On Fri, 2014-14-02 at 22:02:13 UTC, Cody P Schafer wrote:
This provides a basic interface between hv_24x7 and perf. Similar to...
the one provided for gpci, it lacks transaction support and does not
list any events.
Signed-off-by: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/perf/hv-24x7.c | 491 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 491 insertions(+)
create mode 100644 arch/powerpc/perf/hv-24x7.c
diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
new file mode 100644
index 0000000..13de140
--- /dev/null
+++ b/arch/powerpc/perf/hv-24x7.c
+
+/*
+ * read_offset_data - copy data from one buffer to another while treating the
+ * source buffer as a small view on the total avaliable
+ * source data.
+ *
+ * @dest: buffer to copy into
+ * @dest_len: length of @dest in bytes
+ * @requested_offset: the offset within the source data we want. Must be > 0
+ * @src: buffer to copy data from
+ * @src_len: length of @src in bytes
+ * @source_offset: the offset in the sorce data that (src,src_len) refers to.
+ * Must be > 0
+ *
+ * returns the number of bytes copied.
+ *
+ * '.' areas in d are written to.
+ *
+ * u
+ * x w v z
+ * d |.........|
+ * s |----------------------|
+ *
+ * u
+ * x w z v
+ * d |........------|
+ * s |------------------|
+ *
+ * x w u,z,v
+ * d |........|
+ * s |------------------|
+ *
+ * x,w u,v,z
+ * d |------------------|
+ * s |------------------|
+ *
+ * x u
+ * w v z
+ * d |........|
+ * s |------------------|
+ *
+ * x z w v
+ * d |------|
+ * s |------|
+ *
+ * x = source_offset
+ * w = requested_offset
+ * z = source_offset + src_len
+ * v = requested_offset + dest_len
+ *
+ * w_offset_in_s = w - x = requested_offset - source_offset
+ * z_offset_in_s = z - x = src_len
+ * v_offset_in_s = v - x = request_offset + dest_len - src_len
+ * u_offset_in_s = min(z_offset_in_s, v_offset_in_s)
+ *
+ * copy_len = u_offset_in_s - w_offset_in_s = min(z_offset_in_s, v_offset_in_s)
+ * - w_offset_in_s
Comments are great, especially for complicated code like this. But at a glance
I don't actually understand what this comment is trying to tell me.
+ */
+static ssize_t read_offset_data(void *dest, size_t dest_len,
+ loff_t requested_offset, void *src,
+ size_t src_len, loff_t source_offset)
+{
+ size_t w_offset_in_s = requested_offset - source_offset;
+ size_t z_offset_in_s = src_len;
+ size_t v_offset_in_s = requested_offset + dest_len - src_len;
+ size_t u_offset_in_s = min(z_offset_in_s, v_offset_in_s);
+ size_t copy_len = u_offset_in_s - w_offset_in_s;
+
+ if (requested_offset < 0 || source_offset < 0)
+ return -EINVAL;
+
+ if (z_offset_in_s <= w_offset_in_s)
+ return 0;
+
+ memcpy(dest, src + w_offset_in_s, copy_len);
+ return copy_len;
+}
+
+static unsigned long h_get_24x7_catalog_page(char page[static 4096],
+ u32 version, u32 index)
+{
+ WARN_ON(!IS_ALIGNED((unsigned long)page, 4096));
+ return plpar_hcall_norets(H_GET_24X7_CATALOG_PAGE,
+ virt_to_phys(page),
+ version,
+ index);
+}
+
+static ssize_t catalog_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf,
+ loff_t offset, size_t count)
+{
+ unsigned long hret;
+ ssize_t ret = 0;
+ size_t catalog_len = 0, catalog_page_len = 0, page_count = 0;
+ loff_t page_offset = 0;
+ uint32_t catalog_version_num = 0;
+ void *page = kmalloc(4096, GFP_USER);
+ struct hv_24x7_catalog_page_0 *page_0 = page;
+ if (!page)
+ return -ENOMEM;
+
+
+ hret = h_get_24x7_catalog_page(page, 0, 0);
+ if (hret) {
+ ret = -EIO;
+ goto e_free;
+ }
+
+ catalog_version_num = be32_to_cpu(page_0->version);
+ catalog_page_len = be32_to_cpu(page_0->length);
+ catalog_len = catalog_page_len * 4096;
+
+ page_offset = offset / 4096;
+ page_count = count / 4096;
+
+ if (page_offset >= catalog_page_len)
+ goto e_free;
+
+ if (page_offset != 0) {
+ hret = h_get_24x7_catalog_page(page, catalog_version_num,
+ page_offset);
+ if (hret) {
+ ret = -EIO;
+ goto e_free;
+ }
+ }
+
+ ret = read_offset_data(buf, count, offset,
+ page, 4096, page_offset * 4096);
+e_free:
+ if (hret)
+ pr_err("h_get_24x7_catalog_page(ver=%d, page=%lld) failed: rc=%ld\n",
+ catalog_version_num, page_offset, hret);
+ kfree(page);
+
+ pr_devel("catalog_read: offset=%lld(%lld) count=%zu(%zu) catalog_len=%zu(%zu) => %zd\n",
+ offset, page_offset, count, page_count, catalog_len,
+ catalog_page_len, ret);
+
+ return ret;
+}
+
+#define PAGE_0_ATTR(_name, _fmt, _expr) \
+static ssize_t _name##_show(struct device *dev, \
+ struct device_attribute *dev_attr, \
+ char *buf) \
+{ \
+ unsigned long hret; \
+ ssize_t ret = 0; \
+ void *page = kmalloc(4096, GFP_USER); \
+ struct hv_24x7_catalog_page_0 *page_0 = page; \
+ if (!page) \
+ return -ENOMEM; \
+ hret = h_get_24x7_catalog_page(page, 0, 0); \
+ if (hret) { \
+ ret = -EIO; \
+ goto e_free; \
+ } \
+ ret = sprintf(buf, _fmt, _expr); \
+e_free: \
+ kfree(page); \
+ return ret; \
+} \
+static DEVICE_ATTR_RO(_name)
+
+PAGE_0_ATTR(catalog_version, "%lld\n",
+ (unsigned long long)be32_to_cpu(page_0->version));
+PAGE_0_ATTR(catalog_len, "%lld\n",
+ (unsigned long long)be32_to_cpu(page_0->length) * 4096);
+static BIN_ATTR_RO(catalog, 0/* real length varies */);
So we're dumping the catalog out as a binary blob.
Why do we want to do that?
It clearly violates the sysfs rule-of-sorts of ASCII and one value per file.
Obviously there can be exceptions, but what's our justification?
+static struct bin_attribute *if_bin_attrs[] = {
+ &bin_attr_catalog,
+ NULL,
+};
+
+static struct attribute *if_attrs[] = {
+ &dev_attr_catalog_len.attr,
+ &dev_attr_catalog_version.attr,
+ NULL,
+};
+
+static struct attribute_group if_group = {
+ .name = "interface",
+ .bin_attrs = if_bin_attrs,
+ .attrs = if_attrs,
+};
Both pmus have an "interface" directory, but they don't seem to have anything
in common? Its feels a little ad-hoc.