Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933566AbXHXKCs (ORCPT ); Fri, 24 Aug 2007 06:02:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764518AbXHXKCF (ORCPT ); Fri, 24 Aug 2007 06:02:05 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:60016 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763986AbXHXKCC convert rfc822-to-8bit (ORCPT ); Fri, 24 Aug 2007 06:02:02 -0400 From: "Rafael J. Wysocki" To: Andrew Morton Subject: [PATCH -mm 2/2] Hibernation: Arbitrary boot kernel support on x86_64 Date: Fri, 24 Aug 2007 12:11:54 +0200 User-Agent: KMail/1.9.5 Cc: Andi Kleen , LKML , Pavel Machek , pm list References: <200708241206.57178.rjw@sisk.pl> In-Reply-To: <200708241206.57178.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200708241211.55319.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8670 Lines: 235 From: Rafael J. Wysocki Make it possible to restore a hibernation image on x86_64 with the help of a kernel different from the one in the image. The idea is to split the core restoration code into two separate parts and to place each of them in a different page. ?The first part belongs to the boot kernel and is executed as the last step of the image kernel's memory restoration procedure. ?It restores all of the image kernel's memory that has not been restored yet except for the one page containing the very code that is being executed at that time. ?The final operation performed by it is a jump to the second part of the core restoration code that belongs to the image kernel and has just been restored. ?This code restores the last remaining page of the image kernel's memory containing the first, already executed, part of the core restoration code (temporary page tables created by the boot kernel are used at this stage). ?It also makes the CPU switch to the image kernel's page tables and restores the state of general purpose registers (including the stack pointer) from before the hibernation. The main issue with this idea is that in order to jump to the second part of the restoration code the boot kernel needs to know its address. ?However, this address may be passed to it in the image header. ?Namely, the part of the image header previously used for checking if the version of the image kernel is correct can be replaced with some architecture specific data that will allow the boot kernel to jump to the right address within the image kernel. ?These data should also be used for checking if the image kernel is compatible with the boot kernel (as far as the memory restroration procedure is concerned). It can be done, for example, with the help of a "magic" value that has to be equal in both kernels, so that they can be regarded as compatible. Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek --- arch/x86_64/kernel/suspend.c | 43 ++++++++++++++++++++++++++ arch/x86_64/kernel/suspend_asm.S | 63 +++++++++++++++++++++++++++++++++------ include/asm-x86_64/suspend.h | 6 +++ 3 files changed, 103 insertions(+), 9 deletions(-) Index: linux-2.6.23-rc3/arch/x86_64/kernel/suspend_asm.S =================================================================== --- linux-2.6.23-rc3.orig/arch/x86_64/kernel/suspend_asm.S 2007-08-21 20:36:49.000000000 +0200 +++ linux-2.6.23-rc3/arch/x86_64/kernel/suspend_asm.S 2007-08-21 21:16:01.000000000 +0200 @@ -2,8 +2,8 @@ * * Distribute under GPLv2. * - * swsusp_arch_resume may not use any stack, nor any variable that is - * not "NoSave" during copying pages: + * swsusp_arch_resume must not use any stack or any nonlocal variables while + * copying pages: * * Its rewriting one kernel image with another. What is stack in "old" * image could very well be data page in "new" image, and overwriting @@ -36,10 +36,20 @@ ENTRY(swsusp_arch_suspend) pushfq popq pt_regs_eflags(%rax) + /* save the address of restore_registers */ + movq $restore_registers, %rax + movq %rax, restore_jump_address(%rip) + call swsusp_save ret ENTRY(restore_image) + /* compute the address of the page we are at and store it in R9 */ + movq $(restore_image - __START_KERNEL_map), %rax + movq $__PAGE_OFFSET, %r9 + addq %rax, %r9 + andq $PAGE_MASK, %r9 + /* switch to temporary page tables */ movq $__PAGE_OFFSET, %rdx movq temp_level4_pgt(%rip), %rax @@ -54,6 +64,11 @@ ENTRY(restore_image) movq %rcx, %cr3; movq %rax, %cr4; # turn PGE back on + /* prepare to jump to the image kernel */ + movq restore_jump_address(%rip), %rax + + /* copy image data to their original locations */ + xorq %r10, %r10 movq restore_pblist(%rip), %rdx loop: testq %rdx, %rdx @@ -62,16 +77,46 @@ loop: /* get addresses from the pbe and copy the page */ movq pbe_address(%rdx), %rsi movq pbe_orig_address(%rdx), %rdi - movq $512, %rcx + /* skip the page we are at (address stored in R9) */ + cmpq %rdi, %r9 + jne 1f + /* save the address of the data to be copied to the skipped page */ + movq %rsi, %r10 + jmp 2f +1: movq $(PAGE_SIZE >> 3), %rcx rep movsq /* progress to the next pbe */ - movq pbe_next(%rdx), %rdx +2: movq pbe_next(%rdx), %rdx jmp loop done: + /* jump to the restore_registers address from the image header */ + jmpq *%rax + /* + * NOTE: This assumes that the boot kernel's text mapping covers the + * image kernel's page containing restore_registers and the address of + * this page is the same as in the image kernel's text mapping (it + * should always be true, because the text mapping is linear, starting + * from 0, and is supposed to cover the entire kernel text for every + * kernel). + */ + +.balign PAGE_SIZE + /* code below belongs to the image kernel */ +ENTRY(restore_registers) + /* check if we have one more image page to copy */ + testq %r10, %r10 + jz 1f + /* copy the skipped page */ + movq %r10, %rsi + movq %r9, %rdi + movq $(PAGE_SIZE >> 3), %rcx + rep + movsq + /* go back to the original page tables */ - movq $(init_level4_pgt - __START_KERNEL_map), %rax +1: movq $(init_level4_pgt - __START_KERNEL_map), %rax addq phys_base(%rip), %rax movq %rax, %cr3 @@ -84,10 +129,7 @@ done: movq %rcx, %cr3 movq %rax, %cr4; # turn PGE back on - movl $24, %eax - movl %eax, %ds - - /* We don't restore %rax, it must be 0 anyway */ + /* restore GPRs (we don't restore %rax, it must be 0 anyway) */ movq $saved_context, %rax movq pt_regs_rsp(%rax), %rsp movq pt_regs_rbp(%rax), %rbp @@ -109,4 +151,7 @@ done: xorq %rax, %rax + /* tell the hibernation core that we've just restored the memory */ + movq %rax, in_suspend(%rip) + ret Index: linux-2.6.23-rc3/arch/x86_64/kernel/suspend.c =================================================================== --- linux-2.6.23-rc3.orig/arch/x86_64/kernel/suspend.c 2007-08-21 20:36:49.000000000 +0200 +++ linux-2.6.23-rc3/arch/x86_64/kernel/suspend.c 2007-08-21 21:07:45.000000000 +0200 @@ -144,6 +144,12 @@ void fix_processor_context(void) /* Defined in arch/x86_64/kernel/suspend_asm.S */ extern int restore_image(void); +/* + * Address to jump to in the last phase of restore in order to get to the image + * kernel's text (this value is passed in the image header). + */ +unsigned long restore_jump_address; + pgd_t *temp_level4_pgt; static int res_phys_pud_init(pud_t *pud, unsigned long address, unsigned long end) @@ -230,4 +236,41 @@ int pfn_is_nosave(unsigned long pfn) unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT; return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn); } + +struct restore_data_record { + unsigned long jump_address; + unsigned long control; +}; + +#define RESTORE_MAGIC 0x0123456789ABCDEFUL + +/** + * arch_hibernation_header_save - populate the architecture specific part + * of a hibernation image header + * @addr: address to save the data at + */ +int arch_hibernation_header_save(void *addr, unsigned int max_size) +{ + struct restore_data_record *rdr = addr; + + if (max_size < sizeof(struct restore_data_record)) + return -EOVERFLOW; + rdr->jump_address = restore_jump_address; + rdr->control = (restore_jump_address ^ RESTORE_MAGIC); + return 0; +} + +/** + * arch_hibernation_header_restore - read the architecture specific data + * from the hibernation image header + * @addr: address to read the data from + */ +int arch_hibernation_header_restore(void *addr) +{ + struct restore_data_record *rdr = addr; + + restore_jump_address = rdr->jump_address; + return (rdr->control == (restore_jump_address ^ RESTORE_MAGIC)) ? + 0 : -EINVAL; +} #endif /* CONFIG_HIBERNATION */ Index: linux-2.6.23-rc3/include/asm-x86_64/suspend.h =================================================================== --- linux-2.6.23-rc3.orig/include/asm-x86_64/suspend.h 2007-08-21 20:36:49.000000000 +0200 +++ linux-2.6.23-rc3/include/asm-x86_64/suspend.h 2007-08-21 20:37:47.000000000 +0200 @@ -43,4 +43,10 @@ extern void fix_processor_context(void); /* routines for saving/restoring kernel state */ extern int acpi_save_state_mem(void); +#define ARCH_HAS_HIBERNATION_HEADER + +/* arch/x86_64/kernel/suspend.c */ +extern int arch_hibernation_header_save(void *addr, unsigned int max_size); +extern int arch_hibernation_header_restore(void *addr); + #endif /* __ASM_X86_64_SUSPEND_H */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/