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authorFrederic Weisbecker <fweisbec@gmail.com>2010-04-23 05:59:55 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2010-05-01 04:32:14 +0200
commitfeef47d0cb530e8419dfa0b48141b538b89b1b1a (patch)
treead40b07e8b240eca134770120b5c644ec0062ce2 /kernel
parentf93a20541134fa767e8dc4eb32e956d30b9f6b92 (diff)
downloadlinux-2.6.38-lt-ux500-feef47d0cb530e8419dfa0b48141b538b89b1b1a.tar.gz
hw-breakpoints: Get the number of available registers on boot dynamically
The breakpoint generic layer assumes that archs always know in advance the static number of address registers available to host breakpoints through the HBP_NUM macro. However this is not true for every archs. For example Arm needs to get this information dynamically to handle the compatiblity between different versions. To solve this, this patch proposes to drop the static HBP_NUM macro and let the arch provide the number of available slots through a new hw_breakpoint_slots() function. For archs that have CONFIG_HAVE_MIXED_BREAKPOINTS_REGS selected, it will be called once as the number of registers fits for instruction and data breakpoints together. For the others it will be called first to get the number of instruction breakpoint registers and another time to get the data breakpoint registers, the targeted type is given as a parameter of hw_breakpoint_slots(). Reported-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/hw_breakpoint.c53
-rw-r--r--kernel/trace/trace_ksym.c26
2 files changed, 48 insertions, 31 deletions
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 974498b858f..684b710cbb9 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -40,20 +40,12 @@
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/init.h>
+#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/hw_breakpoint.h>
-enum bp_type_idx {
- TYPE_INST = 0,
-#ifdef CONFIG_HAVE_MIXED_BREAKPOINTS_REGS
- TYPE_DATA = 0,
-#else
- TYPE_DATA = 1,
-#endif
- TYPE_MAX
-};
/*
* Constraints data
@@ -63,11 +55,15 @@ enum bp_type_idx {
static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]);
/* Number of pinned task breakpoints in a cpu */
-static DEFINE_PER_CPU(unsigned int, nr_task_bp_pinned[TYPE_MAX][HBP_NUM]);
+static DEFINE_PER_CPU(unsigned int, *nr_task_bp_pinned[TYPE_MAX]);
/* Number of non-pinned cpu/task breakpoints in a cpu */
static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]);
+static int nr_slots[TYPE_MAX];
+
+static int constraints_initialized;
+
/* Gather the number of total pinned and un-pinned bp in a cpuset */
struct bp_busy_slots {
unsigned int pinned;
@@ -99,7 +95,7 @@ static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
int i;
unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
- for (i = HBP_NUM -1; i >= 0; i--) {
+ for (i = nr_slots[type] - 1; i >= 0; i--) {
if (tsk_pinned[i] > 0)
return i + 1;
}
@@ -292,6 +288,10 @@ static int __reserve_bp_slot(struct perf_event *bp)
enum bp_type_idx type;
int weight;
+ /* We couldn't initialize breakpoint constraints on boot */
+ if (!constraints_initialized)
+ return -ENOMEM;
+
/* Basic checks */
if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY ||
bp->attr.bp_type == HW_BREAKPOINT_INVALID)
@@ -304,7 +304,7 @@ static int __reserve_bp_slot(struct perf_event *bp)
fetch_this_slot(&slots, weight);
/* Flexible counters need to keep at least one slot */
- if (slots.pinned + (!!slots.flexible) > HBP_NUM)
+ if (slots.pinned + (!!slots.flexible) > nr_slots[type])
return -ENOSPC;
toggle_bp_slot(bp, true, type, weight);
@@ -551,7 +551,36 @@ static struct notifier_block hw_breakpoint_exceptions_nb = {
static int __init init_hw_breakpoint(void)
{
+ unsigned int **task_bp_pinned;
+ int cpu, err_cpu;
+ int i;
+
+ for (i = 0; i < TYPE_MAX; i++)
+ nr_slots[i] = hw_breakpoint_slots(i);
+
+ for_each_possible_cpu(cpu) {
+ for (i = 0; i < TYPE_MAX; i++) {
+ task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu);
+ *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i],
+ GFP_KERNEL);
+ if (!*task_bp_pinned)
+ goto err_alloc;
+ }
+ }
+
+ constraints_initialized = 1;
+
return register_die_notifier(&hw_breakpoint_exceptions_nb);
+
+ err_alloc:
+ for_each_possible_cpu(err_cpu) {
+ if (err_cpu == cpu)
+ break;
+ for (i = 0; i < TYPE_MAX; i++)
+ kfree(per_cpu(nr_task_bp_pinned[i], cpu));
+ }
+
+ return -ENOMEM;
}
core_initcall(init_hw_breakpoint);
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index d59cd687947..8eaf00749b6 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -34,12 +34,6 @@
#include <asm/atomic.h>
-/*
- * For now, let us restrict the no. of symbols traced simultaneously to number
- * of available hardware breakpoint registers.
- */
-#define KSYM_TRACER_MAX HBP_NUM
-
#define KSYM_TRACER_OP_LEN 3 /* rw- */
struct trace_ksym {
@@ -53,7 +47,6 @@ struct trace_ksym {
static struct trace_array *ksym_trace_array;
-static unsigned int ksym_filter_entry_count;
static unsigned int ksym_tracing_enabled;
static HLIST_HEAD(ksym_filter_head);
@@ -181,13 +174,6 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
struct trace_ksym *entry;
int ret = -ENOMEM;
- if (ksym_filter_entry_count >= KSYM_TRACER_MAX) {
- printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No"
- " new requests for tracing can be accepted now.\n",
- KSYM_TRACER_MAX);
- return -ENOSPC;
- }
-
entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL);
if (!entry)
return -ENOMEM;
@@ -203,13 +189,17 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr)
if (IS_ERR(entry->ksym_hbp)) {
ret = PTR_ERR(entry->ksym_hbp);
- printk(KERN_INFO "ksym_tracer request failed. Try again"
- " later!!\n");
+ if (ret == -ENOSPC) {
+ printk(KERN_ERR "ksym_tracer: Maximum limit reached."
+ " No new requests for tracing can be accepted now.\n");
+ } else {
+ printk(KERN_INFO "ksym_tracer request failed. Try again"
+ " later!!\n");
+ }
goto err;
}
hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head);
- ksym_filter_entry_count++;
return 0;
@@ -265,7 +255,6 @@ static void __ksym_trace_reset(void)
hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,
ksym_hlist) {
unregister_wide_hw_breakpoint(entry->ksym_hbp);
- ksym_filter_entry_count--;
hlist_del_rcu(&(entry->ksym_hlist));
synchronize_rcu();
kfree(entry);
@@ -338,7 +327,6 @@ static ssize_t ksym_trace_filter_write(struct file *file,
goto out_unlock;
}
/* Error or "symbol:---" case: drop it */
- ksym_filter_entry_count--;
hlist_del_rcu(&(entry->ksym_hlist));
synchronize_rcu();
kfree(entry);