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Profile_pc was broken when using paravirtualization because the assumption the kernel was running at CPL 0 was violated, causing bad logic to read a random value off the stack. The only way to be in kernel lock functions is to be in kernel code, so validate that assumption explicitly by checking the CS value. We don't want to be fooled by BIOS / APM segments and try to read those stacks, so only match KERNEL_CS. I moved some stuff in segment.h to make it prettier. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: 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 - PDA [ per-cpu private 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_PDA (GDT_ENTRY_KERNEL_BASE + 15)
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#define __KERNEL_PDA (GDT_ENTRY_PDA * 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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