| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _ASM_X86_SWITCH_TO_H |
| #define _ASM_X86_SWITCH_TO_H |
| |
| #include <linux/sched/task_stack.h> |
| |
| struct task_struct; /* one of the stranger aspects of C forward declarations */ |
| |
| struct task_struct *__switch_to_asm(struct task_struct *prev, |
| struct task_struct *next); |
| |
| __visible struct task_struct *__switch_to(struct task_struct *prev, |
| struct task_struct *next); |
| |
| /* This runs runs on the previous thread's stack. */ |
| static inline void prepare_switch_to(struct task_struct *prev, |
| struct task_struct *next) |
| { |
| #ifdef CONFIG_VMAP_STACK |
| /* |
| * If we switch to a stack that has a top-level paging entry |
| * that is not present in the current mm, the resulting #PF will |
| * will be promoted to a double-fault and we'll panic. Probe |
| * the new stack now so that vmalloc_fault can fix up the page |
| * tables if needed. This can only happen if we use a stack |
| * in vmap space. |
| * |
| * We assume that the stack is aligned so that it never spans |
| * more than one top-level paging entry. |
| * |
| * To minimize cache pollution, just follow the stack pointer. |
| */ |
| READ_ONCE(*(unsigned char *)next->thread.sp); |
| #endif |
| } |
| |
| asmlinkage void ret_from_fork(void); |
| |
| /* |
| * This is the structure pointed to by thread.sp for an inactive task. The |
| * order of the fields must match the code in __switch_to_asm(). |
| */ |
| struct inactive_task_frame { |
| #ifdef CONFIG_X86_64 |
| unsigned long r15; |
| unsigned long r14; |
| unsigned long r13; |
| unsigned long r12; |
| #else |
| unsigned long si; |
| unsigned long di; |
| #endif |
| unsigned long bx; |
| |
| /* |
| * These two fields must be together. They form a stack frame header, |
| * needed by get_frame_pointer(). |
| */ |
| unsigned long bp; |
| unsigned long ret_addr; |
| }; |
| |
| struct fork_frame { |
| struct inactive_task_frame frame; |
| struct pt_regs regs; |
| }; |
| |
| #define switch_to(prev, next, last) \ |
| do { \ |
| prepare_switch_to(prev, next); \ |
| \ |
| ((last) = __switch_to_asm((prev), (next))); \ |
| } while (0) |
| |
| #ifdef CONFIG_X86_32 |
| static inline void refresh_sysenter_cs(struct thread_struct *thread) |
| { |
| /* Only happens when SEP is enabled, no need to test "SEP"arately: */ |
| if (unlikely(this_cpu_read(cpu_tss_rw.x86_tss.ss1) == thread->sysenter_cs)) |
| return; |
| |
| this_cpu_write(cpu_tss_rw.x86_tss.ss1, thread->sysenter_cs); |
| wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0); |
| } |
| #endif |
| |
| /* This is used when switching tasks or entering/exiting vm86 mode. */ |
| static inline void update_sp0(struct task_struct *task) |
| { |
| /* On x86_64, sp0 always points to the entry trampoline stack, which is constant: */ |
| #ifdef CONFIG_X86_32 |
| load_sp0(task->thread.sp0); |
| #else |
| if (static_cpu_has(X86_FEATURE_XENPV)) |
| load_sp0(task_top_of_stack(task)); |
| #endif |
| } |
| |
| #endif /* _ASM_X86_SWITCH_TO_H */ |