forked from Minki/linux
187e91fe5e
__startup_64() is normally using fixup_pointer() to access globals in a
position-independent fashion. However 'next_early_pgt' was accessed
directly, which wasn't guaranteed to work.
Luckily GCC was generating a R_X86_64_PC32 PC-relative relocation for
'next_early_pgt', but Clang emitted a R_X86_64_32S, which led to
accessing invalid memory and rebooting the kernel.
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Davidson <md@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c88d71508e
("x86/boot/64: Rewrite startup_64() in C")
Link: http://lkml.kernel.org/r/20170816190808.131748-1-glider@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
320 lines
8.5 KiB
C
320 lines
8.5 KiB
C
/*
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* prepare to run common code
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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*/
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#define DISABLE_BRANCH_PROFILING
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/percpu.h>
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#include <linux/start_kernel.h>
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#include <linux/io.h>
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#include <linux/memblock.h>
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#include <asm/processor.h>
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#include <asm/proto.h>
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#include <asm/smp.h>
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#include <asm/setup.h>
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#include <asm/desc.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include <asm/sections.h>
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#include <asm/kdebug.h>
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#include <asm/e820/api.h>
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#include <asm/bios_ebda.h>
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#include <asm/bootparam_utils.h>
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#include <asm/microcode.h>
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#include <asm/kasan.h>
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/*
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* Manage page tables very early on.
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*/
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extern pgd_t early_top_pgt[PTRS_PER_PGD];
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extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
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static unsigned int __initdata next_early_pgt;
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pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
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#define __head __section(.head.text)
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static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
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{
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return ptr - (void *)_text + (void *)physaddr;
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}
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void __head __startup_64(unsigned long physaddr)
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{
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unsigned long load_delta, *p;
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pgdval_t *pgd;
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p4dval_t *p4d;
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pudval_t *pud;
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pmdval_t *pmd, pmd_entry;
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int i;
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unsigned int *next_pgt_ptr;
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/* Is the address too large? */
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if (physaddr >> MAX_PHYSMEM_BITS)
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for (;;);
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/*
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* Compute the delta between the address I am compiled to run at
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* and the address I am actually running at.
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*/
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load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
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/* Is the address not 2M aligned? */
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if (load_delta & ~PMD_PAGE_MASK)
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for (;;);
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/* Fixup the physical addresses in the page table */
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pgd = fixup_pointer(&early_top_pgt, physaddr);
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pgd[pgd_index(__START_KERNEL_map)] += load_delta;
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if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
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p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
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p4d[511] += load_delta;
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}
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pud = fixup_pointer(&level3_kernel_pgt, physaddr);
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pud[510] += load_delta;
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pud[511] += load_delta;
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pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
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pmd[506] += load_delta;
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/*
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* Set up the identity mapping for the switchover. These
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* entries should *NOT* have the global bit set! This also
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* creates a bunch of nonsense entries but that is fine --
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* it avoids problems around wraparound.
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*/
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next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
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pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
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pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
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if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
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p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
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i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
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pgd[i + 0] = (pgdval_t)p4d + _KERNPG_TABLE;
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pgd[i + 1] = (pgdval_t)p4d + _KERNPG_TABLE;
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i = (physaddr >> P4D_SHIFT) % PTRS_PER_P4D;
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p4d[i + 0] = (pgdval_t)pud + _KERNPG_TABLE;
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p4d[i + 1] = (pgdval_t)pud + _KERNPG_TABLE;
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} else {
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i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
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pgd[i + 0] = (pgdval_t)pud + _KERNPG_TABLE;
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pgd[i + 1] = (pgdval_t)pud + _KERNPG_TABLE;
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}
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i = (physaddr >> PUD_SHIFT) % PTRS_PER_PUD;
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pud[i + 0] = (pudval_t)pmd + _KERNPG_TABLE;
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pud[i + 1] = (pudval_t)pmd + _KERNPG_TABLE;
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pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
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pmd_entry += physaddr;
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for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
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int idx = i + (physaddr >> PMD_SHIFT) % PTRS_PER_PMD;
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pmd[idx] = pmd_entry + i * PMD_SIZE;
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}
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/*
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* Fixup the kernel text+data virtual addresses. Note that
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* we might write invalid pmds, when the kernel is relocated
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* cleanup_highmap() fixes this up along with the mappings
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* beyond _end.
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*/
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pmd = fixup_pointer(level2_kernel_pgt, physaddr);
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for (i = 0; i < PTRS_PER_PMD; i++) {
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if (pmd[i] & _PAGE_PRESENT)
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pmd[i] += load_delta;
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}
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/* Fixup phys_base */
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p = fixup_pointer(&phys_base, physaddr);
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*p += load_delta;
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}
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/* Wipe all early page tables except for the kernel symbol map */
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static void __init reset_early_page_tables(void)
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{
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memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
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next_early_pgt = 0;
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write_cr3(__pa_nodebug(early_top_pgt));
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}
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/* Create a new PMD entry */
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int __init early_make_pgtable(unsigned long address)
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{
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unsigned long physaddr = address - __PAGE_OFFSET;
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pgdval_t pgd, *pgd_p;
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p4dval_t p4d, *p4d_p;
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pudval_t pud, *pud_p;
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pmdval_t pmd, *pmd_p;
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/* Invalid address or early pgt is done ? */
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if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
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return -1;
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again:
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pgd_p = &early_top_pgt[pgd_index(address)].pgd;
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pgd = *pgd_p;
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/*
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* The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
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* critical -- __PAGE_OFFSET would point us back into the dynamic
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* range and we might end up looping forever...
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*/
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if (!IS_ENABLED(CONFIG_X86_5LEVEL))
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p4d_p = pgd_p;
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else if (pgd)
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p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
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else {
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if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
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reset_early_page_tables();
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goto again;
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}
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p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
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memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
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*pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
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}
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p4d_p += p4d_index(address);
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p4d = *p4d_p;
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if (p4d)
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pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
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else {
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if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
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reset_early_page_tables();
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goto again;
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}
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pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
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memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
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*p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
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}
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pud_p += pud_index(address);
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pud = *pud_p;
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if (pud)
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pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
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else {
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if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
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reset_early_page_tables();
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goto again;
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}
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pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
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memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
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*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
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}
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pmd = (physaddr & PMD_MASK) + early_pmd_flags;
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pmd_p[pmd_index(address)] = pmd;
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return 0;
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}
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/* Don't add a printk in there. printk relies on the PDA which is not initialized
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yet. */
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static void __init clear_bss(void)
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{
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memset(__bss_start, 0,
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(unsigned long) __bss_stop - (unsigned long) __bss_start);
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}
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static unsigned long get_cmd_line_ptr(void)
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{
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unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
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cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
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return cmd_line_ptr;
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}
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static void __init copy_bootdata(char *real_mode_data)
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{
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char * command_line;
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unsigned long cmd_line_ptr;
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memcpy(&boot_params, real_mode_data, sizeof boot_params);
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sanitize_boot_params(&boot_params);
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cmd_line_ptr = get_cmd_line_ptr();
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if (cmd_line_ptr) {
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command_line = __va(cmd_line_ptr);
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memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
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}
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}
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asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
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{
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int i;
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/*
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* Build-time sanity checks on the kernel image and module
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* area mappings. (these are purely build-time and produce no code)
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*/
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BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
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BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
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BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
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BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
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BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
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BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
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BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
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(__START_KERNEL & PGDIR_MASK)));
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BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
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cr4_init_shadow();
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/* Kill off the identity-map trampoline */
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reset_early_page_tables();
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clear_bss();
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clear_page(init_top_pgt);
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kasan_early_init();
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for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
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set_intr_gate(i, early_idt_handler_array[i]);
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load_idt((const struct desc_ptr *)&idt_descr);
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copy_bootdata(__va(real_mode_data));
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/*
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* Load microcode early on BSP.
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*/
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load_ucode_bsp();
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/* set init_top_pgt kernel high mapping*/
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init_top_pgt[511] = early_top_pgt[511];
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x86_64_start_reservations(real_mode_data);
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}
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void __init x86_64_start_reservations(char *real_mode_data)
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{
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/* version is always not zero if it is copied */
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if (!boot_params.hdr.version)
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copy_bootdata(__va(real_mode_data));
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x86_early_init_platform_quirks();
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switch (boot_params.hdr.hardware_subarch) {
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case X86_SUBARCH_INTEL_MID:
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x86_intel_mid_early_setup();
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break;
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default:
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break;
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}
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start_kernel();
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}
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