1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * Asm versions of Xen pv-ops, suitable for direct use. 4 * 5 * We only bother with direct forms (ie, vcpu in percpu data) of the 6 * operations here; the indirect forms are better handled in C. 7 */ 8 9#include <asm/errno.h> 10#include <asm/asm-offsets.h> 11#include <asm/percpu.h> 12#include <asm/processor-flags.h> 13#include <asm/segment.h> 14#include <asm/thread_info.h> 15#include <asm/asm.h> 16#include <asm/frame.h> 17#include <asm/unwind_hints.h> 18 19#include <xen/interface/xen.h> 20 21#include <linux/init.h> 22#include <linux/linkage.h> 23#include <../entry/calling.h> 24 25.pushsection .noinstr.text, "ax" 26/* 27 * Disabling events is simply a matter of making the event mask 28 * non-zero. 29 */ 30SYM_FUNC_START(xen_irq_disable_direct) 31 movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 32 ret 33SYM_FUNC_END(xen_irq_disable_direct) 34 35/* 36 * Force an event check by making a hypercall, but preserve regs 37 * before making the call. 38 */ 39SYM_FUNC_START(check_events) 40 FRAME_BEGIN 41 push %rax 42 push %rcx 43 push %rdx 44 push %rsi 45 push %rdi 46 push %r8 47 push %r9 48 push %r10 49 push %r11 50 call xen_force_evtchn_callback 51 pop %r11 52 pop %r10 53 pop %r9 54 pop %r8 55 pop %rdi 56 pop %rsi 57 pop %rdx 58 pop %rcx 59 pop %rax 60 FRAME_END 61 ret 62SYM_FUNC_END(check_events) 63 64/* 65 * Enable events. This clears the event mask and tests the pending 66 * event status with one and operation. If there are pending events, 67 * then enter the hypervisor to get them handled. 68 */ 69SYM_FUNC_START(xen_irq_enable_direct) 70 FRAME_BEGIN 71 /* Unmask events */ 72 movb $0, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 73 74 /* 75 * Preempt here doesn't matter because that will deal with any 76 * pending interrupts. The pending check may end up being run 77 * on the wrong CPU, but that doesn't hurt. 78 */ 79 80 /* Test for pending */ 81 testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending 82 jz 1f 83 84 call check_events 851: 86 FRAME_END 87 ret 88SYM_FUNC_END(xen_irq_enable_direct) 89 90/* 91 * (xen_)save_fl is used to get the current interrupt enable status. 92 * Callers expect the status to be in X86_EFLAGS_IF, and other bits 93 * may be set in the return value. We take advantage of this by 94 * making sure that X86_EFLAGS_IF has the right value (and other bits 95 * in that byte are 0), but other bits in the return value are 96 * undefined. We need to toggle the state of the bit, because Xen and 97 * x86 use opposite senses (mask vs enable). 98 */ 99SYM_FUNC_START(xen_save_fl_direct) 100 testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 101 setz %ah 102 addb %ah, %ah 103 ret 104SYM_FUNC_END(xen_save_fl_direct) 105 106SYM_FUNC_START(xen_read_cr2) 107 FRAME_BEGIN 108 _ASM_MOV PER_CPU_VAR(xen_vcpu), %_ASM_AX 109 _ASM_MOV XEN_vcpu_info_arch_cr2(%_ASM_AX), %_ASM_AX 110 FRAME_END 111 ret 112SYM_FUNC_END(xen_read_cr2); 113 114SYM_FUNC_START(xen_read_cr2_direct) 115 FRAME_BEGIN 116 _ASM_MOV PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_arch_cr2, %_ASM_AX 117 FRAME_END 118 ret 119SYM_FUNC_END(xen_read_cr2_direct); 120.popsection 121 122.macro xen_pv_trap name 123SYM_CODE_START(xen_\name) 124 UNWIND_HINT_EMPTY 125 pop %rcx 126 pop %r11 127 jmp \name 128SYM_CODE_END(xen_\name) 129_ASM_NOKPROBE(xen_\name) 130.endm 131 132xen_pv_trap asm_exc_divide_error 133xen_pv_trap asm_xenpv_exc_debug 134xen_pv_trap asm_exc_int3 135xen_pv_trap asm_xenpv_exc_nmi 136xen_pv_trap asm_exc_overflow 137xen_pv_trap asm_exc_bounds 138xen_pv_trap asm_exc_invalid_op 139xen_pv_trap asm_exc_device_not_available 140xen_pv_trap asm_xenpv_exc_double_fault 141xen_pv_trap asm_exc_coproc_segment_overrun 142xen_pv_trap asm_exc_invalid_tss 143xen_pv_trap asm_exc_segment_not_present 144xen_pv_trap asm_exc_stack_segment 145xen_pv_trap asm_exc_general_protection 146xen_pv_trap asm_exc_page_fault 147xen_pv_trap asm_exc_spurious_interrupt_bug 148xen_pv_trap asm_exc_coprocessor_error 149xen_pv_trap asm_exc_alignment_check 150#ifdef CONFIG_X86_MCE 151xen_pv_trap asm_xenpv_exc_machine_check 152#endif /* CONFIG_X86_MCE */ 153xen_pv_trap asm_exc_simd_coprocessor_error 154#ifdef CONFIG_IA32_EMULATION 155xen_pv_trap entry_INT80_compat 156#endif 157xen_pv_trap asm_exc_xen_unknown_trap 158xen_pv_trap asm_exc_xen_hypervisor_callback 159 160 __INIT 161SYM_CODE_START(xen_early_idt_handler_array) 162 i = 0 163 .rept NUM_EXCEPTION_VECTORS 164 UNWIND_HINT_EMPTY 165 pop %rcx 166 pop %r11 167 jmp early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE 168 i = i + 1 169 .fill xen_early_idt_handler_array + i*XEN_EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc 170 .endr 171SYM_CODE_END(xen_early_idt_handler_array) 172 __FINIT 173 174hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32 175/* 176 * Xen64 iret frame: 177 * 178 * ss 179 * rsp 180 * rflags 181 * cs 182 * rip <-- standard iret frame 183 * 184 * flags 185 * 186 * rcx } 187 * r11 }<-- pushed by hypercall page 188 * rsp->rax } 189 */ 190SYM_CODE_START(xen_iret) 191 UNWIND_HINT_EMPTY 192 pushq $0 193 jmp hypercall_iret 194SYM_CODE_END(xen_iret) 195 196/* 197 * XEN pv doesn't use trampoline stack, PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is 198 * also the kernel stack. Reusing swapgs_restore_regs_and_return_to_usermode() 199 * in XEN pv would cause %rsp to move up to the top of the kernel stack and 200 * leave the IRET frame below %rsp, which is dangerous to be corrupted if #NMI 201 * interrupts. And swapgs_restore_regs_and_return_to_usermode() pushing the IRET 202 * frame at the same address is useless. 203 */ 204SYM_CODE_START(xenpv_restore_regs_and_return_to_usermode) 205 UNWIND_HINT_REGS 206 POP_REGS 207 208 /* stackleak_erase() can work safely on the kernel stack. */ 209 STACKLEAK_ERASE_NOCLOBBER 210 211 addq $8, %rsp /* skip regs->orig_ax */ 212 jmp xen_iret 213SYM_CODE_END(xenpv_restore_regs_and_return_to_usermode) 214 215/* 216 * Xen handles syscall callbacks much like ordinary exceptions, which 217 * means we have: 218 * - kernel gs 219 * - kernel rsp 220 * - an iret-like stack frame on the stack (including rcx and r11): 221 * ss 222 * rsp 223 * rflags 224 * cs 225 * rip 226 * r11 227 * rsp->rcx 228 */ 229 230/* Normal 64-bit system call target */ 231SYM_CODE_START(xen_syscall_target) 232 UNWIND_HINT_EMPTY 233 popq %rcx 234 popq %r11 235 236 /* 237 * Neither Xen nor the kernel really knows what the old SS and 238 * CS were. The kernel expects __USER_DS and __USER_CS, so 239 * report those values even though Xen will guess its own values. 240 */ 241 movq $__USER_DS, 4*8(%rsp) 242 movq $__USER_CS, 1*8(%rsp) 243 244 jmp entry_SYSCALL_64_after_hwframe 245SYM_CODE_END(xen_syscall_target) 246 247#ifdef CONFIG_IA32_EMULATION 248 249/* 32-bit compat syscall target */ 250SYM_CODE_START(xen_syscall32_target) 251 UNWIND_HINT_EMPTY 252 popq %rcx 253 popq %r11 254 255 /* 256 * Neither Xen nor the kernel really knows what the old SS and 257 * CS were. The kernel expects __USER32_DS and __USER32_CS, so 258 * report those values even though Xen will guess its own values. 259 */ 260 movq $__USER32_DS, 4*8(%rsp) 261 movq $__USER32_CS, 1*8(%rsp) 262 263 jmp entry_SYSCALL_compat_after_hwframe 264SYM_CODE_END(xen_syscall32_target) 265 266/* 32-bit compat sysenter target */ 267SYM_CODE_START(xen_sysenter_target) 268 UNWIND_HINT_EMPTY 269 /* 270 * NB: Xen is polite and clears TF from EFLAGS for us. This means 271 * that we don't need to guard against single step exceptions here. 272 */ 273 popq %rcx 274 popq %r11 275 276 /* 277 * Neither Xen nor the kernel really knows what the old SS and 278 * CS were. The kernel expects __USER32_DS and __USER32_CS, so 279 * report those values even though Xen will guess its own values. 280 */ 281 movq $__USER32_DS, 4*8(%rsp) 282 movq $__USER32_CS, 1*8(%rsp) 283 284 jmp entry_SYSENTER_compat_after_hwframe 285SYM_CODE_END(xen_sysenter_target) 286 287#else /* !CONFIG_IA32_EMULATION */ 288 289SYM_CODE_START(xen_syscall32_target) 290SYM_CODE_START(xen_sysenter_target) 291 UNWIND_HINT_EMPTY 292 lea 16(%rsp), %rsp /* strip %rcx, %r11 */ 293 mov $-ENOSYS, %rax 294 pushq $0 295 jmp hypercall_iret 296SYM_CODE_END(xen_sysenter_target) 297SYM_CODE_END(xen_syscall32_target) 298 299#endif /* CONFIG_IA32_EMULATION */ 300