[PATCH v6 1/6] xen: xensyms support

From: Boris Ostrovsky
Date: Sun Aug 09 2015 - 21:33:12 EST


Export Xen symbols to dom0 via /proc/xen/xensyms (similar to
/proc/kallsyms).

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
drivers/xen/Kconfig | 8 +++
drivers/xen/xenfs/Makefile | 1 +
drivers/xen/xenfs/super.c | 3 +
drivers/xen/xenfs/xenfs.h | 1 +
drivers/xen/xenfs/xensyms.c | 152 +++++++++++++++++++++++++++++++++++++++
include/xen/interface/platform.h | 18 +++++
6 files changed, 183 insertions(+)
create mode 100644 drivers/xen/xenfs/xensyms.c

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 7cd226d..9367604 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -280,4 +280,12 @@ config XEN_ACPI
def_bool y
depends on X86 && ACPI

+config XEN_SYMS
+ bool "Xen symbols"
+ depends on X86 && XEN_DOM0 && XENFS
+ default y if KALLSYMS
+ help
+ Exports hypervisor symbols (along with their types and addresses) via
+ /proc/xen/xensyms file, similar to /proc/kallsyms
+
endmenu
diff --git a/drivers/xen/xenfs/Makefile b/drivers/xen/xenfs/Makefile
index b019865..1a83010 100644
--- a/drivers/xen/xenfs/Makefile
+++ b/drivers/xen/xenfs/Makefile
@@ -2,3 +2,4 @@ obj-$(CONFIG_XENFS) += xenfs.o

xenfs-y = super.o
xenfs-$(CONFIG_XEN_DOM0) += xenstored.o
+xenfs-$(CONFIG_XEN_SYMS) += xensyms.o
diff --git a/drivers/xen/xenfs/super.c b/drivers/xen/xenfs/super.c
index 06092e0..8559a71 100644
--- a/drivers/xen/xenfs/super.c
+++ b/drivers/xen/xenfs/super.c
@@ -57,6 +57,9 @@ static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
{ "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR},
{ "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR},
+#ifdef CONFIG_XEN_SYMS
+ { "xensyms", &xensyms_ops, S_IRUSR},
+#endif
{""},
};

diff --git a/drivers/xen/xenfs/xenfs.h b/drivers/xen/xenfs/xenfs.h
index 6b80c77..2c5934e 100644
--- a/drivers/xen/xenfs/xenfs.h
+++ b/drivers/xen/xenfs/xenfs.h
@@ -3,5 +3,6 @@

extern const struct file_operations xsd_kva_file_ops;
extern const struct file_operations xsd_port_file_ops;
+extern const struct file_operations xensyms_ops;

#endif /* _XENFS_XENBUS_H */
diff --git a/drivers/xen/xenfs/xensyms.c b/drivers/xen/xenfs/xensyms.c
new file mode 100644
index 0000000..ed16f8d
--- /dev/null
+++ b/drivers/xen/xenfs/xensyms.c
@@ -0,0 +1,152 @@
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/proc_fs.h>
+#include <linux/slab.h>
+#include <xen/interface/platform.h>
+#include <asm/xen/hypercall.h>
+#include <xen/xen-ops.h>
+#include "xenfs.h"
+
+
+#define XEN_KSYM_NAME_LEN 127 /* Hypervisor may have different name length */
+
+struct xensyms {
+ struct xen_platform_op op;
+ char *name;
+ uint32_t namelen;
+};
+
+/* Grab next output page from the hypervisor */
+static int xensyms_next_sym(struct xensyms *xs)
+{
+ int ret;
+ struct xenpf_symdata *symdata = &xs->op.u.symdata;
+ uint64_t symnum;
+
+ memset(xs->name, 0, xs->namelen);
+ symdata->namelen = xs->namelen;
+
+ symnum = symdata->symnum;
+
+ ret = HYPERVISOR_dom0_op(&xs->op);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * If hypervisor's symbol didn't fit into the buffer then allocate
+ * a larger buffer and try again
+ */
+ if (unlikely(symdata->namelen > xs->namelen)) {
+ kfree(xs->name);
+
+ xs->namelen = symdata->namelen;
+ xs->name = kzalloc(xs->namelen, GFP_KERNEL);
+ if (!xs->name)
+ return 1;
+
+ set_xen_guest_handle(symdata->name, xs->name);
+ symdata->symnum--; /* Rewind */
+
+ ret = HYPERVISOR_dom0_op(&xs->op);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (symdata->symnum == symnum)
+ /* End of symbols */
+ return 1;
+
+ return 0;
+}
+
+static void *xensyms_start(struct seq_file *m, loff_t *pos)
+{
+ struct xensyms *xs = (struct xensyms *)m->private;
+
+ xs->op.u.symdata.symnum = *pos;
+
+ if (xensyms_next_sym(xs))
+ return NULL;
+
+ return m->private;
+}
+
+static void *xensyms_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ struct xensyms *xs = (struct xensyms *)m->private;
+
+ xs->op.u.symdata.symnum = ++(*pos);
+
+ if (xensyms_next_sym(xs))
+ return NULL;
+
+ return p;
+}
+
+static int xensyms_show(struct seq_file *m, void *p)
+{
+ struct xensyms *xs = (struct xensyms *)m->private;
+ struct xenpf_symdata *symdata = &xs->op.u.symdata;
+
+ seq_printf(m, "%016llx %c %s\n", symdata->address,
+ symdata->type, xs->name);
+
+ return 0;
+}
+
+static void xensyms_stop(struct seq_file *m, void *p)
+{
+}
+
+static const struct seq_operations xensyms_seq_ops = {
+ .start = xensyms_start,
+ .next = xensyms_next,
+ .show = xensyms_show,
+ .stop = xensyms_stop,
+};
+
+static int xensyms_open(struct inode *inode, struct file *file)
+{
+ struct seq_file *m;
+ struct xensyms *xs;
+ int ret;
+
+ ret = seq_open_private(file, &xensyms_seq_ops,
+ sizeof(struct xensyms));
+ if (ret)
+ return ret;
+
+ m = file->private_data;
+ xs = (struct xensyms *)m->private;
+
+ xs->namelen = XEN_KSYM_NAME_LEN + 1;
+ xs->name = kzalloc(xs->namelen, GFP_KERNEL);
+ if (!xs->name) {
+ seq_release_private(inode, file);
+ return -ENOMEM;
+ }
+ set_xen_guest_handle(xs->op.u.symdata.name, xs->name);
+ xs->op.cmd = XENPF_get_symbol;
+ xs->op.u.symdata.namelen = xs->namelen;
+
+ return 0;
+}
+
+static int xensyms_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *m = file->private_data;
+ struct xensyms *xs = (struct xensyms *)m->private;
+
+ kfree(xs->name);
+ return seq_release_private(inode, file);
+}
+
+const struct file_operations xensyms_ops = {
+ .open = xensyms_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = xensyms_release
+};
diff --git a/include/xen/interface/platform.h b/include/xen/interface/platform.h
index 5cc49ea..8e03587 100644
--- a/include/xen/interface/platform.h
+++ b/include/xen/interface/platform.h
@@ -474,6 +474,23 @@ struct xenpf_core_parking {
};
DEFINE_GUEST_HANDLE_STRUCT(xenpf_core_parking);

+#define XENPF_get_symbol 63
+struct xenpf_symdata {
+ /* IN/OUT variables */
+ uint32_t namelen; /* size of 'name' buffer */
+
+ /* IN/OUT variables */
+ uint32_t symnum; /* IN: Symbol to read */
+ /* OUT: Next available symbol. If same as IN */
+ /* then we reached the end */
+
+ /* OUT variables */
+ GUEST_HANDLE(char) name;
+ uint64_t address;
+ char type;
+};
+DEFINE_GUEST_HANDLE_STRUCT(xenpf_symdata);
+
struct xen_platform_op {
uint32_t cmd;
uint32_t interface_version; /* XENPF_INTERFACE_VERSION */
@@ -495,6 +512,7 @@ struct xen_platform_op {
struct xenpf_cpu_hotadd cpu_add;
struct xenpf_mem_hotadd mem_add;
struct xenpf_core_parking core_parking;
+ struct xenpf_symdata symdata;
uint8_t pad[128];
} u;
};
--
1.8.1.4

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