7c3576d261
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>
145 lines
4.1 KiB
C
145 lines
4.1 KiB
C
#ifndef _ASM_SEGMENT_H
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#define _ASM_SEGMENT_H
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/*
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* The layout of the per-CPU GDT under Linux:
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*
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* 0 - null
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* 1 - reserved
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* 2 - reserved
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* 3 - reserved
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*
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* 4 - unused <==== new cacheline
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* 5 - unused
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*
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* ------- start of TLS (Thread-Local Storage) segments:
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*
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* 6 - TLS segment #1 [ glibc's TLS segment ]
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* 7 - TLS segment #2 [ Wine's %fs Win32 segment ]
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* 8 - TLS segment #3
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* 9 - reserved
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* 10 - reserved
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* 11 - reserved
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*
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* ------- start of kernel segments:
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*
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* 12 - kernel code segment <==== new cacheline
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* 13 - kernel data segment
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* 14 - default user CS
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* 15 - default user DS
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* 16 - TSS
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* 17 - LDT
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* 18 - PNPBIOS support (16->32 gate)
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* 19 - PNPBIOS support
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* 20 - PNPBIOS support
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* 21 - PNPBIOS support
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* 22 - PNPBIOS support
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* 23 - APM BIOS support
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* 24 - APM BIOS support
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* 25 - APM BIOS support
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*
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* 26 - ESPFIX small SS
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* 27 - per-cpu [ offset to per-cpu data area ]
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* 28 - unused
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* 29 - unused
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* 30 - unused
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* 31 - TSS for double fault handler
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*/
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#define GDT_ENTRY_TLS_ENTRIES 3
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#define GDT_ENTRY_TLS_MIN 6
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#define GDT_ENTRY_TLS_MAX (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
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#define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES * 8)
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#define GDT_ENTRY_DEFAULT_USER_CS 14
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#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS * 8 + 3)
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#define GDT_ENTRY_DEFAULT_USER_DS 15
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#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS * 8 + 3)
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#define GDT_ENTRY_KERNEL_BASE 12
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#define GDT_ENTRY_KERNEL_CS (GDT_ENTRY_KERNEL_BASE + 0)
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#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS * 8)
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#define GDT_ENTRY_KERNEL_DS (GDT_ENTRY_KERNEL_BASE + 1)
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#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS * 8)
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#define GDT_ENTRY_TSS (GDT_ENTRY_KERNEL_BASE + 4)
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#define GDT_ENTRY_LDT (GDT_ENTRY_KERNEL_BASE + 5)
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#define GDT_ENTRY_PNPBIOS_BASE (GDT_ENTRY_KERNEL_BASE + 6)
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#define GDT_ENTRY_APMBIOS_BASE (GDT_ENTRY_KERNEL_BASE + 11)
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#define GDT_ENTRY_ESPFIX_SS (GDT_ENTRY_KERNEL_BASE + 14)
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#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8)
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#define GDT_ENTRY_PERCPU (GDT_ENTRY_KERNEL_BASE + 15)
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#define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8)
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#define GDT_ENTRY_DOUBLEFAULT_TSS 31
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/*
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* The GDT has 32 entries
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*/
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#define GDT_ENTRIES 32
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#define GDT_SIZE (GDT_ENTRIES * 8)
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/* Simple and small GDT entries for booting only */
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#define GDT_ENTRY_BOOT_CS 2
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#define __BOOT_CS (GDT_ENTRY_BOOT_CS * 8)
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#define GDT_ENTRY_BOOT_DS (GDT_ENTRY_BOOT_CS + 1)
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#define __BOOT_DS (GDT_ENTRY_BOOT_DS * 8)
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/* The PnP BIOS entries in the GDT */
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#define GDT_ENTRY_PNPBIOS_CS32 (GDT_ENTRY_PNPBIOS_BASE + 0)
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#define GDT_ENTRY_PNPBIOS_CS16 (GDT_ENTRY_PNPBIOS_BASE + 1)
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#define GDT_ENTRY_PNPBIOS_DS (GDT_ENTRY_PNPBIOS_BASE + 2)
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#define GDT_ENTRY_PNPBIOS_TS1 (GDT_ENTRY_PNPBIOS_BASE + 3)
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#define GDT_ENTRY_PNPBIOS_TS2 (GDT_ENTRY_PNPBIOS_BASE + 4)
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/* The PnP BIOS selectors */
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#define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32 * 8) /* segment for calling fn */
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#define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16 * 8) /* code segment for BIOS */
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#define PNP_DS (GDT_ENTRY_PNPBIOS_DS * 8) /* data segment for BIOS */
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#define PNP_TS1 (GDT_ENTRY_PNPBIOS_TS1 * 8) /* transfer data segment */
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#define PNP_TS2 (GDT_ENTRY_PNPBIOS_TS2 * 8) /* another data segment */
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/*
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* The interrupt descriptor table has room for 256 idt's,
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* the global descriptor table is dependent on the number
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* of tasks we can have..
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*/
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#define IDT_ENTRIES 256
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/* Bottom two bits of selector give the ring privilege level */
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#define SEGMENT_RPL_MASK 0x3
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/* Bit 2 is table indicator (LDT/GDT) */
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#define SEGMENT_TI_MASK 0x4
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/* User mode is privilege level 3 */
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#define USER_RPL 0x3
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/* LDT segment has TI set, GDT has it cleared */
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#define SEGMENT_LDT 0x4
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#define SEGMENT_GDT 0x0
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#ifndef CONFIG_PARAVIRT
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#define get_kernel_rpl() 0
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#endif
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/*
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* Matching rules for certain types of segments.
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*/
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/* Matches only __KERNEL_CS, ignoring PnP / USER / APM segments */
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#define SEGMENT_IS_KERNEL_CODE(x) (((x) & 0xfc) == GDT_ENTRY_KERNEL_CS * 8)
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/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
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#define SEGMENT_IS_FLAT_CODE(x) (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
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/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
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#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
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#endif
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