Re: [PATCH RFC] generic ELF support for kexec

Christophe Leroy
2019-06-26T16:11:14Z

Hi Sven,

On 06/25/2019 06:54 PM, Sven Schnelle wrote:
> Hi List,
>
> i recently started working on kexec for PA-RISC. While doing so, i figured
> that powerpc already has support for reading ELF images inside of the Kernel.
> My first attempt was to steal the source code and modify it for PA-RISC, but
> it turned out that i didn't had to change much. Only ARM specific stuff like
> fdt blob fetching had to be removed.
>
> So instead of duplicating the code, i thought about moving the ELF stuff to
> the core kexec code, and exposing several function to use that code from the
> arch specific code.
>
> I'm attaching the patch to this Mail. What do you think about that change?
> s390 also uses ELF files, and (maybe?) could also switch to this implementation.
> But i don't know anything about S/390 and don't have one in my basement. So
> i'll leave s390 to the IBM folks.
>
> I haven't really tested PowerPC yet. Can anyone give me a helping hand what
> would be a good target to test this code in QEMU? Or even better, test this
> code on real Hardware?

Where did you start from ? Your patch doesn't apply on latest
powerpc/merge branch
(https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git):

[root@localhost linux-powerpc]# git am -3
/root/Downloads/RFC-generic-ELF-support-for-kexec.patch
Applying: generic ELF support for kexec
Using index info to reconstruct a base tree...
M arch/powerpc/kernel/kexec_elf_64.c
M kernel/Makefile
Falling back to patching base and 3-way merge...
Auto-merging kernel/Makefile
Auto-merging arch/powerpc/kernel/kexec_elf_64.c
CONFLICT (content): Merge conflict in arch/powerpc/kernel/kexec_elf_64.c
error: Failed to merge in the changes.
Patch failed at 0001 generic ELF support for kexec

Neither does it apply on 5.2-rc6

Looks like it cleanly applies on 5.1

Could you generate your patch using 'git format-patch -M -C ' ? It would
be a lot easier to see the real changes:

arch/Kconfig | 3 +
arch/powerpc/Kconfig | 1 +
arch/powerpc/kernel/kexec_elf_64.c | 547
+--------------------
include/linux/kexec.h | 35 ++
kernel/Makefile | 1 +
.../kexec_elf_64.c => kernel/kexec_file_elf.c | 192 ++------
6 files changed, 96 insertions(+), 683 deletions(-)
copy arch/powerpc/kernel/kexec_elf_64.c => kernel/kexec_file_elf.c (77%)

Thanks
Christophe

>
> If that change is acceptable i would finish the patch and submit it. I think
> best would be to push this change through Helge's parisc tree, so we don't
> have any dependencies to sort out.
>
> Regards,
> Sven
>
> [PATCH] kexec: add generic support for elf kernel images
>
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> ---
> arch/Kconfig | 3 +
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/kernel/kexec_elf_64.c | 547 +--------------------------
> include/linux/kexec.h | 35 ++
> kernel/Makefile | 1 +
> kernel/kexec_file_elf.c | 574 +++++++++++++++++++++++++++++
> 6 files changed, 619 insertions(+), 542 deletions(-)
> create mode 100644 kernel/kexec_file_elf.c
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index c47b328eada0..de7520100136 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -18,6 +18,9 @@ config KEXEC_CORE
> select CRASH_CORE
> bool
>
> +config KEXEC_FILE_ELF
> + bool
> +
> config HAVE_IMA_KEXEC
> bool
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 8c1c636308c8..48241260b6ae 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -502,6 +502,7 @@ config KEXEC_FILE
> select KEXEC_CORE
> select HAVE_IMA_KEXEC
> select BUILD_BIN2C
> + select KEXEC_FILE_ELF
> depends on PPC64
> depends on CRYPTO=y
> depends on CRYPTO_SHA256=y
> diff --git a/arch/powerpc/kernel/kexec_elf_64.c b/arch/powerpc/kernel/kexec_elf_64.c
> index ba4f18a43ee8..0059e36913e9 100644
> --- a/arch/powerpc/kernel/kexec_elf_64.c
> +++ b/arch/powerpc/kernel/kexec_elf_64.c
> @@ -21,8 +21,6 @@
> * GNU General Public License for more details.
> */
>
> -#define pr_fmt(fmt) "kexec_elf: " fmt
> -
> #include <linux/elf.h>
> #include <linux/kexec.h>
> #include <linux/libfdt.h>
> @@ -31,540 +29,6 @@
> #include <linux/slab.h>
> #include <linux/types.h>
>
> -#define PURGATORY_STACK_SIZE (16 * 1024)
> -
> -#define elf_addr_to_cpu elf64_to_cpu
> -
> -#ifndef Elf_Rel
> -#define Elf_Rel Elf64_Rel
> -#endif /* Elf_Rel */
> -
> -struct elf_info {
> - /*
> - * Where the ELF binary contents are kept.
> - * Memory managed by the user of the struct.
> - */
> - const char *buffer;
> -
> - const struct elfhdr *ehdr;
> - const struct elf_phdr *proghdrs;
> - struct elf_shdr *sechdrs;
> -};
> -
> -static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
> -{
> - return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
> -}
> -
> -static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
> -{
> - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
> - value = le64_to_cpu(value);
> - else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
> - value = be64_to_cpu(value);
> -
> - return value;
> -}
> -
> -static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
> -{
> - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
> - value = le16_to_cpu(value);
> - else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
> - value = be16_to_cpu(value);
> -
> - return value;
> -}
> -
> -static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
> -{
> - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
> - value = le32_to_cpu(value);
> - else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
> - value = be32_to_cpu(value);
> -
> - return value;
> -}
> -
> -/**
> - * elf_is_ehdr_sane - check that it is safe to use the ELF header
> - * @buf_len: size of the buffer in which the ELF file is loaded.
> - */
> -static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
> -{
> - if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
> - pr_debug("Bad program header size.\n");
> - return false;
> - } else if (ehdr->e_shnum > 0 &&
> - ehdr->e_shentsize != sizeof(struct elf_shdr)) {
> - pr_debug("Bad section header size.\n");
> - return false;
> - } else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
> - ehdr->e_version != EV_CURRENT) {
> - pr_debug("Unknown ELF version.\n");
> - return false;
> - }
> -
> - if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
> - size_t phdr_size;
> -
> - /*
> - * e_phnum is at most 65535 so calculating the size of the
> - * program header cannot overflow.
> - */
> - phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
> -
> - /* Sanity check the program header table location. */
> - if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
> - pr_debug("Program headers at invalid location.\n");
> - return false;
> - } else if (ehdr->e_phoff + phdr_size > buf_len) {
> - pr_debug("Program headers truncated.\n");
> - return false;
> - }
> - }
> -
> - if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
> - size_t shdr_size;
> -
> - /*
> - * e_shnum is at most 65536 so calculating
> - * the size of the section header cannot overflow.
> - */
> - shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
> -
> - /* Sanity check the section header table location. */
> - if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
> - pr_debug("Section headers at invalid location.\n");
> - return false;
> - } else if (ehdr->e_shoff + shdr_size > buf_len) {
> - pr_debug("Section headers truncated.\n");
> - return false;
> - }
> - }
> -
> - return true;
> -}
> -
> -static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
> -{
> - struct elfhdr *buf_ehdr;
> -
> - if (len < sizeof(*buf_ehdr)) {
> - pr_debug("Buffer is too small to hold ELF header.\n");
> - return -ENOEXEC;
> - }
> -
> - memset(ehdr, 0, sizeof(*ehdr));
> - memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
> - if (!elf_is_elf_file(ehdr)) {
> - pr_debug("No ELF header magic.\n");
> - return -ENOEXEC;
> - }
> -
> - if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
> - pr_debug("Not a supported ELF class.\n");
> - return -ENOEXEC;
> - } else if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
> - ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
> - pr_debug("Not a supported ELF data format.\n");
> - return -ENOEXEC;
> - }
> -
> - buf_ehdr = (struct elfhdr *) buf;
> - if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
> - pr_debug("Bad ELF header size.\n");
> - return -ENOEXEC;
> - }
> -
> - ehdr->e_type = elf16_to_cpu(ehdr, buf_ehdr->e_type);
> - ehdr->e_machine = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
> - ehdr->e_version = elf32_to_cpu(ehdr, buf_ehdr->e_version);
> - ehdr->e_entry = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
> - ehdr->e_phoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
> - ehdr->e_shoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
> - ehdr->e_flags = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
> - ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
> - ehdr->e_phnum = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
> - ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
> - ehdr->e_shnum = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
> - ehdr->e_shstrndx = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
> -
> - return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
> -}
> -
> -/**
> - * elf_is_phdr_sane - check that it is safe to use the program header
> - * @buf_len: size of the buffer in which the ELF file is loaded.
> - */
> -static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
> -{
> -
> - if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
> - pr_debug("ELF segment location wraps around.\n");
> - return false;
> - } else if (phdr->p_offset + phdr->p_filesz > buf_len) {
> - pr_debug("ELF segment not in file.\n");
> - return false;
> - } else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
> - pr_debug("ELF segment address wraps around.\n");
> - return false;
> - }
> -
> - return true;
> -}
> -
> -static int elf_read_phdr(const char *buf, size_t len, struct elf_info *elf_info,
> - int idx)
> -{
> - /* Override the const in proghdrs, we are the ones doing the loading. */
> - struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
> - const char *pbuf;
> - struct elf_phdr *buf_phdr;
> -
> - pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
> - buf_phdr = (struct elf_phdr *) pbuf;
> -
> - phdr->p_type = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
> - phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
> - phdr->p_paddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
> - phdr->p_vaddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
> - phdr->p_flags = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
> -
> - /*
> - * The following fields have a type equivalent to Elf_Addr
> - * both in 32 bit and 64 bit ELF.
> - */
> - phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
> - phdr->p_memsz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
> - phdr->p_align = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
> -
> - return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
> -}
> -
> -/**
> - * elf_read_phdrs - read the program headers from the buffer
> - *
> - * This function assumes that the program header table was checked for sanity.
> - * Use elf_is_ehdr_sane() if it wasn't.
> - */
> -static int elf_read_phdrs(const char *buf, size_t len,
> - struct elf_info *elf_info)
> -{
> - size_t phdr_size, i;
> - const struct elfhdr *ehdr = elf_info->ehdr;
> -
> - /*
> - * e_phnum is at most 65535 so calculating the size of the
> - * program header cannot overflow.
> - */
> - phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
> -
> - elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
> - if (!elf_info->proghdrs)
> - return -ENOMEM;
> -
> - for (i = 0; i < ehdr->e_phnum; i++) {
> - int ret;
> -
> - ret = elf_read_phdr(buf, len, elf_info, i);
> - if (ret) {
> - kfree(elf_info->proghdrs);
> - elf_info->proghdrs = NULL;
> - return ret;
> - }
> - }
> -
> - return 0;
> -}
> -
> -/**
> - * elf_is_shdr_sane - check that it is safe to use the section header
> - * @buf_len: size of the buffer in which the ELF file is loaded.
> - */
> -static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)
> -{
> - bool size_ok;
> -
> - /* SHT_NULL headers have undefined values, so we can't check them. */
> - if (shdr->sh_type == SHT_NULL)
> - return true;
> -
> - /* Now verify sh_entsize */
> - switch (shdr->sh_type) {
> - case SHT_SYMTAB:
> - size_ok = shdr->sh_entsize == sizeof(Elf_Sym);
> - break;
> - case SHT_RELA:
> - size_ok = shdr->sh_entsize == sizeof(Elf_Rela);
> - break;
> - case SHT_DYNAMIC:
> - size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);
> - break;
> - case SHT_REL:
> - size_ok = shdr->sh_entsize == sizeof(Elf_Rel);
> - break;
> - case SHT_NOTE:
> - case SHT_PROGBITS:
> - case SHT_HASH:
> - case SHT_NOBITS:
> - default:
> - /*
> - * This is a section whose entsize requirements
> - * I don't care about. If I don't know about
> - * the section I can't care about it's entsize
> - * requirements.
> - */
> - size_ok = true;
> - break;
> - }
> -
> - if (!size_ok) {
> - pr_debug("ELF section with wrong entry size.\n");
> - return false;
> - } else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {
> - pr_debug("ELF section address wraps around.\n");
> - return false;
> - }
> -
> - if (shdr->sh_type != SHT_NOBITS) {
> - if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {
> - pr_debug("ELF section location wraps around.\n");
> - return false;
> - } else if (shdr->sh_offset + shdr->sh_size > buf_len) {
> - pr_debug("ELF section not in file.\n");
> - return false;
> - }
> - }
> -
> - return true;
> -}
> -
> -static int elf_read_shdr(const char *buf, size_t len, struct elf_info *elf_info,
> - int idx)
> -{
> - struct elf_shdr *shdr = &elf_info->sechdrs[idx];
> - const struct elfhdr *ehdr = elf_info->ehdr;
> - const char *sbuf;
> - struct elf_shdr *buf_shdr;
> -
> - sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);
> - buf_shdr = (struct elf_shdr *) sbuf;
> -
> - shdr->sh_name = elf32_to_cpu(ehdr, buf_shdr->sh_name);
> - shdr->sh_type = elf32_to_cpu(ehdr, buf_shdr->sh_type);
> - shdr->sh_addr = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);
> - shdr->sh_offset = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);
> - shdr->sh_link = elf32_to_cpu(ehdr, buf_shdr->sh_link);
> - shdr->sh_info = elf32_to_cpu(ehdr, buf_shdr->sh_info);
> -
> - /*
> - * The following fields have a type equivalent to Elf_Addr
> - * both in 32 bit and 64 bit ELF.
> - */
> - shdr->sh_flags = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);
> - shdr->sh_size = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);
> - shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);
> - shdr->sh_entsize = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);
> -
> - return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;
> -}
> -
> -/**
> - * elf_read_shdrs - read the section headers from the buffer
> - *
> - * This function assumes that the section header table was checked for sanity.
> - * Use elf_is_ehdr_sane() if it wasn't.
> - */
> -static int elf_read_shdrs(const char *buf, size_t len,
> - struct elf_info *elf_info)
> -{
> - size_t shdr_size, i;
> -
> - /*
> - * e_shnum is at most 65536 so calculating
> - * the size of the section header cannot overflow.
> - */
> - shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;
> -
> - elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);
> - if (!elf_info->sechdrs)
> - return -ENOMEM;
> -
> - for (i = 0; i < elf_info->ehdr->e_shnum; i++) {
> - int ret;
> -
> - ret = elf_read_shdr(buf, len, elf_info, i);
> - if (ret) {
> - kfree(elf_info->sechdrs);
> - elf_info->sechdrs = NULL;
> - return ret;
> - }
> - }
> -
> - return 0;
> -}
> -
> -/**
> - * elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
> - * @buf: Buffer to read ELF file from.
> - * @len: Size of @buf.
> - * @ehdr: Pointer to existing struct which will be populated.
> - * @elf_info: Pointer to existing struct which will be populated.
> - *
> - * This function allows reading ELF files with different byte order than
> - * the kernel, byte-swapping the fields as needed.
> - *
> - * Return:
> - * On success returns 0, and the caller should call elf_free_info(elf_info) to
> - * free the memory allocated for the section and program headers.
> - */
> -int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
> - struct elf_info *elf_info)
> -{
> - int ret;
> -
> - ret = elf_read_ehdr(buf, len, ehdr);
> - if (ret)
> - return ret;
> -
> - elf_info->buffer = buf;
> - elf_info->ehdr = ehdr;
> - if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
> - ret = elf_read_phdrs(buf, len, elf_info);
> - if (ret)
> - return ret;
> - }
> - if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
> - ret = elf_read_shdrs(buf, len, elf_info);
> - if (ret) {
> - kfree(elf_info->proghdrs);
> - return ret;
> - }
> - }
> -
> - return 0;
> -}
> -
> -/**
> - * elf_free_info - free memory allocated by elf_read_from_buffer
> - */
> -void elf_free_info(struct elf_info *elf_info)
> -{
> - kfree(elf_info->proghdrs);
> - kfree(elf_info->sechdrs);
> - memset(elf_info, 0, sizeof(*elf_info));
> -}
> -/**
> - * build_elf_exec_info - read ELF executable and check that we can use it
> - */
> -static int build_elf_exec_info(const char *buf, size_t len, struct elfhdr *ehdr,
> - struct elf_info *elf_info)
> -{
> - int i;
> - int ret;
> -
> - ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
> - if (ret)
> - return ret;
> -
> - /* Big endian vmlinux has type ET_DYN. */
> - if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
> - pr_err("Not an ELF executable.\n");
> - goto error;
> - } else if (!elf_info->proghdrs) {
> - pr_err("No ELF program header.\n");
> - goto error;
> - }
> -
> - for (i = 0; i < ehdr->e_phnum; i++) {
> - /*
> - * Kexec does not support loading interpreters.
> - * In addition this check keeps us from attempting
> - * to kexec ordinay executables.
> - */
> - if (elf_info->proghdrs[i].p_type == PT_INTERP) {
> - pr_err("Requires an ELF interpreter.\n");
> - goto error;
> - }
> - }
> -
> - return 0;
> -error:
> - elf_free_info(elf_info);
> - return -ENOEXEC;
> -}
> -
> -static int elf64_probe(const char *buf, unsigned long len)
> -{
> - struct elfhdr ehdr;
> - struct elf_info elf_info;
> - int ret;
> -
> - ret = build_elf_exec_info(buf, len, &ehdr, &elf_info);
> - if (ret)
> - return ret;
> -
> - elf_free_info(&elf_info);
> -
> - return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
> -}
> -
> -/**
> - * elf_exec_load - load ELF executable image
> - * @lowest_load_addr: On return, will be the address where the first PT_LOAD
> - * section will be loaded in memory.
> - *
> - * Return:
> - * 0 on success, negative value on failure.
> - */
> -static int elf_exec_load(struct kimage *image, struct elfhdr *ehdr,
> - struct elf_info *elf_info,
> - unsigned long *lowest_load_addr)
> -{
> - unsigned long base = 0, lowest_addr = UINT_MAX;
> - int ret;
> - size_t i;
> - struct kexec_buf kbuf = { .image = image, .buf_max = ppc64_rma_size,
> - .top_down = false };
> -
> - /* Read in the PT_LOAD segments. */
> - for (i = 0; i < ehdr->e_phnum; i++) {
> - unsigned long load_addr;
> - size_t size;
> - const struct elf_phdr *phdr;
> -
> - phdr = &elf_info->proghdrs[i];
> - if (phdr->p_type != PT_LOAD)
> - continue;
> -
> - size = phdr->p_filesz;
> - if (size > phdr->p_memsz)
> - size = phdr->p_memsz;
> -
> - kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
> - kbuf.bufsz = size;
> - kbuf.memsz = phdr->p_memsz;
> - kbuf.buf_align = phdr->p_align;
> - kbuf.buf_min = phdr->p_paddr + base;
> - ret = kexec_add_buffer(&kbuf);
> - if (ret)
> - goto out;
> - load_addr = kbuf.mem;
> -
> - if (load_addr < lowest_addr)
> - lowest_addr = load_addr;
> - }
> -
> - /* Update entry point to reflect new load address. */
> - ehdr->e_entry += base;
> -
> - *lowest_load_addr = lowest_addr;
> - ret = 0;
> - out:
> - return ret;
> -}
> -
> static void *elf64_load(struct kimage *image, char *kernel_buf,
> unsigned long kernel_len, char *initrd,
> unsigned long initrd_len, char *cmdline,
> @@ -577,17 +41,17 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
> void *fdt;
> const void *slave_code;
> struct elfhdr ehdr;
> - struct elf_info elf_info;
> + struct kexec_elf_info elf_info;
> struct kexec_buf kbuf = { .image = image, .buf_min = 0,
> .buf_max = ppc64_rma_size };
> struct kexec_buf pbuf = { .image = image, .buf_min = 0,
> .buf_max = ppc64_rma_size, .top_down = true };
>
> - ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
> + ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
> if (ret)
> goto out;
>
> - ret = elf_exec_load(image, &ehdr, &elf_info, &kernel_load_addr);
> + ret = kexec_elf_load(image, &ehdr, &elf_info, &kbuf, &kernel_load_addr);
> if (ret)
> goto out;
>
> @@ -652,13 +116,12 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
> pr_err("Error setting up the purgatory.\n");
>
> out:
> - elf_free_info(&elf_info);
> -
> + kexec_free_elf_info(&elf_info);
> /* Make kimage_file_post_load_cleanup free the fdt buffer for us. */
> return ret ? ERR_PTR(ret) : fdt;
> }
>
> const struct kexec_file_ops kexec_elf64_ops = {
> - .probe = elf64_probe,
> + .probe = kexec_elf_probe,
> .load = elf64_load,
> };
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index b9b1bc5f9669..49b23b425f84 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -216,6 +216,41 @@ extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
> void **addr, unsigned long *sz);
> #endif /* CONFIG_KEXEC_FILE */
>
> +#ifdef CONFIG_KEXEC_FILE_ELF
> +
> +struct kexec_elf_info {
> + /*
> + * Where the ELF binary contents are kept.
> + * Memory managed by the user of the struct.
> + */
> + const char *buffer;
> +
> + const struct elfhdr *ehdr;
> + const struct elf_phdr *proghdrs;
> + struct elf_shdr *sechdrs;
> +};
> +
> +void kexec_free_elf_info(struct kexec_elf_info *elf_info);
> +
> +int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
> + struct kexec_elf_info *elf_info);
> +
> +int kexec_elf_kernel_load(struct kimage *image, struct kexec_buf *kbuf,
> + char *kernel_buf, unsigned long kernel_len,
> + unsigned long *kernel_load_addr);
> +
> +int kexec_elf_probe(const char *buf, unsigned long len);
> +
> +int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
> + struct kexec_elf_info *elf_info,
> + struct kexec_buf *kbuf,
> + unsigned long *lowest_load_addr);
> +
> +int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
> + struct kexec_elf_info *elf_info,
> + struct kexec_buf *kbuf,
> + unsigned long *lowest_load_addr);
> +#endif
> struct kimage {
> kimage_entry_t head;
> kimage_entry_t *entry;
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 33824f0385b3..fdba91785977 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -64,6 +64,7 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o
> obj-$(CONFIG_KEXEC_CORE) += kexec_core.o
> obj-$(CONFIG_KEXEC) += kexec.o
> obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
> +obj-$(CONFIG_KEXEC_FILE_ELF) += kexec_file_elf.o
> obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
> obj-$(CONFIG_COMPAT) += compat.o
> obj-$(CONFIG_CGROUPS) += cgroup/
> diff --git a/kernel/kexec_file_elf.c b/kernel/kexec_file_elf.c
> new file mode 100644
> index 000000000000..bb966c93492c
> --- /dev/null
> +++ b/kernel/kexec_file_elf.c
> @@ -0,0 +1,574 @@
> +/*
> + * Load ELF vmlinux file for the kexec_file_load syscall.
> + *
> + * Copyright (C) 2004 Adam Litke (agl@us.ibm.com)
> + * Copyright (C) 2004 IBM Corp.
> + * Copyright (C) 2005 R Sharada (sharada@in.ibm.com)
> + * Copyright (C) 2006 Mohan Kumar M (mohan@in.ibm.com)
> + * Copyright (C) 2016 IBM Corporation
> + *
> + * Based on kexec-tools' kexec-elf-exec.c and kexec-elf-ppc64.c.
> + * Heavily modified for the kernel by
> + * Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation (version 2 of the License).
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#define pr_fmt(fmt) "kexec_elf: " fmt
> +
> +#include <linux/elf.h>
> +#include <linux/kexec.h>
> +#include <linux/libfdt.h>
> +#include <linux/module.h>
> +#include <linux/of_fdt.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#define elf_addr_to_cpu elf64_to_cpu
> +
> +#ifndef Elf_Rel
> +#define Elf_Rel Elf64_Rel
> +#endif /* Elf_Rel */
> +
> +static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
> +{
> + return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
> +}
> +
> +static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
> +{
> + if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
> + value = le64_to_cpu(value);
> + else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
> + value = be64_to_cpu(value);
> +
> + return value;
> +}
> +
> +static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
> +{
> + if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
> + value = le16_to_cpu(value);
> + else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
> + value = be16_to_cpu(value);
> +
> + return value;
> +}
> +
> +static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
> +{
> + if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
> + value = le32_to_cpu(value);
> + else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
> + value = be32_to_cpu(value);
> +
> + return value;
> +}
> +
> +/**
> + * elf_is_ehdr_sane - check that it is safe to use the ELF header
> + * @buf_len: size of the buffer in which the ELF file is loaded.
> + */
> +static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
> +{
> + if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
> + pr_debug("Bad program header size.\n");
> + return false;
> + } else if (ehdr->e_shnum > 0 &&
> + ehdr->e_shentsize != sizeof(struct elf_shdr)) {
> + pr_debug("Bad section header size.\n");
> + return false;
> + } else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
> + ehdr->e_version != EV_CURRENT) {
> + pr_debug("Unknown ELF version.\n");
> + return false;
> + }
> +
> + if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
> + size_t phdr_size;
> +
> + /*
> + * e_phnum is at most 65535 so calculating the size of the
> + * program header cannot overflow.
> + */
> + phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
> +
> + /* Sanity check the program header table location. */
> + if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
> + pr_debug("Program headers at invalid location.\n");
> + return false;
> + } else if (ehdr->e_phoff + phdr_size > buf_len) {
> + pr_debug("Program headers truncated.\n");
> + return false;
> + }
> + }
> +
> + if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
> + size_t shdr_size;
> +
> + /*
> + * e_shnum is at most 65536 so calculating
> + * the size of the section header cannot overflow.
> + */
> + shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
> +
> + /* Sanity check the section header table location. */
> + if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
> + pr_debug("Section headers at invalid location.\n");
> + return false;
> + } else if (ehdr->e_shoff + shdr_size > buf_len) {
> + pr_debug("Section headers truncated.\n");
> + return false;
> + }
> + }
> +
> + return true;
> +}
> +
> +static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
> +{
> + struct elfhdr *buf_ehdr;
> +
> + if (len < sizeof(*buf_ehdr)) {
> + pr_debug("Buffer is too small to hold ELF header.\n");
> + return -ENOEXEC;
> + }
> +
> + memset(ehdr, 0, sizeof(*ehdr));
> + memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
> + if (!elf_is_elf_file(ehdr)) {
> + pr_debug("No ELF header magic.\n");
> + return -ENOEXEC;
> + }
> +
> + if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
> + pr_debug("Not a supported ELF class.\n");
> + return -ENOEXEC;
> + } else if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
> + ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
> + pr_debug("Not a supported ELF data format.\n");
> + return -ENOEXEC;
> + }
> +
> + buf_ehdr = (struct elfhdr *) buf;
> + if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
> + pr_debug("Bad ELF header size.\n");
> + return -ENOEXEC;
> + }
> +
> + ehdr->e_type = elf16_to_cpu(ehdr, buf_ehdr->e_type);
> + ehdr->e_machine = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
> + ehdr->e_version = elf32_to_cpu(ehdr, buf_ehdr->e_version);
> + ehdr->e_entry = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
> + ehdr->e_phoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
> + ehdr->e_shoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
> + ehdr->e_flags = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
> + ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
> + ehdr->e_phnum = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
> + ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
> + ehdr->e_shnum = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
> + ehdr->e_shstrndx = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
> +
> + return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
> +}
> +
> +/**
> + * elf_is_phdr_sane - check that it is safe to use the program header
> + * @buf_len: size of the buffer in which the ELF file is loaded.
> + */
> +static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
> +{
> +
> + if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
> + pr_debug("ELF segment location wraps around.\n");
> + return false;
> + } else if (phdr->p_offset + phdr->p_filesz > buf_len) {
> + pr_debug("ELF segment not in file.\n");
> + return false;
> + } else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
> + pr_debug("ELF segment address wraps around.\n");
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static int elf_read_phdr(const char *buf, size_t len, struct kexec_elf_info *elf_info,
> + int idx)
> +{
> + /* Override the const in proghdrs, we are the ones doing the loading. */
> + struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
> + const char *pbuf;
> + struct elf_phdr *buf_phdr;
> +
> + pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
> + buf_phdr = (struct elf_phdr *) pbuf;
> +
> + phdr->p_type = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
> + phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
> + phdr->p_paddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
> + phdr->p_vaddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
> + phdr->p_flags = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
> +
> + /*
> + * The following fields have a type equivalent to Elf_Addr
> + * both in 32 bit and 64 bit ELF.
> + */
> + phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
> + phdr->p_memsz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
> + phdr->p_align = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
> +
> + return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
> +}
> +
> +/**
> + * elf_read_phdrs - read the program headers from the buffer
> + *
> + * This function assumes that the program header table was checked for sanity.
> + * Use elf_is_ehdr_sane() if it wasn't.
> + */
> +static int elf_read_phdrs(const char *buf, size_t len,
> + struct kexec_elf_info *elf_info)
> +{
> + size_t phdr_size, i;
> + const struct elfhdr *ehdr = elf_info->ehdr;
> +
> + /*
> + * e_phnum is at most 65535 so calculating the size of the
> + * program header cannot overflow.
> + */
> + phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
> +
> + elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
> + if (!elf_info->proghdrs)
> + return -ENOMEM;
> +
> + for (i = 0; i < ehdr->e_phnum; i++) {
> + int ret;
> +
> + ret = elf_read_phdr(buf, len, elf_info, i);
> + if (ret) {
> + kfree(elf_info->proghdrs);
> + elf_info->proghdrs = NULL;
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * elf_is_shdr_sane - check that it is safe to use the section header
> + * @buf_len: size of the buffer in which the ELF file is loaded.
> + */
> +static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)
> +{
> + bool size_ok;
> +
> + /* SHT_NULL headers have undefined values, so we can't check them. */
> + if (shdr->sh_type == SHT_NULL)
> + return true;
> +
> + /* Now verify sh_entsize */
> + switch (shdr->sh_type) {
> + case SHT_SYMTAB:
> + size_ok = shdr->sh_entsize == sizeof(Elf_Sym);
> + break;
> + case SHT_RELA:
> + size_ok = shdr->sh_entsize == sizeof(Elf_Rela);
> + break;
> + case SHT_DYNAMIC:
> + size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);
> + break;
> + case SHT_REL:
> + size_ok = shdr->sh_entsize == sizeof(Elf_Rel);
> + break;
> + case SHT_NOTE:
> + case SHT_PROGBITS:
> + case SHT_HASH:
> + case SHT_NOBITS:
> + default:
> + /*
> + * This is a section whose entsize requirements
> + * I don't care about. If I don't know about
> + * the section I can't care about it's entsize
> + * requirements.
> + */
> + size_ok = true;
> + break;
> + }
> +
> + if (!size_ok) {
> + pr_debug("ELF section with wrong entry size.\n");
> + return false;
> + } else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {
> + pr_debug("ELF section address wraps around.\n");
> + return false;
> + }
> +
> + if (shdr->sh_type != SHT_NOBITS) {
> + if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {
> + pr_debug("ELF section location wraps around.\n");
> + return false;
> + } else if (shdr->sh_offset + shdr->sh_size > buf_len) {
> + pr_debug("ELF section not in file.\n");
> + return false;
> + }
> + }
> +
> + return true;
> +}
> +
> +static int elf_read_shdr(const char *buf, size_t len, struct kexec_elf_info *elf_info,
> + int idx)
> +{
> + struct elf_shdr *shdr = &elf_info->sechdrs[idx];
> + const struct elfhdr *ehdr = elf_info->ehdr;
> + const char *sbuf;
> + struct elf_shdr *buf_shdr;
> +
> + sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);
> + buf_shdr = (struct elf_shdr *) sbuf;
> +
> + shdr->sh_name = elf32_to_cpu(ehdr, buf_shdr->sh_name);
> + shdr->sh_type = elf32_to_cpu(ehdr, buf_shdr->sh_type);
> + shdr->sh_addr = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);
> + shdr->sh_offset = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);
> + shdr->sh_link = elf32_to_cpu(ehdr, buf_shdr->sh_link);
> + shdr->sh_info = elf32_to_cpu(ehdr, buf_shdr->sh_info);
> +
> + /*
> + * The following fields have a type equivalent to Elf_Addr
> + * both in 32 bit and 64 bit ELF.
> + */
> + shdr->sh_flags = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);
> + shdr->sh_size = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);
> + shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);
> + shdr->sh_entsize = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);
> +
> + return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;
> +}
> +
> +/**
> + * elf_read_shdrs - read the section headers from the buffer
> + *
> + * This function assumes that the section header table was checked for sanity.
> + * Use elf_is_ehdr_sane() if it wasn't.
> + */
> +static int elf_read_shdrs(const char *buf, size_t len,
> + struct kexec_elf_info *elf_info)
> +{
> + size_t shdr_size, i;
> +
> + /*
> + * e_shnum is at most 65536 so calculating
> + * the size of the section header cannot overflow.
> + */
> + shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;
> +
> + elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);
> + if (!elf_info->sechdrs)
> + return -ENOMEM;
> +
> + for (i = 0; i < elf_info->ehdr->e_shnum; i++) {
> + int ret;
> +
> + ret = elf_read_shdr(buf, len, elf_info, i);
> + if (ret) {
> + kfree(elf_info->sechdrs);
> + elf_info->sechdrs = NULL;
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
> + * @buf: Buffer to read ELF file from.
> + * @len: Size of @buf.
> + * @ehdr: Pointer to existing struct which will be populated.
> + * @elf_info: Pointer to existing struct which will be populated.
> + *
> + * This function allows reading ELF files with different byte order than
> + * the kernel, byte-swapping the fields as needed.
> + *
> + * Return:
> + * On success returns 0, and the caller should call kexec_free_elf_info(elf_info) to
> + * free the memory allocated for the section and program headers.
> + */
> +int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
> + struct kexec_elf_info *elf_info)
> +{
> + int ret;
> +
> + ret = elf_read_ehdr(buf, len, ehdr);
> + if (ret)
> + return ret;
> +
> + elf_info->buffer = buf;
> + elf_info->ehdr = ehdr;
> + if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
> + ret = elf_read_phdrs(buf, len, elf_info);
> + if (ret)
> + return ret;
> + }
> + if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
> + ret = elf_read_shdrs(buf, len, elf_info);
> + if (ret) {
> + kfree(elf_info->proghdrs);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * kexec_free_elf_info - free memory allocated by elf_read_from_buffer
> + */
> +void kexec_free_elf_info(struct kexec_elf_info *elf_info)
> +{
> + kfree(elf_info->proghdrs);
> + kfree(elf_info->sechdrs);
> + memset(elf_info, 0, sizeof(*elf_info));
> +}
> +EXPORT_SYMBOL(kexec_free_elf_info);
> +
> +/**
> + * kexec_build_elf_info - read ELF executable and check that we can use it
> + */
> +int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
> + struct kexec_elf_info *elf_info)
> +{
> + int i;
> + int ret;
> +
> + ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
> + if (ret)
> + return ret;
> +
> + /* Big endian vmlinux has type ET_DYN. */
> + if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
> + pr_err("Not an ELF executable.\n");
> + goto error;
> + } else if (!elf_info->proghdrs) {
> + pr_err("No ELF program header.\n");
> + goto error;
> + }
> +
> + for (i = 0; i < ehdr->e_phnum; i++) {
> + /*
> + * Kexec does not support loading interpreters.
> + * In addition this check keeps us from attempting
> + * to kexec ordinay executables.
> + */
> + if (elf_info->proghdrs[i].p_type == PT_INTERP) {
> + pr_err("Requires an ELF interpreter.\n");
> + goto error;
> + }
> + }
> +
> + return 0;
> +error:
> + kexec_free_elf_info(elf_info);
> + return -ENOEXEC;
> +}
> +EXPORT_SYMBOL(kexec_build_elf_info);
> +
> +/**
> + * elf_exec_load - load ELF executable image
> + * @lowest_load_addr: On return, will be the address where the first PT_LOAD
> + * section will be loaded in memory.
> + *
> + * Return:
> + * 0 on success, negative value on failure.
> + */
> +int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
> + struct kexec_elf_info *elf_info,
> + struct kexec_buf *kbuf,
> + unsigned long *lowest_load_addr)
> +{
> + unsigned long lowest_addr = UINT_MAX;
> + int ret;
> + size_t i;
> + /* Read in the PT_LOAD segments. */
> + for (i = 0; i < ehdr->e_phnum; i++) {
> + unsigned long load_addr;
> + size_t size;
> + const struct elf_phdr *phdr;
> +
> + phdr = &elf_info->proghdrs[i];
> + if (phdr->p_type != PT_LOAD)
> + continue;
> +
> + size = phdr->p_filesz;
> + if (size > phdr->p_memsz)
> + size = phdr->p_memsz;
> +
> + kbuf->buffer = (void *) elf_info->buffer + phdr->p_offset;
> + kbuf->bufsz = size;
> + kbuf->memsz = phdr->p_memsz;
> + kbuf->buf_align = phdr->p_align;
> + kbuf->buf_min = phdr->p_paddr;
> + kbuf->mem = KEXEC_BUF_MEM_UNKNOWN;
> + ret = kexec_add_buffer(kbuf);
> + if (ret)
> + goto out;
> + load_addr = kbuf->mem;
> +
> + if (load_addr < lowest_addr)
> + lowest_addr = load_addr;
> + }
> +
> + image->start = ehdr->e_entry;
> + *lowest_load_addr = lowest_addr;
> + ret = 0;
> + out:
> + return ret;
> +}
> +EXPORT_SYMBOL(kexec_elf_load);
> +
> +int kexec_elf_kernel_load(struct kimage *image, struct kexec_buf *kbuf,
> + char *kernel_buf, unsigned long kernel_len,
> + unsigned long *kernel_load_addr)
> +{
> + int ret;
> + struct elfhdr ehdr;
> + struct kexec_elf_info elf_info;
> +
> + ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
> + if (ret)
> + goto out;
> +
> + ret = kexec_elf_load(image, &ehdr, &elf_info, kbuf, kernel_load_addr);
> +out:
> + kexec_free_elf_info(&elf_info);
> + return ret;
> +
> +}
> +EXPORT_SYMBOL(kexec_elf_kernel_load);
> +
> +int kexec_elf_probe(const char *buf, unsigned long len)
> +{
> + struct elfhdr ehdr;
> + struct kexec_elf_info elf_info;
> + int ret;
> +
> + ret = kexec_build_elf_info(buf, len, &ehdr, &elf_info);
> + if (ret)
> + return ret;
> +
> + kexec_free_elf_info(&elf_info);
> +
> + return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
> +}
> +EXPORT_SYMBOL(kexec_elf_probe);
>