diff options
Diffstat (limited to 'arch/x86/include/asm/segment.h')
| -rw-r--r-- | arch/x86/include/asm/segment.h | 406 |
1 files changed, 244 insertions, 162 deletions
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index c48a95035a77..f59ae7186940 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -1,10 +1,15 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_SEGMENT_H #define _ASM_X86_SEGMENT_H #include <linux/const.h> +#include <asm/alternative.h> +#include <asm/ibt.h> -/* Constructor for a conventional segment GDT (or LDT) entry */ -/* This is a macro so it can be used in initializers */ +/* + * 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) | \ @@ -12,263 +17,340 @@ (((base) & _AC(0x00ffffff,ULL)) << 16) | \ (((limit) & _AC(0x0000ffff,ULL)))) -/* Simple and small GDT entries for booting only */ +/* Simple and small GDT entries for booting only: */ #define GDT_ENTRY_BOOT_CS 2 -#define __BOOT_CS (GDT_ENTRY_BOOT_CS * 8) +#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 -#define GDT_ENTRY_BOOT_DS (GDT_ENTRY_BOOT_CS + 1) -#define __BOOT_DS (GDT_ENTRY_BOOT_DS * 8) +/* + * When running on Xen PV, the actual privilege level of the kernel is 1, + * not 0. Testing the Requested Privilege Level in a segment selector to + * determine whether the context is user mode or kernel mode with + * SEGMENT_RPL_MASK is wrong because the PV kernel's privilege level + * matches the 0x3 mask. + * + * Testing with USER_SEGMENT_RPL_MASK is valid for both native and Xen PV + * kernels because privilege level 2 is never used. + */ +#define USER_SEGMENT_RPL_MASK 0x2 -#define GDT_ENTRY_BOOT_TSS (GDT_ENTRY_BOOT_CS + 2) -#define __BOOT_TSS (GDT_ENTRY_BOOT_TSS * 8) +/* User mode is privilege level 3: */ +#define USER_RPL 0x3 -#ifdef CONFIG_X86_32 +/* 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 + +#if defined(CONFIG_X86_32) && !defined(BUILD_VDSO32_64) /* * The layout of the per-CPU GDT under Linux: * - * 0 - null + * 0 - null <=== cacheline #1 * 1 - reserved * 2 - reserved * 3 - reserved * - * 4 - unused <==== new cacheline + * 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 + * 8 - TLS segment #3 <=== cacheline #3 * 9 - reserved * 10 - reserved * 11 - reserved * * ------- start of kernel segments: * - * 12 - kernel code segment <==== new cacheline + * 12 - kernel code segment <=== cacheline #4 * 13 - kernel data segment * 14 - default user CS * 15 - default user DS - * 16 - TSS + * 16 - TSS <=== cacheline #5 * 17 - LDT * 18 - PNPBIOS support (16->32 gate) * 19 - PNPBIOS support - * 20 - PNPBIOS support + * 20 - PNPBIOS support <=== cacheline #6 * 21 - PNPBIOS support * 22 - PNPBIOS support * 23 - APM BIOS support - * 24 - 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 ] + * 28 - VDSO getcpu * 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_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_CPUNODE 28 -#define GDT_ENTRY_KERNEL_BASE (12) +#define GDT_ENTRY_DOUBLEFAULT_TSS 31 -#define GDT_ENTRY_KERNEL_CS (GDT_ENTRY_KERNEL_BASE+0) +/* + * Number of entries in the GDT table: + */ +#define GDT_ENTRIES 32 + +/* + * Segment selector values corresponding to the above entries: + */ -#define GDT_ENTRY_KERNEL_DS (GDT_ENTRY_KERNEL_BASE+1) +#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 __USER32_CS __USER_CS +#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS*8) -#define GDT_ENTRY_TSS (GDT_ENTRY_KERNEL_BASE+4) -#define GDT_ENTRY_LDT (GDT_ENTRY_KERNEL_BASE+5) +/* segment for calling fn: */ +#define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32*8) +/* code segment for BIOS: */ +#define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16*8) -#define GDT_ENTRY_PNPBIOS_BASE (GDT_ENTRY_KERNEL_BASE+6) -#define GDT_ENTRY_APMBIOS_BASE (GDT_ENTRY_KERNEL_BASE+11) +/* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */ +#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == PNP_CS32) -#define GDT_ENTRY_ESPFIX_SS (GDT_ENTRY_KERNEL_BASE+14) -#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS*8) +/* 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) -#define GDT_ENTRY_PERCPU (GDT_ENTRY_KERNEL_BASE+15) #ifdef CONFIG_SMP -#define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8) +# define __KERNEL_PERCPU (GDT_ENTRY_PERCPU*8) #else -#define __KERNEL_PERCPU 0 +# define __KERNEL_PERCPU 0 #endif -#define GDT_ENTRY_STACK_CANARY (GDT_ENTRY_KERNEL_BASE+16) -#ifdef CONFIG_CC_STACKPROTECTOR -#define __KERNEL_STACK_CANARY (GDT_ENTRY_STACK_CANARY*8) -#else -#define __KERNEL_STACK_CANARY 0 -#endif +#define __CPUNODE_SEG (GDT_ENTRY_CPUNODE*8 + 3) -#define GDT_ENTRY_DOUBLEFAULT_TSS 31 +#else /* 64-bit: */ -/* - * The GDT has 32 entries - */ -#define GDT_ENTRIES 32 - -/* The PnP BIOS entries in the GDT */ -#define GDT_ENTRY_PNPBIOS_CS32 (GDT_ENTRY_PNPBIOS_BASE + 0) -#define GDT_ENTRY_PNPBIOS_CS16 (GDT_ENTRY_PNPBIOS_BASE + 1) -#define GDT_ENTRY_PNPBIOS_DS (GDT_ENTRY_PNPBIOS_BASE + 2) -#define GDT_ENTRY_PNPBIOS_TS1 (GDT_ENTRY_PNPBIOS_BASE + 3) -#define GDT_ENTRY_PNPBIOS_TS2 (GDT_ENTRY_PNPBIOS_BASE + 4) - -/* The PnP BIOS selectors */ -#define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32 * 8) /* segment for calling fn */ -#define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16 * 8) /* code segment for BIOS */ -#define PNP_DS (GDT_ENTRY_PNPBIOS_DS * 8) /* data segment for BIOS */ -#define PNP_TS1 (GDT_ENTRY_PNPBIOS_TS1 * 8) /* transfer data segment */ -#define PNP_TS2 (GDT_ENTRY_PNPBIOS_TS2 * 8) /* another data segment */ - -/* Bottom two bits of selector give the ring privilege level */ -#define SEGMENT_RPL_MASK 0x3 -/* Bit 2 is table indicator (LDT/GDT) */ -#define SEGMENT_TI_MASK 0x4 +#include <asm/cache.h> -/* User mode is privilege level 3 */ -#define USER_RPL 0x3 -/* LDT segment has TI set, GDT has it cleared */ -#define SEGMENT_LDT 0x4 -#define SEGMENT_GDT 0x0 +#define GDT_ENTRY_KERNEL32_CS 1 +#define GDT_ENTRY_KERNEL_CS 2 +#define GDT_ENTRY_KERNEL_DS 3 /* - * Matching rules for certain types of segments. + * 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 -/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */ -#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8) +/* 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 -#else -#include <asm/cache.h> - -#define GDT_ENTRY_KERNEL32_CS 1 -#define GDT_ENTRY_KERNEL_CS 2 -#define GDT_ENTRY_KERNEL_DS 3 +#define GDT_ENTRY_CPUNODE 15 -#define __KERNEL32_CS (GDT_ENTRY_KERNEL32_CS * 8) +/* + * Number of entries in the GDT table: + */ +#define GDT_ENTRIES 16 /* - * we cannot use the same code segment descriptor for user and kernel - * -- not even in the long flat mode, because of different DPL /kkeil - * The segment offset needs to contain a RPL. Grr. -AK - * GDT layout to get 64bit syscall right (sysret hardcodes gdt offsets) + * 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 GDT_ENTRY_DEFAULT_USER32_CS 4 -#define GDT_ENTRY_DEFAULT_USER_DS 5 -#define GDT_ENTRY_DEFAULT_USER_CS 6 -#define __USER32_CS (GDT_ENTRY_DEFAULT_USER32_CS*8+3) -#define __USER32_DS __USER_DS +#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 __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) +#define __CPUNODE_SEG (GDT_ENTRY_CPUNODE*8 + 3) -#define GDT_ENTRY_TSS 8 /* needs two entries */ -#define GDT_ENTRY_LDT 10 /* needs two entries */ -#define GDT_ENTRY_TLS_MIN 12 -#define GDT_ENTRY_TLS_MAX 14 +#endif -#define GDT_ENTRY_PER_CPU 15 /* Abused to load per CPU data from limit */ -#define __PER_CPU_SEG (GDT_ENTRY_PER_CPU * 8 + 3) +#define IDT_ENTRIES 256 +#define NUM_EXCEPTION_VECTORS 32 -/* TLS indexes for 64bit - hardcoded in arch_prctl */ -#define FS_TLS 0 -#define GS_TLS 1 +/* Bitmask of exception vectors which push an error code on the stack: */ +#define EXCEPTION_ERRCODE_MASK 0x20027d00 -#define GS_TLS_SEL ((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3) -#define FS_TLS_SEL ((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3) +#define GDT_SIZE (GDT_ENTRIES*8) +#define GDT_ENTRY_TLS_ENTRIES 3 +#define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8) -#define GDT_ENTRIES 16 +/* Bit size and mask of CPU number stored in the per CPU data (and TSC_AUX) */ +#define VDSO_CPUNODE_BITS 12 +#define VDSO_CPUNODE_MASK 0xfff -#endif +#ifndef __ASSEMBLER__ -#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) -#ifndef CONFIG_PARAVIRT -#define get_kernel_rpl() 0 -#endif +/* Helper functions to store/load CPU and node numbers */ -/* User mode is privilege level 3 */ -#define USER_RPL 0x3 -/* LDT segment has TI set, GDT has it cleared */ -#define SEGMENT_LDT 0x4 -#define SEGMENT_GDT 0x0 +static inline unsigned long vdso_encode_cpunode(int cpu, unsigned long node) +{ + return (node << VDSO_CPUNODE_BITS) | cpu; +} -/* Bottom two bits of selector give the ring privilege level */ -#define SEGMENT_RPL_MASK 0x3 -/* Bit 2 is table indicator (LDT/GDT) */ -#define SEGMENT_TI_MASK 0x4 +static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node) +{ + unsigned long p; + + /* + * Load CPU and node number from the GDT. LSL is faster than RDTSCP + * and works on all CPUs. This is volatile so that it orders + * correctly with respect to barrier() and to keep GCC from cleverly + * hoisting it out of the calling function. + * + * If RDPID is available, use it. + */ + alternative_io ("lsl %[seg],%k[p]", + "rdpid %[p]", + X86_FEATURE_RDPID, + [p] "=r" (p), [seg] "r" (__CPUNODE_SEG)); + + if (cpu) + *cpu = (p & VDSO_CPUNODE_MASK); + if (node) + *node = (p >> VDSO_CPUNODE_BITS); +} -#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) +#endif /* !__ASSEMBLER__ */ #ifdef __KERNEL__ -#ifndef __ASSEMBLY__ -extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5]; /* - * Load a segment. Fall back on loading the zero - * segment if something goes wrong.. + * 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 loadsegment(seg, value) \ +#define EARLY_IDT_HANDLER_SIZE (9 + ENDBR_INSN_SIZE) + +/* + * xen_early_idt_handler_array is for Xen pv guests: for each entry in + * early_idt_handler_array it contains a prequel in the form of + * pop %rcx; pop %r11; jmp early_idt_handler_array[i]; summing up to + * max 8 bytes. + */ +#define XEN_EARLY_IDT_HANDLER_SIZE (8 + ENDBR_INSN_SIZE) + +#ifndef __ASSEMBLER__ + +extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE]; +extern void early_ignore_irq(void); + +#ifdef CONFIG_XEN_PV +extern const char xen_early_idt_handler_array[NUM_EXCEPTION_VECTORS][XEN_EARLY_IDT_HANDLER_SIZE]; +#endif + +/* + * Load a segment. Fall back on loading the zero segment if something goes + * wrong. This variant assumes that loading zero fully clears the segment. + * This is always the case on Intel CPUs and, even on 64-bit AMD CPUs, any + * failure to fully clear the cached descriptor is only observable for + * FS and GS. + */ +#define __loadsegment_simple(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) \ - \ + _ASM_EXTABLE_TYPE_REG(1b, 1b, EX_TYPE_ZERO_REG, %k0)\ : "+r" (__val) : : "memory"); \ } while (0) -/* - * Save a segment register away - */ -#define savesegment(seg, value) \ - asm("mov %%" #seg ",%0":"=r" (value) : : "memory") +#define __loadsegment_ss(value) __loadsegment_simple(ss, (value)) +#define __loadsegment_ds(value) __loadsegment_simple(ds, (value)) +#define __loadsegment_es(value) __loadsegment_simple(es, (value)) + +#ifdef CONFIG_X86_32 /* - * x86_32 user gs accessors. + * On 32-bit systems, the hidden parts of FS and GS are unobservable if + * the selector is NULL, so there's no funny business here. */ -#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 */ - -static inline unsigned long get_limit(unsigned long segment) +#define __loadsegment_fs(value) __loadsegment_simple(fs, (value)) +#define __loadsegment_gs(value) __loadsegment_simple(gs, (value)) + +#else + +static inline void __loadsegment_fs(unsigned short value) { - unsigned long __limit; - asm("lsll %1,%0" : "=r" (__limit) : "r" (segment)); - return __limit + 1; + asm volatile(" \n" + "1: movw %0, %%fs \n" + "2: \n" + + _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_CLEAR_FS) + + : : "rm" (value) : "memory"); } -#endif /* !__ASSEMBLY__ */ +/* __loadsegment_gs is intentionally undefined. Use load_gs_index instead. */ + +#endif + +#define loadsegment(seg, value) __loadsegment_ ## seg (value) + +/* + * Save a segment register away: + */ +#define savesegment(seg, value) \ + asm("mov %%" #seg ",%0":"=r" (value) : : "memory") + +#endif /* !__ASSEMBLER__ */ #endif /* __KERNEL__ */ #endif /* _ASM_X86_SEGMENT_H */ |