[PATCH v16 11/12] powerpc: Use OF alloc and free for FDT

Lakshmi Ramasubramanian
2021-02-04T16:59:32Z

of_alloc_and_init_fdt() and of_free_fdt() have been defined in
drivers/of/kexec.c to allocate and free memory for FDT.

Use of_alloc_and_init_fdt() and of_free_fdt() to allocate and
initialize the FDT, and to free the FDT respectively.

powerpc sets the FDT address in image_loader_data field in
"struct kimage" and the memory is freed in
kimage_file_post_load_cleanup(). This cleanup function uses kfree()
to free the memory. But since of_alloc_and_init_fdt() uses kvmalloc()
for allocation, the buffer needs to be freed using kvfree().

Define "fdt" field in "struct kimage_arch" for powerpc to store
the address of FDT, and free the memory in powerpc specific
arch_kimage_file_post_load_cleanup().

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Rob Herring <robh@kernel.org>
Suggested-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
arch/powerpc/include/asm/kexec.h | 2 ++
arch/powerpc/kexec/elf_64.c | 26 ++++++++++++++++----------
arch/powerpc/kexec/file_load_64.c | 3 +++
3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index 2c0be93d239a..d7d13cac4d31 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -111,6 +111,8 @@ struct kimage_arch {
unsigned long elf_headers_mem;
unsigned long elf_headers_sz;
void *elf_headers;
+
+ void *fdt;
};

char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index d0e459bb2f05..51d2d8eb6c1b 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -19,6 +19,7 @@
#include <linux/kexec.h>
#include <linux/libfdt.h>
#include <linux/module.h>
+#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/slab.h>
#include <linux/types.h>
@@ -32,7 +33,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
unsigned int fdt_size;
unsigned long kernel_load_addr;
unsigned long initrd_load_addr = 0, fdt_load_addr;
- void *fdt;
+ void *fdt = NULL;
const void *slave_code;
struct elfhdr ehdr;
char *modified_cmdline = NULL;
@@ -103,18 +104,12 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
}

fdt_size = fdt_totalsize(initial_boot_params) * 2;
- fdt = kmalloc(fdt_size, GFP_KERNEL);
+ fdt = of_alloc_and_init_fdt(fdt_size);
if (!fdt) {
pr_err("Not enough memory for the device tree.\n");
ret = -ENOMEM;
goto out;
}
- ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
- if (ret < 0) {
- pr_err("Error setting up the new device tree.\n");
- ret = -EINVAL;
- goto out;
- }

ret = setup_new_fdt_ppc64(image, fdt, initrd_load_addr,
initrd_len, cmdline);
@@ -131,6 +126,10 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
ret = kexec_add_buffer(&kbuf);
if (ret)
goto out;
+
+ /* FDT will be freed in arch_kimage_file_post_load_cleanup */
+ image->arch.fdt = fdt;
+
fdt_load_addr = kbuf.mem;

pr_debug("Loaded device tree at 0x%lx\n", fdt_load_addr);
@@ -145,8 +144,15 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
kfree(modified_cmdline);
kexec_free_elf_info(&elf_info);

- /* Make kimage_file_post_load_cleanup free the fdt buffer for us. */
- return ret ? ERR_PTR(ret) : fdt;
+ /*
+ * Once FDT buffer has been successfully passed to kexec_add_buffer(),
+ * the FDT buffer address is saved in image->arch.fdt. In that case,
+ * the memory cannot be freed here in case of any other error.
+ */
+ if (ret && !image->arch.fdt)
+ of_free_fdt(fdt);
+
+ return ret ? ERR_PTR(ret) : NULL;
}

const struct kexec_file_ops kexec_elf64_ops = {
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 3cab318aa3b9..d9d5b5569a6d 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -1113,5 +1113,8 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
image->arch.elf_headers = NULL;
image->arch.elf_headers_sz = 0;

+ of_free_fdt(image->arch.fdt);
+ image->arch.fdt = NULL;
+
return kexec_image_post_load_cleanup_default(image);
}
--
2.30.0