Message-Id: <1390849071-21989-12-git-send-email-vgoyal@redhat.com>
Date:	Mon, 27 Jan 2014 13:57:51 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org
Cc:	ebiederm@...ssion.com, hpa@...or.com, mjg59@...f.ucam.org,
	greg@...ah.com, jkosina@...e.cz, Vivek Goyal <vgoyal@...hat.com>
Subject: [PATCH 11/11] kexec: Support for Kexec on panic using new system call

This patch adds support for loading a kexec on panic (kdump) kernel usning
new system call. Right now this primarily works with bzImage loader only.
But changes to ELF loader should be minimal as all the core infrastrcture
is there.

Only thing preventing making ELF load in crash reseved memory is
that kernel vmlinux is of type ET_EXEC and it expects to be loaded at
address it has been compiled for. At that location current kernel is
already running. One first needs to make vmlinux fully relocatable
and export it is type ET_DYN and then modify this ELF loader to support
images of type ET_DYN.

I am leaving it as a future TODO item.

Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
---
 arch/x86/include/asm/crash.h       |   9 +
 arch/x86/include/asm/kexec.h       |  25 +-
 arch/x86/kernel/crash.c            | 574 +++++++++++++++++++++++++++++++++++++
 arch/x86/kernel/kexec-bzimage.c    |  27 +-
 arch/x86/kernel/kexec-elf.c        |   4 +-
 arch/x86/kernel/machine_kexec.c    |  21 +-
 arch/x86/kernel/machine_kexec_64.c |  38 +++
 kernel/kexec.c                     |  83 +++++-
 8 files changed, 763 insertions(+), 18 deletions(-)
 create mode 100644 arch/x86/include/asm/crash.h

diff --git a/arch/x86/include/asm/crash.h b/arch/x86/include/asm/crash.h
new file mode 100644
index 0000000..2dd2eb8
--- /dev/null
+++ b/arch/x86/include/asm/crash.h
@@ -0,0 +1,9 @@
+#ifndef _ASM_X86_CRASH_H
+#define _ASM_X86_CRASH_H
+
+int load_crashdump_segments(struct kimage *image);
+int crash_copy_backup_region(struct kimage *image);
+int crash_setup_memmap_entries(struct kimage *image,
+		struct boot_params *params);
+
+#endif /* _ASM_X86_CRASH_H */
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 9bd6fec..a330d85 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -25,6 +25,8 @@
 #include <asm/ptrace.h>
 #include <asm/bootparam.h>
 
+struct kimage;
+
 /*
  * KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
  * I.e. Maximum page that is mapped directly into kernel memory,
@@ -62,6 +64,10 @@
 # define KEXEC_ARCH KEXEC_ARCH_X86_64
 #endif
 
+/* Memory to backup during crash kdump */
+#define KEXEC_BACKUP_SRC_START	(0UL)
+#define KEXEC_BACKUP_SRC_END	(655360UL)	/* 640K */
+
 /*
  * CPU does not save ss and sp on stack if execution is already
  * running in kernel mode at the time of NMI occurrence. This code
@@ -161,8 +167,21 @@ struct kimage_arch {
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
+	/* Details of backup region */
+	unsigned long backup_src_start;
+	unsigned long backup_src_sz;
+
+	/* Physical address of backup segment */
+	unsigned long backup_load_addr;
+
+	/* Core ELF header buffer */
+	unsigned long elf_headers;
+	unsigned long elf_headers_sz;
+	unsigned long elf_load_addr;
 };
+#endif /* CONFIG_X86_32 */
 
+#ifdef CONFIG_X86_64
 struct kexec_entry64_regs {
 	uint64_t rax;
 	uint64_t rbx;
@@ -189,11 +208,13 @@ extern crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss;
 
 extern int kexec_setup_initrd(struct boot_params *boot_params,
 		unsigned long initrd_load_addr, unsigned long initrd_len);
-extern int kexec_setup_cmdline(struct boot_params *boot_params,
+extern int kexec_setup_cmdline(struct kimage *image,
+		struct boot_params *boot_params,
 		unsigned long bootparams_load_addr,
 		unsigned long cmdline_offset, char *cmdline,
 		unsigned long cmdline_len);
-extern int kexec_setup_boot_parameters(struct boot_params *params);
+extern int kexec_setup_boot_parameters(struct kimage *image,
+					struct boot_params *params);
 
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index a57902e..8eabde4 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -4,6 +4,9 @@
  * Created by: Hariprasad Nellitheertha (hari@...ibm.com)
  *
  * Copyright (C) IBM Corporation, 2004. All rights reserved.
+ * Copyright (C) Red Hat Inc., 2014. All rights reserved.
+ * Authors:
+ * 	Vivek Goyal <vgoyal@...hat.com>
  *
  */
 
@@ -16,6 +19,7 @@
 #include <linux/elf.h>
 #include <linux/elfcore.h>
 #include <linux/module.h>
+#include <linux/slab.h>
 
 #include <asm/processor.h>
 #include <asm/hardirq.h>
@@ -28,6 +32,45 @@
 #include <asm/reboot.h>
 #include <asm/virtext.h>
 
+/* Alignment required for elf header segment */
+#define ELF_CORE_HEADER_ALIGN   4096
+
+/* This primarily reprsents number of split ranges due to exclusion */
+#define CRASH_MAX_RANGES	16
+
+struct crash_mem_range {
+	unsigned long long start, end;
+};
+
+struct crash_mem {
+	unsigned int nr_ranges;
+	struct crash_mem_range ranges[CRASH_MAX_RANGES];
+};
+
+/* Misc data about ram ranges needed to prepare elf headers */
+struct crash_elf_data {
+	struct kimage *image;
+	/*
+	 * Total number of ram ranges we have after various ajustments for
+	 * GART, crash reserved region etc.
+	 */
+	unsigned int max_nr_ranges;
+	unsigned long gart_start, gart_end;
+
+	/* Pointer to elf header */
+	void *ehdr;
+	/* Pointer to next phdr */
+	void *bufp;
+	struct crash_mem mem;
+};
+
+/* Used while prepareing memory map entries for second kernel */
+struct crash_memmap_data {
+	struct boot_params *params;
+	/* Type of memory */
+	unsigned int type;
+};
+
 int in_crash_kexec;
 
 /*
@@ -137,3 +180,534 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 #endif
 	crash_save_cpu(regs, safe_smp_processor_id());
 }
+
+#ifdef CONFIG_X86_64
+
+static int get_nr_ram_ranges_callback(unsigned long start_pfn,
+				unsigned long nr_pfn, void *arg)
+{
+	int *nr_ranges = arg;
+
+	(*nr_ranges)++;
+	return 0;
+}
+
+static int get_gart_ranges_callback(u64 start, u64 end, void *arg)
+{
+	struct crash_elf_data *ced = arg;
+
+	ced->gart_start = start;
+	ced->gart_end = end;
+
+	/* Not expecting more than 1 gart aperture */
+	return 1;
+}
+
+
+/* Gather all the required information to prepare elf headers for ram regions */
+static int fill_up_ced(struct crash_elf_data *ced, struct kimage *image)
+{
+	unsigned int nr_ranges = 0;
+
+	ced->image = image;
+
+	walk_system_ram_range(0, -1, &nr_ranges,
+				get_nr_ram_ranges_callback);
+
+	ced->max_nr_ranges = nr_ranges;
+
+	/*
+	 * We don't create ELF headers for GART aperture as an attempt
+	 * to dump this memory in second kernel leads to hang/crash.
+	 * If gart aperture is present, one needs to exclude that region
+	 * and that could lead to need of extra phdr.
+	 */
+
+	walk_ram_res("GART", IORESOURCE_MEM, 0, -1,
+				ced, get_gart_ranges_callback);
+
+	/*
+	 * If we have gart region, excluding that could potentially split
+	 * a memory range, resulting in extra header. Account for  that.
+	 */
+	if (ced->gart_end)
+		ced->max_nr_ranges++;
+
+	/* Exclusion of crash region could split memory ranges */
+	ced->max_nr_ranges++;
+
+	/* If crashk_low_res is there, another range split possible */
+	if (crashk_low_res.end != 0)
+		ced->max_nr_ranges++;
+
+	return 0;
+}
+
+static int exclude_mem_range(struct crash_mem *mem,
+		unsigned long long mstart, unsigned long long mend)
+{
+	int i, j;
+	unsigned long long start, end;
+	struct crash_mem_range temp_range = {0, 0};
+
+	for (i = 0; i < mem->nr_ranges; i++) {
+		start = mem->ranges[i].start;
+		end = mem->ranges[i].end;
+
+		if (mstart > end || mend < start)
+			continue;
+
+		/* Truncate any area outside of range */
+		if (mstart < start)
+			mstart = start;
+		if (mend > end)
+			mend = end;
+
+		/* Found completely overlapping range */
+		if (mstart == start && mend == end) {
+			mem->ranges[i].start = 0;
+			mem->ranges[i].end = 0;
+			if (i < mem->nr_ranges - 1) {
+				/* Shift rest of the ranges to left */
+				for(j = i; j < mem->nr_ranges - 1; j++) {
+					mem->ranges[j].start =
+						mem->ranges[j+1].start;
+					mem->ranges[j].end =
+							mem->ranges[j+1].end;
+				}
+			}
+			mem->nr_ranges--;
+			return 0;
+		}
+
+		if (mstart > start && mend < end) {
+			/* Split original range */
+			mem->ranges[i].end = mstart - 1;
+			temp_range.start = mend + 1;
+			temp_range.end = end;
+		} else if (mstart != start)
+			mem->ranges[i].end = mstart - 1;
+		else
+			mem->ranges[i].start = mend + 1;
+		break;
+	}
+
+	/* If a split happend, add the split in array */
+	if (!temp_range.end)
+		return 0;
+
+	/* Split happened */
+	if (i == CRASH_MAX_RANGES - 1) {
+		printk("Too many crash ranges after split\n");
+		return -ENOMEM;
+	}
+
+	/* Location where new range should go */
+	j = i + 1;
+	if (j < mem->nr_ranges) {
+		/* Move over all ranges one place */
+		for (i = mem->nr_ranges - 1; i >= j; i--)
+			mem->ranges[i + 1] = mem->ranges[i];
+	}
+
+	mem->ranges[j].start = temp_range.start;
+	mem->ranges[j].end = temp_range.end;
+	mem->nr_ranges++;
+	return 0;
+}
+
+/*
+ * Look for any unwanted ranges between mstart, mend and remove them. This
+ * might lead to split and split ranges are put in ced->mem.ranges[] array
+ */
+static int elf_header_exclude_ranges(struct crash_elf_data *ced,
+		unsigned long long mstart, unsigned long long mend)
+{
+	struct crash_mem *cmem = &ced->mem;
+	int ret = 0;
+
+	memset(cmem->ranges, 0, sizeof(cmem->ranges));
+
+	cmem->ranges[0].start = mstart;
+	cmem->ranges[0].end = mend;
+	cmem->nr_ranges = 1;
+
+	/* Exclude crashkernel region */
+	ret = exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
+	if (ret)
+		return ret;
+
+	ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+	if (ret)
+		return ret;
+
+	/* Exclude GART region */
+	if (ced->gart_end) {
+		ret = exclude_mem_range(cmem, ced->gart_start, ced->gart_end);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
+static int prepare_elf64_ram_headers_callback(u64 start, u64 end, void *arg)
+{
+	struct crash_elf_data *ced = arg;
+	Elf64_Ehdr *ehdr;
+	Elf64_Phdr *phdr;
+	unsigned long mstart, mend;
+	struct kimage *image = ced->image;
+	struct crash_mem *cmem;
+	int ret, i;
+
+	ehdr = ced->ehdr;
+
+	/* Exclude unwanted mem ranges */
+	ret = elf_header_exclude_ranges(ced, start, end);
+	if (ret)
+		return ret;
+
+	/* Go through all the ranges in ced->mem.ranges[] and prepare phdr */
+	cmem = &ced->mem;
+
+	for (i = 0; i < cmem->nr_ranges; i++) {
+		mstart = cmem->ranges[i].start;
+		mend = cmem->ranges[i].end;
+
+		phdr = ced->bufp;
+		ced->bufp += sizeof(Elf64_Phdr);
+
+		phdr->p_type = PT_LOAD;
+		phdr->p_flags = PF_R|PF_W|PF_X;
+		phdr->p_offset  = mstart;
+
+		/*
+		 * If a range matches backup region, adjust offset to backup
+		 * segment.
+		 */
+		if (mstart == image->arch.backup_src_start &&
+		    (mend - mstart + 1) == image->arch.backup_src_sz)
+			phdr->p_offset = image->arch.backup_load_addr;
+
+		phdr->p_paddr = mstart;
+		phdr->p_vaddr = (unsigned long long) __va(mstart);
+		phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
+		phdr->p_align = 0;
+		ehdr->e_phnum++;
+		pr_debug("Crash PT_LOAD elf header. phdr=%p"
+			" vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d"
+			" p_offset=0x%llx\n", phdr, phdr->p_vaddr,
+			phdr->p_paddr, phdr->p_filesz, ehdr->e_phnum,
+			phdr->p_offset);
+	}
+
+	return ret;
+}
+
+static int prepare_elf64_headers(struct crash_elf_data *ced,
+		unsigned long *addr, unsigned long *sz)
+{
+	Elf64_Ehdr *ehdr;
+	Elf64_Phdr *phdr;
+	unsigned long nr_cpus = NR_CPUS, nr_phdr, elf_sz;
+	unsigned char *buf, *bufp;
+	unsigned int cpu;
+	unsigned long long notes_addr;
+	int ret;
+
+	/* extra phdr for vmcoreinfo elf note */
+	nr_phdr = nr_cpus + 1;
+	nr_phdr += ced->max_nr_ranges;
+
+	/*
+	 * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
+	 * area on x86_64 (ffffffff80000000 - ffffffffa0000000).
+	 * I think this is required by tools like gdb. So same physical
+	 * memory will be mapped in two elf headers. One will contain kernel
+	 * text virtual addresses and other will have __va(physical) addresses.
+	 */
+
+	nr_phdr++;
+	elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
+	elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
+
+	buf = vzalloc(elf_sz);
+	if (!buf)
+		return -ENOMEM;
+
+	bufp = buf;
+	ehdr = (Elf64_Ehdr *)bufp;
+	bufp += sizeof(Elf64_Ehdr);
+	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
+	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
+	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
+	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
+	ehdr->e_ident[EI_OSABI] = ELF_OSABI;
+	memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
+	ehdr->e_type = ET_CORE;
+	ehdr->e_machine = ELF_ARCH;
+	ehdr->e_version = EV_CURRENT;
+	ehdr->e_entry = 0;
+	ehdr->e_phoff = sizeof(Elf64_Ehdr);
+	ehdr->e_shoff = 0;
+	ehdr->e_flags = 0;
+	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
+	ehdr->e_phentsize = sizeof(Elf64_Phdr);
+	ehdr->e_phnum = 0;
+	ehdr->e_shentsize = 0;
+	ehdr->e_shnum = 0;
+	ehdr->e_shstrndx = 0;
+
+	/* Prepare one phdr of type PT_NOTE for each present cpu */
+	for_each_present_cpu(cpu) {
+		phdr = (Elf64_Phdr *)bufp;
+		bufp += sizeof(Elf64_Phdr);
+		phdr->p_type = PT_NOTE;
+		phdr->p_flags = 0;
+		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
+		phdr->p_offset = phdr->p_paddr = notes_addr;
+		phdr->p_vaddr = 0;
+		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
+		phdr->p_align = 0;
+		(ehdr->e_phnum)++;
+	}
+
+	/* Prepare one PT_NOTE header for vmcoreinfo */
+	phdr = (Elf64_Phdr *)bufp;
+	bufp += sizeof(Elf64_Phdr);
+	phdr->p_type = PT_NOTE;
+	phdr->p_flags = 0;
+	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
+	phdr->p_vaddr = 0;
+	phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
+	phdr->p_align = 0;
+	(ehdr->e_phnum)++;
+
+#ifdef CONFIG_X86_64
+	/* Prepare PT_LOAD type program header for kernel text region */
+	phdr = (Elf64_Phdr *)bufp;
+	bufp += sizeof(Elf64_Phdr);
+	phdr->p_type = PT_LOAD;
+	phdr->p_flags = PF_R|PF_W|PF_X;
+	phdr->p_vaddr = (Elf64_Addr)_text;
+	phdr->p_filesz = phdr->p_memsz = _end - _text;
+	phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
+	phdr->p_align = 0;
+	(ehdr->e_phnum)++;
+#endif
+
+	/* Prepare PT_LOAD headers for system ram chunks. */
+	ced->ehdr = ehdr;
+	ced->bufp = bufp;
+	ret = walk_system_ram_res(0, -1, ced,
+			prepare_elf64_ram_headers_callback);
+	if (ret < 0)
+		return ret;
+
+	*addr = (unsigned long)buf;
+	*sz = elf_sz;
+	return 0;
+}
+
+/* Prepare elf headers. Return addr and size */
+static int prepare_elf_headers(struct kimage *image, unsigned long *addr,
+					unsigned long *sz)
+{
+	struct crash_elf_data *ced;
+	int ret;
+
+	ced = kzalloc(sizeof(*ced), GFP_KERNEL);
+	if (!ced)
+		return -ENOMEM;
+
+	ret = fill_up_ced(ced, image);
+	if (ret)
+		goto out;
+
+	/* By default prepare 64bit headers */
+	ret =  prepare_elf64_headers(ced, addr, sz);
+out:
+	kfree(ced);
+	return ret;
+}
+
+static int add_e820_entry(struct boot_params *params, struct e820entry *entry)
+{
+	unsigned int nr_e820_entries;
+
+	nr_e820_entries = params->e820_entries;
+	if (nr_e820_entries >= E820MAX)
+		return 1;
+
+	memcpy(&params->e820_map[nr_e820_entries], entry,
+                        sizeof(struct e820entry));
+	params->e820_entries++;
+
+	pr_debug("Add e820 entry to bootparams. addr=0x%llx size=0x%llx"
+		" type=%d\n", entry->addr, entry->size, entry->type);
+	return 0;
+}
+
+static int memmap_entry_callback(u64 start, u64 end, void *arg)
+{
+	struct crash_memmap_data *cmd = arg;
+	struct boot_params *params = cmd->params;
+	struct e820entry ei;
+
+	ei.addr = start;
+	ei.size = end - start + 1;
+	ei.type = cmd->type;
+	add_e820_entry(params, &ei);
+
+	return 0;
+}
+
+static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
+		unsigned long long mstart, unsigned long long mend)
+{
+	unsigned long start, end;
+	int ret = 0;
+
+	memset(cmem->ranges, 0, sizeof(cmem->ranges));
+
+	cmem->ranges[0].start = mstart;
+	cmem->ranges[0].end = mend;
+	cmem->nr_ranges = 1;
+
+	/* Exclude Backup region */
+	start = image->arch.backup_load_addr;
+	end = start + image->arch.backup_src_sz - 1;
+	ret = exclude_mem_range(cmem, start, end);
+	if (ret)
+		return ret;
+
+	/* Exclude elf header region */
+	start = image->arch.elf_load_addr;
+	end = start + image->arch.elf_headers_sz - 1;
+	ret = exclude_mem_range(cmem, start, end);
+	return ret;
+}
+
+/* Prepare memory map for crash dump kernel */
+int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
+{
+	int i, ret = 0;
+	unsigned long flags;
+	struct e820entry ei;
+	struct crash_memmap_data cmd;
+	struct crash_mem *cmem;
+
+	cmem = vzalloc(sizeof(struct crash_mem));
+	if (!cmem)
+		return -ENOMEM;
+
+	memset(&cmd, 0, sizeof(struct crash_memmap_data));
+	cmd.params = params;
+
+	/* Add first 640K segment */
+	ei.addr = image->arch.backup_src_start;
+	ei.size = image->arch.backup_src_sz;
+	ei.type = E820_RAM;
+	add_e820_entry(params, &ei);
+
+	/* Add ACPI tables */
+	cmd.type = E820_ACPI;
+	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+	walk_ram_res("ACPI Tables", flags, 0, -1, &cmd, memmap_entry_callback);
+
+	/* Add ACPI Non-volatile Storage */
+	cmd.type = E820_NVS;
+	walk_ram_res("ACPI Non-volatile Storage", flags, 0, -1, &cmd,
+			memmap_entry_callback);
+
+	/* Add crashk_low_res region */
+	if (crashk_low_res.end) {
+		ei.addr = crashk_low_res.start;
+		ei.size = crashk_low_res.end - crashk_low_res.start + 1;
+		ei.type = E820_RAM;
+		add_e820_entry(params, &ei);
+	}
+
+	/* Exclude some ranges from crashk_res and add rest to memmap */
+	ret = memmap_exclude_ranges(image, cmem, crashk_res.start,
+						crashk_res.end);
+	if (ret)
+		goto out;
+
+	for (i = 0; i < cmem->nr_ranges; i++) {
+		ei.addr = cmem->ranges[i].start;
+		ei.size = cmem->ranges[i].end - ei.addr + 1;
+		ei.type = E820_RAM;
+
+		/* If entry is less than a page, skip it */
+		if (ei.size < PAGE_SIZE) {
+			continue;
+		}
+		add_e820_entry(params, &ei);
+	}
+
+out:
+	vfree(cmem);
+	return ret;
+}
+
+static int determine_backup_region(u64 start, u64 end, void *arg)
+{
+	struct kimage *image = arg;
+
+	image->arch.backup_src_start = start;
+	image->arch.backup_src_sz = end - start + 1;
+
+	/* Expecting only one range for backup region */
+	return 1;
+}
+
+int load_crashdump_segments(struct kimage *image)
+{
+	unsigned long src_start, src_sz;
+	unsigned long elf_addr, elf_sz;
+	int ret;
+
+	/*
+	 * Determine and load a segment for backup area. First 640K RAM
+	 * region is backup source
+	 */
+
+	ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
+				image, determine_backup_region);
+
+	/* Zero or postive return values are ok */
+	if (ret < 0)
+		return ret;
+
+	src_start = image->arch.backup_src_start;
+	src_sz = image->arch.backup_src_sz;
+
+	/* Add backup segment. */
+	if (src_sz) {
+		ret = kexec_add_buffer(image, __va(src_start), src_sz, src_sz,
+					PAGE_SIZE, 0, -1, 0,
+					&image->arch.backup_load_addr);
+		if (ret)
+			return ret;
+	}
+
+	/* Prepare elf headers and add a segment */
+	ret = prepare_elf_headers(image, &elf_addr, &elf_sz);
+	if (ret)
+		return ret;
+
+	image->arch.elf_headers = elf_addr;
+	image->arch.elf_headers_sz = elf_sz;
+
+	ret = kexec_add_buffer(image, (char *)elf_addr, elf_sz, elf_sz,
+			ELF_CORE_HEADER_ALIGN, 0, -1, 0,
+			&image->arch.elf_load_addr);
+	if (ret)
+		kfree((void *)image->arch.elf_headers);
+
+	return ret;
+}
+
+#endif /* CONFIG_X86_64 */
diff --git a/arch/x86/kernel/kexec-bzimage.c b/arch/x86/kernel/kexec-bzimage.c
index cbfcd00..f66188d 100644
--- a/arch/x86/kernel/kexec-bzimage.c
+++ b/arch/x86/kernel/kexec-bzimage.c
@@ -8,6 +8,9 @@
 
 #include <asm/bootparam.h>
 #include <asm/setup.h>
+#include <asm/crash.h>
+
+#define MAX_ELFCOREHDR_STR_LEN	30 	/* elfcorehdr=0x<64bit-value> */
 
 #ifdef CONFIG_X86_64
 
@@ -100,11 +103,28 @@ void *bzImage64_load(struct kimage *image, char *kernel,
 		return ERR_PTR(-EINVAL);
 	}
 
+	/*
+	 * In case of crash dump, we will append elfcorehdr=<addr> to
+	 * command line. Make sure it does not overflow
+	 */
+	if (cmdline_len + MAX_ELFCOREHDR_STR_LEN > header->cmdline_size) {
+		ret = -EINVAL;
+		pr_debug("Kernel command line too long\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	/* Allocate loader specific data */
 	ldata = kzalloc(sizeof(struct bzimage64_data), GFP_KERNEL);
 	if (!ldata)
 		return ERR_PTR(-ENOMEM);
 
+	/* Allocate and load backup region */
+	if (image->type == KEXEC_TYPE_CRASH) {
+		ret = load_crashdump_segments(image);
+		if (ret)
+			goto out_free_loader_data;
+	}
+
 	/*
 	 * Load purgatory. For 64bit entry point, purgatory  code can be
 	 * anywhere.
@@ -118,7 +138,8 @@ void *bzImage64_load(struct kimage *image, char *kernel,
 	pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
 
 	/* Load Bootparams and cmdline */
-	params_cmdline_sz = sizeof(struct boot_params) + cmdline_len;
+	params_cmdline_sz = sizeof(struct boot_params) + cmdline_len +
+				MAX_ELFCOREHDR_STR_LEN;
 	params = kzalloc(params_cmdline_sz, GFP_KERNEL);
 	if (!params) {
 		ret = -ENOMEM;
@@ -167,7 +188,7 @@ void *bzImage64_load(struct kimage *image, char *kernel,
 			goto out_free_params;
 	}
 
-	ret = kexec_setup_cmdline(params, bootparam_load_addr,
+	ret = kexec_setup_cmdline(image, params, bootparam_load_addr,
 			sizeof(struct boot_params), cmdline, cmdline_len);
 	if (ret)
 		goto out_free_params;
@@ -198,7 +219,7 @@ void *bzImage64_load(struct kimage *image, char *kernel,
 	if (ret)
 		goto out_free_params;
 
-	ret = kexec_setup_boot_parameters(params);
+	ret = kexec_setup_boot_parameters(image, params);
 	if (ret)
 		goto out_free_params;
 
diff --git a/arch/x86/kernel/kexec-elf.c b/arch/x86/kernel/kexec-elf.c
index ff1017c..e7ce2d0 100644
--- a/arch/x86/kernel/kexec-elf.c
+++ b/arch/x86/kernel/kexec-elf.c
@@ -164,7 +164,7 @@ void *elf_x86_64_load(struct kimage *image, char *kernel,
 			goto out_free_params;
 	}
 
-	ret = kexec_setup_cmdline(params, bootparam_load_addr,
+	ret = kexec_setup_cmdline(image, params, bootparam_load_addr,
 			sizeof(struct boot_params), cmdline, cmdline_len);
 	if (ret)
 		goto out_free_params;
@@ -195,7 +195,7 @@ void *elf_x86_64_load(struct kimage *image, char *kernel,
 	if (ret)
 		goto out_free_params;
 
-	ret = kexec_setup_boot_parameters(params);
+	ret = kexec_setup_boot_parameters(image, params);
 	if (ret)
 		goto out_free_params;
 
diff --git a/arch/x86/kernel/machine_kexec.c b/arch/x86/kernel/machine_kexec.c
index ac55890..26d474b 100644
--- a/arch/x86/kernel/machine_kexec.c
+++ b/arch/x86/kernel/machine_kexec.c
@@ -10,9 +10,11 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/kexec.h>
 #include <linux/string.h>
 #include <asm/bootparam.h>
 #include <asm/setup.h>
+#include <asm/crash.h>
 
 /*
  * Common code for x86 and x86_64 used for kexec.
@@ -36,18 +38,24 @@ int kexec_setup_initrd(struct boot_params *boot_params,
 	return 0;
 }
 
-int kexec_setup_cmdline(struct boot_params *boot_params,
+int kexec_setup_cmdline(struct kimage *image, struct boot_params *boot_params,
 		unsigned long bootparams_load_addr,
 		unsigned long cmdline_offset, char *cmdline,
 		unsigned long cmdline_len)
 {
 	char *cmdline_ptr = ((char *)boot_params) + cmdline_offset;
-	unsigned long cmdline_ptr_phys;
+	unsigned long cmdline_ptr_phys, len;
 	uint32_t cmdline_low_32, cmdline_ext_32;
 
 	memcpy(cmdline_ptr, cmdline, cmdline_len);
+	if (image->type == KEXEC_TYPE_CRASH) {
+		len = sprintf(cmdline_ptr + cmdline_len - 1,
+			" elfcorehdr=0x%lx", image->arch.elf_load_addr);
+		cmdline_len += len;
+	}
 	cmdline_ptr[cmdline_len - 1] = '\0';
 
+	pr_debug("Final command line is:%s\n", cmdline_ptr);
 	cmdline_ptr_phys = bootparams_load_addr + cmdline_offset;
 	cmdline_low_32 = cmdline_ptr_phys & 0xffffffffUL;
 	cmdline_ext_32 = cmdline_ptr_phys >> 32;
@@ -75,7 +83,8 @@ static int setup_memory_map_entries(struct boot_params *params)
 	return 0;
 }
 
-int kexec_setup_boot_parameters(struct boot_params *params)
+int kexec_setup_boot_parameters(struct kimage *image,
+				struct boot_params *params)
 {
 	unsigned int nr_e820_entries;
 	unsigned long long mem_k, start, end;
@@ -102,7 +111,11 @@ int kexec_setup_boot_parameters(struct boot_params *params)
 	/* Default sysdesc table */
 	params->sys_desc_table.length = 0;
 
-	setup_memory_map_entries(params);
+	if (image->type == KEXEC_TYPE_CRASH)
+		crash_setup_memmap_entries(image, params);
+	else
+		setup_memory_map_entries(params);
+
 	nr_e820_entries = params->e820_entries;
 
 	for(i = 0; i < nr_e820_entries; i++) {
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index e35bcaf..e852a51 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -181,6 +181,38 @@ static void load_segments(void)
 		);
 }
 
+/* Update purgatory as needed after various image segments have been prepared */
+static int arch_update_purgatory(struct kimage *image)
+{
+	int ret = 0;
+
+	if (!image->file_mode)
+		return 0;
+
+	/* Setup copying of backup region */
+	if (image->type == KEXEC_TYPE_CRASH) {
+		ret = kexec_purgatory_get_set_symbol(image, "backup_dest",
+				&image->arch.backup_load_addr,
+				sizeof(image->arch.backup_load_addr), 0);
+		if (ret)
+			return ret;
+
+		ret = kexec_purgatory_get_set_symbol(image, "backup_src",
+				&image->arch.backup_src_start,
+				sizeof(image->arch.backup_src_start), 0);
+		if (ret)
+			return ret;
+
+		ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
+				&image->arch.backup_src_sz,
+				sizeof(image->arch.backup_src_sz), 0);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
 int machine_kexec_prepare(struct kimage *image)
 {
 	unsigned long start_pgtable;
@@ -194,6 +226,11 @@ int machine_kexec_prepare(struct kimage *image)
 	if (result)
 		return result;
 
+	/* update purgatory as needed */
+	result = arch_update_purgatory(image);
+	if (result)
+		return result;
+
 	return 0;
 }
 
@@ -330,6 +367,7 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
 {
 	int idx = image->file_handler_idx;
 
+	vfree((void *)image->arch.elf_headers);
 	if (kexec_file_type[idx].cleanup)
 		return kexec_file_type[idx].cleanup(image);
 	return 0;
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 9e4718b..3ea1d41 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -548,7 +548,6 @@ static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry,
 	*rimage = image;
 	return 0;
 
-
 out_free_control_pages:
 	kimage_free_page_list(&image->control_pages);
 out_free_image:
@@ -556,6 +555,54 @@ out_free_image:
 	return result;
 }
 
+static int kimage_file_crash_alloc(struct kimage **rimage, int kernel_fd,
+		int initrd_fd, const char __user *cmdline_ptr,
+		unsigned long cmdline_len)
+{
+	int result;
+	struct kimage *image;
+
+	/* Allocate and initialize a controlling structure */
+	image = do_kimage_alloc_init();
+	if (!image)
+		return -ENOMEM;
+
+	image->file_mode = 1;
+	image->file_handler_idx = -1;
+
+	/* Enable the special crash kernel control page allocation policy. */
+	image->control_page = crashk_res.start;
+	image->type = KEXEC_TYPE_CRASH;
+
+	result = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
+			cmdline_ptr, cmdline_len);
+	if (result)
+		goto out_free_image;
+
+	result = sanity_check_segment_list(image);
+	if (result)
+		goto out_free_post_load_bufs;
+
+	result = -ENOMEM;
+	image->control_code_page = kimage_alloc_control_pages(image,
+					   get_order(KEXEC_CONTROL_PAGE_SIZE));
+	if (!image->control_code_page) {
+		printk(KERN_ERR "Could not allocate control_code_buffer\n");
+		goto out_free_post_load_bufs;
+	}
+
+	*rimage = image;
+	return 0;
+
+out_free_post_load_bufs:
+	kimage_file_post_load_cleanup(image);
+	kfree(image->image_loader_data);
+out_free_image:
+	kfree(image);
+	return result;
+}
+
+
 static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
 				unsigned long nr_segments,
 				struct kexec_segment __user *segments)
@@ -1137,10 +1184,15 @@ static int kimage_load_crash_segment(struct kimage *image,
 	unsigned long maddr;
 	size_t ubytes, mbytes;
 	int result;
-	unsigned char __user *buf;
+	unsigned char __user *buf = NULL;
+	unsigned char *kbuf = NULL;
 
 	result = 0;
-	buf = segment->buf;
+	if (image->file_mode)
+		kbuf = segment->kbuf;
+	else
+		buf = segment->buf;
+
 	ubytes = segment->bufsz;
 	mbytes = segment->memsz;
 	maddr = segment->mem;
@@ -1163,7 +1215,12 @@ static int kimage_load_crash_segment(struct kimage *image,
 			/* Zero the trailing part of the page */
 			memset(ptr + uchunk, 0, mchunk - uchunk);
 		}
-		result = copy_from_user(ptr, buf, uchunk);
+
+		/* For file based kexec, source pages are in kernel memory */
+		if (image->file_mode)
+			memcpy(ptr, kbuf, uchunk);
+		else
+			result = copy_from_user(ptr, buf, uchunk);
 		kexec_flush_icache_page(page);
 		kunmap(page);
 		if (result) {
@@ -1172,7 +1229,10 @@ static int kimage_load_crash_segment(struct kimage *image,
 		}
 		ubytes -= uchunk;
 		maddr  += mchunk;
-		buf    += mchunk;
+		if (image->file_mode)
+			kbuf += mchunk;
+		else
+			buf += mchunk;
 		mbytes -= mchunk;
 	}
 out:
@@ -1392,7 +1452,11 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, const char __us
 	if (flags & KEXEC_FILE_UNLOAD)
 		goto exchange;
 
-	ret = kimage_file_normal_alloc(&image, kernel_fd, initrd_fd,
+	if (flags & KEXEC_FILE_ON_CRASH)
+		ret = kimage_file_crash_alloc(&image, kernel_fd, initrd_fd,
+				cmdline_ptr, cmdline_len);
+	else
+		ret = kimage_file_normal_alloc(&image, kernel_fd, initrd_fd,
 				cmdline_ptr, cmdline_len);
 	if (ret)
 		goto out;
@@ -2211,7 +2275,12 @@ int kexec_add_buffer(struct kimage *image, char *buffer,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	walk_system_ram_res(0, -1, kbuf, walk_ram_range_callback);
+	if (image->type == KEXEC_TYPE_CRASH)
+		walk_ram_res("Crash kernel", IORESOURCE_MEM | IORESOURCE_BUSY,
+				crashk_res.start, crashk_res.end, kbuf,
+				walk_ram_range_callback);
+	else
+		walk_system_ram_res(0, -1, kbuf, walk_ram_range_callback);
 
 	kbuf->image = NULL;
 	kfree(kbuf);
-- 
1.8.4.2

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