Re: [PATCH v10 4/8] powerpc: Use ima kexec node functions

[Lakshmi Ramasubramanian]

On 12/5/20 11:51 AM, Thiago Jung Bauermann wrote:

Lakshmi Ramasubramanian <nra...@linux.microsoft.com> writes:

do_get_kexec_buffer() and get_addr_size_cells() are called by
ima_get_kexec_buffer(), ima_free_kexec_buffer, and remove_ima_buffer()
to retrieve the address and size of the buffer used for carrying
forward the IMA measurement log across kexec system call. These
functions correctly handle a device tree property that is a child node
of the root node, but not anything other than the immediate root
child nodes.

Use the architecture independent functions get_ima_kexec_buffer()
and get_root_addr_size_cells() defined in "drivers/of/ima_kexec.c",

s/ima_kexec.c/kexec.c/

Thanks for catching this. I'll fix it.

to get the address and size of the IMA measurement log buffer from
the device tree. Remove do_get_kexec_buffer() and get_addr_size_cells()
since they are not used anymore.

Co-developed-by: Prakhar Srivastava <prsr...@linux.microsoft.com>
Signed-off-by: Prakhar Srivastava <prsr...@linux.microsoft.com>
Signed-off-by: Lakshmi Ramasubramanian <nra...@linux.microsoft.com>

Looks good. Thanks!

Reviewed-by: Thiago Jung Bauermann <bauer...@linux.ibm.com>

Thanks Thiago.

 -lakshmi

---
  arch/powerpc/kexec/ima.c | 58 +++++-----------------------------------
  1 file changed, 7 insertions(+), 51 deletions(-)

diff --git a/arch/powerpc/kexec/ima.c b/arch/powerpc/kexec/ima.c
index a36c39db4b1a..906e8212435d 100644
--- a/arch/powerpc/kexec/ima.c
+++ b/arch/powerpc/kexec/ima.c
@@ -13,40 +13,6 @@
  #include <linux/libfdt.h>
  #include <asm/ima.h>

-static int get_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;
-}
-
-static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
-                              size_t *size)
-{
-       int ret, addr_cells, size_cells;
-
-       ret = get_addr_size_cells(&addr_cells, &size_cells);
-       if (ret)
-               return ret;
-
-       if (len < 4 * (addr_cells + size_cells))
-               return -ENOENT;
-
-       *addr = of_read_number(prop, addr_cells);
-       *size = of_read_number(prop + 4 * addr_cells, size_cells);
-
-       return 0;
-}
-
  /**
   * ima_get_kexec_buffer - get IMA buffer from the previous kernel
   * @addr:     On successful return, set to point to the buffer contents.
@@ -56,16 +22,11 @@ static int do_get_kexec_buffer(const void *prop, int len, 
unsigned long *addr,
   */
  int ima_get_kexec_buffer(void **addr, size_t *size)
  {
-       int ret, len;
+       int ret;
        unsigned long tmp_addr;
        size_t tmp_size;
-       const void *prop;

- prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);

-       if (!prop)
-               return -ENOENT;
-
-       ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
+       ret = get_ima_kexec_buffer(NULL, 0, &tmp_addr, &tmp_size);
        if (ret)
                return ret;

@@ -89,7 +50,7 @@ int ima_free_kexec_buffer(void)

        if (!prop)
                return -ENOENT;

- ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);

+       ret = get_ima_kexec_buffer(NULL, 0, &addr, &size);
        if (ret)
                return ret;

@@ -98,7 +59,6 @@ int ima_free_kexec_buffer(void)

                return ret;

return memblock_free(addr, size);

-
  }

/**

@@ -112,19 +72,15 @@ int ima_free_kexec_buffer(void)
   */
  void remove_ima_buffer(void *fdt, int chosen_node)
  {
-       int ret, len;
+       int ret;
        unsigned long addr;
        size_t size;
-       const void *prop;

- prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);

-       if (!prop)
+       ret = get_ima_kexec_buffer(fdt, chosen_node, &addr, &size);
+       if (ret)
                return;

- ret = do_get_kexec_buffer(prop, len, &addr, &size);

        fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
-       if (ret)
-               return;

ret = delete_fdt_mem_rsv(fdt, addr, size);

        if (!ret)
@@ -191,7 +147,7 @@ int setup_ima_buffer(const struct kimage *image, void *fdt, 
int chosen_node)
        if (!image->arch.ima_buffer_size)
                return 0;

- ret = get_addr_size_cells(&addr_cells, &size_cells);

+       ret = get_root_addr_size_cells(&addr_cells, &size_cells);
        if (ret)
                return ret;