From 4bfaaef01a1badb9e8ffb0c0a37cd2379008d21f Mon Sep 17 00:00:00 2001 From: Magnus Damm Date: Tue, 26 Sep 2006 10:52:38 +0200 Subject: [PATCH] Avoid overwriting the current pgd (V4, x86_64) kexec: Avoid overwriting the current pgd (V4, x86_64) This patch upgrades the x86_64-specific kexec code to avoid overwriting the current pgd. Overwriting the current pgd is bad when CONFIG_CRASH_DUMP is used to start a secondary kernel that dumps the memory of the previous kernel. The code introduces a new set of page tables. These tables are used to provide an executable identity mapping without overwriting the current pgd. Signed-off-by: Magnus Damm Signed-off-by: Andi Kleen --- arch/x86_64/kernel/machine_kexec.c | 71 ++++++++++++++++++++------------------ 1 file changed, 37 insertions(+), 34 deletions(-) (limited to 'arch/x86_64/kernel/machine_kexec.c') diff --git a/arch/x86_64/kernel/machine_kexec.c b/arch/x86_64/kernel/machine_kexec.c index 2e94c072d84..0497e3bd5bf 100644 --- a/arch/x86_64/kernel/machine_kexec.c +++ b/arch/x86_64/kernel/machine_kexec.c @@ -15,6 +15,15 @@ #include #include +#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE))) +static u64 kexec_pgd[512] PAGE_ALIGNED; +static u64 kexec_pud0[512] PAGE_ALIGNED; +static u64 kexec_pmd0[512] PAGE_ALIGNED; +static u64 kexec_pte0[512] PAGE_ALIGNED; +static u64 kexec_pud1[512] PAGE_ALIGNED; +static u64 kexec_pmd1[512] PAGE_ALIGNED; +static u64 kexec_pte1[512] PAGE_ALIGNED; + static void init_level2_page(pmd_t *level2p, unsigned long addr) { unsigned long end_addr; @@ -144,32 +153,19 @@ static void load_segments(void) ); } -typedef NORET_TYPE void (*relocate_new_kernel_t)(unsigned long indirection_page, - unsigned long control_code_buffer, - unsigned long start_address, - unsigned long pgtable) ATTRIB_NORET; - -extern const unsigned char relocate_new_kernel[]; -extern const unsigned long relocate_new_kernel_size; - int machine_kexec_prepare(struct kimage *image) { - unsigned long start_pgtable, control_code_buffer; + unsigned long start_pgtable; int result; /* Calculate the offsets */ start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT; - control_code_buffer = start_pgtable + PAGE_SIZE; /* Setup the identity mapped 64bit page table */ result = init_pgtable(image, start_pgtable); if (result) return result; - /* Place the code in the reboot code buffer */ - memcpy(__va(control_code_buffer), relocate_new_kernel, - relocate_new_kernel_size); - return 0; } @@ -184,28 +180,34 @@ void machine_kexec_cleanup(struct kimage *image) */ NORET_TYPE void machine_kexec(struct kimage *image) { - unsigned long page_list; - unsigned long control_code_buffer; - unsigned long start_pgtable; - relocate_new_kernel_t rnk; + unsigned long page_list[PAGES_NR]; + void *control_page; /* Interrupts aren't acceptable while we reboot */ local_irq_disable(); - /* Calculate the offsets */ - page_list = image->head; - start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT; - control_code_buffer = start_pgtable + PAGE_SIZE; - - /* Set the low half of the page table to my identity mapped - * page table for kexec. Leave the high half pointing at the - * kernel pages. Don't bother to flush the global pages - * as that will happen when I fully switch to my identity mapped - * page table anyway. - */ - memcpy(__va(read_cr3()), __va(start_pgtable), PAGE_SIZE/2); - __flush_tlb(); - + control_page = page_address(image->control_code_page) + PAGE_SIZE; + memcpy(control_page, relocate_kernel, PAGE_SIZE); + + page_list[PA_CONTROL_PAGE] = __pa(control_page); + page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel; + page_list[PA_PGD] = __pa(kexec_pgd); + page_list[VA_PGD] = (unsigned long)kexec_pgd; + page_list[PA_PUD_0] = __pa(kexec_pud0); + page_list[VA_PUD_0] = (unsigned long)kexec_pud0; + page_list[PA_PMD_0] = __pa(kexec_pmd0); + page_list[VA_PMD_0] = (unsigned long)kexec_pmd0; + page_list[PA_PTE_0] = __pa(kexec_pte0); + page_list[VA_PTE_0] = (unsigned long)kexec_pte0; + page_list[PA_PUD_1] = __pa(kexec_pud1); + page_list[VA_PUD_1] = (unsigned long)kexec_pud1; + page_list[PA_PMD_1] = __pa(kexec_pmd1); + page_list[VA_PMD_1] = (unsigned long)kexec_pmd1; + page_list[PA_PTE_1] = __pa(kexec_pte1); + page_list[VA_PTE_1] = (unsigned long)kexec_pte1; + + page_list[PA_TABLE_PAGE] = + (unsigned long)__pa(page_address(image->control_code_page)); /* The segment registers are funny things, they have both a * visible and an invisible part. Whenever the visible part is @@ -222,9 +224,10 @@ NORET_TYPE void machine_kexec(struct kimage *image) */ set_gdt(phys_to_virt(0),0); set_idt(phys_to_virt(0),0); + /* now call it */ - rnk = (relocate_new_kernel_t) control_code_buffer; - (*rnk)(page_list, control_code_buffer, image->start, start_pgtable); + relocate_kernel((unsigned long)image->head, (unsigned long)page_list, + image->start); } /* crashkernel=size@addr specifies the location to reserve for -- cgit v1.2.3