Commit 294688c0 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Andi Kleen

[PATCH] i386: PARAVIRT: Document asm-i386/paravirt.h

Clean things up, and broadly document:
 - the paravirt_ops functions themselves
 - the patching mechanism
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
parent f8822f42
...@@ -21,6 +21,14 @@ struct Xgt_desc_struct; ...@@ -21,6 +21,14 @@ struct Xgt_desc_struct;
struct tss_struct; struct tss_struct;
struct mm_struct; struct mm_struct;
struct desc_struct; struct desc_struct;
/* Lazy mode for batching updates / context switch */
enum paravirt_lazy_mode {
PARAVIRT_LAZY_NONE = 0,
PARAVIRT_LAZY_MMU = 1,
PARAVIRT_LAZY_CPU = 2,
};
struct paravirt_ops struct paravirt_ops
{ {
unsigned int kernel_rpl; unsigned int kernel_rpl;
...@@ -37,22 +45,33 @@ struct paravirt_ops ...@@ -37,22 +45,33 @@ struct paravirt_ops
*/ */
unsigned (*patch)(u8 type, u16 clobber, void *firstinsn, unsigned len); unsigned (*patch)(u8 type, u16 clobber, void *firstinsn, unsigned len);
/* Basic arch-specific setup */
void (*arch_setup)(void); void (*arch_setup)(void);
char *(*memory_setup)(void); char *(*memory_setup)(void);
void (*init_IRQ)(void); void (*init_IRQ)(void);
void (*time_init)(void);
/*
* 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_start)(pgd_t *pgd_base);
void (*pagetable_setup_done)(pgd_t *pgd_base); void (*pagetable_setup_done)(pgd_t *pgd_base);
/* Print a banner to identify the environment */
void (*banner)(void); void (*banner)(void);
/* Set and set time of day */
unsigned long (*get_wallclock)(void); unsigned long (*get_wallclock)(void);
int (*set_wallclock)(unsigned long); int (*set_wallclock)(unsigned long);
void (*time_init)(void);
/* cpuid emulation, mostly so that caps bits can be disabled */
void (*cpuid)(unsigned int *eax, unsigned int *ebx, void (*cpuid)(unsigned int *eax, unsigned int *ebx,
unsigned int *ecx, unsigned int *edx); unsigned int *ecx, unsigned int *edx);
/* hooks for various privileged instructions */
unsigned long (*get_debugreg)(int regno); unsigned long (*get_debugreg)(int regno);
void (*set_debugreg)(int regno, unsigned long value); void (*set_debugreg)(int regno, unsigned long value);
...@@ -71,15 +90,23 @@ struct paravirt_ops ...@@ -71,15 +90,23 @@ struct paravirt_ops
unsigned long (*read_cr4)(void); unsigned long (*read_cr4)(void);
void (*write_cr4)(unsigned long); void (*write_cr4)(unsigned long);
/*
* 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); unsigned long (*save_fl)(void);
void (*restore_fl)(unsigned long); void (*restore_fl)(unsigned long);
void (*irq_disable)(void); void (*irq_disable)(void);
void (*irq_enable)(void); void (*irq_enable)(void);
void (*safe_halt)(void); void (*safe_halt)(void);
void (*halt)(void); void (*halt)(void);
void (*wbinvd)(void); void (*wbinvd)(void);
/* err = 0/-EFAULT. wrmsr returns 0/-EFAULT. */ /* MSR, PMC and TSR operations.
err = 0/-EFAULT. wrmsr returns 0/-EFAULT. */
u64 (*read_msr)(unsigned int msr, int *err); u64 (*read_msr)(unsigned int msr, int *err);
int (*write_msr)(unsigned int msr, u64 val); int (*write_msr)(unsigned int msr, u64 val);
...@@ -88,6 +115,7 @@ struct paravirt_ops ...@@ -88,6 +115,7 @@ struct paravirt_ops
u64 (*get_scheduled_cycles)(void); u64 (*get_scheduled_cycles)(void);
unsigned long (*get_cpu_khz)(void); unsigned long (*get_cpu_khz)(void);
/* Segment descriptor handling */
void (*load_tr_desc)(void); void (*load_tr_desc)(void);
void (*load_gdt)(const struct Xgt_desc_struct *); void (*load_gdt)(const struct Xgt_desc_struct *);
void (*load_idt)(const struct Xgt_desc_struct *); void (*load_idt)(const struct Xgt_desc_struct *);
...@@ -105,9 +133,12 @@ struct paravirt_ops ...@@ -105,9 +133,12 @@ struct paravirt_ops
void (*load_esp0)(struct tss_struct *tss, struct thread_struct *t); void (*load_esp0)(struct tss_struct *tss, struct thread_struct *t);
void (*set_iopl_mask)(unsigned mask); void (*set_iopl_mask)(unsigned mask);
void (*io_delay)(void); void (*io_delay)(void);
/*
* Hooks for intercepting the creation/use/destruction of an
* mm_struct.
*/
void (*activate_mm)(struct mm_struct *prev, void (*activate_mm)(struct mm_struct *prev,
struct mm_struct *next); struct mm_struct *next);
void (*dup_mmap)(struct mm_struct *oldmm, void (*dup_mmap)(struct mm_struct *oldmm,
...@@ -115,30 +146,43 @@ struct paravirt_ops ...@@ -115,30 +146,43 @@ struct paravirt_ops
void (*exit_mmap)(struct mm_struct *mm); void (*exit_mmap)(struct mm_struct *mm);
#ifdef CONFIG_X86_LOCAL_APIC #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)(unsigned long reg, unsigned long v);
void (*apic_write_atomic)(unsigned long reg, unsigned long v); void (*apic_write_atomic)(unsigned long reg, unsigned long v);
unsigned long (*apic_read)(unsigned long reg); unsigned long (*apic_read)(unsigned long reg);
void (*setup_boot_clock)(void); void (*setup_boot_clock)(void);
void (*setup_secondary_clock)(void); void (*setup_secondary_clock)(void);
void (*startup_ipi_hook)(int phys_apicid,
unsigned long start_eip,
unsigned long start_esp);
#endif #endif
/* TLB operations */
void (*flush_tlb_user)(void); void (*flush_tlb_user)(void);
void (*flush_tlb_kernel)(void); void (*flush_tlb_kernel)(void);
void (*flush_tlb_single)(unsigned long addr); void (*flush_tlb_single)(unsigned long addr);
void (*map_pt_hook)(int type, pte_t *va, u32 pfn); void (*map_pt_hook)(int type, pte_t *va, u32 pfn);
/* Hooks for allocating/releasing pagetable pages */
void (*alloc_pt)(u32 pfn); void (*alloc_pt)(u32 pfn);
void (*alloc_pd)(u32 pfn); void (*alloc_pd)(u32 pfn);
void (*alloc_pd_clone)(u32 pfn, u32 clonepfn, u32 start, u32 count); void (*alloc_pd_clone)(u32 pfn, u32 clonepfn, u32 start, u32 count);
void (*release_pt)(u32 pfn); void (*release_pt)(u32 pfn);
void (*release_pd)(u32 pfn); void (*release_pd)(u32 pfn);
/* Pagetable manipulation functions */
void (*set_pte)(pte_t *ptep, pte_t pteval); 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_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 (*set_pmd)(pmd_t *pmdp, pmd_t pmdval);
void (*pte_update)(struct mm_struct *mm, unsigned long addr, pte_t *ptep); 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); void (*pte_update_defer)(struct mm_struct *mm,
unsigned long addr, pte_t *ptep);
pte_t (*ptep_get_and_clear)(pte_t *ptep); pte_t (*ptep_get_and_clear)(pte_t *ptep);
...@@ -164,13 +208,12 @@ struct paravirt_ops ...@@ -164,13 +208,12 @@ struct paravirt_ops
pgd_t (*make_pgd)(unsigned long pgd); pgd_t (*make_pgd)(unsigned long pgd);
#endif #endif
void (*set_lazy_mode)(int mode); /* Set deferred update mode, used for batching operations. */
void (*set_lazy_mode)(enum paravirt_lazy_mode mode);
/* These two are jmp to, not actually called. */ /* These two are jmp to, not actually called. */
void (*irq_enable_sysexit)(void); void (*irq_enable_sysexit)(void);
void (*iret)(void); void (*iret)(void);
void (*startup_ipi_hook)(int phys_apicid, unsigned long start_eip, unsigned long start_esp);
}; };
/* Mark a paravirt probe function. */ /* Mark a paravirt probe function. */
...@@ -188,8 +231,10 @@ extern struct paravirt_ops paravirt_ops; ...@@ -188,8 +231,10 @@ extern struct paravirt_ops paravirt_ops;
#define paravirt_clobber(clobber) \ #define paravirt_clobber(clobber) \
[paravirt_clobber] "i" (clobber) [paravirt_clobber] "i" (clobber)
#define PARAVIRT_CALL "call *(paravirt_ops+%c[paravirt_typenum]*4);" /*
* Generate some code, and mark it as patchable by the
* apply_paravirt() alternate instruction patcher.
*/
#define _paravirt_alt(insn_string, type, clobber) \ #define _paravirt_alt(insn_string, type, clobber) \
"771:\n\t" insn_string "\n" "772:\n" \ "771:\n\t" insn_string "\n" "772:\n" \
".pushsection .parainstructions,\"a\"\n" \ ".pushsection .parainstructions,\"a\"\n" \
...@@ -199,9 +244,74 @@ extern struct paravirt_ops paravirt_ops; ...@@ -199,9 +244,74 @@ extern struct paravirt_ops paravirt_ops;
" .short " clobber "\n" \ " .short " clobber "\n" \
".popsection\n" ".popsection\n"
/* Generate patchable code, with the default asm parameters. */
#define paravirt_alt(insn_string) \ #define paravirt_alt(insn_string) \
_paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]") _paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]")
/*
* 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_ops structure, and can therefore be freely
* converted back into a structure offset.
*/
#define PARAVIRT_CALL "call *(paravirt_ops+%c[paravirt_typenum]*4);"
/*
* These macros are intended to wrap calls into a paravirt_ops
* operation, 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 paravirt_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_CALL0(__rettype, __op) \ #define PVOP_CALL0(__rettype, __op) \
({ \ ({ \
__rettype __ret; \ __rettype __ret; \
...@@ -1026,6 +1136,7 @@ static inline unsigned long __raw_local_irq_save(void) ...@@ -1026,6 +1136,7 @@ static inline unsigned long __raw_local_irq_save(void)
[paravirt_sti_type] "i" (PARAVIRT_PATCH(irq_enable)), \ [paravirt_sti_type] "i" (PARAVIRT_PATCH(irq_enable)), \
paravirt_clobber(CLBR_EAX) paravirt_clobber(CLBR_EAX)
/* Make sure as little as possible of this mess escapes. */
#undef PARAVIRT_CALL #undef PARAVIRT_CALL
#undef PVOP_VCALL0 #undef PVOP_VCALL0
#undef PVOP_CALL0 #undef PVOP_CALL0
......
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