_stack and return valid node id.
---
arch/x86/Kconfig.debug | 12 ++++++++++++
arch/x86/mm/numa_64.c | 3 +++
include/asm-x86/topology.h | 12 ++++++++++--
3 files changed, 25 insertions(+), 2 deletions(-)
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -47,6 +47,18 @@ config DEBUG_PAGEALLOC
This results in a large slowdown, but helps to find certain types
of memory corruptions.
+config DEBUG_PER_CPU_MAPS
+ bool "Debug access to per_cpu maps"
+ depends on DEBUG_KERNEL
+ depends on X86_64_SMP
+ default n
+ help
+ Say Y to verify that the per_cpu map being accessed has
+ been setup. Adds a fair amount of code to kernel memory
+ and decreases performance.
+
+ Say N if unsure.
+
config DEBUG_RODATA
bool "Write protect kernel read-only data structures"
depends on DEBUG_KERNEL
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -37,6 +37,9 @@ int x86_cpu_to_node_map_init[NR_CPUS] =
void *x86_cpu_to_node_map_early_ptr;
DEFINE_PER_CPU(int, x86_cpu_to_node_map) = NUMA_NO_NODE;
EXPORT_PER_CPU_SYMBOL(x86_cpu_to_node_map);
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+EXPORT_SYMBOL(x86_cpu_to_node_map_early_ptr);
+#endif
s16 apicid_to_node[MAX_LOCAL_APIC] __cpuinitdata = {
[0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
--- a/include/asm-x86/topology.h
+++ b/include/asm-x86/topology.h
@@ -58,7 +58,7 @@ static inline int early_cpu_to_node(int
if (cpu_to_node_map)
return cpu_to_node_map[cpu];
- else if(per_cpu_offset(cpu))
+ else if (per_cpu_offset(cpu))
return per_cpu(x86_cpu_to_node_map, cpu);
else
return NUMA_NO_NODE;
@@ -66,7 +66,15 @@ static inline int early_cpu_to_node(int
static inline int cpu_to_node(int cpu)
{
- if(per_cpu_offset(cpu))
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+ if (x86_cpu_to_node_map_early_ptr) {
+ printk("KERN_NOTICE cpu_to_node(%d): usage too early!\n",
+ (int)cpu);
+ dump_stack();
+ return ((int *)x86_cpu_to_node_map_early_ptr)[cpu];
+ }
+#endif
+ if (per_cpu_offset(cpu))
return per_cpu(x86_cpu_to_node_map, cpu);
else
return NUMA_NO_NODE;
--
--
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