diff options
| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2007-05-02 13:27:16 -0400 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2007-05-02 13:27:16 -0400 |
| commit | 7c3576d261ce046789a7db14f43303f8120910c7 (patch) | |
| tree | ad27a8459bbcdb183fe2411aec3b840942992ad5 /include/asm-i386/pda.h | |
| parent | 7a61d35d4b4056e7711031202da7605e052f4137 (diff) | |
[PATCH] i386: Convert PDA into the percpu section
Currently x86 (similar to x84-64) has a special per-cpu structure
called "i386_pda" which can be easily and efficiently referenced via
the %fs register. An ELF section is more flexible than a structure,
allowing any piece of code to use this area. Indeed, such a section
already exists: the per-cpu area.
So this patch:
(1) Removes the PDA and uses per-cpu variables for each current member.
(2) Replaces the __KERNEL_PDA segment with __KERNEL_PERCPU.
(3) Creates a per-cpu mirror of __per_cpu_offset called this_cpu_off, which
can be used to calculate addresses for this CPU's variables.
(4) Simplifies startup, because %fs doesn't need to be loaded with a
special segment at early boot; it can be deferred until the first
percpu area is allocated (or never for UP).
The result is less code and one less x86-specific concept.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Diffstat (limited to 'include/asm-i386/pda.h')
| -rw-r--r-- | include/asm-i386/pda.h | 99 |
1 files changed, 0 insertions, 99 deletions
diff --git a/include/asm-i386/pda.h b/include/asm-i386/pda.h deleted file mode 100644 index aef7f732f77e..000000000000 --- a/include/asm-i386/pda.h +++ /dev/null | |||
| @@ -1,99 +0,0 @@ | |||
| 1 | /* | ||
| 2 | Per-processor Data Areas | ||
| 3 | Jeremy Fitzhardinge <jeremy@goop.org> 2006 | ||
| 4 | Based on asm-x86_64/pda.h by Andi Kleen. | ||
| 5 | */ | ||
| 6 | #ifndef _I386_PDA_H | ||
| 7 | #define _I386_PDA_H | ||
| 8 | |||
| 9 | #include <linux/stddef.h> | ||
| 10 | #include <linux/types.h> | ||
| 11 | #include <asm/percpu.h> | ||
| 12 | |||
| 13 | struct i386_pda | ||
| 14 | { | ||
| 15 | struct i386_pda *_pda; /* pointer to self */ | ||
| 16 | |||
| 17 | int cpu_number; | ||
| 18 | struct task_struct *pcurrent; /* current process */ | ||
| 19 | struct pt_regs *irq_regs; | ||
| 20 | }; | ||
| 21 | |||
| 22 | DECLARE_PER_CPU(struct i386_pda, _cpu_pda); | ||
| 23 | #define cpu_pda(i) (&per_cpu(_cpu_pda, (i))) | ||
| 24 | #define pda_offset(field) offsetof(struct i386_pda, field) | ||
| 25 | |||
| 26 | extern void __bad_pda_field(void); | ||
| 27 | |||
| 28 | /* This variable is never instantiated. It is only used as a stand-in | ||
| 29 | for the real per-cpu PDA memory, so that gcc can understand what | ||
| 30 | memory operations the inline asms() below are performing. This | ||
| 31 | eliminates the need to make the asms volatile or have memory | ||
| 32 | clobbers, so gcc can readily analyse them. */ | ||
| 33 | extern struct i386_pda _proxy_pda; | ||
| 34 | |||
| 35 | #define pda_to_op(op,field,val) \ | ||
| 36 | do { \ | ||
| 37 | typedef typeof(_proxy_pda.field) T__; \ | ||
| 38 | if (0) { T__ tmp__; tmp__ = (val); } \ | ||
| 39 | switch (sizeof(_proxy_pda.field)) { \ | ||
| 40 | case 1: \ | ||
| 41 | asm(op "b %1,%%fs:%c2" \ | ||
| 42 | : "+m" (_proxy_pda.field) \ | ||
| 43 | :"ri" ((T__)val), \ | ||
| 44 | "i"(pda_offset(field))); \ | ||
| 45 | break; \ | ||
| 46 | case 2: \ | ||
| 47 | asm(op "w %1,%%fs:%c2" \ | ||
| 48 | : "+m" (_proxy_pda.field) \ | ||
| 49 | :"ri" ((T__)val), \ | ||
| 50 | "i"(pda_offset(field))); \ | ||
| 51 | break; \ | ||
| 52 | case 4: \ | ||
| 53 | asm(op "l %1,%%fs:%c2" \ | ||
| 54 | : "+m" (_proxy_pda.field) \ | ||
| 55 | :"ri" ((T__)val), \ | ||
| 56 | "i"(pda_offset(field))); \ | ||
| 57 | break; \ | ||
| 58 | default: __bad_pda_field(); \ | ||
| 59 | } \ | ||
| 60 | } while (0) | ||
| 61 | |||
| 62 | #define pda_from_op(op,field) \ | ||
| 63 | ({ \ | ||
| 64 | typeof(_proxy_pda.field) ret__; \ | ||
| 65 | switch (sizeof(_proxy_pda.field)) { \ | ||
| 66 | case 1: \ | ||
| 67 | asm(op "b %%fs:%c1,%0" \ | ||
| 68 | : "=r" (ret__) \ | ||
| 69 | : "i" (pda_offset(field)), \ | ||
| 70 | "m" (_proxy_pda.field)); \ | ||
| 71 | break; \ | ||
| 72 | case 2: \ | ||
| 73 | asm(op "w %%fs:%c1,%0" \ | ||
| 74 | : "=r" (ret__) \ | ||
| 75 | : "i" (pda_offset(field)), \ | ||
| 76 | "m" (_proxy_pda.field)); \ | ||
| 77 | break; \ | ||
| 78 | case 4: \ | ||
| 79 | asm(op "l %%fs:%c1,%0" \ | ||
| 80 | : "=r" (ret__) \ | ||
| 81 | : "i" (pda_offset(field)), \ | ||
| 82 | "m" (_proxy_pda.field)); \ | ||
| 83 | break; \ | ||
| 84 | default: __bad_pda_field(); \ | ||
| 85 | } \ | ||
| 86 | ret__; }) | ||
| 87 | |||
| 88 | /* Return a pointer to a pda field */ | ||
| 89 | #define pda_addr(field) \ | ||
| 90 | ((typeof(_proxy_pda.field) *)((unsigned char *)read_pda(_pda) + \ | ||
| 91 | pda_offset(field))) | ||
| 92 | |||
| 93 | #define read_pda(field) pda_from_op("mov",field) | ||
| 94 | #define write_pda(field,val) pda_to_op("mov",field,val) | ||
| 95 | #define add_pda(field,val) pda_to_op("add",field,val) | ||
| 96 | #define sub_pda(field,val) pda_to_op("sub",field,val) | ||
| 97 | #define or_pda(field,val) pda_to_op("or",field,val) | ||
| 98 | |||
| 99 | #endif /* _I386_PDA_H */ | ||