[PATCH v3 2/3] of: kexec: Refactor IMA buffer related functions to make them reusable

From: Stefan Berger
Date: Tue Jun 28 2022 - 12:59:09 EST


Refactor IMA buffer related functions to make them reusable for carrying
TPM logs across kexec.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Frank Rowand <frowand.list@xxxxxxxxx>
Cc: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
drivers/of/kexec.c | 99 +++++++++++++++++++++++++++++-----------------
1 file changed, 62 insertions(+), 37 deletions(-)

diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index b9bd1cff1793..601ea9727b0e 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -115,6 +115,18 @@ static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
return 0;
}

+static int get_kexec_buffer(const char *name, unsigned long *addr, size_t *size)
+{
+ const void *prop;
+ int len;
+
+ prop = of_get_property(of_chosen, name, &len);
+ if (!prop)
+ return -ENOENT;
+
+ return do_get_kexec_buffer(prop, len, addr, size);
+}
+
/**
* ima_get_kexec_buffer - get IMA buffer from the previous kernel
* @addr: On successful return, set to point to the buffer contents.
@@ -124,19 +136,14 @@ 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;

if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
return -ENOTSUPP;

- 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_kexec_buffer("linux,ima-kexec-buffer", &tmp_addr, &tmp_size);
if (ret)
return ret;

@@ -174,6 +181,28 @@ int ima_free_kexec_buffer(void)
return memblock_phys_free(addr, size);
}

+static int remove_buffer(void *fdt, int chosen_node, const char *name)
+{
+ int ret, len;
+ unsigned long addr;
+ size_t size;
+ const void *prop;
+
+ prop = fdt_getprop(fdt, chosen_node, name, &len);
+ if (!prop)
+ return -ENOENT;
+
+ ret = do_get_kexec_buffer(prop, len, &addr, &size);
+ fdt_delprop(fdt, chosen_node, name);
+ if (ret)
+ return ret;
+
+ ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
+ if (!ret)
+ pr_debug("Remove old %s buffer reserveration", name);
+ return ret;
+}
+
/**
* remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
*
@@ -185,29 +214,34 @@ int ima_free_kexec_buffer(void)
*/
static void remove_ima_buffer(void *fdt, int chosen_node)
{
- int ret, len;
- unsigned long addr;
- size_t size;
- const void *prop;
-
if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
return;

- prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
- if (!prop)
- return;
+ remove_buffer(fdt, chosen_node, "linux,ima-kexec-buffer");
+}

- ret = do_get_kexec_buffer(prop, len, &addr, &size);
- fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
+#ifdef CONFIG_IMA_KEXEC
+static int setup_buffer(void *fdt, int chosen_node, const char *name,
+ uint64_t addr, uint64_t size)
+{
+ int ret;
+
+ if (!size)
+ return 0;
+
+ ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
+ name, addr, size);
+ if (ret < 0)
+ return -EINVAL;
+
+ ret = fdt_add_mem_rsv(fdt, addr, size);
if (ret)
- return;
+ return -EINVAL;
+
+ return 0;

- ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
- if (!ret)
- pr_debug("Removed old IMA buffer reservation.\n");
}

-#ifdef CONFIG_IMA_KEXEC
/**
* setup_ima_buffer - add IMA buffer information to the fdt
* @image: kexec image being loaded.
@@ -221,23 +255,14 @@ static int setup_ima_buffer(const struct kimage *image, void *fdt,
{
int ret;

- if (!image->ima_buffer_size)
- return 0;
-
- ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
- "linux,ima-kexec-buffer",
- image->ima_buffer_addr,
- image->ima_buffer_size);
- if (ret < 0)
- return -EINVAL;
-
- ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
- image->ima_buffer_size);
+ ret = setup_buffer(fdt, chosen_node, "linux,ima-kexec-buffer",
+ image->ima_buffer_addr, image->ima_buffer_size);
if (ret)
- return -EINVAL;
+ return ret;

- pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
- image->ima_buffer_addr, image->ima_buffer_size);
+ if (image->ima_buffer_addr)
+ pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
+ image->ima_buffer_addr, image->ima_buffer_size);

return 0;
}
--
2.35.1