Re: [PATCH v16 11/12] powerpc: Use OF alloc and free for FDT
From: Rob Herring <robh@kernel.org>
Date: 2021-02-04 19:28:02
Also in:
linux-arm-kernel, linux-devicetree, linux-integrity, lkml
On Thu, Feb 4, 2021 at 10:42 AM Lakshmi Ramasubramanian [off-list ref] wrote:
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().
You could just change the kexec core to call kvfree() instead.
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().
However, given all the other buffers have an explicit field in kimage or kimage_arch, changing powerpc is to match arm64 is better IMO.
quoted hunk ↗ jump to hunk
Signed-off-by: Lakshmi Ramasubramanian <redacted> Suggested-by: Rob Herring <robh@kernel.org> Suggested-by: Thiago Jung Bauermann <redacted> --- 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,
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()). The arm64 version is calling of_alloc_and_init_fdt() and then of_kexec_setup_new_fdt() directly. So we can just make of_alloc_and_init_fdt() also call of_kexec_setup_new_fdt() (really, just tweak of_kexec_setup_new_fdt do the alloc and copy). I don't think the architecture needs to pick the size either. It's doubtful that either one is that sensitive to the amount of extra space.
quoted hunk ↗ jump to hunk
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);
Just call kvfree() directly.
quoted hunk ↗ jump to hunk
+ + 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