[PATCH 5/6] kexec-bzImage: Support for loading bzImage using 64bit entry

[Vivek Goyal <vgoyal@redhat.com>]

This is loader specific code which can load bzImage and set it up for
64bit entry. This does not take care of 32bit entry or real mode entry
yet.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 arch/x86/include/asm/kexec-bzimage.h |   12 +
 arch/x86/include/asm/kexec.h         |   26 +++
 arch/x86/kernel/Makefile             |    2 +
 arch/x86/kernel/kexec-bzimage.c      |  375 ++++++++++++++++++++++++++++++++++
 arch/x86/kernel/machine_kexec_64.c   |    4 +-
 arch/x86/kernel/purgatory_entry_64.S |  119 +++++++++++
 6 files changed, 537 insertions(+), 1 deletions(-)
 create mode 100644 arch/x86/include/asm/kexec-bzimage.h
 create mode 100644 arch/x86/kernel/kexec-bzimage.c
 create mode 100644 arch/x86/kernel/purgatory_entry_64.S

diff --git a/arch/x86/include/asm/kexec-bzimage.h b/arch/x86/include/asm/kexec-bzimage.h
new file mode 100644
index 0000000..d556727
--- /dev/null
+++ b/arch/x86/include/asm/kexec-bzimage.h
@@ -0,0 +1,12 @@
+#ifndef _ASM_BZIMAGE_H
+#define _ASM_BZIMAGE_H
+
+extern int bzImage64_probe(const char *buf, unsigned long len);
+extern void *bzImage64_load(struct kimage *image, char *kernel,
+		unsigned long kernel_len, char *initrd,
+		unsigned long initrd_len, char *cmdline,
+		unsigned long cmdline_len);
+extern int bzImage64_prep_entry(struct kimage *image);
+extern int bzImage64_cleanup(struct kimage *image);
+
+#endif  /* _ASM_BZIMAGE_H */
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 17483a4..94f1257 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -15,6 +15,9 @@
 # define PAGES_NR		4
 #endif
 
+#define KEXEC_PURGATORY_PAGE_SIZE	4096
+#define KEXEC_PURGATORY_CODE_MAX_SIZE	2048
+
 # define KEXEC_CONTROL_CODE_MAX_SIZE	2048
 
 #ifndef __ASSEMBLY__
@@ -141,6 +144,9 @@ relocate_kernel(unsigned long indirection_page,
 		unsigned long page_list,
 		unsigned long start_address,
 		unsigned int preserve_context);
+void purgatory_entry64(void);
+extern unsigned long purgatory_entry64_regs;
+extern struct desc_struct entry64_gdt;
 #endif
 
 #define ARCH_HAS_KIMAGE_ARCH
@@ -161,6 +167,26 @@ struct kimage_arch {
 	pmd_t *pmd;
 	pte_t *pte;
 };
+
+struct kexec_entry64_regs {
+	uint64_t rax;
+	uint64_t rbx;
+	uint64_t rcx;
+	uint64_t rdx;
+	uint64_t rsi;
+	uint64_t rdi;
+	uint64_t rsp;
+	uint64_t rbp;
+	uint64_t r8;
+	uint64_t r9;
+	uint64_t r10;
+	uint64_t r11;
+	uint64_t r12;
+	uint64_t r13;
+	uint64_t r14;
+	uint64_t r15;
+	uint64_t rip;
+};
 #endif
 
 typedef void crash_vmclear_fn(void);
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 9b0a34e..5d074c2 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o
 obj-$(CONFIG_X86_TSC)		+= trace_clock.o
 obj-$(CONFIG_KEXEC)		+= machine_kexec_$(BITS).o
 obj-$(CONFIG_KEXEC)		+= relocate_kernel_$(BITS).o crash.o
+obj-$(CONFIG_KEXEC)		+= kexec-bzimage.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump_$(BITS).o
 obj-y				+= kprobes/
 obj-$(CONFIG_MODULES)		+= module.o
@@ -122,4 +123,5 @@ ifeq ($(CONFIG_X86_64),y)
 
 	obj-$(CONFIG_PCI_MMCONFIG)	+= mmconf-fam10h_64.o
 	obj-y				+= vsmp_64.o
+	obj-$(CONFIG_KEXEC)		+= purgatory_entry_64.o
 endif
diff --git a/arch/x86/kernel/kexec-bzimage.c b/arch/x86/kernel/kexec-bzimage.c
new file mode 100644
index 0000000..a1032d4
--- /dev/null
+++ b/arch/x86/kernel/kexec-bzimage.c
@@ -0,0 +1,375 @@
+#include <linux/string.h>
+#include <linux/printk.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/kexec.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+
+#include <asm/bootparam.h>
+#include <asm/setup.h>
+
+#ifdef CONFIG_X86_64
+
+struct bzimage64_data {
+	unsigned long kernel_load_addr;
+	unsigned long bootparams_load_addr;
+
+	/*
+	 * Temporary buffer to hold bootparams buffer. This should be
+	 * freed once the bootparam segment has been loaded.
+	 */
+	void *bootparams_buf;
+	struct page *purgatory_page;
+};
+
+int bzImage64_probe(const char *buf, unsigned long len)
+{
+	int ret = -ENOEXEC;
+	struct setup_header *header;
+
+	if (len < 2 * 512) {
+		pr_debug("File is too short to be a bzImage\n");
+		return ret;
+	}
+
+	header = (struct setup_header *)(buf + 0x1F1);
+	if (memcmp((char *)&header->header, "HdrS", 4) != 0) {
+		pr_debug("Not a bzImage\n");
+		return ret;
+	}
+
+	if (header->boot_flag != 0xAA55) {
+                /* No x86 boot sector present */
+		pr_debug("No x86 boot sector present\n");
+		return ret;
+	}
+
+	if (header->version < 0x020C) {
+                /* Must be at least protocol version 2.12 */
+		pr_debug("Must be at least protocol version 2.12\n");
+		return ret;
+	}
+
+	if ((header->loadflags & 1) == 0) {
+		/* Not a bzImage */
+		pr_debug("zImage not a bzImage\n");
+		return ret;
+	}
+
+	if ((header->xloadflags & 3) != 3) {
+		/* XLF_KERNEL_64 and XLF_CAN_BE_LOADED_ABOVE_4G should be set */
+		pr_debug("Not a relocatable bzImage64\n");
+		return ret;
+	}
+
+        /* I've got a bzImage */
+	pr_debug("It's a relocatable bzImage64\n");
+	ret = 0;
+
+	return ret;
+}
+
+static int setup_memory_map_entries(struct boot_params *params)
+{
+	unsigned int nr_e820_entries;
+
+	/* TODO: What about EFI */
+	nr_e820_entries = e820_saved.nr_map;
+	if (nr_e820_entries > E820MAX)
+		nr_e820_entries = E820MAX;
+
+	params->e820_entries = nr_e820_entries;
+	memcpy(&params->e820_map, &e820_saved.map,
+			nr_e820_entries * sizeof(struct e820entry));
+
+	return 0;
+}
+
+static void setup_linux_system_parameters(struct boot_params *params)
+{
+	unsigned int nr_e820_entries;
+	unsigned long long mem_k, start, end;
+	int i;
+
+	/* Get subarch from existing bootparams */
+	params->hdr.hardware_subarch = boot_params.hdr.hardware_subarch;
+
+	/* Copying screen_info will do? */
+	memcpy(&params->screen_info, &boot_params.screen_info,
+				sizeof(struct screen_info));
+
+	/* Fill in memsize later */
+	params->screen_info.ext_mem_k = 0;
+	params->alt_mem_k = 0;
+
+	/* Default APM info */
+	memset(&params->apm_bios_info, 0, sizeof(params->apm_bios_info));
+
+	/* Default drive info */
+	memset(&params->hd0_info, 0, sizeof(params->hd0_info));
+	memset(&params->hd1_info, 0, sizeof(params->hd1_info));
+
+	/* Default sysdesc table */
+	params->sys_desc_table.length = 0;
+
+	setup_memory_map_entries(params);
+	nr_e820_entries = params->e820_entries;
+
+	for(i = 0; i < nr_e820_entries; i++) {
+		if (params->e820_map[i].type != E820_RAM)
+			continue;
+		start = params->e820_map[i].addr;
+		end = params->e820_map[i].addr + params->e820_map[i].size - 1;
+
+		if ((start <= 0x100000) && end > 0x100000) {
+			mem_k = (end >> 10) - (0x100000 >> 10);
+			params->screen_info.ext_mem_k = mem_k;
+			params->alt_mem_k = mem_k;
+			if (mem_k > 0xfc00)
+				params->screen_info.ext_mem_k = 0xfc00; /* 64M*/
+			if (mem_k > 0xffffffff)
+				params->alt_mem_k = 0xffffffff;
+		}
+	}
+
+	/* Setup EDD info */
+	memcpy(params->eddbuf, boot_params.eddbuf,
+				EDDMAXNR * sizeof(struct edd_info));
+	params->eddbuf_entries = boot_params.eddbuf_entries;
+
+	memcpy(params->edd_mbr_sig_buffer, boot_params.edd_mbr_sig_buffer,
+			EDD_MBR_SIG_MAX * sizeof(unsigned int));
+}
+
+static void setup_initrd(struct boot_params *boot_params, unsigned long initrd_load_addr, unsigned long initrd_len)
+{
+	boot_params->hdr.ramdisk_image = initrd_load_addr & 0xffffffffUL;
+	boot_params->hdr.ramdisk_size = initrd_len & 0xffffffffUL;
+
+	boot_params->ext_ramdisk_image = initrd_load_addr >> 32;
+	boot_params->ext_ramdisk_size = initrd_len >> 32;
+}
+
+static void setup_cmdline(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;
+	uint32_t cmdline_low_32, cmdline_ext_32;
+
+	memcpy(cmdline_ptr, cmdline, cmdline_len);
+	cmdline_ptr[cmdline_len - 1] = '\0';
+
+	cmdline_ptr_phys = bootparams_load_addr + cmdline_offset;
+	cmdline_low_32 = cmdline_ptr_phys & 0xffffffffUL;
+	cmdline_ext_32 = cmdline_ptr_phys >> 32;
+
+	boot_params->hdr.cmd_line_ptr = cmdline_low_32;
+	if (cmdline_ext_32)
+		boot_params->ext_cmd_line_ptr = cmdline_ext_32;
+}
+
+void *bzImage64_load(struct kimage *image, char *kernel,
+		unsigned long kernel_len,
+		char *initrd, unsigned long initrd_len,
+		char *cmdline, unsigned long cmdline_len)
+{
+
+	struct setup_header *header;
+	int setup_sects, kern16_size_needed, kern16_size, ret = 0;
+	unsigned long setup_size, setup_header_size;
+	struct boot_params *params;
+	unsigned long bootparam_load_addr, kernel_load_addr, initrd_load_addr;
+	unsigned long kernel_bufsz, kernel_memsz, kernel_align;
+	char *kernel_buf;
+	struct bzimage64_data *ldata;
+
+	header = (struct setup_header *)(kernel + 0x1F1);
+	setup_sects = header->setup_sects;
+	if (setup_sects == 0)
+		setup_sects = 4;
+
+	kern16_size = (setup_sects + 1) * 512;
+	if (kernel_len < kern16_size) {
+		pr_debug("bzImage truncated\n");
+		return ERR_PTR(-ENOEXEC);
+	}
+
+	if (cmdline_len > header->cmdline_size) {
+		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);
+
+	/* Argument/parameter segment */
+	kern16_size_needed = kern16_size;
+	if (kern16_size_needed < 4096)
+		kern16_size_needed = 4096;
+
+	setup_size = kern16_size_needed + cmdline_len;
+	params = kzalloc(setup_size, GFP_KERNEL);
+	if (!params) {
+		ret = -ENOMEM;
+		goto out_free_loader_data;
+	}
+
+	/* Copy setup header onto bootparams. */
+	setup_header_size = 0x0202 + kernel[0x0201] - 0x1F1;
+
+	/* Is there a limit on setup header size? */
+	memcpy(&params->hdr, (kernel + 0x1F1), setup_header_size);
+	ret = kexec_add_buffer(image, (char *)params, setup_size,
+			setup_size, 16, 0x3000, -1, 1, &bootparam_load_addr);
+	if (ret)
+		goto out_free_params;
+	pr_debug("Loaded boot_param and command line at 0x%lx\n",
+			bootparam_load_addr);
+
+	/* Load kernel */
+	kernel_buf = kernel + kern16_size;
+	kernel_bufsz =  kernel_len - kern16_size;
+	kernel_memsz = ALIGN(header->init_size, 4096);
+	kernel_align = header->kernel_alignment;
+
+	ret = kexec_add_buffer(image, kernel_buf,
+			kernel_bufsz, kernel_memsz, kernel_align, 0x100000,
+			-1, 1, &kernel_load_addr);
+	if (ret)
+		goto out_free_params;
+
+	pr_debug("Loaded 64bit kernel at 0x%lx sz = 0x%lx\n", kernel_load_addr,
+				kernel_memsz);
+
+	/* Load initrd high */
+	if (initrd) {
+		ret = kexec_add_buffer(image, initrd, initrd_len, initrd_len,
+			4096, 0x10000000, ULONG_MAX, 1, &initrd_load_addr);
+		if (ret)
+			goto out_free_params;
+
+		pr_debug("Loaded initrd at 0x%lx sz = 0x%lx\n",
+					initrd_load_addr, initrd_len);
+		setup_initrd(params, initrd_load_addr, initrd_len);
+	}
+
+	setup_cmdline(params, bootparam_load_addr, kern16_size_needed,
+			cmdline, cmdline_len);
+
+	/* bootloader info. Do we need a separate ID for kexec kernel loader? */
+	params->hdr.type_of_loader = 0x0D << 4;
+	params->hdr.loadflags = 0;
+
+	setup_linux_system_parameters(params);
+
+	/*
+	 * Allocate a purgatory page. For 64bit entry point, purgatory
+	 * code can be anywhere.
+	 *
+	 * Control page allocation logic goes through segment list to
+	 * make sure allocated page is not destination page. So allocate
+	 * control page after all required segment have been prepared.
+	 */
+	ldata->purgatory_page = kimage_alloc_control_pages(image,
+					get_order(KEXEC_PURGATORY_PAGE_SIZE));
+
+	if (!ldata->purgatory_page) {
+		printk(KERN_ERR "Could not allocate purgatory page\n");
+		ret = -ENOMEM;
+		goto out_free_params;
+	}
+
+	/*
+	 * Store pointer to params so that it could be freed after loading
+	 * params segment has been loaded and contents have been copied
+	 * somewhere else.
+	 */
+	ldata->bootparams_buf = params;
+	ldata->kernel_load_addr = kernel_load_addr;
+	ldata->bootparams_load_addr = bootparam_load_addr;
+	return ldata;
+
+out_free_params:
+	kfree(params);
+out_free_loader_data:
+	kfree(ldata);
+	return ERR_PTR(ret);
+}
+
+int bzImage64_prep_entry(struct kimage *image)
+{
+	struct bzimage64_data *ldata;
+	char *purgatory_page;
+	unsigned long regs_offset, gdt_offset, purgatory_page_phys;
+	struct kexec_entry64_regs *regs;
+	char *gdt_ptr;
+	unsigned long long *gdt_addr;
+
+	if (!image->file_mode)
+		return 0;
+
+	ldata = image->image_loader_data;
+	if (!ldata)
+		return -EINVAL;
+
+	/* Copy purgatory code to its control page */
+	purgatory_page = page_address(ldata->purgatory_page);
+
+	/* Physical address of purgatory page */
+	purgatory_page_phys = PFN_PHYS(page_to_pfn(ldata->purgatory_page));
+
+	memcpy(purgatory_page, purgatory_entry64,
+			KEXEC_PURGATORY_CODE_MAX_SIZE);
+
+	/* Set registers appropriately */
+	regs_offset =  (unsigned long)&purgatory_entry64_regs -
+			(unsigned long)purgatory_entry64;
+	regs = (struct kexec_entry64_regs *) (purgatory_page + regs_offset);
+
+	regs->rbx = 0; /* Bootstrap Processor */
+	regs->rsi = ldata->bootparams_load_addr;
+	regs->rip = ldata->kernel_load_addr + 0x200;
+
+	/* Fix up gdt */
+	gdt_offset = (unsigned long)&entry64_gdt -
+			(unsigned long)purgatory_entry64;
+
+	gdt_ptr = purgatory_page + gdt_offset;
+
+	/* Skip a word which contains size of gdt table */
+	gdt_addr = (unsigned long long *)(gdt_ptr + 2);
+
+	*gdt_addr = (unsigned long long)gdt_ptr;
+
+	/*
+	 * Update the relocated address of gdt. By the time we load gdt
+	 * in purgatory, we are running using identity mapped tables.
+	 * Load identity mapped address here.
+	 */
+	*gdt_addr = (unsigned long long)(purgatory_page_phys + gdt_offset);
+
+	/*
+	 * Jump to purgatory after control page. By the time we jump to
+	 * purgatory, we are using itentifiy mapped page tables
+	 */
+	kimage_set_start_addr(image, purgatory_page_phys);
+	return 0;
+}
+
+/* This cleanup function is called after various segments have been loaded */
+int bzImage64_cleanup(struct kimage *image)
+{
+	struct bzimage64_data *ldata = image->image_loader_data;
+
+	kfree(ldata->bootparams_buf);
+	ldata->bootparams_buf = NULL;
+	return 0;
+}
+
+#endif /* CONFIG_X86_64 */
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index fb41b73..a66ce1d 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -21,10 +21,12 @@
 #include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
 #include <asm/debugreg.h>
+#include <asm/kexec-bzimage.h>
 
 /* arch dependent functionality related to kexec file based syscall */
 static struct kexec_file_type kexec_file_type[]={
-	{"", NULL, NULL, NULL, NULL},
+	{"bzImage64", bzImage64_probe, bzImage64_load, bzImage64_prep_entry,
+	 bzImage64_cleanup},
 };
 
 static int nr_file_types = sizeof(kexec_file_type)/sizeof(kexec_file_type[0]);
diff --git a/arch/x86/kernel/purgatory_entry_64.S b/arch/x86/kernel/purgatory_entry_64.S
new file mode 100644
index 0000000..12a235f
--- /dev/null
+++ b/arch/x86/kernel/purgatory_entry_64.S
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2013  Red Hat Inc.
+ *
+ * Author(s): Vivek Goyal <vgoyal@redhat.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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+/*
+ * One page for purgatory. Code occupies first KEXEC_PURGATORY_CODE_MAX_SIZE
+ * bytes. Rest is for data/stack etc.
+ */
+#include <asm/page.h>
+
+	.text
+	.align PAGE_SIZE
+	.code64
+	.globl purgatory_entry64, purgatory_entry64_regs, entry64_gdt
+
+
+purgatory_entry64:
+	/* Setup a gdt that should be preserved */
+	lgdt entry64_gdt(%rip)
+
+	/* load the data segments */
+	movl    $0x18, %eax     /* data segment */
+	movl    %eax, %ds
+	movl    %eax, %es
+	movl    %eax, %ss
+	movl    %eax, %fs
+	movl    %eax, %gs
+
+	/* Setup new stack */
+	leaq    stack_init(%rip), %rsp
+	pushq   $0x10 /* CS */
+	leaq    new_cs_exit(%rip), %rax
+	pushq   %rax
+	lretq
+new_cs_exit:
+
+	/*
+	 * Load the registers except rsp. rsp is already loaded with stack
+	 * at the end of this page
+	 */
+	movq	rax(%rip), %rax
+	movq	rbx(%rip), %rbx
+	movq	rcx(%rip), %rcx
+	movq	rdx(%rip), %rdx
+	movq	rsi(%rip), %rsi
+	movq	rdi(%rip), %rdi
+	movq	rbp(%rip), %rbp
+	movq	r8(%rip), %r8
+	movq	r9(%rip), %r9
+	movq	r10(%rip), %r10
+	movq	r11(%rip), %r11
+	movq	r12(%rip), %r12
+	movq	r13(%rip), %r13
+	movq	r14(%rip), %r14
+	movq	r15(%rip), %r15
+
+	/* Jump to the new code... */
+	jmpq	*rip(%rip)
+
+	.balign 16
+purgatory_entry64_regs:
+rax:	.quad 0x00000000
+rbx:	.quad 0x00000000
+rcx:	.quad 0x00000000
+rdx:	.quad 0x00000000
+rsi:	.quad 0x00000000
+rdi:	.quad 0x00000000
+rsp:	.quad 0x00000000
+rbp:	.quad 0x00000000
+r8:	.quad 0x00000000
+r9:	.quad 0x00000000
+r10:	.quad 0x00000000
+r11:	.quad 0x00000000
+r12:	.quad 0x00000000
+r13:	.quad 0x00000000
+r14:	.quad 0x00000000
+r15:	.quad 0x00000000
+rip:	.quad 0x00000000
+
+	/* GDT */
+	.balign 16
+entry64_gdt:
+	/* 0x00 unusable segment
+	 * 0x08 unused
+	 * so use them as gdt ptr
+	 */
+	.word gdt_end - entry64_gdt - 1
+	.quad entry64_gdt
+	.word 0, 0, 0
+
+	/* 0x10 4GB flat code segment */
+	.word 0xFFFF, 0x0000, 0x9A00, 0x00AF
+
+	/* 0x18 4GB flat data segment */
+	.word 0xFFFF, 0x0000, 0x9200, 0x00CF
+gdt_end:
+
+	.globl kexec_purgatory_code_size
+.set kexec_purgatory_code_size, . - purgatory_entry64
+
+/* Fill rest of the page with zeros to be used as stack */
+stack: .fill purgatory_entry64 + PAGE_SIZE - ., 1, 0
+stack_init:
-- 
1.7.7.6


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