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

Michael Ellerman
2021-02-08T04:14:10Z

Rob Herring <robh@kernel.org> writes:
> On Thu, Feb 4, 2021 at 10:42 AM Lakshmi Ramasubramanian
> <nramas@linux.microsoft.com> wrote:
...
>> 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,
>
> The first thing this function does is call setup_new_fdt() which first
> calls of_kexec_setup_new_fdt(). (Note, I really don't understand the
> PPC code split. It looks like there's a 32-bit and 64-bit split, but
> 32-bit looks broken to me. Nothing ever calls setup_new_fdt() except
> setup_new_fdt_ppc64()).

I think that's because 32-bit doesn't support kexec_file_load().

cheers