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-rw-r--r--arch/powerpc/include/asm/lppaca.h8
-rw-r--r--arch/powerpc/kernel/time.c6
-rw-r--r--arch/powerpc/platforms/pseries/dtl.c206
3 files changed, 179 insertions, 41 deletions
diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h
index cfb85ec8575..7f5e0fefebb 100644
--- a/arch/powerpc/include/asm/lppaca.h
+++ b/arch/powerpc/include/asm/lppaca.h
@@ -191,6 +191,14 @@ struct dtl_entry {
#define DISPATCH_LOG_BYTES 4096 /* bytes per cpu */
#define N_DISPATCH_LOG (DISPATCH_LOG_BYTES / sizeof(struct dtl_entry))
+/*
+ * When CONFIG_VIRT_CPU_ACCOUNTING = y, the cpu accounting code controls
+ * reading from the dispatch trace log. If other code wants to consume
+ * DTL entries, it can set this pointer to a function that will get
+ * called once for each DTL entry that gets processed.
+ */
+extern void (*dtl_consumer)(struct dtl_entry *entry, u64 index);
+
#endif /* CONFIG_PPC_BOOK3S */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_LPPACA_H */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index fca20643c36..bcb738b9ff8 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -183,6 +183,8 @@ DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
cputime_t cputime_one_jiffy;
+void (*dtl_consumer)(struct dtl_entry *, u64);
+
static void calc_cputime_factors(void)
{
struct div_result res;
@@ -218,7 +220,7 @@ static u64 read_spurr(u64 tb)
*/
static u64 scan_dispatch_log(u64 stop_tb)
{
- unsigned long i = local_paca->dtl_ridx;
+ u64 i = local_paca->dtl_ridx;
struct dtl_entry *dtl = local_paca->dtl_curr;
struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
struct lppaca *vpa = local_paca->lppaca_ptr;
@@ -229,6 +231,8 @@ static u64 scan_dispatch_log(u64 stop_tb)
if (i == vpa->dtl_idx)
return 0;
while (i < vpa->dtl_idx) {
+ if (dtl_consumer)
+ dtl_consumer(dtl, i);
dtb = dtl->timebase;
tb_delta = dtl->enqueue_to_dispatch_time +
dtl->ready_to_enqueue_time;
diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
index 0357655db49..c371bc06434 100644
--- a/arch/powerpc/platforms/pseries/dtl.c
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -23,6 +23,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/debugfs.h>
+#include <linux/spinlock.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@@ -37,6 +38,7 @@ struct dtl {
int cpu;
int buf_entries;
u64 last_idx;
+ spinlock_t lock;
};
static DEFINE_PER_CPU(struct dtl, cpu_dtl);
@@ -55,25 +57,97 @@ static u8 dtl_event_mask = 0x7;
static int dtl_buf_entries = (16 * 85);
-static int dtl_enable(struct dtl *dtl)
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
+struct dtl_ring {
+ u64 write_index;
+ struct dtl_entry *write_ptr;
+ struct dtl_entry *buf;
+ struct dtl_entry *buf_end;
+ u8 saved_dtl_mask;
+};
+
+static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);
+
+static atomic_t dtl_count;
+
+/*
+ * The cpu accounting code controls the DTL ring buffer, and we get
+ * given entries as they are processed.
+ */
+static void consume_dtle(struct dtl_entry *dtle, u64 index)
{
- unsigned long addr;
- int ret, hwcpu;
+ struct dtl_ring *dtlr = &__get_cpu_var(dtl_rings);
+ struct dtl_entry *wp = dtlr->write_ptr;
+ struct lppaca *vpa = local_paca->lppaca_ptr;
- /* only allow one reader */
- if (dtl->buf)
- return -EBUSY;
+ if (!wp)
+ return;
- /* we need to store the original allocation size for use during read */
- dtl->buf_entries = dtl_buf_entries;
+ *wp = *dtle;
+ barrier();
- dtl->buf = kmalloc_node(dtl->buf_entries * sizeof(struct dtl_entry),
- GFP_KERNEL, cpu_to_node(dtl->cpu));
- if (!dtl->buf) {
- printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
- __func__, dtl->cpu);
- return -ENOMEM;
- }
+ /* check for hypervisor ring buffer overflow, ignore this entry if so */
+ if (index + N_DISPATCH_LOG < vpa->dtl_idx)
+ return;
+
+ ++wp;
+ if (wp == dtlr->buf_end)
+ wp = dtlr->buf;
+ dtlr->write_ptr = wp;
+
+ /* incrementing write_index makes the new entry visible */
+ smp_wmb();
+ ++dtlr->write_index;
+}
+
+static int dtl_start(struct dtl *dtl)
+{
+ struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);
+
+ dtlr->buf = dtl->buf;
+ dtlr->buf_end = dtl->buf + dtl->buf_entries;
+ dtlr->write_index = 0;
+
+ /* setting write_ptr enables logging into our buffer */
+ smp_wmb();
+ dtlr->write_ptr = dtl->buf;
+
+ /* enable event logging */
+ dtlr->saved_dtl_mask = lppaca_of(dtl->cpu).dtl_enable_mask;
+ lppaca_of(dtl->cpu).dtl_enable_mask |= dtl_event_mask;
+
+ dtl_consumer = consume_dtle;
+ atomic_inc(&dtl_count);
+ return 0;
+}
+
+static void dtl_stop(struct dtl *dtl)
+{
+ struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);
+
+ dtlr->write_ptr = NULL;
+ smp_wmb();
+
+ dtlr->buf = NULL;
+
+ /* restore dtl_enable_mask */
+ lppaca_of(dtl->cpu).dtl_enable_mask = dtlr->saved_dtl_mask;
+
+ if (atomic_dec_and_test(&dtl_count))
+ dtl_consumer = NULL;
+}
+
+static u64 dtl_current_index(struct dtl *dtl)
+{
+ return per_cpu(dtl_rings, dtl->cpu).write_index;
+}
+
+#else /* CONFIG_VIRT_CPU_ACCOUNTING */
+
+static int dtl_start(struct dtl *dtl)
+{
+ unsigned long addr;
+ int ret, hwcpu;
/* Register our dtl buffer with the hypervisor. The HV expects the
* buffer size to be passed in the second word of the buffer */
@@ -85,12 +159,11 @@ static int dtl_enable(struct dtl *dtl)
if (ret) {
printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) "
"failed with %d\n", __func__, dtl->cpu, hwcpu, ret);
- kfree(dtl->buf);
return -EIO;
}
/* set our initial buffer indices */
- dtl->last_idx = lppaca_of(dtl->cpu).dtl_idx = 0;
+ lppaca_of(dtl->cpu).dtl_idx = 0;
/* ensure that our updates to the lppaca fields have occurred before
* we actually enable the logging */
@@ -102,17 +175,66 @@ static int dtl_enable(struct dtl *dtl)
return 0;
}
-static void dtl_disable(struct dtl *dtl)
+static void dtl_stop(struct dtl *dtl)
{
int hwcpu = get_hard_smp_processor_id(dtl->cpu);
lppaca_of(dtl->cpu).dtl_enable_mask = 0x0;
unregister_dtl(hwcpu, __pa(dtl->buf));
+}
+
+static u64 dtl_current_index(struct dtl *dtl)
+{
+ return lppaca_of(dtl->cpu).dtl_idx;
+}
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
+static int dtl_enable(struct dtl *dtl)
+{
+ long int n_entries;
+ long int rc;
+ struct dtl_entry *buf = NULL;
+
+ /* only allow one reader */
+ if (dtl->buf)
+ return -EBUSY;
+
+ n_entries = dtl_buf_entries;
+ buf = kmalloc_node(n_entries * sizeof(struct dtl_entry),
+ GFP_KERNEL, cpu_to_node(dtl->cpu));
+ if (!buf) {
+ printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
+ __func__, dtl->cpu);
+ return -ENOMEM;
+ }
+
+ spin_lock(&dtl->lock);
+ rc = -EBUSY;
+ if (!dtl->buf) {
+ /* store the original allocation size for use during read */
+ dtl->buf_entries = n_entries;
+ dtl->buf = buf;
+ dtl->last_idx = 0;
+ rc = dtl_start(dtl);
+ if (rc)
+ dtl->buf = NULL;
+ }
+ spin_unlock(&dtl->lock);
+
+ if (rc)
+ kfree(buf);
+ return rc;
+}
+
+static void dtl_disable(struct dtl *dtl)
+{
+ spin_lock(&dtl->lock);
+ dtl_stop(dtl);
kfree(dtl->buf);
dtl->buf = NULL;
dtl->buf_entries = 0;
+ spin_unlock(&dtl->lock);
}
/* file interface */
@@ -140,8 +262,9 @@ static int dtl_file_release(struct inode *inode, struct file *filp)
static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len,
loff_t *pos)
{
- int rc, cur_idx, last_idx, n_read, n_req, read_size;
+ long int rc, n_read, n_req, read_size;
struct dtl *dtl;
+ u64 cur_idx, last_idx, i;
if ((len % sizeof(struct dtl_entry)) != 0)
return -EINVAL;
@@ -154,41 +277,48 @@ static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len,
/* actual number of entries read */
n_read = 0;
- cur_idx = lppaca_of(dtl->cpu).dtl_idx;
+ spin_lock(&dtl->lock);
+
+ cur_idx = dtl_current_index(dtl);
last_idx = dtl->last_idx;
- if (cur_idx - last_idx > dtl->buf_entries) {
- pr_debug("%s: hv buffer overflow for cpu %d, samples lost\n",
- __func__, dtl->cpu);
- }
+ if (last_idx + dtl->buf_entries <= cur_idx)
+ last_idx = cur_idx - dtl->buf_entries + 1;
+
+ if (last_idx + n_req > cur_idx)
+ n_req = cur_idx - last_idx;
- cur_idx %= dtl->buf_entries;
- last_idx %= dtl->buf_entries;
+ if (n_req > 0)
+ dtl->last_idx = last_idx + n_req;
+
+ spin_unlock(&dtl->lock);
+
+ if (n_req <= 0)
+ return 0;
+
+ i = last_idx % dtl->buf_entries;
/* read the tail of the buffer if we've wrapped */
- if (last_idx > cur_idx) {
- read_size = min(n_req, dtl->buf_entries - last_idx);
+ if (i + n_req > dtl->buf_entries) {
+ read_size = dtl->buf_entries - i;
- rc = copy_to_user(buf, &dtl->buf[last_idx],
+ rc = copy_to_user(buf, &dtl->buf[i],
read_size * sizeof(struct dtl_entry));
if (rc)
return -EFAULT;
- last_idx = 0;
+ i = 0;
n_req -= read_size;
n_read += read_size;
buf += read_size * sizeof(struct dtl_entry);
}
/* .. and now the head */
- read_size = min(n_req, cur_idx - last_idx);
- rc = copy_to_user(buf, &dtl->buf[last_idx],
- read_size * sizeof(struct dtl_entry));
+ rc = copy_to_user(buf, &dtl->buf[i], n_req * sizeof(struct dtl_entry));
if (rc)
return -EFAULT;
- n_read += read_size;
- dtl->last_idx += n_read;
+ n_read += n_req;
return n_read * sizeof(struct dtl_entry);
}
@@ -220,11 +350,6 @@ static int dtl_init(void)
struct dentry *event_mask_file, *buf_entries_file;
int rc, i;
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING
- /* disable this for now */
- return -ENODEV;
-#endif
-
if (!firmware_has_feature(FW_FEATURE_SPLPAR))
return -ENODEV;
@@ -251,6 +376,7 @@ static int dtl_init(void)
/* set up the per-cpu log structures */
for_each_possible_cpu(i) {
struct dtl *dtl = &per_cpu(cpu_dtl, i);
+ spin_lock_init(&dtl->lock);
dtl->cpu = i;
rc = dtl_setup_file(dtl);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-10-31 05:17:48 +0000