On 12/15/20 10:16 AM, Rob Herring wrote:
On Mon, Dec 14, 2020 at 11:18:48AM -0800, Lakshmi Ramasubramanian wrote:
The functions do_get_kexec_buffer() and get_addr_size_cells(),
defined in arch/powerpc/kexec/ima.c, retrieve the address and size
of the given property from the device tree blob. These functions do
not have architecture specific code, but are currently limited to
powerpc. do_get_kexec_buffer() correctly handles a device tree property
that is a child node of the root node, but not anything other than
the immediate root child nodes.
Move architecture independent functions get_ima_kexec_buffer() and
get_root_addr_size_cells() to "drivers/of/kexec.c". These functions
retrieve the chosen node "linux,ima-kexec-buffer" from the device tree,
and return the address and size of the buffer used for carrying forward
the IMA measurement log across kexec system call.
Co-developed-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
---
drivers/of/kexec.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of.h | 3 ++
2 files changed, 71 insertions(+)
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index 66787be081fe..9af5371340b1 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -30,6 +30,10 @@
/**
* fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
*
+ * @fdt: Flattened Device Tree to update
+ * @start: Starting address of the reservation to delete
+ * @size: Size of the reservation to delete
+ *
This belongs in the patch adding fdt_find_and_del_mem_rsv.
Yes.
* Return: 0 on success, or negative errno on error.
*/
static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
@@ -226,3 +230,67 @@ int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
return 0;
}
+
+/**
+ * get_root_addr_size_cells - Get address and size of root node
+ *
+ * @addr_cells: Return address of the root node
+ * @size_cells: Return size of the root node
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+int get_root_addr_size_cells(int *addr_cells, int *size_cells)
+{
+ struct device_node *root;
+
+ root = of_find_node_by_path("/");
+ if (!root)
+ return -EINVAL;
+
+ *addr_cells = of_n_addr_cells(root);
+ *size_cells = of_n_size_cells(root);
+
+ of_node_put(root);
+
+ return 0;
+}
+
+/**
+ * get_ima_kexec_buffer - Get address and size of IMA kexec buffer
+ *
+ * @fdt: Flattened Device Tree
+ * @chosen_node: Offset of chosen node in the FDT
+ * @addr: Return address of the node
+ * @size: Return size of the node
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+int get_ima_kexec_buffer(void *fdt, int chosen_node,
+ unsigned long *addr, size_t *size)
+{
+ const void *prop;
+ int addr_cells, size_cells, prop_len;
+ int rc;
+
+ rc = get_root_addr_size_cells(&addr_cells, &size_cells);
+ if (rc)
+ return rc;
+
+ if (fdt)
+ prop = fdt_getprop(fdt, chosen_node,
+ "linux,ima-kexec-buffer", &prop_len);
+ else
+ prop = of_get_property(of_chosen,
+ "linux,ima-kexec-buffer", &prop_len);
This is an odd structure. The DT APIs are generally of_foo() for
unflattened tree and of_flat_foo() for FDT.
Ok - will update.
+
+ if (!prop)
+ return -ENOENT;
+
+ if (prop_len < 4 * (addr_cells + size_cells))
+ return -EINVAL;
+
+ *addr = of_read_number(prop, addr_cells);
+ *size = of_read_number(prop + 4 * addr_cells, size_cells);
+
+ return 0;
+}
diff --git a/include/linux/of.h b/include/linux/of.h
index 3375f5295875..fb2ef274135d 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -562,6 +562,9 @@ struct kimage;
int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
unsigned long initrd_load_addr, unsigned long initrd_len,
const char *cmdline);
+int get_root_addr_size_cells(int *addr_cells, int *size_cells);
+int get_ima_kexec_buffer(void *fdt, int chosen_node,
+ unsigned long *addr, size_t *size);
The whole point of moving code out of arch code was to avoid all these
cross tree calls.
I was expecting the next step to be moving setup_ima_buffer() call into
of_kexec_setup_new_fdt with all the code in powerpc/kexec/ima.c moved
here. Then the end result to enable on arm64 is just selecting
HAVE_IMA_KEXEC and adding fields to kimage_arch.
setup_ima_buffer() implemented for powerpc can be simplified by using
fdt_appendprop_addrrange() to add the IMA buffer's address and size to
"linux,ima-kexec-buffer" node. With that change, setup_ima_buffer() can
be moved into of_kexec_setup_new_fdt along with all the code in
powerpc/kexec/ima.c to drivers'of/kexec.c
I'll make the above change and post the next version shortly.
thanks,
-lakshmi
