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Diffstat (limited to 'kernel/arch/x86/include/asm/segment.h')
| -rw-r--r-- | kernel/arch/x86/include/asm/segment.h | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/kernel/arch/x86/include/asm/segment.h b/kernel/arch/x86/include/asm/segment.h new file mode 100644 index 000000000..7d5a1929d --- /dev/null +++ b/kernel/arch/x86/include/asm/segment.h @@ -0,0 +1,300 @@ +#ifndef _ASM_X86_SEGMENT_H +#define _ASM_X86_SEGMENT_H + +#include <linux/const.h> + +/* + * Constructor for a conventional segment GDT (or LDT) entry. + * This is a macro so it can be used in initializers. + */ +#define GDT_ENTRY(flags, base, limit) \ + ((((base) & _AC(0xff000000,ULL)) << (56-24)) | \ + (((flags) & _AC(0x0000f0ff,ULL)) << 40) | \ + (((limit) & _AC(0x000f0000,ULL)) << (48-16)) | \ + (((base) & _AC(0x00ffffff,ULL)) << 16) | \ + (((limit) & _AC(0x0000ffff,ULL)))) + +/* Simple and small GDT entries for booting only: */ + +#define GDT_ENTRY_BOOT_CS 2 +#define GDT_ENTRY_BOOT_DS 3 +#define GDT_ENTRY_BOOT_TSS 4 +#define __BOOT_CS (GDT_ENTRY_BOOT_CS*8) +#define __BOOT_DS (GDT_ENTRY_BOOT_DS*8) +#define __BOOT_TSS (GDT_ENTRY_BOOT_TSS*8) + +/* + * Bottom two bits of selector give the ring + * privilege level + */ +#define SEGMENT_RPL_MASK 0x3 + +/* User mode is privilege level 3: */ +#define USER_RPL 0x3 + +/* Bit 2 is Table Indicator (TI): selects between LDT or GDT */ +#define SEGMENT_TI_MASK 0x4 +/* LDT segment has TI set ... */ +#define SEGMENT_LDT 0x4 +/* ... GDT has it cleared */ +#define SEGMENT_GDT 0x0 + +#define GDT_ENTRY_INVALID_SEG 0 + +#ifdef CONFIG_X86_32 +/* + * The layout of the per-CPU GDT under Linux: + * + * 0 - null <=== cacheline #1 + * 1 - reserved + * 2 - reserved + * 3 - reserved + * + * 4 - unused <=== cacheline #2 + * 5 - unused + * + * ------- start of TLS (Thread-Local Storage) segments: + * + * 6 - TLS segment #1 [ glibc's TLS segment ] + * 7 - TLS segment #2 [ Wine's %fs Win32 segment ] + * 8 - TLS segment #3 <=== cacheline #3 + * 9 - reserved + * 10 - reserved + * 11 - reserved + * + * ------- start of kernel segments: + * + * 12 - kernel code segment <=== cacheline #4 + * 13 - kernel data segment + * 14 - default user CS + * 15 - default user DS + * 16 - TSS <=== cacheline #5 + * 17 - LDT + * 18 - PNPBIOS support (16->32 gate) + * 19 - PNPBIOS support + * 20 - PNPBIOS support <=== cacheline #6 + * 21 - PNPBIOS support + * 22 - PNPBIOS support + * 23 - APM BIOS support + * 24 - APM BIOS support <=== cacheline #7 + * 25 - APM BIOS support + * + * 26 - ESPFIX small SS + * 27 - per-cpu [ offset to per-cpu data area ] + * 28 - stack_canary-20 [ for stack protector ] <=== cacheline #8 + * 29 - unused + * 30 - unused + * 31 - TSS for double fault handler + */ +#define GDT_ENTRY_TLS_MIN 6 +#define GDT_ENTRY_TLS_MAX (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1) + +#define GDT_ENTRY_KERNEL_CS 12 +#define GDT_ENTRY_KERNEL_DS 13 +#define GDT_ENTRY_DEFAULT_USER_CS 14 +#define GDT_ENTRY_DEFAULT_USER_DS 15 +#define GDT_ENTRY_TSS 16 +#define GDT_ENTRY_LDT 17 +#define GDT_ENTRY_PNPBIOS_CS32 18 +#define GDT_ENTRY_PNPBIOS_CS16 19 +#define GDT_ENTRY_PNPBIOS_DS 20 +#define GDT_ENTRY_PNPBIOS_TS1 21 +#define GDT_ENTRY_PNPBIOS_TS2 22 +#define GDT_ENTRY_APMBIOS_BASE 23 + +#define GDT_ENTRY_ESPFIX_SS 26 +#define GDT_ENTRY_PERCPU 27 +#define GDT_ENTRY_STACK_CANARY 28 + +#define GDT_ENTRY_DOUBLEFAULT_TSS 31 + +/* + * Number of entries in the GDT table: + */ +#define GDT_ENTRIES 32 + +/* + * Segment selector values corresponding to the above entries: + */ + +#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) +#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8) +#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) +#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) +#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS*8) + +/* segment for calling fn: */ +#define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32*8) +/* code segment for BIOS: */ +#define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16*8) + +/* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */ +#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == PNP_CS32) + +/* data segment for BIOS: */ +#define PNP_DS (GDT_ENTRY_PNPBIOS_DS*8) +/* transfer data segment: */ +#define PNP_TS1 (GDT_ENTRY_PNPBIOS_TS1*8) +/* another data segment: */ +#define PNP_TS2 (GDT_ENTRY_PNPBIOS_TS2*8) + +#ifdef CONFIG_SMP +# define __KERNEL_PERCPU (GDT_ENTRY_PERCPU*8) +#else +# define __KERNEL_PERCPU 0 +#endif + +#ifdef CONFIG_CC_STACKPROTECTOR +# define __KERNEL_STACK_CANARY (GDT_ENTRY_STACK_CANARY*8) +#else +# define __KERNEL_STACK_CANARY 0 +#endif + +#else /* 64-bit: */ + +#include <asm/cache.h> + +#define GDT_ENTRY_KERNEL32_CS 1 +#define GDT_ENTRY_KERNEL_CS 2 +#define GDT_ENTRY_KERNEL_DS 3 + +/* + * We cannot use the same code segment descriptor for user and kernel mode, + * not even in long flat mode, because of different DPL. + * + * GDT layout to get 64-bit SYSCALL/SYSRET support right. SYSRET hardcodes + * selectors: + * + * if returning to 32-bit userspace: cs = STAR.SYSRET_CS, + * if returning to 64-bit userspace: cs = STAR.SYSRET_CS+16, + * + * ss = STAR.SYSRET_CS+8 (in either case) + * + * thus USER_DS should be between 32-bit and 64-bit code selectors: + */ +#define GDT_ENTRY_DEFAULT_USER32_CS 4 +#define GDT_ENTRY_DEFAULT_USER_DS 5 +#define GDT_ENTRY_DEFAULT_USER_CS 6 + +/* Needs two entries */ +#define GDT_ENTRY_TSS 8 +/* Needs two entries */ +#define GDT_ENTRY_LDT 10 + +#define GDT_ENTRY_TLS_MIN 12 +#define GDT_ENTRY_TLS_MAX 14 + +/* Abused to load per CPU data from limit */ +#define GDT_ENTRY_PER_CPU 15 + +/* + * Number of entries in the GDT table: + */ +#define GDT_ENTRIES 16 + +/* + * Segment selector values corresponding to the above entries: + * + * Note, selectors also need to have a correct RPL, + * expressed with the +3 value for user-space selectors: + */ +#define __KERNEL32_CS (GDT_ENTRY_KERNEL32_CS*8) +#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) +#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8) +#define __USER32_CS (GDT_ENTRY_DEFAULT_USER32_CS*8 + 3) +#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) +#define __USER32_DS __USER_DS +#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) +#define __PER_CPU_SEG (GDT_ENTRY_PER_CPU*8 + 3) + +/* TLS indexes for 64-bit - hardcoded in arch_prctl(): */ +#define FS_TLS 0 +#define GS_TLS 1 + +#define GS_TLS_SEL ((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3) +#define FS_TLS_SEL ((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3) + +#endif + +#ifndef CONFIG_PARAVIRT +# define get_kernel_rpl() 0 +#endif + +#define IDT_ENTRIES 256 +#define NUM_EXCEPTION_VECTORS 32 + +/* Bitmask of exception vectors which push an error code on the stack: */ +#define EXCEPTION_ERRCODE_MASK 0x00027d00 + +#define GDT_SIZE (GDT_ENTRIES*8) +#define GDT_ENTRY_TLS_ENTRIES 3 +#define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8) + +#ifdef __KERNEL__ + +/* + * early_idt_handler_array is an array of entry points referenced in the + * early IDT. For simplicity, it's a real array with one entry point + * every nine bytes. That leaves room for an optional 'push $0' if the + * vector has no error code (two bytes), a 'push $vector_number' (two + * bytes), and a jump to the common entry code (up to five bytes). + */ +#define EARLY_IDT_HANDLER_SIZE 9 + +#ifndef __ASSEMBLY__ + +extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE]; +#ifdef CONFIG_TRACING +# define trace_early_idt_handler_array early_idt_handler_array +#endif + +/* + * Load a segment. Fall back on loading the zero + * segment if something goes wrong.. + */ +#define loadsegment(seg, value) \ +do { \ + unsigned short __val = (value); \ + \ + asm volatile(" \n" \ + "1: movl %k0,%%" #seg " \n" \ + \ + ".section .fixup,\"ax\" \n" \ + "2: xorl %k0,%k0 \n" \ + " jmp 1b \n" \ + ".previous \n" \ + \ + _ASM_EXTABLE(1b, 2b) \ + \ + : "+r" (__val) : : "memory"); \ +} while (0) + +/* + * Save a segment register away: + */ +#define savesegment(seg, value) \ + asm("mov %%" #seg ",%0":"=r" (value) : : "memory") + +/* + * x86-32 user GS accessors: + */ +#ifdef CONFIG_X86_32 +# ifdef CONFIG_X86_32_LAZY_GS +# define get_user_gs(regs) (u16)({ unsigned long v; savesegment(gs, v); v; }) +# define set_user_gs(regs, v) loadsegment(gs, (unsigned long)(v)) +# define task_user_gs(tsk) ((tsk)->thread.gs) +# define lazy_save_gs(v) savesegment(gs, (v)) +# define lazy_load_gs(v) loadsegment(gs, (v)) +# else /* X86_32_LAZY_GS */ +# define get_user_gs(regs) (u16)((regs)->gs) +# define set_user_gs(regs, v) do { (regs)->gs = (v); } while (0) +# define task_user_gs(tsk) (task_pt_regs(tsk)->gs) +# define lazy_save_gs(v) do { } while (0) +# define lazy_load_gs(v) do { } while (0) +# endif /* X86_32_LAZY_GS */ +#endif /* X86_32 */ + +#endif /* !__ASSEMBLY__ */ +#endif /* __KERNEL__ */ + +#endif /* _ASM_X86_SEGMENT_H */ |