[PATCH 1/4] fdt: common API to populate kaslr seed

seanedmond
2023-08-29T20:32:27Z

From: Dhananjay Phadke <dphadke@linux.microsoft.com>

fdt_fixup_kaslr_seed() will update given FDT with random seed value.
Source for random seed can be TPM or RNG driver in u-boot or sec
firmware (ARM).

Signed-off-by: Dhananjay Phadke <dphadke@linux.microsoft.com>
Signed-off-by: Sean Edmond <senaedmond@microsoft.com>
---
arch/arm/cpu/armv8/sec_firmware.c | 39 +++++++++++--------------------
common/fdt_support.c | 19 +++++++++++++++
drivers/core/ofnode.c | 17 ++++++++++++++
include/dm/ofnode.h | 12 ++++++++++
include/fdt_support.h | 9 +++++++
5 files changed, 71 insertions(+), 25 deletions(-)

diff --git a/arch/arm/cpu/armv8/sec_firmware.c b/arch/arm/cpu/armv8/sec_firmware.c
index c0e8726346..5f04cd8aec 100644
--- a/arch/arm/cpu/armv8/sec_firmware.c
+++ b/arch/arm/cpu/armv8/sec_firmware.c
@@ -411,46 +411,35 @@ int sec_firmware_init(const void *sec_firmware_img,
/*
* fdt_fix_kaslr - Add kalsr-seed node in Device tree
* @fdt: Device tree
- * @eret: 0 in case of error, 1 for success
+ * @eret: 0 for success
*/
int fdt_fixup_kaslr(void *fdt)
{
- int nodeoffset;
- int err, ret = 0;
- u8 rand[8];
+ int ret = 0;

#if defined(CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT)
+ u8 rand[8];
+ ofnode root;
+
/* Check if random seed generation is supported */
if (sec_firmware_support_hwrng() == false) {
printf("WARNING: SEC firmware not running, no kaslr-seed\n");
- return 0;
+ return -EOPNOTSUPP;
}

- err = sec_firmware_get_random(rand, 8);
- if (err < 0) {
+ ret = sec_firmware_get_random(rand, 8);
+ if (ret < 0) {
printf("WARNING: No random number to set kaslr-seed\n");
- return 0;
+ return ret;
}

- err = fdt_check_header(fdt);
- if (err < 0) {
- printf("fdt_chosen: %s\n", fdt_strerror(err));
- return 0;
+ ret = root_ofnode_from_fdt(fdt, &root);
+ if (ret < 0) {
+ printf("WARNING: Unable to get root ofnode\n");
+ return ret;
}

- /* find or create "/chosen" node. */
- nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
- if (nodeoffset < 0)
- return 0;
-
- err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", rand,
- sizeof(rand));
- if (err < 0) {
- printf("WARNING: can't set kaslr-seed %s.\n",
- fdt_strerror(err));
- return 0;
- }
- ret = 1;
+ ret = fdt_fixup_kaslr_seed(root, rand, sizeof(rand));
#endif

return ret;
diff --git a/common/fdt_support.c b/common/fdt_support.c
index 5e49078f8c..52be4375b4 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -631,6 +631,25 @@ void fdt_fixup_ethernet(void *fdt)
}
}

+int fdt_fixup_kaslr_seed(ofnode node, const u8 *seed, int len)
+{
+ ofnode chosen;
+ int ret;
+
+ /* find or create "/chosen" node. */
+ ret = ofnode_add_subnode(node, "chosen", &chosen);
+ if (ret && ret != -EEXIST)
+ return -ENOENT;
+
+ ret = ofnode_write_prop(chosen, "kaslr-seed", seed, len, true);
+ if (ret) {
+ printf("WARNING: can't set kaslr-seed\n");
+ return ret;
+ }
+
+ return 0;
+}
+
int fdt_record_loadable(void *blob, u32 index, const char *name,
uintptr_t load_addr, u32 size, uintptr_t entry_point,
const char *type, const char *os, const char *arch)
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index 8df16e56af..4be21133b8 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -870,6 +870,23 @@ ofnode oftree_path(oftree tree, const char *path)
}
}

+int root_ofnode_from_fdt(void *fdt, ofnode *root_node)
+{
+ oftree tree;
+ /* If OFNODE_MULTI_TREE is not set, and if fdt is not the control FDT,
+ * oftree_from_fdt() will return NULL
+ */
+ tree = oftree_from_fdt(fdt);
+
+ if (!oftree_valid(tree)) {
+ printf("Cannot create oftree\n");
+ return -EINVAL;
+ }
+ *root_node = oftree_root(tree);
+
+ return 0;
+}
+
const void *ofnode_read_chosen_prop(const char *propname, int *sizep)
{
ofnode chosen_node;
diff --git a/include/dm/ofnode.h b/include/dm/ofnode.h
index 0f38b3e736..e79bb62be8 100644
--- a/include/dm/ofnode.h
+++ b/include/dm/ofnode.h
@@ -901,6 +901,18 @@ ofnode oftree_path(oftree tree, const char *path);
*/
ofnode oftree_root(oftree tree);

+/**
+ * root_ofnode_from_fdt() - Gets the root ofnode given an FDT blob.
+ * Note, this will fail if OFNODE_MULTI_TREE
+ * is not set.
+ *
+ * @fdt: Device tree to use
+ * @root_node : Root ofnode
+ *
+ * Return: 0 if OK, -ve on error
+ */
+int root_ofnode_from_fdt(void *fdt, ofnode *root_node);
+
/**
* ofnode_read_chosen_prop() - get the value of a chosen property
*
diff --git a/include/fdt_support.h b/include/fdt_support.h
index 2cd8366898..d967118bed 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -11,6 +11,7 @@
!defined(USE_HOSTCC)

#include <asm/u-boot.h>
+#include <dm/ofnode.h>
#include <linux/libfdt.h>
#include <abuf.h>

@@ -121,6 +122,14 @@ static inline int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[],
#endif

void fdt_fixup_ethernet(void *fdt);
+
+/*
+ * fdt_fixup_kaslr_seed - Add kaslr-seed node in Device tree
+ * @node: ofnode
+ * @eret: 0 for success
+ */
+int fdt_fixup_kaslr_seed(ofnode node, const u8 *seed, int len);
+
int fdt_find_and_setprop(void *fdt, const char *node, const char *prop,
const void *val, int len, int create);
void fdt_fixup_qe_firmware(void *fdt);
--
2.40.0