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Date: Thu, 13 Dec 2012 14:02:00 -0800 From: Yinghai Lu <yinghai@...nel.org> To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com> Cc: "Eric W. Biederman" <ebiederm@...ssion.com>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org> Subject: [PATCH v6 06/27] x86, 64bit: Set extra ident mapping for whole kernel range Current when kernel is loaded above 1G, only [_text, _text+2M] is set up with extra ident page table. That is not enough, some variables that could be used early are out of that range, like BRK for early page table. Need to set map for [_text, _end] include text/data/bss/brk... Also current kernel is not allowed to be loaded above 512g, it thinks that address is too big. We need to add one extra spare page for level3 to point that 512g range. Need to check _text range and set level4 pg with that spare level3 page, and set level3 with level2 page to cover [_text, _end] with extra mapping. At last, to handle crossing GB boundary, we need to add another level2 spare page. To handle crossing 512GB boundary, we need to add another level3 spare page to next 512G range. Test on with kexec-tools with local test code to force loading kernel cross 1G, 5G, 512g, 513g. We need this to put relocatable 64bit bzImage high above 1g. -v4: add crossing GB boundary handling. -v5: use spare pages from BRK, so could save pages when kernel is not loaded above 1GB. Signed-off-by: Yinghai Lu <yinghai@...nel.org> Cc: "Eric W. Biederman" <ebiederm@...ssion.com> --- arch/x86/kernel/head_64.S | 203 +++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 187 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 980053c..7d13874 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -20,6 +20,7 @@ #include <asm/processor-flags.h> #include <asm/percpu.h> #include <asm/nops.h> +#include <asm/setup.h> #ifdef CONFIG_PARAVIRT #include <asm/asm-offsets.h> @@ -42,6 +43,13 @@ L3_PAGE_OFFSET = pud_index(__PAGE_OFFSET) L4_START_KERNEL = pgd_index(__START_KERNEL_map) L3_START_KERNEL = pud_index(__START_KERNEL_map) +/* two for level3, and two for level2 */ +SPARE_MAP_SIZE = (4 * PAGE_SIZE) +RESERVE_BRK(spare_map, SPARE_MAP_SIZE) + +#define spare_page(x) (__brk_base + (x) * PAGE_SIZE) +#define add_one_spare_page addq $PAGE_SIZE, _brk_end(%rip) + .text __HEAD .code64 @@ -78,12 +86,6 @@ startup_64: testl %eax, %eax jnz bad_address - /* Is the address too large? */ - leaq _text(%rip), %rdx - movq $PGDIR_SIZE, %rax - cmpq %rax, %rdx - jae bad_address - /* Fixup the physical addresses in the page table */ addq %rbp, init_level4_pgt + 0(%rip) @@ -97,25 +99,196 @@ startup_64: addq %rbp, level2_fixmap_pgt + (506*8)(%rip) - /* Add an Identity mapping if I am above 1G */ + /* Add an Identity mapping if _end is above 1G */ + leaq _end(%rip), %r9 + decq %r9 + cmp $PUD_SIZE, %r9 + jl ident_complete + + /* Clear spare pages */ + leaq __brk_base(%rip), %rdi + xorq %rax, %rax + movq $(SPARE_MAP_SIZE/8), %rcx +1: decq %rcx + movq %rax, (%rdi) + leaq 8(%rdi), %rdi + jnz 1b + + /* get end */ + andq $PMD_PAGE_MASK, %r9 + /* round start to 1G if it is below 1G */ leaq _text(%rip), %rdi andq $PMD_PAGE_MASK, %rdi + cmp $PUD_SIZE, %rdi + jg 1f + movq $PUD_SIZE, %rdi +1: + /* get 512G index */ + movq %r9, %r8 + shrq $PGDIR_SHIFT, %r8 + andq $(PTRS_PER_PGD - 1), %r8 + movq %rdi, %rax + shrq $PGDIR_SHIFT, %rax + andq $(PTRS_PER_PGD - 1), %rax + + /* cross two 512G ? */ + cmp %r8, %rax + jne set_level3_other_512g + + /* all in first 512G ? */ + cmp $0, %rax + je skip_level3_spare + + /* same 512G other than first 512g */ + /* + * We need one level3, one or two level 2, + * so use first one for level3. + */ + leaq (spare_page(0) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + leaq init_level4_pgt(%rip), %rbx + movq %rdx, 0(%rbx, %rax, 8) + addq $L4_PAGE_OFFSET, %rax + movq %rdx, 0(%rbx, %rax, 8) + /* one level3 in BRK */ + add_one_spare_page + + /* get 1G index */ + movq %r9, %r8 + shrq $PUD_SHIFT, %r8 + andq $(PTRS_PER_PUD - 1), %r8 + movq %rdi, %rax + shrq $PUD_SHIFT, %rax + andq $(PTRS_PER_PUD - 1), %rax + + /* same 1G ? */ + cmp %r8, %rax + je set_level2_start_only_not_first_512g + + /* set level2 for end */ + leaq spare_page(0)(%rip), %rbx + leaq (spare_page(2) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + movq %rdx, 0(%rbx, %r8, 8) + /* second one level2 in BRK */ + add_one_spare_page + +set_level2_start_only_not_first_512g: + leaq spare_page(0)(%rip), %rbx + leaq (spare_page(1) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + movq %rdx, 0(%rbx, %rax, 8) + /* first one level2 in BRK */ + add_one_spare_page + + /* one spare level3 before level2*/ + leaq spare_page(1)(%rip), %rbx + jmp set_level2_spare + +set_level3_other_512g: + /* + * We need one or two level3, and two level2, + * so use first two for level2. + */ + /* for level2 last on first 512g */ + leaq level3_ident_pgt(%rip), %rcx + /* start is in first 512G ? */ + cmp $0, %rax + je set_level2_start_other_512g + + /* Set level3 for _text */ + leaq (spare_page(3) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + leaq init_level4_pgt(%rip), %rbx + movq %rdx, 0(%rbx, %rax, 8) + addq $L4_PAGE_OFFSET, %rax + movq %rdx, 0(%rbx, %rax, 8) + /* first one level3 in BRK */ + add_one_spare_page + + /* for level2 last not on first 512G */ + leaq spare_page(3)(%rip), %rcx +set_level2_start_other_512g: + /* always need to set level2 */ movq %rdi, %rax shrq $PUD_SHIFT, %rax andq $(PTRS_PER_PUD - 1), %rax - jz ident_complete + movq %rcx, %rbx /* %rcx : level3 spare or level3_ident_pgt */ + leaq (spare_page(0) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + movq %rdx, 0(%rbx, %rax, 8) + /* first one level2 in BRK */ + add_one_spare_page + +set_level3_end_other_512g: + leaq (spare_page(2) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + leaq init_level4_pgt(%rip), %rbx + movq %rdx, 0(%rbx, %r8, 8) + addq $L4_PAGE_OFFSET, %r8 + movq %rdx, 0(%rbx, %r8, 8) + /* second one level3 in BRK */ + add_one_spare_page + + /* always need to set level2 */ + movq %r9, %r8 + shrq $PUD_SHIFT, %r8 + andq $(PTRS_PER_PUD - 1), %r8 + leaq spare_page(2)(%rip), %rbx + leaq (spare_page(1) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + movq %rdx, 0(%rbx, %r8, 8) + /* second one level2 in BRK */ + add_one_spare_page + + /* no spare level3 before level2 */ + leaq spare_page(0)(%rip), %rbx + jmp set_level2_spare + +skip_level3_spare: + /* We have one or two level2 */ + /* get 1G index */ + movq %r9, %r8 + shrq $PUD_SHIFT, %r8 + andq $(PTRS_PER_PUD - 1), %r8 + movq %rdi, %rax + shrq $PUD_SHIFT, %rax + andq $(PTRS_PER_PUD - 1), %rax + + /* same 1G ? */ + cmp %r8, %rax + je set_level2_start_only_first_512g - leaq (level2_spare_pgt - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + /* set level2 without level3 spare */ leaq level3_ident_pgt(%rip), %rbx + leaq (spare_page(1) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx + movq %rdx, 0(%rbx, %r8, 8) + /* second one level2 in BRK */ + add_one_spare_page + +set_level2_start_only_first_512g: + /* set level2 without level3 spare */ + leaq level3_ident_pgt(%rip), %rbx + leaq (spare_page(0) - __START_KERNEL_map + _KERNPG_TABLE)(%rbp), %rdx movq %rdx, 0(%rbx, %rax, 8) + /* first one level2 in BRK */ + add_one_spare_page + + /* no spare level3 */ + leaq spare_page(0)(%rip), %rbx +set_level2_spare: movq %rdi, %rax shrq $PMD_SHIFT, %rax andq $(PTRS_PER_PMD - 1), %rax leaq __PAGE_KERNEL_IDENT_LARGE_EXEC(%rdi), %rdx - leaq level2_spare_pgt(%rip), %rbx - movq %rdx, 0(%rbx, %rax, 8) + /* %rbx is set before */ + movq %r9, %r8 + shrq $PMD_SHIFT, %r8 + andq $(PTRS_PER_PMD - 1), %r8 + cmp %r8, %rax + jl 1f + addq $PTRS_PER_PMD, %r8 +1: movq %rdx, 0(%rbx, %rax, 8) + addq $PMD_SIZE, %rdx + incq %rax + cmp %r8, %rax + jle 1b + ident_complete: /* @@ -439,11 +612,9 @@ NEXT_PAGE(level2_kernel_pgt) * If you want to increase this then increase MODULES_VADDR * too.) */ - PMDS(0, __PAGE_KERNEL_LARGE_EXEC, - KERNEL_IMAGE_SIZE/PMD_SIZE) - -NEXT_PAGE(level2_spare_pgt) - .fill 512, 8, 0 + PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE) + /* hold the whole page */ + .fill (PTRS_PER_PMD - (KERNEL_IMAGE_SIZE/PMD_SIZE)), 8, 0 #undef PMDS #undef NEXT_PAGE -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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