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

From: Vivek Goyal
Date: Wed Nov 20 2013 - 12:52:27 EST

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@xxxxxxxxxx>
---
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@xxxxxxxxxx>
+ *
+ * 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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