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

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Message-Id: <20220628165820.883222-3-stefanb@linux.ibm.com>
Date:   Tue, 28 Jun 2022 12:58:19 -0400
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     kexec@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Cc:     nayna@...ux.ibm.com, nasastry@...ibm.com, mpe@...erman.id.au,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mimi Zohar <zohar@...ux.ibm.com>
Subject: [PATCH v3 2/3] of: kexec: Refactor IMA buffer related functions to make them reusable

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

Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Frank Rowand <frowand.list@...il.com>
Cc: Mimi Zohar <zohar@...ux.ibm.com>
---
 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