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[Xen-devel] [PATCH v2 06/11] x86/xen: Add i386 kexec/kdump implementation



Add i386 kexec/kdump implementation.

v2 - suggestions/fixes:
   - allocate transition page table pages below 4 GiB
     (suggested by Jan Beulich).

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
 arch/x86/xen/machine_kexec_32.c   |  247 ++++++++++++++++++++++++++++
 arch/x86/xen/relocate_kernel_32.S |  323 +++++++++++++++++++++++++++++++++++++
 2 files changed, 570 insertions(+), 0 deletions(-)
 create mode 100644 arch/x86/xen/machine_kexec_32.c
 create mode 100644 arch/x86/xen/relocate_kernel_32.S

diff --git a/arch/x86/xen/machine_kexec_32.c b/arch/x86/xen/machine_kexec_32.c
new file mode 100644
index 0000000..116c302
--- /dev/null
+++ b/arch/x86/xen/machine_kexec_32.c
@@ -0,0 +1,247 @@
+/*
+ * Copyright (c) 2011 Daniel Kiper
+ * Copyright (c) 2012 Daniel Kiper, Oracle Corporation
+ *
+ * kexec/kdump implementation for Xen was written by Daniel Kiper.
+ * Initial work on it was sponsored by Google under Google Summer
+ * of Code 2011 program and Citrix. Konrad Rzeszutek Wilk from Oracle
+ * was the mentor for this project.
+ *
+ * Some ideas are taken from:
+ *   - native kexec/kdump implementation,
+ *   - kexec/kdump implementation for Xen Linux Kernel Ver. 2.6.18,
+ *   - PV-GRUB.
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/kexec.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+
+#include <xen/xen.h>
+#include <xen/xen-ops.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/kexec.h>
+#include <asm/xen/page.h>
+
+#define __ma(vaddr)    (virt_to_machine(vaddr).maddr)
+
+static struct page *kimage_alloc_pages(gfp_t gfp_mask,
+                                       unsigned int order,
+                                       unsigned long limit)
+{
+       struct page *pages;
+       unsigned int address_bits, i;
+
+       pages = alloc_pages(gfp_mask, order);
+
+       if (!pages)
+               return NULL;
+
+       address_bits = (limit == ULONG_MAX) ? BITS_PER_LONG : ilog2(limit);
+
+       /* Relocate set of pages below given limit. */
+       if (xen_create_contiguous_region((unsigned long)page_address(pages),
+                                                       order, address_bits)) {
+               __free_pages(pages, order);
+               return NULL;
+       }
+
+       BUG_ON(PagePrivate(pages));
+
+       pages->mapping = NULL;
+       set_page_private(pages, order);
+
+       for (i = 0; i < (1 << order); ++i)
+               SetPageReserved(pages + i);
+
+       return pages;
+}
+
+static void kimage_free_pages(struct page *page)
+{
+       unsigned int i, order;
+
+       order = page_private(page);
+
+       for (i = 0; i < (1 << order); ++i)
+               ClearPageReserved(page + i);
+
+       xen_destroy_contiguous_region((unsigned long)page_address(page), order);
+       __free_pages(page, order);
+}
+
+static unsigned long xen_page_to_mfn(struct page *page)
+{
+       return pfn_to_mfn(page_to_pfn(page));
+}
+
+static struct page *xen_mfn_to_page(unsigned long mfn)
+{
+       return pfn_to_page(mfn_to_pfn(mfn));
+}
+
+static unsigned long xen_virt_to_machine(volatile void *address)
+{
+       return virt_to_machine(address).maddr;
+}
+
+static void *xen_machine_to_virt(unsigned long address)
+{
+       return phys_to_virt(machine_to_phys(XMADDR(address)).paddr);
+}
+
+static void *alloc_pgtable_page(struct kimage *image)
+{
+       struct page *page;
+
+       page = kimage_alloc_control_pages(image, 0);
+
+       if (!page || !page_address(page))
+               return NULL;
+
+       memset(page_address(page), 0, PAGE_SIZE);
+
+       return page_address(page);
+}
+
+static int alloc_transition_pgtable(struct kimage *image)
+{
+       image->arch.pgd = alloc_pgtable_page(image);
+
+       if (!image->arch.pgd)
+               return -ENOMEM;
+
+       image->arch.pmd0 = alloc_pgtable_page(image);
+
+       if (!image->arch.pmd0)
+               return -ENOMEM;
+
+       image->arch.pmd1 = alloc_pgtable_page(image);
+
+       if (!image->arch.pmd1)
+               return -ENOMEM;
+
+       image->arch.pte0 = alloc_pgtable_page(image);
+
+       if (!image->arch.pte0)
+               return -ENOMEM;
+
+       image->arch.pte1 = alloc_pgtable_page(image);
+
+       if (!image->arch.pte1)
+               return -ENOMEM;
+
+       return 0;
+}
+
+static int machine_xen_kexec_prepare(struct kimage *image)
+{
+#ifdef CONFIG_KEXEC_JUMP
+       if (image->preserve_context) {
+               pr_info_once("kexec: Context preservation is not "
+                               "supported in Xen domains.\n");
+               return -ENOSYS;
+       }
+#endif
+
+       return alloc_transition_pgtable(image);
+}
+
+static int machine_xen_kexec_load(struct kimage *image)
+{
+       void *control_page;
+       struct xen_kexec_load xkl = {};
+
+       /* Image is unloaded, nothing to do. */
+       if (!image)
+               return 0;
+
+       control_page = page_address(image->control_code_page);
+       memcpy(control_page, xen_relocate_kernel, xen_kexec_control_code_size);
+
+       xkl.type = image->type;
+       xkl.image.page_list[XK_MA_CONTROL_PAGE] = __ma(control_page);
+       xkl.image.page_list[XK_MA_TABLE_PAGE] = 0; /* Unused. */
+       xkl.image.page_list[XK_MA_PGD_PAGE] = __ma(image->arch.pgd);
+       xkl.image.page_list[XK_MA_PUD0_PAGE] = 0; /* Unused. */
+       xkl.image.page_list[XK_MA_PUD1_PAGE] = 0; /* Unused. */
+       xkl.image.page_list[XK_MA_PMD0_PAGE] = __ma(image->arch.pmd0);
+       xkl.image.page_list[XK_MA_PMD1_PAGE] = __ma(image->arch.pmd1);
+       xkl.image.page_list[XK_MA_PTE0_PAGE] = __ma(image->arch.pte0);
+       xkl.image.page_list[XK_MA_PTE1_PAGE] = __ma(image->arch.pte1);
+       xkl.image.indirection_page = image->head;
+       xkl.image.start_address = image->start;
+
+       return HYPERVISOR_kexec_op(KEXEC_CMD_kexec_load, &xkl);
+}
+
+static void machine_xen_kexec_cleanup(struct kimage *image)
+{
+}
+
+static void machine_xen_kexec_unload(struct kimage *image)
+{
+       int rc;
+       struct xen_kexec_load xkl = {};
+
+       if (!image)
+               return;
+
+       xkl.type = image->type;
+       rc = HYPERVISOR_kexec_op(KEXEC_CMD_kexec_unload, &xkl);
+
+       WARN(rc, "kexec: %s: HYPERVISOR_kexec_op(): %i\n", __func__, rc);
+}
+
+static void machine_xen_kexec_shutdown(void)
+{
+}
+
+static void machine_xen_kexec(struct kimage *image)
+{
+       int rc;
+       struct xen_kexec_exec xke = {};
+
+       xke.type = image->type;
+       rc = HYPERVISOR_kexec_op(KEXEC_CMD_kexec, &xke);
+
+       pr_emerg("kexec: %s: HYPERVISOR_kexec_op(): %i\n", __func__, rc);
+       BUG();
+}
+
+void __init xen_init_kexec_ops(void)
+{
+       if (!xen_initial_domain())
+               return;
+
+       kexec_ops.crash_alloc_temp_store = true;
+       kexec_ops.kimage_alloc_pages = kimage_alloc_pages;
+       kexec_ops.kimage_free_pages = kimage_free_pages;
+       kexec_ops.page_to_pfn = xen_page_to_mfn;
+       kexec_ops.pfn_to_page = xen_mfn_to_page;
+       kexec_ops.virt_to_phys = xen_virt_to_machine;
+       kexec_ops.phys_to_virt = xen_machine_to_virt;
+       kexec_ops.machine_kexec_prepare = machine_xen_kexec_prepare;
+       kexec_ops.machine_kexec_load = machine_xen_kexec_load;
+       kexec_ops.machine_kexec_cleanup = machine_xen_kexec_cleanup;
+       kexec_ops.machine_kexec_unload = machine_xen_kexec_unload;
+       kexec_ops.machine_kexec_shutdown = machine_xen_kexec_shutdown;
+       kexec_ops.machine_kexec = machine_xen_kexec;
+}
diff --git a/arch/x86/xen/relocate_kernel_32.S 
b/arch/x86/xen/relocate_kernel_32.S
new file mode 100644
index 0000000..0e81830
--- /dev/null
+++ b/arch/x86/xen/relocate_kernel_32.S
@@ -0,0 +1,323 @@
+/*
+ * Copyright (c) 2002-2005 Eric Biederman <ebiederm@xxxxxxxxxxxx>
+ * Copyright (c) 2011 Daniel Kiper
+ * Copyright (c) 2012 Daniel Kiper, Oracle Corporation
+ *
+ * kexec/kdump implementation for Xen was written by Daniel Kiper.
+ * Initial work on it was sponsored by Google under Google Summer
+ * of Code 2011 program and Citrix. Konrad Rzeszutek Wilk from Oracle
+ * was the mentor for this project.
+ *
+ * Some ideas are taken from:
+ *   - native kexec/kdump implementation,
+ *   - kexec/kdump implementation for Xen Linux Kernel Ver. 2.6.18,
+ *   - PV-GRUB.
+ *
+ * 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; either veesion 2 of the License, or
+ * (at your option) any later veesion.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <asm/cache.h>
+#include <asm/page_types.h>
+#include <asm/pgtable_types.h>
+#include <asm/processor-flags.h>
+
+#include <asm/xen/kexec.h>
+
+#define ARG_INDIRECTION_PAGE   0x4
+#define ARG_PAGE_LIST          0x8
+#define ARG_START_ADDRESS      0xc
+
+#define PTR(x) (x << 2)
+
+       .text
+       .align  PAGE_SIZE
+       .globl  xen_kexec_control_code_size, xen_relocate_kernel
+
+xen_relocate_kernel:
+       /*
+        * Must be relocatable PIC code callable as a C function.
+        *
+        * This function is called by Xen but here hypervisor is dead.
+        * We are playing on bare metal.
+        *
+        * Every machine address passed to this function through
+        * page_list (e.g. XK_MA_CONTROL_PAGE) is established
+        * by dom0 during kexec load phase.
+        *
+        * Every virtual address passed to this function through page_list
+        * (e.g. XK_VA_CONTROL_PAGE) is established by hypervisor during
+        * HYPERVISOR_kexec_op(KEXEC_CMD_kexec_load) hypercall.
+        *
+        * 0x4(%esp) - indirection_page,
+        * 0x8(%esp) - page_list,
+        * 0xc(%esp) - start_address,
+        * 0x10(%esp) - cpu_has_pae (ignored),
+        * 0x14(%esp) - preserve_context (ignored).
+        */
+
+       /* Zero out flags, and disable interrupts. */
+       pushl   $0
+       popfl
+
+       /* Get page_list address. */
+       movl    ARG_PAGE_LIST(%esp), %esi
+
+       /*
+        * Map the control page at its virtual address
+        * in transition page table.
+        */
+       movl    PTR(XK_VA_CONTROL_PAGE)(%esi), %eax
+
+       /* Get PGD address and PGD entry index. */
+       movl    PTR(XK_VA_PGD_PAGE)(%esi), %ebx
+       movl    %eax, %ecx
+       shrl    $PGDIR_SHIFT, %ecx
+       andl    $(PTRS_PER_PGD - 1), %ecx
+
+       /* Fill PGD entry with PMD0 reference. */
+       movl    PTR(XK_MA_PMD0_PAGE)(%esi), %edx
+       orl     $_PAGE_PRESENT, %edx
+       movl    %edx, (%ebx, %ecx, 8)
+
+       /* Get PMD0 address and PMD0 entry index. */
+       movl    PTR(XK_VA_PMD0_PAGE)(%esi), %ebx
+       movl    %eax, %ecx
+       shrl    $PMD_SHIFT, %ecx
+       andl    $(PTRS_PER_PMD - 1), %ecx
+
+       /* Fill PMD0 entry with PTE0 reference. */
+       movl    PTR(XK_MA_PTE0_PAGE)(%esi), %edx
+       orl     $_KERNPG_TABLE, %edx
+       movl    %edx, (%ebx, %ecx, 8)
+
+       /* Get PTE0 address and PTE0 entry index. */
+       movl    PTR(XK_VA_PTE0_PAGE)(%esi), %ebx
+       movl    %eax, %ecx
+       shrl    $PAGE_SHIFT, %ecx
+       andl    $(PTRS_PER_PTE - 1), %ecx
+
+       /* Fill PTE0 entry with control page reference. */
+       movl    PTR(XK_MA_CONTROL_PAGE)(%esi), %edx
+       orl     $__PAGE_KERNEL_EXEC, %edx
+       movl    %edx, (%ebx, %ecx, 8)
+
+       /*
+        * Identity map the control page at its machine address
+        * in transition page table.
+        */
+       movl    PTR(XK_MA_CONTROL_PAGE)(%esi), %eax
+
+       /* Get PGD address and PGD entry index. */
+       movl    PTR(XK_VA_PGD_PAGE)(%esi), %ebx
+       movl    %eax, %ecx
+       shrl    $PGDIR_SHIFT, %ecx
+       andl    $(PTRS_PER_PGD - 1), %ecx
+
+       /* Fill PGD entry with PMD1 reference. */
+       movl    PTR(XK_MA_PMD1_PAGE)(%esi), %edx
+       orl     $_PAGE_PRESENT, %edx
+       movl    %edx, (%ebx, %ecx, 8)
+
+       /* Get PMD1 address and PMD1 entry index. */
+       movl    PTR(XK_VA_PMD1_PAGE)(%esi), %ebx
+       movl    %eax, %ecx
+       shrl    $PMD_SHIFT, %ecx
+       andl    $(PTRS_PER_PMD - 1), %ecx
+
+       /* Fill PMD1 entry with PTE1 reference. */
+       movl    PTR(XK_MA_PTE1_PAGE)(%esi), %edx
+       orl     $_KERNPG_TABLE, %edx
+       movl    %edx, (%ebx, %ecx, 8)
+
+       /* Get PTE1 address and PTE1 entry index. */
+       movl    PTR(XK_VA_PTE1_PAGE)(%esi), %ebx
+       movl    %eax, %ecx
+       shrl    $PAGE_SHIFT, %ecx
+       andl    $(PTRS_PER_PTE - 1), %ecx
+
+       /* Fill PTE1 entry with control page reference. */
+       movl    PTR(XK_MA_CONTROL_PAGE)(%esi), %edx
+       orl     $__PAGE_KERNEL_EXEC, %edx
+       movl    %edx, (%ebx, %ecx, 8)
+
+       /*
+        * Get machine address of control page now.
+        * This is impossible after page table switch.
+        */
+       movl    PTR(XK_MA_CONTROL_PAGE)(%esi), %ebx
+
+       /* Get machine address of transition page table now too. */
+       movl    PTR(XK_MA_PGD_PAGE)(%esi), %ecx
+
+       /* Get start_address too. */
+       movl    ARG_START_ADDRESS(%esp), %edx
+
+       /* Get indirection_page address too. */
+       movl    ARG_INDIRECTION_PAGE(%esp), %edi
+
+       /* Switch to transition page table. */
+       movl    %ecx, %cr3
+
+       /* Load IDT. */
+       lidtl   (idt_48 - xen_relocate_kernel)(%ebx)
+
+       /* Load GDT. */
+       leal    (gdt - xen_relocate_kernel)(%ebx), %eax
+       movl    %eax, (gdt_48 - xen_relocate_kernel + 2)(%ebx)
+       lgdtl   (gdt_48 - xen_relocate_kernel)(%ebx)
+
+       /* Load data segment registers. */
+       movl    $(gdt_ds - gdt), %eax
+       movl    %eax, %ds
+       movl    %eax, %es
+       movl    %eax, %fs
+       movl    %eax, %gs
+       movl    %eax, %ss
+
+       /* Setup a new stack at the end of machine address of control page. */
+       leal    PAGE_SIZE(%ebx), %esp
+
+       /* Store start_address on the stack. */
+       pushl   %edx
+
+       /* Jump to identity mapped page. */
+       pushl   $0
+       pushl   $(gdt_cs - gdt)
+       addl    $(identity_mapped - xen_relocate_kernel), %ebx
+       pushl   %ebx
+       iretl
+
+identity_mapped:
+       /*
+        * Set %cr0 to a known state:
+        *   - disable alignment check,
+        *   - disable floating point emulation,
+        *   - disable paging,
+        *   - no task switch,
+        *   - disable write protect,
+        *   - enable protected mode.
+        */
+       movl    %cr0, %eax
+       andl    $~(X86_CR0_AM | X86_CR0_EM | X86_CR0_PG | X86_CR0_TS | 
X86_CR0_WP), %eax
+       orl     $(X86_CR0_PE), %eax
+       movl    %eax, %cr0
+
+       /* Set %cr4 to a known state. */
+       xorl    %eax, %eax
+       movl    %eax, %cr4
+
+       jmp     1f
+
+1:
+       /* Flush the TLB (needed?). */
+       movl    %eax, %cr3
+
+       /* Do the copies. */
+       movl    %edi, %ecx      /* Put the indirection_page in %ecx. */
+       xorl    %edi, %edi
+       xorl    %esi, %esi
+       jmp     1f
+
+0:
+       /*
+        * Top, read another doubleword from the indirection page.
+        * Indirection page is an array which contains source
+        * and destination address pairs. If all pairs could
+        * not fit in one page then at the end of given
+        * indirection page is pointer to next one.
+        * Copy is stopped when done indicator
+        * is found in indirection page.
+        */
+       movl    (%ebx), %ecx
+       addl    $4, %ebx
+
+1:
+       testl   $0x1, %ecx      /* Is it a destination page? */
+       jz      2f
+
+       movl    %ecx, %edi
+       andl    $PAGE_MASK, %edi
+       jmp     0b
+
+2:
+       testl   $0x2, %ecx      /* Is it an indirection page? */
+       jz      2f
+
+       movl    %ecx, %ebx
+       andl    $PAGE_MASK, %ebx
+       jmp     0b
+
+2:
+       testl   $0x4, %ecx      /* Is it the done indicator? */
+       jz      2f
+       jmp     3f
+
+2:
+       testl   $0x8, %ecx      /* Is it the source indicator? */
+       jz      0b              /* Ignore it otherwise. */
+
+       movl    %ecx, %esi
+       andl    $PAGE_MASK, %esi
+       movl    $1024, %ecx
+
+       /* Copy page. */
+       rep     movsl
+       jmp     0b
+
+3:
+       /*
+        * To be certain of avoiding problems with self-modifying code
+        * I need to execute a serializing instruction here.
+        * So I flush the TLB by reloading %cr3 here, it's handy,
+        * and not processor dependent.
+        */
+       xorl    %eax, %eax
+       movl    %eax, %cr3
+
+       /*
+        * Set all of the registers to known values.
+        * Leave %esp alone.
+        */
+       xorl    %ebx, %ebx
+       xorl    %ecx, %ecx
+       xorl    %edx, %edx
+       xorl    %esi, %esi
+       xorl    %edi, %edi
+       xorl    %ebp, %ebp
+
+       /* Jump to start_address. */
+       retl
+
+       .align  L1_CACHE_BYTES
+
+gdt:
+       .quad   0x0000000000000000      /* NULL descriptor. */
+
+gdt_cs:
+       .quad   0x00cf9a000000ffff      /* 4 GiB code segment at 0x00000000. */
+
+gdt_ds:
+       .quad   0x00cf92000000ffff      /* 4 GiB data segment at 0x00000000. */
+gdt_end:
+
+gdt_48:
+       .word   gdt_end - gdt - 1       /* GDT limit. */
+       .long   0                       /* GDT base - filled in by code above. 
*/
+
+idt_48:
+       .word   0                       /* IDT limit. */
+       .long   0                       /* IDT base. */
+
+xen_kexec_control_code_size:
+       .long   . - xen_relocate_kernel
-- 
1.5.6.5


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