[PATCH v2 0/7] kexec: add generic support for elf kernel images

[PATCH v2 0/7] kexec: add generic support for elf kernel images

[Sven Schnelle]

Hi List,

i've split up the patch a bit more. The first one move the generic elf stuff
out of arch/powerpc to linux/kexec_elf.c, and prefixes the exposed functions
with kexec_. That other patches remove stuff that is not used as proposed in
the review.

Changes to v1:
 - split up patch into smaller pieces
 - rebase onto powerpc/next
 - remove unused variable in kexec_elf_load()

Changes to RFC version:
 - remove unused Elf_Rel macro
 - remove section header parsing
 - remove PURGATORY_STACK_SIZE
 - change order of elf_*_to_cpu() functions
 - remove elf_addr_to_cpu macro
 
Sven Schnelle (7):
  kexec: add KEXEC_ELF
  kexec_elf: change order of elf_*_to_cpu() functions
  kexec_elf: remove parsing of section headers
  kexec_elf: remove PURGATORY_STACK_SIZE
  kexec_elf: remove elf_addr_to_cpu macro
  kexec_elf: remove Elf_Rel macro
  kexec_elf: remove unused variable in kexec_elf_load()

 arch/Kconfig                       |   3 +
 arch/powerpc/Kconfig               |   1 +
 arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
 include/linux/kexec.h              |  23 ++
 kernel/Makefile                    |   1 +
 kernel/kexec_elf.c                 | 389 ++++++++++++++++++++
 6 files changed, 427 insertions(+), 541 deletions(-)
 create mode 100644 kernel/kexec_elf.c

-- 
2.20.1

[PATCH v2 0/7] kexec: add generic support for elf kernel images

[Sven Schnelle]

Hi List,

i've split up the patch a bit more. The first one move the generic elf stuff
out of arch/powerpc to linux/kexec_elf.c, and prefixes the exposed functions
with kexec_. That other patches remove stuff that is not used as proposed in
the review.

Changes to v1:
 - split up patch into smaller pieces
 - rebase onto powerpc/next
 - remove unused variable in kexec_elf_load()

Changes to RFC version:
 - remove unused Elf_Rel macro
 - remove section header parsing
 - remove PURGATORY_STACK_SIZE
 - change order of elf_*_to_cpu() functions
 - remove elf_addr_to_cpu macro
 
Sven Schnelle (7):
  kexec: add KEXEC_ELF
  kexec_elf: change order of elf_*_to_cpu() functions
  kexec_elf: remove parsing of section headers
  kexec_elf: remove PURGATORY_STACK_SIZE
  kexec_elf: remove elf_addr_to_cpu macro
  kexec_elf: remove Elf_Rel macro
  kexec_elf: remove unused variable in kexec_elf_load()

 arch/Kconfig                       |   3 +
 arch/powerpc/Kconfig               |   1 +
 arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
 include/linux/kexec.h              |  23 ++
 kernel/Makefile                    |   1 +
 kernel/kexec_elf.c                 | 389 ++++++++++++++++++++
 6 files changed, 427 insertions(+), 541 deletions(-)
 create mode 100644 kernel/kexec_elf.c

-- 
2.20.1


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[PATCH v2 1/7] kexec: add KEXEC_ELF

[Sven Schnelle]

Right now powerpc provides an implementation to read elf files
with the kexec_file() syscall. Make that available as a public
kexec interface so it can be re-used on other architectures.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 arch/Kconfig                       |   3 +
 arch/powerpc/Kconfig               |   1 +
 arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
 include/linux/kexec.h              |  24 ++
 kernel/Makefile                    |   1 +
 kernel/kexec_elf.c                 | 537 ++++++++++++++++++++++++++++
 6 files changed, 576 insertions(+), 541 deletions(-)
 create mode 100644 kernel/kexec_elf.c

diff --git a/arch/Kconfig b/arch/Kconfig
index c47b328eada0..30694aca4316 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -18,6 +18,9 @@ config KEXEC_CORE
 	select CRASH_CORE
 	bool
 
+config KEXEC_ELF
+	bool
+
 config HAVE_IMA_KEXEC
 	bool
 
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 12cee37f15c4..addc2dad78e0 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -510,6 +510,7 @@ config KEXEC_FILE
 	select KEXEC_CORE
 	select HAVE_IMA_KEXEC
 	select BUILD_BIN2C
+	select KEXEC_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..30bd57a93c17 100644
--- a/arch/powerpc/kernel/kexec_elf_64.c
+++ b/arch/powerpc/kernel/kexec_elf_64.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Load ELF vmlinux file for the kexec_file_load syscall.
  *
@@ -10,15 +11,6 @@
  * 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
@@ -39,532 +31,6 @@
 #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 +43,18 @@ 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 };
+				  .buf_max = ppc64_rma_size, .top_down = true,
+				  .mem = KEXEC_BUF_MEM_UNKNOWN };
 
-	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;
 
@@ -606,6 +73,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 		kbuf.bufsz = kbuf.memsz = initrd_len;
 		kbuf.buf_align = PAGE_SIZE;
 		kbuf.top_down = false;
+		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 		ret = kexec_add_buffer(&kbuf);
 		if (ret)
 			goto out;
@@ -638,6 +106,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	kbuf.bufsz = kbuf.memsz = fdt_size;
 	kbuf.buf_align = PAGE_SIZE;
 	kbuf.top_down = true;
+	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 	ret = kexec_add_buffer(&kbuf);
 	if (ret)
 		goto out;
@@ -652,13 +121,13 @@ 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..da2a6b1d69e7 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -216,6 +216,30 @@ 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_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;
+};
+
+int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
+			       struct kexec_elf_info *elf_info);
+
+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);
+
+void kexec_free_elf_info(struct kexec_elf_info *elf_info);
+int kexec_elf_probe(const char *buf, unsigned long len);
+#endif
 struct kimage {
 	kimage_entry_t head;
 	kimage_entry_t *entry;
diff --git a/kernel/Makefile b/kernel/Makefile
index 33824f0385b3..7062306de9b7 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-$(CONFIG_KEXEC_ELF) += kexec_elf.o
 obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup/
diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
new file mode 100644
index 000000000000..6e9f52171ede
--- /dev/null
+++ b/kernel/kexec_elf.c
@@ -0,0 +1,537 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt)	"kexec_elf: " fmt
+
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <linux/module.h>
+#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 */
+
+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.
+ */
+static 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));
+}
+/**
+ * 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;
+}
+
+
+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;
+}
+
+/**
+ * kexec_elf_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 base = 0, 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 + 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;
+}
+
+
-- 
2.20.1

[PATCH v2 1/7] kexec: add KEXEC_ELF

[Sven Schnelle]

Right now powerpc provides an implementation to read elf files
with the kexec_file() syscall. Make that available as a public
kexec interface so it can be re-used on other architectures.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 arch/Kconfig                       |   3 +
 arch/powerpc/Kconfig               |   1 +
 arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
 include/linux/kexec.h              |  24 ++
 kernel/Makefile                    |   1 +
 kernel/kexec_elf.c                 | 537 ++++++++++++++++++++++++++++
 6 files changed, 576 insertions(+), 541 deletions(-)
 create mode 100644 kernel/kexec_elf.c

diff --git a/arch/Kconfig b/arch/Kconfig
index c47b328eada0..30694aca4316 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -18,6 +18,9 @@ config KEXEC_CORE
 	select CRASH_CORE
 	bool
 
+config KEXEC_ELF
+	bool
+
 config HAVE_IMA_KEXEC
 	bool
 
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 12cee37f15c4..addc2dad78e0 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -510,6 +510,7 @@ config KEXEC_FILE
 	select KEXEC_CORE
 	select HAVE_IMA_KEXEC
 	select BUILD_BIN2C
+	select KEXEC_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..30bd57a93c17 100644
--- a/arch/powerpc/kernel/kexec_elf_64.c
+++ b/arch/powerpc/kernel/kexec_elf_64.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Load ELF vmlinux file for the kexec_file_load syscall.
  *
@@ -10,15 +11,6 @@
  * 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
@@ -39,532 +31,6 @@
 #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 +43,18 @@ 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 };
+				  .buf_max = ppc64_rma_size, .top_down = true,
+				  .mem = KEXEC_BUF_MEM_UNKNOWN };
 
-	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;
 
@@ -606,6 +73,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 		kbuf.bufsz = kbuf.memsz = initrd_len;
 		kbuf.buf_align = PAGE_SIZE;
 		kbuf.top_down = false;
+		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 		ret = kexec_add_buffer(&kbuf);
 		if (ret)
 			goto out;
@@ -638,6 +106,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	kbuf.bufsz = kbuf.memsz = fdt_size;
 	kbuf.buf_align = PAGE_SIZE;
 	kbuf.top_down = true;
+	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 	ret = kexec_add_buffer(&kbuf);
 	if (ret)
 		goto out;
@@ -652,13 +121,13 @@ 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..da2a6b1d69e7 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -216,6 +216,30 @@ 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_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;
+};
+
+int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
+			       struct kexec_elf_info *elf_info);
+
+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);
+
+void kexec_free_elf_info(struct kexec_elf_info *elf_info);
+int kexec_elf_probe(const char *buf, unsigned long len);
+#endif
 struct kimage {
 	kimage_entry_t head;
 	kimage_entry_t *entry;
diff --git a/kernel/Makefile b/kernel/Makefile
index 33824f0385b3..7062306de9b7 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-$(CONFIG_KEXEC_ELF) += kexec_elf.o
 obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup/
diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
new file mode 100644
index 000000000000..6e9f52171ede
--- /dev/null
+++ b/kernel/kexec_elf.c
@@ -0,0 +1,537 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt)	"kexec_elf: " fmt
+
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <linux/module.h>
+#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 */
+
+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.
+ */
+static 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));
+}
+/**
+ * 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;
+}
+
+
+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;
+}
+
+/**
+ * kexec_elf_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 base = 0, 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 + 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;
+}
+
+
-- 
2.20.1


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Re: [PATCH v2 1/7] kexec: add KEXEC_ELF

[Christophe Leroy]

Hi Sven,

On 07/09/2019 07:43 PM, Sven Schnelle wrote:
> Right now powerpc provides an implementation to read elf files
> with the kexec_file() syscall. Make that available as a public
> kexec interface so it can be re-used on other architectures.
> 
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> ---
>   arch/Kconfig                       |   3 +
>   arch/powerpc/Kconfig               |   1 +
>   arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
>   include/linux/kexec.h              |  24 ++
>   kernel/Makefile                    |   1 +
>   kernel/kexec_elf.c                 | 537 ++++++++++++++++++++++++++++
>   6 files changed, 576 insertions(+), 541 deletions(-)
>   create mode 100644 kernel/kexec_elf.c

Why are you persisting at not using -C when creating your patch ? Do you 
want to hide the changes you did while copying 
arch/powerpc/kernel/kexec_elf_64.c to kernel/kexec_elf.c ?
Or you want to make life harder for the reviewers ?

git format-patch -C shows:

  arch/Kconfig                                       |   3 +
  arch/powerpc/Kconfig                               |   1 +
  arch/powerpc/kernel/kexec_elf_64.c                 | 551 
+--------------------
  include/linux/kexec.h                              |  24 +
  kernel/Makefile                                    |   1 +
  .../kernel/kexec_elf_64.c => kernel/kexec_elf.c    | 199 ++------
  6 files changed, 75 insertions(+), 704 deletions(-)
  copy arch/powerpc/kernel/kexec_elf_64.c => kernel/kexec_elf.c (71%)

I mentionned it a couple of times, I even resent your last patch 
formatted that way to show the advantage. I can ear if you find it 
worthless, but tell what your concern are with that, don't just ignore 
it please.

Cheers
Christophe

> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index c47b328eada0..30694aca4316 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -18,6 +18,9 @@ config KEXEC_CORE
>   	select CRASH_CORE
>   	bool
>   
> +config KEXEC_ELF
> +	bool
> +
>   config HAVE_IMA_KEXEC
>   	bool
>   
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 12cee37f15c4..addc2dad78e0 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -510,6 +510,7 @@ config KEXEC_FILE
>   	select KEXEC_CORE
>   	select HAVE_IMA_KEXEC
>   	select BUILD_BIN2C
> +	select KEXEC_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..30bd57a93c17 100644
> --- a/arch/powerpc/kernel/kexec_elf_64.c
> +++ b/arch/powerpc/kernel/kexec_elf_64.c
> @@ -1,3 +1,4 @@
> +// SPDX-License-Identifier: GPL-2.0-only
>   /*
>    * Load ELF vmlinux file for the kexec_file_load syscall.
>    *
> @@ -10,15 +11,6 @@
>    * 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
> @@ -39,532 +31,6 @@
>   #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 +43,18 @@ 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 };
> +				  .buf_max = ppc64_rma_size, .top_down = true,
> +				  .mem = KEXEC_BUF_MEM_UNKNOWN };
>   
> -	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;
>   
> @@ -606,6 +73,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>   		kbuf.bufsz = kbuf.memsz = initrd_len;
>   		kbuf.buf_align = PAGE_SIZE;
>   		kbuf.top_down = false;
> +		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>   		ret = kexec_add_buffer(&kbuf);
>   		if (ret)
>   			goto out;
> @@ -638,6 +106,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>   	kbuf.bufsz = kbuf.memsz = fdt_size;
>   	kbuf.buf_align = PAGE_SIZE;
>   	kbuf.top_down = true;
> +	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>   	ret = kexec_add_buffer(&kbuf);
>   	if (ret)
>   		goto out;
> @@ -652,13 +121,13 @@ 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..da2a6b1d69e7 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -216,6 +216,30 @@ 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_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;
> +};
> +
> +int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
> +			       struct kexec_elf_info *elf_info);
> +
> +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);
> +
> +void kexec_free_elf_info(struct kexec_elf_info *elf_info);
> +int kexec_elf_probe(const char *buf, unsigned long len);
> +#endif
>   struct kimage {
>   	kimage_entry_t head;
>   	kimage_entry_t *entry;
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 33824f0385b3..7062306de9b7 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-$(CONFIG_KEXEC_ELF) += kexec_elf.o
>   obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
>   obj-$(CONFIG_COMPAT) += compat.o
>   obj-$(CONFIG_CGROUPS) += cgroup/
> diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
> new file mode 100644
> index 000000000000..6e9f52171ede
> --- /dev/null
> +++ b/kernel/kexec_elf.c
> @@ -0,0 +1,537 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#define pr_fmt(fmt)	"kexec_elf: " fmt
> +
> +#include <linux/elf.h>
> +#include <linux/kexec.h>
> +#include <linux/module.h>
> +#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 */
> +
> +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.
> + */
> +static 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));
> +}
> +/**
> + * 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;
> +}
> +
> +
> +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;
> +}
> +
> +/**
> + * kexec_elf_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 base = 0, 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 + 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;
> +}
> +
> +
> 

Re: [PATCH v2 1/7] kexec: add KEXEC_ELF

[Christophe Leroy]

Hi Sven,

On 07/09/2019 07:43 PM, Sven Schnelle wrote:
> Right now powerpc provides an implementation to read elf files
> with the kexec_file() syscall. Make that available as a public
> kexec interface so it can be re-used on other architectures.
> 
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> ---
>   arch/Kconfig                       |   3 +
>   arch/powerpc/Kconfig               |   1 +
>   arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
>   include/linux/kexec.h              |  24 ++
>   kernel/Makefile                    |   1 +
>   kernel/kexec_elf.c                 | 537 ++++++++++++++++++++++++++++
>   6 files changed, 576 insertions(+), 541 deletions(-)
>   create mode 100644 kernel/kexec_elf.c

Why are you persisting at not using -C when creating your patch ? Do you 
want to hide the changes you did while copying 
arch/powerpc/kernel/kexec_elf_64.c to kernel/kexec_elf.c ?
Or you want to make life harder for the reviewers ?

git format-patch -C shows:

  arch/Kconfig                                       |   3 +
  arch/powerpc/Kconfig                               |   1 +
  arch/powerpc/kernel/kexec_elf_64.c                 | 551 
+--------------------
  include/linux/kexec.h                              |  24 +
  kernel/Makefile                                    |   1 +
  .../kernel/kexec_elf_64.c => kernel/kexec_elf.c    | 199 ++------
  6 files changed, 75 insertions(+), 704 deletions(-)
  copy arch/powerpc/kernel/kexec_elf_64.c => kernel/kexec_elf.c (71%)

I mentionned it a couple of times, I even resent your last patch 
formatted that way to show the advantage. I can ear if you find it 
worthless, but tell what your concern are with that, don't just ignore 
it please.

Cheers
Christophe

> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index c47b328eada0..30694aca4316 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -18,6 +18,9 @@ config KEXEC_CORE
>   	select CRASH_CORE
>   	bool
>   
> +config KEXEC_ELF
> +	bool
> +
>   config HAVE_IMA_KEXEC
>   	bool
>   
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 12cee37f15c4..addc2dad78e0 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -510,6 +510,7 @@ config KEXEC_FILE
>   	select KEXEC_CORE
>   	select HAVE_IMA_KEXEC
>   	select BUILD_BIN2C
> +	select KEXEC_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..30bd57a93c17 100644
> --- a/arch/powerpc/kernel/kexec_elf_64.c
> +++ b/arch/powerpc/kernel/kexec_elf_64.c
> @@ -1,3 +1,4 @@
> +// SPDX-License-Identifier: GPL-2.0-only
>   /*
>    * Load ELF vmlinux file for the kexec_file_load syscall.
>    *
> @@ -10,15 +11,6 @@
>    * 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
> @@ -39,532 +31,6 @@
>   #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 +43,18 @@ 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 };
> +				  .buf_max = ppc64_rma_size, .top_down = true,
> +				  .mem = KEXEC_BUF_MEM_UNKNOWN };
>   
> -	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;
>   
> @@ -606,6 +73,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>   		kbuf.bufsz = kbuf.memsz = initrd_len;
>   		kbuf.buf_align = PAGE_SIZE;
>   		kbuf.top_down = false;
> +		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>   		ret = kexec_add_buffer(&kbuf);
>   		if (ret)
>   			goto out;
> @@ -638,6 +106,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>   	kbuf.bufsz = kbuf.memsz = fdt_size;
>   	kbuf.buf_align = PAGE_SIZE;
>   	kbuf.top_down = true;
> +	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>   	ret = kexec_add_buffer(&kbuf);
>   	if (ret)
>   		goto out;
> @@ -652,13 +121,13 @@ 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..da2a6b1d69e7 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -216,6 +216,30 @@ 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_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;
> +};
> +
> +int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
> +			       struct kexec_elf_info *elf_info);
> +
> +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);
> +
> +void kexec_free_elf_info(struct kexec_elf_info *elf_info);
> +int kexec_elf_probe(const char *buf, unsigned long len);
> +#endif
>   struct kimage {
>   	kimage_entry_t head;
>   	kimage_entry_t *entry;
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 33824f0385b3..7062306de9b7 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-$(CONFIG_KEXEC_ELF) += kexec_elf.o
>   obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
>   obj-$(CONFIG_COMPAT) += compat.o
>   obj-$(CONFIG_CGROUPS) += cgroup/
> diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
> new file mode 100644
> index 000000000000..6e9f52171ede
> --- /dev/null
> +++ b/kernel/kexec_elf.c
> @@ -0,0 +1,537 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#define pr_fmt(fmt)	"kexec_elf: " fmt
> +
> +#include <linux/elf.h>
> +#include <linux/kexec.h>
> +#include <linux/module.h>
> +#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 */
> +
> +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.
> + */
> +static 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));
> +}
> +/**
> + * 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;
> +}
> +
> +
> +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;
> +}
> +
> +/**
> + * kexec_elf_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 base = 0, 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 + 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;
> +}
> +
> +
> 



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Re: [PATCH v2 1/7] kexec: add KEXEC_ELF

[Sven Schnelle]

Hi Christophe,

On Wed, Jul 10, 2019 at 01:19:13PM +0000, Christophe Leroy wrote:
> Hi Sven,
> 
> On 07/09/2019 07:43 PM, Sven Schnelle wrote:
> > Right now powerpc provides an implementation to read elf files
> > with the kexec_file() syscall. Make that available as a public
> > kexec interface so it can be re-used on other architectures.
> > 
> > Signed-off-by: Sven Schnelle <svens@stackframe.org>
> > ---
> >   arch/Kconfig                       |   3 +
> >   arch/powerpc/Kconfig               |   1 +
> >   arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
> >   include/linux/kexec.h              |  24 ++
> >   kernel/Makefile                    |   1 +
> >   kernel/kexec_elf.c                 | 537 ++++++++++++++++++++++++++++
> >   6 files changed, 576 insertions(+), 541 deletions(-)
> >   create mode 100644 kernel/kexec_elf.c
> 
> Why are you persisting at not using -C when creating your patch ? Do you
> want to hide the changes you did while copying
> arch/powerpc/kernel/kexec_elf_64.c to kernel/kexec_elf.c ?
> Or you want to make life harder for the reviewers ?

Sorry, never used -C before. I used:

git send-email --annotate -v2 -7 --to kexec@lists.infradead.org --cc deller@gmx.de,linuxppc-dev@lists.ozlabs.org -v --format-patch -C -M

However, it looks like it only works when started this way:

git send-email --format-patch -M -C --annotate -v2 -7 --to kexec@lists.infradead.org --cc deller@gmx.de,linuxppc-dev@lists.ozlabs.org -v

I'll resend v2.

Best Regards,
Sven

Re: [PATCH v2 1/7] kexec: add KEXEC_ELF

[Sven Schnelle]

Hi Christophe,

On Wed, Jul 10, 2019 at 01:19:13PM +0000, Christophe Leroy wrote:
> Hi Sven,
> 
> On 07/09/2019 07:43 PM, Sven Schnelle wrote:
> > Right now powerpc provides an implementation to read elf files
> > with the kexec_file() syscall. Make that available as a public
> > kexec interface so it can be re-used on other architectures.
> > 
> > Signed-off-by: Sven Schnelle <svens@stackframe.org>
> > ---
> >   arch/Kconfig                       |   3 +
> >   arch/powerpc/Kconfig               |   1 +
> >   arch/powerpc/kernel/kexec_elf_64.c | 551 +----------------------------
> >   include/linux/kexec.h              |  24 ++
> >   kernel/Makefile                    |   1 +
> >   kernel/kexec_elf.c                 | 537 ++++++++++++++++++++++++++++
> >   6 files changed, 576 insertions(+), 541 deletions(-)
> >   create mode 100644 kernel/kexec_elf.c
> 
> Why are you persisting at not using -C when creating your patch ? Do you
> want to hide the changes you did while copying
> arch/powerpc/kernel/kexec_elf_64.c to kernel/kexec_elf.c ?
> Or you want to make life harder for the reviewers ?

Sorry, never used -C before. I used:

git send-email --annotate -v2 -7 --to kexec@lists.infradead.org --cc deller@gmx.de,linuxppc-dev@lists.ozlabs.org -v --format-patch -C -M

However, it looks like it only works when started this way:

git send-email --format-patch -M -C --annotate -v2 -7 --to kexec@lists.infradead.org --cc deller@gmx.de,linuxppc-dev@lists.ozlabs.org -v

I'll resend v2.

Best Regards,
Sven

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[PATCH v2 2/7] kexec_elf: change order of elf_*_to_cpu() functions

[Sven Schnelle]

Change the order to have a 64/32/16 order, no functional change.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 6e9f52171ede..76e7df64d715 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -31,22 +31,22 @@ static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
 	return value;
 }
 
-static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
+static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
 {
 	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
-		value = le16_to_cpu(value);
+		value = le32_to_cpu(value);
 	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
-		value = be16_to_cpu(value);
+		value = be32_to_cpu(value);
 
 	return value;
 }
 
-static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
+static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
 {
 	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
-		value = le32_to_cpu(value);
+		value = le16_to_cpu(value);
 	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
-		value = be32_to_cpu(value);
+		value = be16_to_cpu(value);
 
 	return value;
 }
-- 
2.20.1

[PATCH v2 2/7] kexec_elf: change order of elf_*_to_cpu() functions

[Sven Schnelle]

Change the order to have a 64/32/16 order, no functional change.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 6e9f52171ede..76e7df64d715 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -31,22 +31,22 @@ static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
 	return value;
 }
 
-static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
+static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
 {
 	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
-		value = le16_to_cpu(value);
+		value = le32_to_cpu(value);
 	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
-		value = be16_to_cpu(value);
+		value = be32_to_cpu(value);
 
 	return value;
 }
 
-static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
+static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
 {
 	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
-		value = le32_to_cpu(value);
+		value = le16_to_cpu(value);
 	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
-		value = be32_to_cpu(value);
+		value = be16_to_cpu(value);
 
 	return value;
 }
-- 
2.20.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v2 3/7] kexec_elf: remove parsing of section headers

[Sven Schnelle]

We're not using them, so we can drop the parsing.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 include/linux/kexec.h |   1 -
 kernel/kexec_elf.c    | 137 ------------------------------------------
 2 files changed, 138 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index da2a6b1d69e7..f0b809258ed3 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -226,7 +226,6 @@ struct kexec_elf_info {
 
 	const struct elfhdr *ehdr;
 	const struct elf_phdr *proghdrs;
-	struct elf_shdr *sechdrs;
 };
 
 int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 76e7df64d715..effe9dc0b055 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -244,134 +244,6 @@ static int elf_read_phdrs(const char *buf, size_t len,
 	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.
@@ -404,14 +276,6 @@ static int elf_read_from_buffer(const char *buf, size_t len,
 		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;
 }
 
@@ -421,7 +285,6 @@ static int elf_read_from_buffer(const char *buf, size_t len,
 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));
 }
 /**
-- 
2.20.1

[PATCH v2 3/7] kexec_elf: remove parsing of section headers

[Sven Schnelle]

We're not using them, so we can drop the parsing.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 include/linux/kexec.h |   1 -
 kernel/kexec_elf.c    | 137 ------------------------------------------
 2 files changed, 138 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index da2a6b1d69e7..f0b809258ed3 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -226,7 +226,6 @@ struct kexec_elf_info {
 
 	const struct elfhdr *ehdr;
 	const struct elf_phdr *proghdrs;
-	struct elf_shdr *sechdrs;
 };
 
 int kexec_build_elf_info(const char *buf, size_t len, struct elfhdr *ehdr,
diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 76e7df64d715..effe9dc0b055 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -244,134 +244,6 @@ static int elf_read_phdrs(const char *buf, size_t len,
 	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.
@@ -404,14 +276,6 @@ static int elf_read_from_buffer(const char *buf, size_t len,
 		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;
 }
 
@@ -421,7 +285,6 @@ static int elf_read_from_buffer(const char *buf, size_t len,
 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));
 }
 /**
-- 
2.20.1


_______________________________________________
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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v2 4/7] kexec_elf: remove PURGATORY_STACK_SIZE

[Sven Schnelle]

It's not used anywhere so just drop it.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index effe9dc0b055..70d31b8feeae 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -8,8 +8,6 @@
 #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
-- 
2.20.1

[PATCH v2 4/7] kexec_elf: remove PURGATORY_STACK_SIZE

[Sven Schnelle]

It's not used anywhere so just drop it.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index effe9dc0b055..70d31b8feeae 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -8,8 +8,6 @@
 #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
-- 
2.20.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v2 5/7] kexec_elf: remove elf_addr_to_cpu macro

[Sven Schnelle]

It had only one definition, so just use the function directly.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 70d31b8feeae..99e6d63b5dfc 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -8,8 +8,6 @@
 #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 */
@@ -143,9 +141,9 @@ static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
 	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_entry     = elf64_to_cpu(ehdr, buf_ehdr->e_entry);
+	ehdr->e_phoff     = elf64_to_cpu(ehdr, buf_ehdr->e_phoff);
+	ehdr->e_shoff     = elf64_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);
@@ -190,18 +188,18 @@ static int elf_read_phdr(const char *buf, size_t len,
 	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_offset = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
+	phdr->p_paddr  = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
+	phdr->p_vaddr  = elf64_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);
+	phdr->p_filesz = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
+	phdr->p_memsz  = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
+	phdr->p_align  = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_align);
 
 	return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
 }
-- 
2.20.1

[PATCH v2 5/7] kexec_elf: remove elf_addr_to_cpu macro

[Sven Schnelle]

It had only one definition, so just use the function directly.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 70d31b8feeae..99e6d63b5dfc 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -8,8 +8,6 @@
 #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 */
@@ -143,9 +141,9 @@ static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
 	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_entry     = elf64_to_cpu(ehdr, buf_ehdr->e_entry);
+	ehdr->e_phoff     = elf64_to_cpu(ehdr, buf_ehdr->e_phoff);
+	ehdr->e_shoff     = elf64_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);
@@ -190,18 +188,18 @@ static int elf_read_phdr(const char *buf, size_t len,
 	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_offset = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
+	phdr->p_paddr  = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
+	phdr->p_vaddr  = elf64_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);
+	phdr->p_filesz = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
+	phdr->p_memsz  = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
+	phdr->p_align  = elf64_to_cpu(elf_info->ehdr, buf_phdr->p_align);
 
 	return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
 }
-- 
2.20.1


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[PATCH v2 6/7] kexec_elf: remove Elf_Rel macro

[Sven Schnelle]

It wasn't used anywhere, so lets drop it.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 99e6d63b5dfc..b7e47ddd7cad 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -8,10 +8,6 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 
-#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;
-- 
2.20.1

[PATCH v2 6/7] kexec_elf: remove Elf_Rel macro

[Sven Schnelle]

It wasn't used anywhere, so lets drop it.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index 99e6d63b5dfc..b7e47ddd7cad 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -8,10 +8,6 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 
-#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;
-- 
2.20.1


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[PATCH v2 7/7] kexec_elf: remove unused variable in kexec_elf_load()

[Sven Schnelle]

base was never unsigned, so we can remove it.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index b7e47ddd7cad..a56ec5481e71 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -348,7 +348,7 @@ int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 			 struct kexec_buf *kbuf,
 			 unsigned long *lowest_load_addr)
 {
-	unsigned long base = 0, lowest_addr = UINT_MAX;
+	unsigned long lowest_addr = UINT_MAX;
 	int ret;
 	size_t i;
 
@@ -370,7 +370,7 @@ int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 		kbuf->bufsz = size;
 		kbuf->memsz = phdr->p_memsz;
 		kbuf->buf_align = phdr->p_align;
-		kbuf->buf_min = phdr->p_paddr + base;
+		kbuf->buf_min = phdr->p_paddr;
 		ret = kexec_add_buffer(kbuf);
 		if (ret)
 			goto out;
@@ -380,9 +380,6 @@ int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 			lowest_addr = load_addr;
 	}
 
-	/* Update entry point to reflect new load address. */
-	ehdr->e_entry += base;
-
 	*lowest_load_addr = lowest_addr;
 	ret = 0;
  out:
-- 
2.20.1

[PATCH v2 7/7] kexec_elf: remove unused variable in kexec_elf_load()

[Sven Schnelle]

base was never unsigned, so we can remove it.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 kernel/kexec_elf.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
index b7e47ddd7cad..a56ec5481e71 100644
--- a/kernel/kexec_elf.c
+++ b/kernel/kexec_elf.c
@@ -348,7 +348,7 @@ int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 			 struct kexec_buf *kbuf,
 			 unsigned long *lowest_load_addr)
 {
-	unsigned long base = 0, lowest_addr = UINT_MAX;
+	unsigned long lowest_addr = UINT_MAX;
 	int ret;
 	size_t i;
 
@@ -370,7 +370,7 @@ int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 		kbuf->bufsz = size;
 		kbuf->memsz = phdr->p_memsz;
 		kbuf->buf_align = phdr->p_align;
-		kbuf->buf_min = phdr->p_paddr + base;
+		kbuf->buf_min = phdr->p_paddr;
 		ret = kexec_add_buffer(kbuf);
 		if (ret)
 			goto out;
@@ -380,9 +380,6 @@ int kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
 			lowest_addr = load_addr;
 	}
 
-	/* Update entry point to reflect new load address. */
-	ehdr->e_entry += base;
-
 	*lowest_load_addr = lowest_addr;
 	ret = 0;
  out:
-- 
2.20.1


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