powerpc: Move ima buffer fields to struct kimage

The fields ima_buffer_addr and ima_buffer_size in "struct kimage_arch"
for powerpc are used to carry forward the IMA measurement list across
kexec system call. These fields are not architecture specific, but are
currently limited to powerpc.

arch_ima_add_kexec_buffer() defined in "arch/powerpc/kexec/ima.c"
sets ima_buffer_addr and ima_buffer_size for the kexec system call.
This function does not have architecture specific code, but is
currently limited to powerpc.

Move ima_buffer_addr and ima_buffer_size to "struct kimage".
Set ima_buffer_addr and ima_buffer_size in ima_add_kexec_buffer()
in security/integrity/ima/ima_kexec.c.

Co-developed-by: Prakhar Srivastava <[e-mail]>
Signed-off-by: Prakhar Srivastava <[e-mail]>
Signed-off-by: Lakshmi Ramasubramanian <[e-mail]>
Suggested-by: Will Deacon <[e-mail]>
Reviewed-by: Thiago Jung Bauermann <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/powerpc/include/asm/ima.h

···
 #endif
 
 #ifdef CONFIG_IMA_KEXEC
-int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
-			      size_t size);
-
 int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node);
 #else
 static inline int setup_ima_buffer(const struct kimage *image, void *fdt,

arch/powerpc/include/asm/kexec.h

···
 	unsigned long backup_start;
 	void *backup_buf;
 	void *fdt;
-
-#ifdef CONFIG_IMA_KEXEC
-	phys_addr_t ima_buffer_addr;
-	size_t ima_buffer_size;
-#endif
 };
 
 char *setup_kdump_cmdline(struct kimage *image, char *cmdline,

arch/powerpc/kexec/ima.c

···
 }
 
 #ifdef CONFIG_IMA_KEXEC
-/**
- * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
- *
- * Architectures should use this function to pass on the IMA buffer
- * information to the next kernel.
- *
- * Return: 0 on success, negative errno on error.
- */
-int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
-			      size_t size)
-{
-	image->arch.ima_buffer_addr = load_addr;
-	image->arch.ima_buffer_size = size;
-
-	return 0;
-}
-
 static int write_number(void *p, u64 value, int cells)
 {
 	if (cells == 1) {
···
 	u8 value[16];
 
 	remove_ima_buffer(fdt, chosen_node);
-	if (!image->arch.ima_buffer_size)
+	if (!image->ima_buffer_size)
 		return 0;
 
 	ret = get_addr_size_cells(&addr_cells, &size_cells);
···
 	if (entry_size > sizeof(value))
 		return -EINVAL;
 
-	ret = write_number(value, image->arch.ima_buffer_addr, addr_cells);
+	ret = write_number(value, image->ima_buffer_addr, addr_cells);
 	if (ret)
 		return ret;
 
-	ret = write_number(value + 4 * addr_cells, image->arch.ima_buffer_size,
+	ret = write_number(value + 4 * addr_cells, image->ima_buffer_size,
 			   size_cells);
 	if (ret)
 		return ret;
···
 	if (ret < 0)
 		return -EINVAL;
 
-	ret = fdt_add_mem_rsv(fdt, image->arch.ima_buffer_addr,
-			      image->arch.ima_buffer_size);
+	ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
+			      image->ima_buffer_size);
 	if (ret)
 		return -EINVAL;
 
 	pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
-		 image->arch.ima_buffer_addr, image->arch.ima_buffer_size);
+		 image->ima_buffer_addr, image->ima_buffer_size);
 
 	return 0;
 }

include/linux/kexec.h

···
 #ifdef CONFIG_IMA_KEXEC
 	/* Virtual address of IMA measurement buffer for kexec syscall */
 	void *ima_buffer;
+
+	phys_addr_t ima_buffer_addr;
+	size_t ima_buffer_size;
 #endif
 
 	/* Core ELF header buffer */

security/integrity/ima/ima_kexec.c

···
 		return;
 	}
 
-	ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);
-	if (ret) {
-		pr_err("Error passing over kexec measurement buffer.\n");
-		return;
-	}
-
+	image->ima_buffer_addr = kbuf.mem;
+	image->ima_buffer_size = kexec_segment_size;
 	image->ima_buffer = kexec_buffer;
 
 	pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n",