paravirt.h

linux 内核源代码

#ifndef __ASM_PARAVIRT_H
#define __ASM_PARAVIRT_H
/* Various instructions on x86 need to be replaced for
 * para-virtualization: those hooks are defined here. */

#ifdef CONFIG_PARAVIRT
#include <asm/page.h>

/* Bitmask of what can be clobbered: usually at least eax. */
#define CLBR_NONE 0x0
#define CLBR_EAX 0x1
#define CLBR_ECX 0x2
#define CLBR_EDX 0x4
#define CLBR_ANY 0x7

#ifndef __ASSEMBLY__
#include <linux/types.h>
#include <linux/cpumask.h>
#include <asm/kmap_types.h>

struct page;
struct thread_struct;
struct Xgt_desc_struct;
struct tss_struct;
struct mm_struct;
struct desc_struct;

/* general info */
struct pv_info {
	unsigned int kernel_rpl;
	int shared_kernel_pmd;
	int paravirt_enabled;
	const char *name;
};

struct pv_init_ops {
	/*
	 * Patch may replace one of the defined code sequences with
	 * arbitrary code, subject to the same register constraints.
	 * This generally means the code is not free to clobber any
	 * registers other than EAX.  The patch function should return
	 * the number of bytes of code generated, as we nop pad the
	 * rest in generic code.
	 */
	unsigned (*patch)(u8 type, u16 clobber, void *insnbuf,
			  unsigned long addr, unsigned len);

	/* Basic arch-specific setup */
	void (*arch_setup)(void);
	char *(*memory_setup)(void);
	void (*post_allocator_init)(void);

	/* Print a banner to identify the environment */
	void (*banner)(void);
};


struct pv_lazy_ops {
	/* Set deferred update mode, used for batching operations. */
	void (*enter)(void);
	void (*leave)(void);
};

struct pv_time_ops {
	void (*time_init)(void);

	/* Set and set time of day */
	unsigned long (*get_wallclock)(void);
	int (*set_wallclock)(unsigned long);

	unsigned long long (*sched_clock)(void);
	unsigned long (*get_cpu_khz)(void);
};

struct pv_cpu_ops {
	/* hooks for various privileged instructions */
	unsigned long (*get_debugreg)(int regno);
	void (*set_debugreg)(int regno, unsigned long value);

	void (*clts)(void);

	unsigned long (*read_cr0)(void);
	void (*write_cr0)(unsigned long);

	unsigned long (*read_cr4_safe)(void);
	unsigned long (*read_cr4)(void);
	void (*write_cr4)(unsigned long);

	/* Segment descriptor handling */
	void (*load_tr_desc)(void);
	void (*load_gdt)(const struct Xgt_desc_struct *);
	void (*load_idt)(const struct Xgt_desc_struct *);
	void (*store_gdt)(struct Xgt_desc_struct *);
	void (*store_idt)(struct Xgt_desc_struct *);
	void (*set_ldt)(const void *desc, unsigned entries);
	unsigned long (*store_tr)(void);
	void (*load_tls)(struct thread_struct *t, unsigned int cpu);
	void (*write_ldt_entry)(struct desc_struct *,
				int entrynum, u32 low, u32 high);
	void (*write_gdt_entry)(struct desc_struct *,
				int entrynum, u32 low, u32 high);
	void (*write_idt_entry)(struct desc_struct *,
				int entrynum, u32 low, u32 high);
	void (*load_esp0)(struct tss_struct *tss, struct thread_struct *t);

	void (*set_iopl_mask)(unsigned mask);

	void (*wbinvd)(void);
	void (*io_delay)(void);

	/* cpuid emulation, mostly so that caps bits can be disabled */
	void (*cpuid)(unsigned int *eax, unsigned int *ebx,
		      unsigned int *ecx, unsigned int *edx);

	/* MSR, PMC and TSR operations.
	   err = 0/-EFAULT.  wrmsr returns 0/-EFAULT. */
	u64 (*read_msr)(unsigned int msr, int *err);
	int (*write_msr)(unsigned int msr, u64 val);

	u64 (*read_tsc)(void);
	u64 (*read_pmc)(void);

	/* These two are jmp to, not actually called. */
	void (*irq_enable_sysexit)(void);
	void (*iret)(void);

	struct pv_lazy_ops lazy_mode;
};

struct pv_irq_ops {
	void (*init_IRQ)(void);

	/*
	 * Get/set interrupt state.  save_fl and restore_fl are only
	 * expected to use X86_EFLAGS_IF; all other bits
	 * returned from save_fl are undefined, and may be ignored by
	 * restore_fl.
	 */
	unsigned long (*save_fl)(void);
	void (*restore_fl)(unsigned long);
	void (*irq_disable)(void);
	void (*irq_enable)(void);
	void (*safe_halt)(void);
	void (*halt)(void);
};

struct pv_apic_ops {
#ifdef CONFIG_X86_LOCAL_APIC
	/*
	 * Direct APIC operations, principally for VMI.  Ideally
	 * these shouldn't be in this interface.
	 */
	void (*apic_write)(unsigned long reg, unsigned long v);
	void (*apic_write_atomic)(unsigned long reg, unsigned long v);
	unsigned long (*apic_read)(unsigned long reg);
	void (*setup_boot_clock)(void);
	void (*setup_secondary_clock)(void);

	void (*startup_ipi_hook)(int phys_apicid,
				 unsigned long start_eip,
				 unsigned long start_esp);
#endif
};

struct pv_mmu_ops {
	/*
	 * Called before/after init_mm pagetable setup. setup_start
	 * may reset %cr3, and may pre-install parts of the pagetable;
	 * pagetable setup is expected to preserve any existing
	 * mapping.
	 */
	void (*pagetable_setup_start)(pgd_t *pgd_base);
	void (*pagetable_setup_done)(pgd_t *pgd_base);

	unsigned long (*read_cr2)(void);
	void (*write_cr2)(unsigned long);

	unsigned long (*read_cr3)(void);
	void (*write_cr3)(unsigned long);

	/*
	 * Hooks for intercepting the creation/use/destruction of an
	 * mm_struct.
	 */
	void (*activate_mm)(struct mm_struct *prev,
			    struct mm_struct *next);
	void (*dup_mmap)(struct mm_struct *oldmm,
			 struct mm_struct *mm);
	void (*exit_mmap)(struct mm_struct *mm);


	/* TLB operations */
	void (*flush_tlb_user)(void);
	void (*flush_tlb_kernel)(void);
	void (*flush_tlb_single)(unsigned long addr);
	void (*flush_tlb_others)(const cpumask_t *cpus, struct mm_struct *mm,
				 unsigned long va);

	/* Hooks for allocating/releasing pagetable pages */
	void (*alloc_pt)(struct mm_struct *mm, u32 pfn);
	void (*alloc_pd)(u32 pfn);
	void (*alloc_pd_clone)(u32 pfn, u32 clonepfn, u32 start, u32 count);
	void (*release_pt)(u32 pfn);
	void (*release_pd)(u32 pfn);

	/* Pagetable manipulation functions */
	void (*set_pte)(pte_t *ptep, pte_t pteval);
	void (*set_pte_at)(struct mm_struct *mm, unsigned long addr,
			   pte_t *ptep, pte_t pteval);
	void (*set_pmd)(pmd_t *pmdp, pmd_t pmdval);
	void (*pte_update)(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
	void (*pte_update_defer)(struct mm_struct *mm,
				 unsigned long addr, pte_t *ptep);

#ifdef CONFIG_X86_PAE
	void (*set_pte_atomic)(pte_t *ptep, pte_t pteval);
	void (*set_pte_present)(struct mm_struct *mm, unsigned long addr,
				pte_t *ptep, pte_t pte);
	void (*set_pud)(pud_t *pudp, pud_t pudval);
	void (*pte_clear)(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
	void (*pmd_clear)(pmd_t *pmdp);

	unsigned long long (*pte_val)(pte_t);
	unsigned long long (*pmd_val)(pmd_t);
	unsigned long long (*pgd_val)(pgd_t);

	pte_t (*make_pte)(unsigned long long pte);
	pmd_t (*make_pmd)(unsigned long long pmd);
	pgd_t (*make_pgd)(unsigned long long pgd);
#else
	unsigned long (*pte_val)(pte_t);
	unsigned long (*pgd_val)(pgd_t);

	pte_t (*make_pte)(unsigned long pte);
	pgd_t (*make_pgd)(unsigned long pgd);
#endif

#ifdef CONFIG_HIGHPTE
	void *(*kmap_atomic_pte)(struct page *page, enum km_type type);
#endif

	struct pv_lazy_ops lazy_mode;
};

/* This contains all the paravirt structures: we get a convenient
 * number for each function using the offset which we use to indicate
 * what to patch. */
struct paravirt_patch_template
{
	struct pv_init_ops pv_init_ops;
	struct pv_time_ops pv_time_ops;
	struct pv_cpu_ops pv_cpu_ops;
	struct pv_irq_ops pv_irq_ops;
	struct pv_apic_ops pv_apic_ops;
	struct pv_mmu_ops pv_mmu_ops;
};

extern struct pv_info pv_info;
extern struct pv_init_ops pv_init_ops;
extern struct pv_time_ops pv_time_ops;
extern struct pv_cpu_ops pv_cpu_ops;
extern struct pv_irq_ops pv_irq_ops;
extern struct pv_apic_ops pv_apic_ops;
extern struct pv_mmu_ops pv_mmu_ops;

#define PARAVIRT_PATCH(x)					\
	(offsetof(struct paravirt_patch_template, x) / sizeof(void *))

#define paravirt_type(op)				\
	[paravirt_typenum] "i" (PARAVIRT_PATCH(op)),	\
	[paravirt_opptr] "m" (op)
#define paravirt_clobber(clobber)		\
	[paravirt_clobber] "i" (clobber)

/*
 * Generate some code, and mark it as patchable by the
 * apply_paravirt() alternate instruction patcher.
 */
#define _paravirt_alt(insn_string, type, clobber)	\
	"771:\n\t" insn_string "\n" "772:\n"		\
	".pushsection .parainstructions,\"a\"\n"	\
	"  .long 771b\n"				\
	"  .byte " type "\n"				\
	"  .byte 772b-771b\n"				\
	"  .short " clobber "\n"			\
	".popsection\n"

/* Generate patchable code, with the default asm parameters. */
#define paravirt_alt(insn_string)					\
	_paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]")

unsigned paravirt_patch_nop(void);
unsigned paravirt_patch_ignore(unsigned len);
unsigned paravirt_patch_call(void *insnbuf,
			     const void *target, u16 tgt_clobbers,
			     unsigned long addr, u16 site_clobbers,
			     unsigned len);
unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
			    unsigned long addr, unsigned len);
unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
				unsigned long addr, unsigned len);

unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
			      const char *start, const char *end);

int paravirt_disable_iospace(void);

/*
 * This generates an indirect call based on the operation type number.
 * The type number, computed in PARAVIRT_PATCH, is derived from the
 * offset into the paravirt_patch_template structure, and can therefore be
 * freely converted back into a structure offset.
 */
#define PARAVIRT_CALL	"call *%[paravirt_opptr];"

/*
 * These macros are intended to wrap calls through one of the paravirt
 * ops structs, so that they can be later identified and patched at
 * runtime.
 *
 * Normally, a call to a pv_op function is a simple indirect call:
 * (paravirt_ops.operations)(args...).
 *
 * Unfortunately, this is a relatively slow operation for modern CPUs,
 * because it cannot necessarily determine what the destination
 * address is.  In this case, the address is a runtime constant, so at
 * the very least we can patch the call to e a simple direct call, or
 * ideally, patch an inline implementation into the callsite.  (Direct
 * calls are essentially free, because the call and return addresses
 * are completely predictable.)
 *
 * These macros rely on the standard gcc "regparm(3)" calling
 * convention, in which the first three arguments are placed in %eax,
 * %edx, %ecx (in that order), and the remaining arguments are placed
 * on the stack.  All caller-save registers (eax,edx,ecx) are expected
 * to be modified (either clobbered or used for return values).
 *
 * The call instruction itself is marked by placing its start address
 * and size into the .parainstructions section, so that
 * apply_paravirt() in arch/i386/kernel/alternative.c can do the
 * appropriate patching under the control of the backend pv_init_ops
 * implementation.
 *
 * Unfortunately there's no way to get gcc to generate the args setup
 * for the call, and then allow the call itself to be generated by an
 * inline asm.  Because of this, we must do the complete arg setup and
 * return value handling from within these macros.  This is fairly
 * cumbersome.
 *
 * There are 5 sets of PVOP_* macros for dealing with 0-4 arguments.
 * It could be extended to more arguments, but there would be little
 * to be gained from that.  For each number of arguments, there are
 * the two VCALL and CALL variants for void and non-void functions.
 *
 * When there is a return value, the invoker of the macro must specify
 * the return type.  The macro then uses sizeof() on that type to
 * determine whether its a 32 or 64 bit value, and places the return
 * in the right register(s) (just %eax for 32-bit, and %edx:%eax for
 * 64-bit).
 *
 * 64-bit arguments are passed as a pair of adjacent 32-bit arguments
 * in low,high order.
 *
 * Small structures are passed and returned in registers.  The macro
 * calling convention can't directly deal with this, so the wrapper
 * functions must do this.
 *
 * These PVOP_* macros are only defined within this header.  This
 * means that all uses must be wrapped in inline functions.  This also
 * makes sure the incoming and outgoing types are always correct.
 */
#define __PVOP_CALL(rettype, op, pre, post, ...)			\
	({								\
		rettype __ret;						\
		unsigned long __eax, __edx, __ecx;			\
		if (sizeof(rettype) > sizeof(unsigned long)) {		\
			asm volatile(pre				\
				     paravirt_alt(PARAVIRT_CALL)	\
				     post				\
				     : "=a" (__eax), "=d" (__edx),	\
				       "=c" (__ecx)			\
				     : paravirt_type(op),		\
				       paravirt_clobber(CLBR_ANY),	\
				       ##__VA_ARGS__			\
				     : "memory", "cc");			\