1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 #ifndef _ASM_X86_ENTRY_COMMON_H 3 #define _ASM_X86_ENTRY_COMMON_H 4 5 #include <linux/randomize_kstack.h> 6 #include <linux/user-return-notifier.h> 7 8 #include <asm/nospec-branch.h> 9 #include <asm/io_bitmap.h> 10 #include <asm/fpu/api.h> 11 #include <asm/fred.h> 12 13 /* Check that the stack and regs on entry from user mode are sane. */ 14 static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) 15 { 16 if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) { 17 /* 18 * Make sure that the entry code gave us a sensible EFLAGS 19 * register. Native because we want to check the actual CPU 20 * state, not the interrupt state as imagined by Xen. 21 */ 22 unsigned long flags = native_save_fl(); 23 unsigned long mask = X86_EFLAGS_DF | X86_EFLAGS_NT; 24 25 /* 26 * For !SMAP hardware we patch out CLAC on entry. 27 */ 28 if (cpu_feature_enabled(X86_FEATURE_SMAP) || 29 cpu_feature_enabled(X86_FEATURE_XENPV)) 30 mask |= X86_EFLAGS_AC; 31 32 WARN_ON_ONCE(flags & mask); 33 34 /* We think we came from user mode. Make sure pt_regs agrees. */ 35 WARN_ON_ONCE(!user_mode(regs)); 36 37 /* 38 * All entries from user mode (except #DF) should be on the 39 * normal thread stack and should have user pt_regs in the 40 * correct location. 41 */ 42 WARN_ON_ONCE(!on_thread_stack()); 43 WARN_ON_ONCE(regs != task_pt_regs(current)); 44 } 45 } 46 #define arch_enter_from_user_mode arch_enter_from_user_mode 47 48 static inline void arch_exit_work(unsigned long ti_work) 49 { 50 if (ti_work & _TIF_USER_RETURN_NOTIFY) 51 fire_user_return_notifiers(); 52 53 if (unlikely(ti_work & _TIF_IO_BITMAP)) 54 tss_update_io_bitmap(); 55 56 fpregs_assert_state_consistent(); 57 if (unlikely(ti_work & _TIF_NEED_FPU_LOAD)) 58 switch_fpu_return(); 59 } 60 61 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, 62 unsigned long ti_work) 63 { 64 if (IS_ENABLED(CONFIG_X86_DEBUG_FPU) || unlikely(ti_work)) 65 arch_exit_work(ti_work); 66 67 fred_update_rsp0(); 68 69 #ifdef CONFIG_COMPAT 70 /* 71 * Compat syscalls set TS_COMPAT. Make sure we clear it before 72 * returning to user mode. We need to clear it *after* signal 73 * handling, because syscall restart has a fixup for compat 74 * syscalls. The fixup is exercised by the ptrace_syscall_32 75 * selftest. 76 * 77 * We also need to clear TS_REGS_POKED_I386: the 32-bit tracer 78 * special case only applies after poking regs and before the 79 * very next return to user mode. 80 */ 81 current_thread_info()->status &= ~(TS_COMPAT | TS_I386_REGS_POKED); 82 #endif 83 84 /* 85 * This value will get limited by KSTACK_OFFSET_MAX(), which is 10 86 * bits. The actual entropy will be further reduced by the compiler 87 * when applying stack alignment constraints (see cc_stack_align4/8 in 88 * arch/x86/Makefile), which will remove the 3 (x86_64) or 2 (ia32) 89 * low bits from any entropy chosen here. 90 * 91 * Therefore, final stack offset entropy will be 7 (x86_64) or 92 * 8 (ia32) bits. 93 */ 94 choose_random_kstack_offset(rdtsc()); 95 } 96 #define arch_exit_to_user_mode_prepare arch_exit_to_user_mode_prepare 97 98 static __always_inline void arch_exit_to_user_mode(void) 99 { 100 amd_clear_divider(); 101 } 102 #define arch_exit_to_user_mode arch_exit_to_user_mode 103 104 #endif 105