linux/arch/x86/kernel/head64.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  prepare to run common code
 *
 *  Copyright (C) 2000 Andrea Arcangeli <[email protected]> SuSE
 */

#define DISABLE_BRANCH_PROFILING

/* cpu_feature_enabled() cannot be used this early */
#define USE_EARLY_PGTABLE_L5

#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/percpu.h>
#include <linux/start_kernel.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/cc_platform.h>
#include <linux/pgtable.h>

#include <asm/asm.h>
#include <asm/page_64.h>
#include <asm/processor.h>
#include <asm/proto.h>
#include <asm/smp.h>
#include <asm/setup.h>
#include <asm/desc.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/kdebug.h>
#include <asm/e820/api.h>
#include <asm/bios_ebda.h>
#include <asm/bootparam_utils.h>
#include <asm/microcode.h>
#include <asm/kasan.h>
#include <asm/fixmap.h>
#include <asm/realmode.h>
#include <asm/extable.h>
#include <asm/trapnr.h>
#include <asm/sev.h>
#include <asm/tdx.h>
#include <asm/init.h>

/*
 * Manage page tables very early on.
 */
extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
static unsigned int __initdata next_early_pgt;
pmdval_t early_pmd_flags = …;

#ifdef CONFIG_X86_5LEVEL
unsigned int __pgtable_l5_enabled __ro_after_init;
unsigned int pgdir_shift __ro_after_init = …;
EXPORT_SYMBOL(…);
unsigned int ptrs_per_p4d __ro_after_init = …;
EXPORT_SYMBOL(…);
#endif

#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
unsigned long page_offset_base __ro_after_init = …;
EXPORT_SYMBOL(…);
unsigned long vmalloc_base __ro_after_init = …;
EXPORT_SYMBOL(…);
unsigned long vmemmap_base __ro_after_init = …;
EXPORT_SYMBOL(…);
#endif

static inline bool check_la57_support(void)
{ … }

static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdval_t *pmd)
{ … }

/* Code in __startup_64() can be relocated during execution, but the compiler
 * doesn't have to generate PC-relative relocations when accessing globals from
 * that function. Clang actually does not generate them, which leads to
 * boot-time crashes. To work around this problem, every global pointer must
 * be accessed using RIP_REL_REF().
 */
unsigned long __head __startup_64(unsigned long physaddr,
				  struct boot_params *bp)
{ … }

/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
{ … }

/* Create a new PMD entry */
bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
{ … }

static bool __init early_make_pgtable(unsigned long address)
{ … }

void __init do_early_exception(struct pt_regs *regs, int trapnr)
{ … }

/* Don't add a printk in there. printk relies on the PDA which is not initialized 
   yet. */
void __init clear_bss(void)
{ … }

static unsigned long get_cmd_line_ptr(void)
{ … }

static void __init copy_bootdata(char *real_mode_data)
{ … }

asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data)
{ … }

void __init __noreturn x86_64_start_reservations(char *real_mode_data)
{ … }

/*
 * Data structures and code used for IDT setup in head_64.S. The bringup-IDT is
 * used until the idt_table takes over. On the boot CPU this happens in
 * x86_64_start_kernel(), on secondary CPUs in start_secondary(). In both cases
 * this happens in the functions called from head_64.S.
 *
 * The idt_table can't be used that early because all the code modifying it is
 * in idt.c and can be instrumented by tracing or KASAN, which both don't work
 * during early CPU bringup. Also the idt_table has the runtime vectors
 * configured which require certain CPU state to be setup already (like TSS),
 * which also hasn't happened yet in early CPU bringup.
 */
static gate_desc bringup_idt_table[NUM_EXCEPTION_VECTORS] __page_aligned_data;

/* This may run while still in the direct mapping */
static void __head startup_64_load_idt(void *vc_handler)
{ … }

/* This is used when running on kernel addresses */
void early_setup_idt(void)
{ … }

/*
 * Setup boot CPU state needed before kernel switches to virtual addresses.
 */
void __head startup_64_setup_gdt_idt(void)
{ … }