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/ *
*
* Copyright ( C ) 1 9 9 1 , 1 9 9 2 L i n u s T o r v a l d s
*
* Enhanced C P U d e t e c t i o n a n d f e a t u r e s e t t i n g c o d e b y M i k e J a g d i s
* and M a r t i n M a r e s , N o v e m b e r 1 9 9 7 .
* /
.text
# include < l i n u x / t h r e a d s . h >
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# include < l i n u x / i n i t . h >
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# include < l i n u x / l i n k a g e . h >
# include < a s m / s e g m e n t . h >
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# include < a s m / p a g e _ t y p e s . h >
# include < a s m / p g t a b l e _ t y p e s . h >
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# include < a s m / c a c h e . h >
# include < a s m / t h r e a d _ i n f o . h >
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# include < a s m / a s m - o f f s e t s . h >
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# include < a s m / s e t u p . h >
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# include < a s m / p r o c e s s o r - f l a g s . h >
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# include < a s m / m s r - i n d e x . h >
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# include < a s m / c p u f e a t u r e s . h >
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# include < a s m / p e r c p u . h >
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# include < a s m / n o p s . h >
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# include < a s m / b o o t p a r a m . h >
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# include < a s m / e x p o r t . h >
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# include < a s m / p g t a b l e _ 3 2 . h >
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/* Physical address */
# define p a ( X ) ( ( X ) - _ _ P A G E _ O F F S E T )
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/ *
* References t o m e m b e r s o f t h e n e w _ c p u _ d a t a s t r u c t u r e .
* /
# define X 8 6 n e w _ c p u _ d a t a + C P U I N F O _ x86
# define X 8 6 _ V E N D O R n e w _ c p u _ d a t a + C P U I N F O _ x86 _ v e n d o r
# define X 8 6 _ M O D E L n e w _ c p u _ d a t a + C P U I N F O _ x86 _ m o d e l
# define X 8 6 _ M A S K n e w _ c p u _ d a t a + C P U I N F O _ x86 _ m a s k
# define X 8 6 _ H A R D _ M A T H n e w _ c p u _ d a t a + C P U I N F O _ h a r d _ m a t h
# define X 8 6 _ C P U I D n e w _ c p u _ d a t a + C P U I N F O _ c p u i d _ l e v e l
# define X 8 6 _ C A P A B I L I T Y n e w _ c p u _ d a t a + C P U I N F O _ x86 _ c a p a b i l i t y
# define X 8 6 _ V E N D O R _ I D n e w _ c p u _ d a t a + C P U I N F O _ x86 _ v e n d o r _ i d
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# define S I Z E O F _ P T R E G S 1 7 * 4
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/ *
* Worst- c a s e s i z e o f t h e k e r n e l m a p p i n g w e n e e d t o m a k e :
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* a r e l o c a t a b l e k e r n e l c a n l i v e a n y w h e r e i n l o w m e m , s o w e n e e d t o b e a b l e
* to m a p a l l o f l o w m e m .
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* /
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KERNEL_ P A G E S = L O W M E M _ P A G E S
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INIT_ M A P _ S I Z E = P A G E _ T A B L E _ S I Z E ( K E R N E L _ P A G E S ) * P A G E _ S I Z E
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RESERVE_ B R K ( p a g e t a b l e s , I N I T _ M A P _ S I Z E )
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/ *
* 3 2 - bit k e r n e l e n t r y p o i n t ; only used by the boot CPU. On entry,
* % esi p o i n t s t o t h e r e a l - m o d e c o d e a s a 3 2 - b i t p o i n t e r .
* CS a n d D S m u s t b e 4 G B f l a t s e g m e n t s , b u t w e d o n ' t d e p e n d o n
* any p a r t i c u l a r G D T l a y o u t , b e c a u s e w e l o a d o u r o w n a s s o o n a s w e
* can.
* /
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_ _ HEAD
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ENTRY( s t a r t u p _ 3 2 )
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movl p a ( i n i t i a l _ s t a c k ) ,% e c x
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/ * test K E E P _ S E G M E N T S f l a g t o s e e i f t h e b o o t l o a d e r i s a s k i n g
us t o n o t r e l o a d s e g m e n t s * /
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testb $ K E E P _ S E G M E N T S , B P _ l o a d f l a g s ( % e s i )
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jnz 2 f
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/ *
* Set s e g m e n t s t o k n o w n v a l u e s .
* /
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lgdt p a ( b o o t _ g d t _ d e s c r )
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movl $ ( _ _ B O O T _ D S ) ,% e a x
movl % e a x ,% d s
movl % e a x ,% e s
movl % e a x ,% f s
movl % e a x ,% g s
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movl % e a x ,% s s
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2 :
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leal - _ _ P A G E _ O F F S E T ( % e c x ) ,% e s p
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/ *
* Clear B S S f i r s t s o t h a t t h e r e a r e n o s u r p r i s e s . . .
* /
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cld
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xorl % e a x ,% e a x
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movl $ p a ( _ _ b s s _ s t a r t ) ,% e d i
movl $ p a ( _ _ b s s _ s t o p ) ,% e c x
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subl % e d i ,% e c x
shrl $ 2 ,% e c x
rep ; stosl
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/ *
* Copy b o o t u p p a r a m e t e r s o u t o f t h e w a y .
* Note : % esi s t i l l h a s t h e p o i n t e r t o t h e r e a l - m o d e d a t a .
* With t h e k e x e c a s b o o t l o a d e r , p a r a m e t e r s e g m e n t m i g h t b e l o a d e d b e y o n d
* kernel i m a g e a n d m i g h t n o t e v e n b e a d d r e s s a b l e b y e a r l y b o o t p a g e t a b l e s .
* ( kexec o n p a n i c c a s e ) . H e n c e c o p y o u t t h e p a r a m e t e r s b e f o r e i n i t i a l i z i n g
* page t a b l e s .
* /
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movl $ p a ( b o o t _ p a r a m s ) ,% e d i
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movl $ ( P A R A M _ S I Z E / 4 ) ,% e c x
cld
rep
movsl
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movl p a ( b o o t _ p a r a m s ) + N E W _ C L _ P O I N T E R ,% e s i
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andl % e s i ,% e s i
tree-wide: fix comment/printk typos
"gadget", "through", "command", "maintain", "maintain", "controller", "address",
"between", "initiali[zs]e", "instead", "function", "select", "already",
"equal", "access", "management", "hierarchy", "registration", "interest",
"relative", "memory", "offset", "already",
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-11-01 22:38:34 +03:00
jz 1 f # N o c o m m a n d l i n e
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movl $ p a ( b o o t _ c o m m a n d _ l i n e ) ,% e d i
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movl $ ( C O M M A N D _ L I N E _ S I Z E / 4 ) ,% e c x
rep
movsl
1 :
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# ifdef C O N F I G _ O L P C
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/* save OFW's pgdir table for later use when calling into OFW */
movl % c r3 , % e a x
movl % e a x , p a ( o l p c _ o f w _ p g d )
# endif
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# ifdef C O N F I G _ M I C R O C O D E
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/* Early load ucode on BSP. */
call l o a d _ u c o d e _ b s p
# endif
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/* Create early pagetables. */
call m k _ e a r l y _ p g t b l _ 3 2
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/* Do early initialization of the fixmap area */
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movl $ p a ( i n i t i a l _ p g _ f i x m a p ) + P D E _ I D E N T _ A T T R ,% e a x
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# ifdef C O N F I G _ X 8 6 _ P A E
# define K P M D S ( ( ( - _ _ P A G E _ O F F S E T ) > > 3 0 ) & 3 ) / * N u m b e r o f k e r n e l P M D s * /
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movl % e a x ,p a ( i n i t i a l _ p g _ p m d + 0 x10 0 0 * K P M D S - 8 )
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# else
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movl % e a x ,p a ( i n i t i a l _ p a g e _ t a b l e + 0 x f f c )
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# endif
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# ifdef C O N F I G _ P A R A V I R T
/* This is can only trip for a broken bootloader... */
cmpw $ 0 x20 7 , p a ( b o o t _ p a r a m s + B P _ v e r s i o n )
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jb . L d e f a u l t _ e n t r y
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/ * Paravirt- c o m p a t i b l e b o o t p a r a m e t e r s . L o o k t o s e e w h a t a r c h i t e c t u r e
we' r e b o o t i n g u n d e r . * /
movl p a ( b o o t _ p a r a m s + B P _ h a r d w a r e _ s u b a r c h ) , % e a x
cmpl $ n u m _ s u b a r c h _ e n t r i e s , % e a x
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jae . L b a d _ s u b a r c h
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movl p a ( s u b a r c h _ e n t r i e s ) ( ,% e a x ,4 ) , % e a x
subl $ _ _ P A G E _ O F F S E T , % e a x
jmp * % e a x
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.Lbad_subarch :
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WEAK( l g u e s t _ e n t r y )
WEAK( x e n _ e n t r y )
/ * Unknown i m p l e m e n t a t i o n ; there's really
nothing w e c a n d o a t t h i s p o i n t . * /
ud2 a
_ _ INITDATA
subarch_entries :
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.long .Ldefault_entry /* normal x86/PC */
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.long lguest_entry /* lguest hypervisor */
.long xen_entry /* Xen hypervisor */
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.long .Ldefault_entry /* Moorestown MID */
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num_ s u b a r c h _ e n t r i e s = ( . - s u b a r c h _ e n t r i e s ) / 4
.previous
# else
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jmp . L d e f a u l t _ e n t r y
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# endif / * C O N F I G _ P A R A V I R T * /
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# ifdef C O N F I G _ H O T P L U G _ C P U
/ *
* Boot C P U 0 e n t r y p o i n t . I t ' s c a l l e d f r o m p l a y _ d e a d ( ) . E v e r y t h i n g h a s b e e n s e t
* up a l r e a d y e x c e p t s t a c k . W e j u s t s e t u p s t a c k h e r e . T h e n c a l l
* start_ s e c o n d a r y ( ) .
* /
ENTRY( s t a r t _ c p u 0 )
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movl i n i t i a l _ s t a c k , % e c x
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movl % e c x , % e s p
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call * ( i n i t i a l _ c o d e )
1 : jmp 1 b
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ENDPROC( s t a r t _ c p u 0 )
# endif
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/ *
* Non- b o o t C P U e n t r y p o i n t ; entered from trampoline.S
* We c a n ' t l g d t h e r e , b e c a u s e l g d t i t s e l f u s e s a d a t a s e g m e n t , b u t
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* we k n o w t h e t r a m p o l i n e h a s a l r e a d y l o a d e d t h e b o o t _ g d t f o r u s .
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*
* If c p u h o t p l u g i s n o t s u p p o r t e d t h e n t h i s c o d e c a n g o i n i n i t s e c t i o n
* which w i l l b e f r e e d l a t e r
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* /
ENTRY( s t a r t u p _ 3 2 _ s m p )
cld
movl $ ( _ _ B O O T _ D S ) ,% e a x
movl % e a x ,% d s
movl % e a x ,% e s
movl % e a x ,% f s
movl % e a x ,% g s
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movl p a ( i n i t i a l _ s t a c k ) ,% e c x
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movl % e a x ,% s s
leal - _ _ P A G E _ O F F S E T ( % e c x ) ,% e s p
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# ifdef C O N F I G _ M I C R O C O D E
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/* Early load ucode on AP. */
call l o a d _ u c o d e _ a p
# endif
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.Ldefault_entry :
x86-32: Start out cr0 clean, disable paging before modifying cr3/4
Patch
5a5a51db78e x86-32: Start out eflags and cr4 clean
... made x86-32 match x86-64 in that we initialize %eflags and %cr4
from scratch. This broke OLPC XO-1.5, because the XO enters the
kernel with paging enabled, which the kernel doesn't expect.
Since we no longer support 386 (the source of most of the variability
in %cr0 configuration), we can simply match further x86-64 and
initialize %cr0 to a fixed value -- the one variable part remaining in
%cr0 is for FPU control, but all that is handled later on in
initialization; in particular, configuring %cr0 as if the FPU is
present until proven otherwise is correct and necessary for the probe
to work.
To deal with the XO case sanely, explicitly disable paging in %cr0
before we muck with %cr3, %cr4 or EFER -- those operations are
inherently unsafe with paging enabled.
NOTE: There is still a lot of 386-related junk in head_32.S which we
can and should get rid of, however, this is intended as a minimal fix
whereas the cleanup can be deferred to the next merge window.
Reported-by: Andres Salomon <dilinger@queued.net>
Tested-by: Daniel Drake <dsd@laptop.org>
Link: http://lkml.kernel.org/r/50FA0661.2060400@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-01-19 22:29:37 +04:00
# define C R 0 _ S T A T E ( X 8 6 _ C R 0 _ P E | X 8 6 _ C R 0 _ M P | X 8 6 _ C R 0 _ E T | \
X8 6 _ C R 0 _ N E | X 8 6 _ C R 0 _ W P | X 8 6 _ C R 0 _ A M | \
X8 6 _ C R 0 _ P G )
movl $ ( C R 0 _ S T A T E & ~ X 8 6 _ C R 0 _ P G ) ,% e a x
movl % e a x ,% c r0
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/ *
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* We w a n t t o s t a r t o u t w i t h E F L A G S u n a m b i g u o u s l y c l e a r e d . S o m e B I O S e s l e a v e
* bits l i k e N T s e t . T h i s w o u l d c o n f u s e t h e d e b u g g e r i f t h i s c o d e i s t r a c e d . S o
* initialize t h e m p r o p e r l y n o w b e f o r e s w i t c h i n g t o p r o t e c t e d m o d e . T h a t m e a n s
* DF i n p a r t i c u l a r ( e v e n t h o u g h w e h a v e c l e a r e d i t e a r l i e r a f t e r c o p y i n g t h e
* command l i n e ) b e c a u s e G C C e x p e c t s i t .
* /
pushl $ 0
popfl
/ *
* New p a g e t a b l e s m a y b e i n 4 M b y t e p a g e m o d e a n d m a y b e u s i n g t h e g l o b a l p a g e s .
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*
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* NOTE! I f w e a r e o n a 4 8 6 w e m a y h a v e n o c r4 a t a l l ! S p e c i f i c a l l y , c r4 e x i s t s
* if a n d o n l y i f C P U I D e x i s t s a n d h a s f l a g s o t h e r t h a n t h e F P U f l a g s e t .
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* /
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movl $ - 1 ,p a ( X 8 6 _ C P U I D ) # p r e s e t C P U I D l e v e l
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movl $ X 8 6 _ E F L A G S _ I D ,% e c x
pushl % e c x
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popfl # s e t E F L A G S = I D
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pushfl
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popl % e a x # g e t E F L A G S
testl $ X 8 6 _ E F L A G S _ I D ,% e a x # d i d E F L A G S . I D r e m a i n e d s e t ?
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jz . L e n a b l e _ p a g i n g # h w d i s a l l o w e d s e t t i n g o f I D b i t
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# which m e a n s n o C P U I D a n d n o C R 4
xorl % e a x ,% e a x
cpuid
movl % e a x ,p a ( X 8 6 _ C P U I D ) # s a v e l a r g e s t s t d C P U I D f u n c t i o n
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movl $ 1 ,% e a x
cpuid
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andl $ ~ 1 ,% e d x # I g n o r e C P U I D . F P U
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jz . L e n a b l e _ p a g i n g # N o f l a g s o r o n l y C P U I D . F P U = n o C R 4
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2012-09-25 03:05:48 +04:00
movl p a ( m m u _ c r4 _ f e a t u r e s ) ,% e a x
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movl % e a x ,% c r4
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testb $ X 8 6 _ C R 4 _ P A E , % a l # c h e c k i f P A E i s e n a b l e d
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jz . L e n a b l e _ p a g i n g
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/* Check if extended functions are implemented */
movl $ 0 x80 0 0 0 0 0 0 , % e a x
cpuid
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/* Value must be in the range 0x80000001 to 0x8000ffff */
subl $ 0 x80 0 0 0 0 0 1 , % e a x
cmpl $ ( 0 x80 0 0 f f f f - 0 x80 0 0 0 0 0 1 ) , % e a x
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ja . L e n a b l e _ p a g i n g
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/* Clear bogus XD_DISABLE bits */
call v e r i f y _ c p u
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mov $ 0 x80 0 0 0 0 0 1 , % e a x
cpuid
/* Execute Disable bit supported? */
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btl $ ( X 8 6 _ F E A T U R E _ N X & 3 1 ) , % e d x
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jnc . L e n a b l e _ p a g i n g
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/* Setup EFER (Extended Feature Enable Register) */
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movl $ M S R _ E F E R , % e c x
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rdmsr
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btsl $ _ E F E R _ N X , % e a x
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/* Make changes effective */
wrmsr
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.Lenable_paging :
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/ *
* Enable p a g i n g
* /
2010-08-28 17:58:33 +04:00
movl $ p a ( i n i t i a l _ p a g e _ t a b l e ) , % e a x
2005-04-17 02:20:36 +04:00
movl % e a x ,% c r3 / * s e t t h e p a g e t a b l e p o i n t e r . . * /
x86-32: Start out cr0 clean, disable paging before modifying cr3/4
Patch
5a5a51db78e x86-32: Start out eflags and cr4 clean
... made x86-32 match x86-64 in that we initialize %eflags and %cr4
from scratch. This broke OLPC XO-1.5, because the XO enters the
kernel with paging enabled, which the kernel doesn't expect.
Since we no longer support 386 (the source of most of the variability
in %cr0 configuration), we can simply match further x86-64 and
initialize %cr0 to a fixed value -- the one variable part remaining in
%cr0 is for FPU control, but all that is handled later on in
initialization; in particular, configuring %cr0 as if the FPU is
present until proven otherwise is correct and necessary for the probe
to work.
To deal with the XO case sanely, explicitly disable paging in %cr0
before we muck with %cr3, %cr4 or EFER -- those operations are
inherently unsafe with paging enabled.
NOTE: There is still a lot of 386-related junk in head_32.S which we
can and should get rid of, however, this is intended as a minimal fix
whereas the cleanup can be deferred to the next merge window.
Reported-by: Andres Salomon <dilinger@queued.net>
Tested-by: Daniel Drake <dsd@laptop.org>
Link: http://lkml.kernel.org/r/50FA0661.2060400@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-01-19 22:29:37 +04:00
movl $ C R 0 _ S T A T E ,% e a x
2005-04-17 02:20:36 +04:00
movl % e a x ,% c r0 / * . . a n d s e t p a g i n g ( P G ) b i t * /
ljmp $ _ _ B O O T _ C S ,$ 1 f / * C l e a r p r e f e t c h a n d n o r m a l i z e % e i p * /
1 :
2011-02-05 03:14:11 +03:00
/* Shift the stack pointer to a virtual address */
addl $ _ _ P A G E _ O F F S E T , % e s p
2005-04-17 02:20:36 +04:00
/ *
* start s y s t e m 3 2 - b i t s e t u p . W e n e e d t o r e - d o s o m e o f t h e t h i n g s d o n e
* in 1 6 - b i t m o d e f o r t h e " r e a l " o p e r a t i o n s .
* /
2012-04-19 04:16:50 +04:00
movl s e t u p _ o n c e _ r e f ,% e a x
andl % e a x ,% e a x
jz 1 f # D i d w e d o t h i s a l r e a d y ?
call * % e a x
1 :
2013-02-11 18:22:15 +04:00
2005-04-17 02:20:36 +04:00
/ *
2013-02-11 18:22:15 +04:00
* Check i f i t i s 4 8 6
2005-04-17 02:20:36 +04:00
* /
2013-06-28 18:45:16 +04:00
movb $ 4 ,X 8 6 # a t l e a s t 486
2013-02-11 18:22:17 +04:00
cmpl $ - 1 ,X 8 6 _ C P U I D
2016-09-22 00:03:59 +03:00
je . L i s48 6
2005-04-17 02:20:36 +04:00
/* get vendor info */
xorl % e a x ,% e a x # c a l l C P U I D w i t h 0 - > r e t u r n v e n d o r I D
cpuid
movl % e a x ,X 8 6 _ C P U I D # s a v e C P U I D l e v e l
movl % e b x ,X 8 6 _ V E N D O R _ I D # l o 4 c h a r s
movl % e d x ,X 8 6 _ V E N D O R _ I D + 4 # n e x t 4 c h a r s
movl % e c x ,X 8 6 _ V E N D O R _ I D + 8 # l a s t 4 c h a r s
orl % e a x ,% e a x # d o w e h a v e p r o c e s s o r i n f o a s w e l l ?
2016-09-22 00:03:59 +03:00
je . L i s48 6
2005-04-17 02:20:36 +04:00
movl $ 1 ,% e a x # U s e t h e C P U I D i n s t r u c t i o n t o g e t C P U t y p e
cpuid
movb % a l ,% c l # s a v e r e g f o r f u t u r e u s e
andb $ 0 x0 f ,% a h # m a s k p r o c e s s o r f a m i l y
movb % a h ,X 8 6
andb $ 0 x f0 ,% a l # m a s k m o d e l
shrb $ 4 ,% a l
movb % a l ,X 8 6 _ M O D E L
andb $ 0 x0 f ,% c l # m a s k m a s k r e v i s i o n
movb % c l ,X 8 6 _ M A S K
movl % e d x ,X 8 6 _ C A P A B I L I T Y
2016-09-22 00:03:59 +03:00
.Lis486 :
2013-02-11 18:22:17 +04:00
movl $ 0 x50 0 2 2 ,% e c x # s e t A M , W P , N E a n d M P
2013-02-11 18:22:15 +04:00
movl % c r0 ,% e a x
2005-04-17 02:20:36 +04:00
andl $ 0 x80 0 0 0 0 1 1 ,% e a x # S a v e P G , P E , E T
orl % e c x ,% e a x
movl % e a x ,% c r0
2007-02-13 15:26:26 +03:00
lgdt e a r l y _ g d t _ d e s c r
2005-04-17 02:20:36 +04:00
lidt i d t _ d e s c r
ljmp $ ( _ _ K E R N E L _ C S ) ,$ 1 f
1 : movl $ ( _ _ K E R N E L _ D S ) ,% e a x # r e l o a d a l l t h e s e g m e n t r e g i s t e r s
movl % e a x ,% s s # a f t e r c h a n g i n g g d t .
movl $ ( _ _ U S E R _ D S ) ,% e a x # D S / E S c o n t a i n s d e f a u l t U S E R s e g m e n t
movl % e a x ,% d s
movl % e a x ,% e s
2009-01-21 11:26:05 +03:00
movl $ ( _ _ K E R N E L _ P E R C P U ) , % e a x
movl % e a x ,% f s # s e t t h i s c p u ' s p e r c p u
2009-02-09 16:17:40 +03:00
movl $ ( _ _ K E R N E L _ S T A C K _ C A N A R Y ) ,% e a x
2007-02-13 15:26:20 +03:00
movl % e a x ,% g s
2009-02-09 16:17:40 +03:00
xorl % e a x ,% e a x # C l e a r L D T
2005-04-17 02:20:36 +04:00
lldt % a x
[PATCH] i386: Use %gs as the PDA base-segment in the kernel
This patch is the meat of the PDA change. This patch makes several related
changes:
1: Most significantly, %gs is now used in the kernel. This means that on
entry, the old value of %gs is saved away, and it is reloaded with
__KERNEL_PDA.
2: entry.S constructs the stack in the shape of struct pt_regs, and this
is passed around the kernel so that the process's saved register
state can be accessed.
Unfortunately struct pt_regs doesn't currently have space for %gs
(or %fs). This patch extends pt_regs to add space for gs (no space
is allocated for %fs, since it won't be used, and it would just
complicate the code in entry.S to work around the space).
3: Because %gs is now saved on the stack like %ds, %es and the integer
registers, there are a number of places where it no longer needs to
be handled specially; namely context switch, and saving/restoring the
register state in a signal context.
4: And since kernel threads run in kernel space and call normal kernel
code, they need to be created with their %gs == __KERNEL_PDA.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-12-07 04:14:02 +03:00
2016-09-22 00:04:02 +03:00
call * ( i n i t i a l _ c o d e )
1 : jmp 1 b
ENDPROC( s t a r t u p _ 3 2 _ s m p )
2005-04-17 02:20:36 +04:00
2012-04-19 04:16:50 +04:00
# include " v e r i f y _ c p u . S "
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/ *
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* setup_ o n c e
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*
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* The s e t u p w o r k w e o n l y w a n t t o r u n o n t h e B S P .
2005-04-17 02:20:36 +04:00
*
* Warning : % esi i s l i v e a c r o s s t h i s f u n c t i o n .
* /
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_ _ INIT
setup_once :
/ *
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* Set u p a i d t w i t h 2 5 6 i n t e r r u p t g a t e s t h a t p u s h z e r o i f t h e r e
* is n o e r r o r c o d e a n d t h e n j u m p t o e a r l y _ i d t _ h a n d l e r _ c o m m o n .
* It d o e s n ' t a c t u a l l y l o a d t h e i d t - t h a t n e e d s t o b e d o n e o n
* each C P U . I n t e r r u p t s a r e e n a b l e d e l s e w h e r e , w h e n w e c a n b e
* relatively s u r e e v e r y t h i n g i s o k .
2012-04-19 04:16:50 +04:00
* /
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2012-04-19 04:16:50 +04:00
movl $ i d t _ t a b l e ,% e d i
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movl $ e a r l y _ i d t _ h a n d l e r _ a r r a y ,% e a x
2012-04-19 04:16:50 +04:00
movl $ N U M _ E X C E P T I O N _ V E C T O R S ,% e c x
1 :
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movl % e a x ,( % e d i )
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movl % e a x ,4 ( % e d i )
/* interrupt gate, dpl=0, present */
movl $ ( 0 x8 E 0 0 0 0 0 0 + _ _ K E R N E L _ C S ) ,2 ( % e d i )
2015-05-23 02:15:47 +03:00
addl $ E A R L Y _ I D T _ H A N D L E R _ S I Z E ,% e a x
2005-04-17 02:20:36 +04:00
addl $ 8 ,% e d i
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loop 1 b
2006-09-26 12:52:39 +04:00
2012-04-19 04:16:50 +04:00
movl $ 2 5 6 - N U M _ E X C E P T I O N _ V E C T O R S ,% e c x
movl $ i g n o r e _ i n t ,% e d x
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movl $ ( _ _ K E R N E L _ C S < < 1 6 ) ,% e a x
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movw % d x ,% a x / * s e l e c t o r = 0 x00 1 0 = c s * /
2006-09-26 12:52:39 +04:00
movw $ 0 x8 E 0 0 ,% d x / * i n t e r r u p t g a t e - d p l =0 , p r e s e n t * /
2012-04-19 04:16:50 +04:00
2 :
movl % e a x ,( % e d i )
movl % e d x ,4 ( % e d i )
addl $ 8 ,% e d i
loop 2 b
2006-09-26 12:52:39 +04:00
2012-04-19 04:16:50 +04:00
# ifdef C O N F I G _ C C _ S T A C K P R O T E C T O R
/ *
* Configure t h e s t a c k c a n a r y . T h e l i n k e r c a n ' t h a n d l e t h i s b y
* relocation. M a n u a l l y s e t b a s e a d d r e s s i n s t a c k c a n a r y
* segment d e s c r i p t o r .
* /
movl $ g d t _ p a g e ,% e a x
movl $ s t a c k _ c a n a r y ,% e c x
movw % c x , 8 * G D T _ E N T R Y _ S T A C K _ C A N A R Y + 2 ( % e a x )
shrl $ 1 6 , % e c x
movb % c l , 8 * G D T _ E N T R Y _ S T A C K _ C A N A R Y + 4 ( % e a x )
movb % c h , 8 * G D T _ E N T R Y _ S T A C K _ C A N A R Y + 7 ( % e a x )
# endif
2006-09-26 12:52:39 +04:00
2012-04-19 04:16:50 +04:00
andl $ 0 ,s e t u p _ o n c e _ r e f / * O n c e i s e n o u g h , t h a n k s * /
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ret
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ENTRY( e a r l y _ i d t _ h a n d l e r _ a r r a y )
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# 3 6 ( % esp) % e f l a g s
# 3 2 ( % esp) % c s
# 2 8 ( % esp) % e i p
# 2 4 ( % rsp) e r r o r c o d e
i = 0
.rept NUM_EXCEPTION_VECTORS
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.ifeq ( EXCEPTION_ E R R C O D E _ M A S K > > i ) & 1
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pushl $ 0 # D u m m y e r r o r c o d e , t o m a k e s t a c k f r a m e u n i f o r m
.endif
pushl $ i # 20 ( % e s p ) V e c t o r n u m b e r
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jmp e a r l y _ i d t _ h a n d l e r _ c o m m o n
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i = i + 1
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.fill early_idt_handler_array + i* E A R L Y _ I D T _ H A N D L E R _ S I Z E - . , 1 , 0 x c c
2012-04-19 04:16:50 +04:00
.endr
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ENDPROC( e a r l y _ i d t _ h a n d l e r _ a r r a y )
2012-04-19 04:16:50 +04:00
2015-05-23 02:15:47 +03:00
early_idt_handler_common :
/ *
* The s t a c k i s t h e h a r d w a r e f r a m e , a n e r r o r c o d e o r z e r o , a n d t h e
* vector n u m b e r .
* /
2012-04-19 04:16:50 +04:00
cld
2014-03-08 03:05:20 +04:00
2012-04-19 04:16:50 +04:00
incl % s s : e a r l y _ r e c u r s i o n _ f l a g
2006-09-26 12:52:39 +04:00
2016-04-02 17:01:32 +03:00
/* The vector number is in pt_regs->gs */
2006-09-26 12:52:39 +04:00
2016-04-02 17:01:32 +03:00
cld
pushl % f s / * p t _ r e g s - > f s * /
movw $ 0 , 2 ( % e s p ) / * c l e a r h i g h b i t s ( s o m e C P U s l e a v e g a r b a g e ) * /
pushl % e s / * p t _ r e g s - > e s * /
movw $ 0 , 2 ( % e s p ) / * c l e a r h i g h b i t s ( s o m e C P U s l e a v e g a r b a g e ) * /
pushl % d s / * p t _ r e g s - > d s * /
movw $ 0 , 2 ( % e s p ) / * c l e a r h i g h b i t s ( s o m e C P U s l e a v e g a r b a g e ) * /
pushl % e a x / * p t _ r e g s - > a x * /
pushl % e b p / * p t _ r e g s - > b p * /
pushl % e d i / * p t _ r e g s - > d i * /
pushl % e s i / * p t _ r e g s - > s i * /
pushl % e d x / * p t _ r e g s - > d x * /
pushl % e c x / * p t _ r e g s - > c x * /
pushl % e b x / * p t _ r e g s - > b x * /
/* Fix up DS and ES */
movl $ ( _ _ K E R N E L _ D S ) , % e c x
movl % e c x , % d s
movl % e c x , % e s
/* Load the vector number into EDX */
movl P T _ G S ( % e s p ) , % e d x
/* Load GS into pt_regs->gs and clear high bits */
movw % g s , P T _ G S ( % e s p )
movw $ 0 , P T _ G S + 2 ( % e s p )
movl % e s p , % e a x / * a r g s a r e p t _ r e g s ( E A X ) , t r a p n r ( E D X ) * /
call e a r l y _ f i x u p _ e x c e p t i o n
popl % e b x / * p t _ r e g s - > b x * /
popl % e c x / * p t _ r e g s - > c x * /
popl % e d x / * p t _ r e g s - > d x * /
popl % e s i / * p t _ r e g s - > s i * /
popl % e d i / * p t _ r e g s - > d i * /
popl % e b p / * p t _ r e g s - > b p * /
popl % e a x / * p t _ r e g s - > a x * /
popl % d s / * p t _ r e g s - > d s * /
popl % e s / * p t _ r e g s - > e s * /
popl % f s / * p t _ r e g s - > f s * /
popl % g s / * p t _ r e g s - > g s * /
decl % s s : e a r l y _ r e c u r s i o n _ f l a g
addl $ 4 , % e s p / * p o p p t _ r e g s - > o r i g _ a x * /
iret
2015-05-23 02:15:47 +03:00
ENDPROC( e a r l y _ i d t _ h a n d l e r _ c o m m o n )
2012-04-19 04:16:50 +04:00
2005-04-17 02:20:36 +04:00
/* This is the default interrupt "handler" :-) */
ALIGN
ignore_int :
cld
2005-05-01 19:59:02 +04:00
# ifdef C O N F I G _ P R I N T K
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pushl % e a x
pushl % e c x
pushl % e d x
pushl % e s
pushl % d s
movl $ ( _ _ K E R N E L _ D S ) ,% e a x
movl % e a x ,% d s
movl % e a x ,% e s
2006-09-26 12:52:39 +04:00
cmpl $ 2 ,e a r l y _ r e c u r s i o n _ f l a g
je h l t _ l o o p
incl e a r l y _ r e c u r s i o n _ f l a g
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pushl 1 6 ( % e s p )
pushl 2 4 ( % e s p )
pushl 3 2 ( % e s p )
pushl 4 0 ( % e s p )
pushl $ i n t _ m s g
call p r i n t k
2009-01-26 08:09:00 +03:00
call d u m p _ s t a c k
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addl $ ( 5 * 4 ) ,% e s p
popl % d s
popl % e s
popl % e d x
popl % e c x
popl % e a x
2005-05-01 19:59:02 +04:00
# endif
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iret
2016-04-02 17:01:34 +03:00
hlt_loop :
hlt
jmp h l t _ l o o p
2012-04-19 04:16:50 +04:00
ENDPROC( i g n o r e _ i n t )
_ _ INITDATA
.align 4
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GLOBAL( e a r l y _ r e c u r s i o n _ f l a g )
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.long 0
2005-04-17 02:20:36 +04:00
2012-04-19 04:16:50 +04:00
_ _ REFDATA
.align 4
2008-07-27 23:43:11 +04:00
ENTRY( i n i t i a l _ c o d e )
.long i386_start_kernel
2012-04-19 04:16:50 +04:00
ENTRY( s e t u p _ o n c e _ r e f )
.long setup_once
2008-07-27 23:43:11 +04:00
2005-04-17 02:20:36 +04:00
/ *
* BSS s e c t i o n
* /
2009-09-21 02:14:14 +04:00
_ _ PAGE_ A L I G N E D _ B S S
2011-02-25 23:46:13 +03:00
.align PAGE_SIZE
2008-02-10 01:24:09 +03:00
# ifdef C O N F I G _ X 8 6 _ P A E
2016-12-08 19:44:31 +03:00
.globl initial_pg_pmd
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initial_pg_pmd :
2008-02-10 01:24:09 +03:00
.fill 1 0 2 4 * KPMDS,4 ,0
# else
2016-11-16 17:17:09 +03:00
.globl initial_page_table
initial_page_table :
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.fill 1 0 2 4 , 4 , 0
2008-02-10 01:24:09 +03:00
# endif
2011-01-04 09:50:54 +03:00
initial_pg_fixmap :
2007-07-16 10:37:28 +04:00
.fill 1 0 2 4 , 4 , 0
2016-11-16 17:17:09 +03:00
.globl empty_zero_page
empty_zero_page :
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.fill 4 0 9 6 , 1 , 0
2016-11-16 17:17:09 +03:00
.globl swapper_pg_dir
swapper_pg_dir :
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.fill 1 0 2 4 , 4 , 0
2016-01-11 19:04:34 +03:00
EXPORT_ S Y M B O L ( e m p t y _ z e r o _ p a g e )
2009-03-09 11:15:57 +03:00
2005-04-17 02:20:36 +04:00
/ *
* This s t a r t s t h e d a t a s e c t i o n .
* /
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# ifdef C O N F I G _ X 8 6 _ P A E
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_ _ PAGE_ A L I G N E D _ D A T A
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/* Page-aligned for the benefit of paravirt? */
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.align PAGE_SIZE
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ENTRY( i n i t i a l _ p a g e _ t a b l e )
.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R ) ,0 / * l o w i d e n t i t y m a p * /
2008-02-10 01:24:09 +03:00
# if K P M D S = = 3
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.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R ) ,0
.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R + 0 x10 0 0 ) ,0
.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R + 0 x20 0 0 ) ,0
2008-02-10 01:24:09 +03:00
# elif K P M D S = = 2
.long 0 , 0
2010-08-28 17:58:33 +04:00
.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R ) ,0
.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R + 0 x10 0 0 ) ,0
2008-02-10 01:24:09 +03:00
# elif K P M D S = = 1
.long 0 , 0
.long 0 , 0
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.long ( i n i t i a l _ p g _ p m d + P G D _ I D E N T _ A T T R ) ,0
2008-02-10 01:24:09 +03:00
# else
# error " K e r n e l P M D s s h o u l d b e 1 , 2 o r 3 "
# endif
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.align PAGE_SIZE /* needs to be page-sized too */
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# endif
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.data
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.balign 4
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ENTRY( i n i t i a l _ s t a c k )
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/ *
* The S I Z E O F _ P T R E G S g a p i s a c o n v e n t i o n w h i c h h e l p s t h e i n - k e r n e l
* unwinder r e l i a b l y d e t e c t t h e e n d o f t h e s t a c k .
* /
.long init_thread_union + THREAD_ S I Z E - S I Z E O F _ P T R E G S - \
TOP_ O F _ K E R N E L _ S T A C K _ P A D D I N G ;
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_ _ INITRODATA
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int_msg :
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.asciz " Unknown i n t e r r u p t o r f a u l t a t : % p % p % p \ n "
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# include " . . / . . / x86 / x e n / x e n - h e a d . S "
xen: Core Xen implementation
This patch is a rollup of all the core pieces of the Xen
implementation, including:
- booting and setup
- pagetable setup
- privileged instructions
- segmentation
- interrupt flags
- upcalls
- multicall batching
BOOTING AND SETUP
The vmlinux image is decorated with ELF notes which tell the Xen
domain builder what the kernel's requirements are; the domain builder
then constructs the address space accordingly and starts the kernel.
Xen has its own entrypoint for the kernel (contained in an ELF note).
The ELF notes are set up by xen-head.S, which is included into head.S.
In principle it could be linked separately, but it seems to provoke
lots of binutils bugs.
Because the domain builder starts the kernel in a fairly sane state
(32-bit protected mode, paging enabled, flat segments set up), there's
not a lot of setup needed before starting the kernel proper. The main
steps are:
1. Install the Xen paravirt_ops, which is simply a matter of a
structure assignment.
2. Set init_mm to use the Xen-supplied pagetables (analogous to the
head.S generated pagetables in a native boot).
3. Reserve address space for Xen, since it takes a chunk at the top
of the address space for its own use.
4. Call start_kernel()
PAGETABLE SETUP
Once we hit the main kernel boot sequence, it will end up calling back
via paravirt_ops to set up various pieces of Xen specific state. One
of the critical things which requires a bit of extra care is the
construction of the initial init_mm pagetable. Because Xen places
tight constraints on pagetables (an active pagetable must always be
valid, and must always be mapped read-only to the guest domain), we
need to be careful when constructing the new pagetable to keep these
constraints in mind. It turns out that the easiest way to do this is
use the initial Xen-provided pagetable as a template, and then just
insert new mappings for memory where a mapping doesn't already exist.
This means that during pagetable setup, it uses a special version of
xen_set_pte which ignores any attempt to remap a read-only page as
read-write (since Xen will map its own initial pagetable as RO), but
lets other changes to the ptes happen, so that things like NX are set
properly.
PRIVILEGED INSTRUCTIONS AND SEGMENTATION
When the kernel runs under Xen, it runs in ring 1 rather than ring 0.
This means that it is more privileged than user-mode in ring 3, but it
still can't run privileged instructions directly. Non-performance
critical instructions are dealt with by taking a privilege exception
and trapping into the hypervisor and emulating the instruction, but
more performance-critical instructions have their own specific
paravirt_ops. In many cases we can avoid having to do any hypercalls
for these instructions, or the Xen implementation is quite different
from the normal native version.
The privileged instructions fall into the broad classes of:
Segmentation: setting up the GDT and the GDT entries, LDT,
TLS and so on. Xen doesn't allow the GDT to be directly
modified; all GDT updates are done via hypercalls where the new
entries can be validated. This is important because Xen uses
segment limits to prevent the guest kernel from damaging the
hypervisor itself.
Traps and exceptions: Xen uses a special format for trap entrypoints,
so when the kernel wants to set an IDT entry, it needs to be
converted to the form Xen expects. Xen sets int 0x80 up specially
so that the trap goes straight from userspace into the guest kernel
without going via the hypervisor. sysenter isn't supported.
Kernel stack: The esp0 entry is extracted from the tss and provided to
Xen.
TLB operations: the various TLB calls are mapped into corresponding
Xen hypercalls.
Control registers: all the control registers are privileged. The most
important is cr3, which points to the base of the current pagetable,
and we handle it specially.
Another instruction we treat specially is CPUID, even though its not
privileged. We want to control what CPU features are visible to the
rest of the kernel, and so CPUID ends up going into a paravirt_op.
Xen implements this mainly to disable the ACPI and APIC subsystems.
INTERRUPT FLAGS
Xen maintains its own separate flag for masking events, which is
contained within the per-cpu vcpu_info structure. Because the guest
kernel runs in ring 1 and not 0, the IF flag in EFLAGS is completely
ignored (and must be, because even if a guest domain disables
interrupts for itself, it can't disable them overall).
(A note on terminology: "events" and interrupts are effectively
synonymous. However, rather than using an "enable flag", Xen uses a
"mask flag", which blocks event delivery when it is non-zero.)
There are paravirt_ops for each of cli/sti/save_fl/restore_fl, which
are implemented to manage the Xen event mask state. The only thing
worth noting is that when events are unmasked, we need to explicitly
see if there's a pending event and call into the hypervisor to make
sure it gets delivered.
UPCALLS
Xen needs a couple of upcall (or callback) functions to be implemented
by each guest. One is the event upcalls, which is how events
(interrupts, effectively) are delivered to the guests. The other is
the failsafe callback, which is used to report errors in either
reloading a segment register, or caused by iret. These are
implemented in i386/kernel/entry.S so they can jump into the normal
iret_exc path when necessary.
MULTICALL BATCHING
Xen provides a multicall mechanism, which allows multiple hypercalls
to be issued at once in order to mitigate the cost of trapping into
the hypervisor. This is particularly useful for context switches,
since the 4-5 hypercalls they would normally need (reload cr3, update
TLS, maybe update LDT) can be reduced to one. This patch implements a
generic batching mechanism for hypercalls, which gets used in many
places in the Xen code.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Ian Pratt <ian.pratt@xensource.com>
Cc: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Cc: Adrian Bunk <bunk@stusta.de>
2007-07-18 05:37:04 +04:00
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/ *
* The I D T a n d G D T ' d e s c r i p t o r s ' a r e a s t r a n g e 4 8 - b i t o b j e c t
* only u s e d b y t h e l i d t a n d l g d t i n s t r u c t i o n s . T h e y a r e n o t
* like u s u a l s e g m e n t d e s c r i p t o r s - t h e y c o n s i s t o f a 1 6 - b i t
* segment s i z e , a n d 3 2 - b i t l i n e a r a d d r e s s v a l u e :
* /
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.data
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.globl boot_gdt_descr
.globl idt_descr
ALIGN
# early b o o t G D T d e s c r i p t o r ( m u s t u s e 1 : 1 a d d r e s s m a p p i n g )
.word 0 # 3 2 bit a l i g n g d t _ d e s c . a d d r e s s
boot_gdt_descr :
.word _ _ BOOT_ D S + 7
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.long boot_gdt - _ _ PAGE_ O F F S E T
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.word 0 # 3 2 - bit a l i g n i d t _ d e s c . a d d r e s s
idt_descr :
.word _ E N T R I E S * 8 - 1 # i d t c o n t a i n s 256 e n t r i e s
.long idt_table
# boot G D T d e s c r i p t o r ( l a t e r o n u s e d b y C P U #0 ) :
.word 0 # 3 2 bit a l i g n g d t _ d e s c . a d d r e s s
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ENTRY( e a r l y _ g d t _ d e s c r )
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.word _ E N T R I E S * 8 - 1
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.long gdt_page /* Overwritten for secondary CPUs */
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/ *
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* The b o o t _ g d t m u s t m i r r o r t h e e q u i v a l e n t i n s e t u p . S a n d i s
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* used o n l y f o r b o o t i n g .
* /
.align L1_CACHE_BYTES
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ENTRY( b o o t _ g d t )
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.fill _ E N T R Y _ B O O T _ C S ,8 ,0
.quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
.quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
