1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Low-level exception handling code 4 * 5 * Copyright (C) 2012 ARM Ltd. 6 * Authors: Catalin Marinas <catalin.marinas@arm.com> 7 * Will Deacon <will.deacon@arm.com> 8 */ 9 10#include <linux/arm-smccc.h> 11#include <linux/init.h> 12#include <linux/linkage.h> 13 14#include <asm/alternative.h> 15#include <asm/assembler.h> 16#include <asm/asm-offsets.h> 17#include <asm/cpufeature.h> 18#include <asm/errno.h> 19#include <asm/esr.h> 20#include <asm/irq.h> 21#include <asm/memory.h> 22#include <asm/mmu.h> 23#include <asm/processor.h> 24#include <asm/ptrace.h> 25#include <asm/thread_info.h> 26#include <asm/asm-uaccess.h> 27#include <asm/unistd.h> 28 29/* 30 * Context tracking subsystem. Used to instrument transitions 31 * between user and kernel mode. 32 */ 33 .macro ct_user_exit_irqoff 34#ifdef CONFIG_CONTEXT_TRACKING 35 bl enter_from_user_mode 36#endif 37 .endm 38 39 .macro ct_user_enter 40#ifdef CONFIG_CONTEXT_TRACKING 41 bl context_tracking_user_enter 42#endif 43 .endm 44 45 .macro clear_gp_regs 46 .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29 47 mov x\n, xzr 48 .endr 49 .endm 50 51/* 52 * Bad Abort numbers 53 *----------------- 54 */ 55#define BAD_SYNC 0 56#define BAD_IRQ 1 57#define BAD_FIQ 2 58#define BAD_ERROR 3 59 60 .macro kernel_ventry, el, label, regsize = 64 61 .align 7 62#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 63alternative_if ARM64_UNMAP_KERNEL_AT_EL0 64 .if \el == 0 65 .if \regsize == 64 66 mrs x30, tpidrro_el0 67 msr tpidrro_el0, xzr 68 .else 69 mov x30, xzr 70 .endif 71 .endif 72alternative_else_nop_endif 73#endif 74 75 sub sp, sp, #S_FRAME_SIZE 76#ifdef CONFIG_VMAP_STACK 77 /* 78 * Test whether the SP has overflowed, without corrupting a GPR. 79 * Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT) 80 * should always be zero. 81 */ 82 add sp, sp, x0 // sp' = sp + x0 83 sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp 84 tbnz x0, #THREAD_SHIFT, 0f 85 sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0 86 sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp 87 b el\()\el\()_\label 88 890: 90 /* 91 * Either we've just detected an overflow, or we've taken an exception 92 * while on the overflow stack. Either way, we won't return to 93 * userspace, and can clobber EL0 registers to free up GPRs. 94 */ 95 96 /* Stash the original SP (minus S_FRAME_SIZE) in tpidr_el0. */ 97 msr tpidr_el0, x0 98 99 /* Recover the original x0 value and stash it in tpidrro_el0 */ 100 sub x0, sp, x0 101 msr tpidrro_el0, x0 102 103 /* Switch to the overflow stack */ 104 adr_this_cpu sp, overflow_stack + OVERFLOW_STACK_SIZE, x0 105 106 /* 107 * Check whether we were already on the overflow stack. This may happen 108 * after panic() re-enables interrupts. 109 */ 110 mrs x0, tpidr_el0 // sp of interrupted context 111 sub x0, sp, x0 // delta with top of overflow stack 112 tst x0, #~(OVERFLOW_STACK_SIZE - 1) // within range? 113 b.ne __bad_stack // no? -> bad stack pointer 114 115 /* We were already on the overflow stack. Restore sp/x0 and carry on. */ 116 sub sp, sp, x0 117 mrs x0, tpidrro_el0 118#endif 119 b el\()\el\()_\label 120 .endm 121 122 .macro tramp_alias, dst, sym 123 mov_q \dst, TRAMP_VALIAS 124 add \dst, \dst, #(\sym - .entry.tramp.text) 125 .endm 126 127 // This macro corrupts x0-x3. It is the caller's duty 128 // to save/restore them if required. 129 .macro apply_ssbd, state, tmp1, tmp2 130#ifdef CONFIG_ARM64_SSBD 131alternative_cb arm64_enable_wa2_handling 132 b .L__asm_ssbd_skip\@ 133alternative_cb_end 134 ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 135 cbz \tmp2, .L__asm_ssbd_skip\@ 136 ldr \tmp2, [tsk, #TSK_TI_FLAGS] 137 tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@ 138 mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 139 mov w1, #\state 140alternative_cb arm64_update_smccc_conduit 141 nop // Patched to SMC/HVC #0 142alternative_cb_end 143.L__asm_ssbd_skip\@: 144#endif 145 .endm 146 147 .macro kernel_entry, el, regsize = 64 148 .if \regsize == 32 149 mov w0, w0 // zero upper 32 bits of x0 150 .endif 151 stp x0, x1, [sp, #16 * 0] 152 stp x2, x3, [sp, #16 * 1] 153 stp x4, x5, [sp, #16 * 2] 154 stp x6, x7, [sp, #16 * 3] 155 stp x8, x9, [sp, #16 * 4] 156 stp x10, x11, [sp, #16 * 5] 157 stp x12, x13, [sp, #16 * 6] 158 stp x14, x15, [sp, #16 * 7] 159 stp x16, x17, [sp, #16 * 8] 160 stp x18, x19, [sp, #16 * 9] 161 stp x20, x21, [sp, #16 * 10] 162 stp x22, x23, [sp, #16 * 11] 163 stp x24, x25, [sp, #16 * 12] 164 stp x26, x27, [sp, #16 * 13] 165 stp x28, x29, [sp, #16 * 14] 166 167 .if \el == 0 168 clear_gp_regs 169 mrs x21, sp_el0 170 ldr_this_cpu tsk, __entry_task, x20 // Ensure MDSCR_EL1.SS is clear, 171 ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug 172 disable_step_tsk x19, x20 // exceptions when scheduling. 173 174 apply_ssbd 1, x22, x23 175 176 .else 177 add x21, sp, #S_FRAME_SIZE 178 get_current_task tsk 179 /* Save the task's original addr_limit and set USER_DS */ 180 ldr x20, [tsk, #TSK_TI_ADDR_LIMIT] 181 str x20, [sp, #S_ORIG_ADDR_LIMIT] 182 mov x20, #USER_DS 183 str x20, [tsk, #TSK_TI_ADDR_LIMIT] 184 /* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */ 185 .endif /* \el == 0 */ 186 mrs x22, elr_el1 187 mrs x23, spsr_el1 188 stp lr, x21, [sp, #S_LR] 189 190 /* 191 * In order to be able to dump the contents of struct pt_regs at the 192 * time the exception was taken (in case we attempt to walk the call 193 * stack later), chain it together with the stack frames. 194 */ 195 .if \el == 0 196 stp xzr, xzr, [sp, #S_STACKFRAME] 197 .else 198 stp x29, x22, [sp, #S_STACKFRAME] 199 .endif 200 add x29, sp, #S_STACKFRAME 201 202#ifdef CONFIG_ARM64_SW_TTBR0_PAN 203 /* 204 * Set the TTBR0 PAN bit in SPSR. When the exception is taken from 205 * EL0, there is no need to check the state of TTBR0_EL1 since 206 * accesses are always enabled. 207 * Note that the meaning of this bit differs from the ARMv8.1 PAN 208 * feature as all TTBR0_EL1 accesses are disabled, not just those to 209 * user mappings. 210 */ 211alternative_if ARM64_HAS_PAN 212 b 1f // skip TTBR0 PAN 213alternative_else_nop_endif 214 215 .if \el != 0 216 mrs x21, ttbr0_el1 217 tst x21, #TTBR_ASID_MASK // Check for the reserved ASID 218 orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR 219 b.eq 1f // TTBR0 access already disabled 220 and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR 221 .endif 222 223 __uaccess_ttbr0_disable x21 2241: 225#endif 226 227 stp x22, x23, [sp, #S_PC] 228 229 /* Not in a syscall by default (el0_svc overwrites for real syscall) */ 230 .if \el == 0 231 mov w21, #NO_SYSCALL 232 str w21, [sp, #S_SYSCALLNO] 233 .endif 234 235 /* 236 * Set sp_el0 to current thread_info. 237 */ 238 .if \el == 0 239 msr sp_el0, tsk 240 .endif 241 242 /* Save pmr */ 243alternative_if ARM64_HAS_IRQ_PRIO_MASKING 244 mrs_s x20, SYS_ICC_PMR_EL1 245 str x20, [sp, #S_PMR_SAVE] 246alternative_else_nop_endif 247 248 /* 249 * Registers that may be useful after this macro is invoked: 250 * 251 * x20 - ICC_PMR_EL1 252 * x21 - aborted SP 253 * x22 - aborted PC 254 * x23 - aborted PSTATE 255 */ 256 .endm 257 258 .macro kernel_exit, el 259 .if \el != 0 260 disable_daif 261 262 /* Restore the task's original addr_limit. */ 263 ldr x20, [sp, #S_ORIG_ADDR_LIMIT] 264 str x20, [tsk, #TSK_TI_ADDR_LIMIT] 265 266 /* No need to restore UAO, it will be restored from SPSR_EL1 */ 267 .endif 268 269 /* Restore pmr */ 270alternative_if ARM64_HAS_IRQ_PRIO_MASKING 271 ldr x20, [sp, #S_PMR_SAVE] 272 msr_s SYS_ICC_PMR_EL1, x20 273 mrs_s x21, SYS_ICC_CTLR_EL1 274 tbz x21, #6, .L__skip_pmr_sync\@ // Check for ICC_CTLR_EL1.PMHE 275 dsb sy // Ensure priority change is seen by redistributor 276.L__skip_pmr_sync\@: 277alternative_else_nop_endif 278 279 ldp x21, x22, [sp, #S_PC] // load ELR, SPSR 280 .if \el == 0 281 ct_user_enter 282 .endif 283 284#ifdef CONFIG_ARM64_SW_TTBR0_PAN 285 /* 286 * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR 287 * PAN bit checking. 288 */ 289alternative_if ARM64_HAS_PAN 290 b 2f // skip TTBR0 PAN 291alternative_else_nop_endif 292 293 .if \el != 0 294 tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set 295 .endif 296 297 __uaccess_ttbr0_enable x0, x1 298 299 .if \el == 0 300 /* 301 * Enable errata workarounds only if returning to user. The only 302 * workaround currently required for TTBR0_EL1 changes are for the 303 * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache 304 * corruption). 305 */ 306 bl post_ttbr_update_workaround 307 .endif 3081: 309 .if \el != 0 310 and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit 311 .endif 3122: 313#endif 314 315 .if \el == 0 316 ldr x23, [sp, #S_SP] // load return stack pointer 317 msr sp_el0, x23 318 tst x22, #PSR_MODE32_BIT // native task? 319 b.eq 3f 320 321#ifdef CONFIG_ARM64_ERRATUM_845719 322alternative_if ARM64_WORKAROUND_845719 323#ifdef CONFIG_PID_IN_CONTEXTIDR 324 mrs x29, contextidr_el1 325 msr contextidr_el1, x29 326#else 327 msr contextidr_el1, xzr 328#endif 329alternative_else_nop_endif 330#endif 3313: 332#ifdef CONFIG_ARM64_ERRATUM_1418040 333alternative_if_not ARM64_WORKAROUND_1418040 334 b 4f 335alternative_else_nop_endif 336 /* 337 * if (x22.mode32 == cntkctl_el1.el0vcten) 338 * cntkctl_el1.el0vcten = ~cntkctl_el1.el0vcten 339 */ 340 mrs x1, cntkctl_el1 341 eon x0, x1, x22, lsr #3 342 tbz x0, #1, 4f 343 eor x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN 344 msr cntkctl_el1, x1 3454: 346#endif 347 apply_ssbd 0, x0, x1 348 .endif 349 350 msr elr_el1, x21 // set up the return data 351 msr spsr_el1, x22 352 ldp x0, x1, [sp, #16 * 0] 353 ldp x2, x3, [sp, #16 * 1] 354 ldp x4, x5, [sp, #16 * 2] 355 ldp x6, x7, [sp, #16 * 3] 356 ldp x8, x9, [sp, #16 * 4] 357 ldp x10, x11, [sp, #16 * 5] 358 ldp x12, x13, [sp, #16 * 6] 359 ldp x14, x15, [sp, #16 * 7] 360 ldp x16, x17, [sp, #16 * 8] 361 ldp x18, x19, [sp, #16 * 9] 362 ldp x20, x21, [sp, #16 * 10] 363 ldp x22, x23, [sp, #16 * 11] 364 ldp x24, x25, [sp, #16 * 12] 365 ldp x26, x27, [sp, #16 * 13] 366 ldp x28, x29, [sp, #16 * 14] 367 ldr lr, [sp, #S_LR] 368 add sp, sp, #S_FRAME_SIZE // restore sp 369 370 .if \el == 0 371alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 372#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 373 bne 5f 374 msr far_el1, x30 375 tramp_alias x30, tramp_exit_native 376 br x30 3775: 378 tramp_alias x30, tramp_exit_compat 379 br x30 380#endif 381 .else 382 eret 383 .endif 384 sb 385 .endm 386 387 .macro irq_stack_entry 388 mov x19, sp // preserve the original sp 389 390 /* 391 * Compare sp with the base of the task stack. 392 * If the top ~(THREAD_SIZE - 1) bits match, we are on a task stack, 393 * and should switch to the irq stack. 394 */ 395 ldr x25, [tsk, TSK_STACK] 396 eor x25, x25, x19 397 and x25, x25, #~(THREAD_SIZE - 1) 398 cbnz x25, 9998f 399 400 ldr_this_cpu x25, irq_stack_ptr, x26 401 mov x26, #IRQ_STACK_SIZE 402 add x26, x25, x26 403 404 /* switch to the irq stack */ 405 mov sp, x26 4069998: 407 .endm 408 409 /* 410 * x19 should be preserved between irq_stack_entry and 411 * irq_stack_exit. 412 */ 413 .macro irq_stack_exit 414 mov sp, x19 415 .endm 416 417/* GPRs used by entry code */ 418tsk .req x28 // current thread_info 419 420/* 421 * Interrupt handling. 422 */ 423 .macro irq_handler 424 ldr_l x1, handle_arch_irq 425 mov x0, sp 426 irq_stack_entry 427 blr x1 428 irq_stack_exit 429 .endm 430 431#ifdef CONFIG_ARM64_PSEUDO_NMI 432 /* 433 * Set res to 0 if irqs were unmasked in interrupted context. 434 * Otherwise set res to non-0 value. 435 */ 436 .macro test_irqs_unmasked res:req, pmr:req 437alternative_if ARM64_HAS_IRQ_PRIO_MASKING 438 sub \res, \pmr, #GIC_PRIO_IRQON 439alternative_else 440 mov \res, xzr 441alternative_endif 442 .endm 443#endif 444 445 .macro gic_prio_kentry_setup, tmp:req 446#ifdef CONFIG_ARM64_PSEUDO_NMI 447 alternative_if ARM64_HAS_IRQ_PRIO_MASKING 448 mov \tmp, #(GIC_PRIO_PSR_I_SET | GIC_PRIO_IRQON) 449 msr_s SYS_ICC_PMR_EL1, \tmp 450 alternative_else_nop_endif 451#endif 452 .endm 453 454 .macro gic_prio_irq_setup, pmr:req, tmp:req 455#ifdef CONFIG_ARM64_PSEUDO_NMI 456 alternative_if ARM64_HAS_IRQ_PRIO_MASKING 457 orr \tmp, \pmr, #GIC_PRIO_PSR_I_SET 458 msr_s SYS_ICC_PMR_EL1, \tmp 459 alternative_else_nop_endif 460#endif 461 .endm 462 463 .text 464 465/* 466 * Exception vectors. 467 */ 468 .pushsection ".entry.text", "ax" 469 470 .align 11 471ENTRY(vectors) 472 kernel_ventry 1, sync_invalid // Synchronous EL1t 473 kernel_ventry 1, irq_invalid // IRQ EL1t 474 kernel_ventry 1, fiq_invalid // FIQ EL1t 475 kernel_ventry 1, error_invalid // Error EL1t 476 477 kernel_ventry 1, sync // Synchronous EL1h 478 kernel_ventry 1, irq // IRQ EL1h 479 kernel_ventry 1, fiq_invalid // FIQ EL1h 480 kernel_ventry 1, error // Error EL1h 481 482 kernel_ventry 0, sync // Synchronous 64-bit EL0 483 kernel_ventry 0, irq // IRQ 64-bit EL0 484 kernel_ventry 0, fiq_invalid // FIQ 64-bit EL0 485 kernel_ventry 0, error // Error 64-bit EL0 486 487#ifdef CONFIG_COMPAT 488 kernel_ventry 0, sync_compat, 32 // Synchronous 32-bit EL0 489 kernel_ventry 0, irq_compat, 32 // IRQ 32-bit EL0 490 kernel_ventry 0, fiq_invalid_compat, 32 // FIQ 32-bit EL0 491 kernel_ventry 0, error_compat, 32 // Error 32-bit EL0 492#else 493 kernel_ventry 0, sync_invalid, 32 // Synchronous 32-bit EL0 494 kernel_ventry 0, irq_invalid, 32 // IRQ 32-bit EL0 495 kernel_ventry 0, fiq_invalid, 32 // FIQ 32-bit EL0 496 kernel_ventry 0, error_invalid, 32 // Error 32-bit EL0 497#endif 498END(vectors) 499 500#ifdef CONFIG_VMAP_STACK 501 /* 502 * We detected an overflow in kernel_ventry, which switched to the 503 * overflow stack. Stash the exception regs, and head to our overflow 504 * handler. 505 */ 506__bad_stack: 507 /* Restore the original x0 value */ 508 mrs x0, tpidrro_el0 509 510 /* 511 * Store the original GPRs to the new stack. The orginal SP (minus 512 * S_FRAME_SIZE) was stashed in tpidr_el0 by kernel_ventry. 513 */ 514 sub sp, sp, #S_FRAME_SIZE 515 kernel_entry 1 516 mrs x0, tpidr_el0 517 add x0, x0, #S_FRAME_SIZE 518 str x0, [sp, #S_SP] 519 520 /* Stash the regs for handle_bad_stack */ 521 mov x0, sp 522 523 /* Time to die */ 524 bl handle_bad_stack 525 ASM_BUG() 526#endif /* CONFIG_VMAP_STACK */ 527 528/* 529 * Invalid mode handlers 530 */ 531 .macro inv_entry, el, reason, regsize = 64 532 kernel_entry \el, \regsize 533 mov x0, sp 534 mov x1, #\reason 535 mrs x2, esr_el1 536 bl bad_mode 537 ASM_BUG() 538 .endm 539 540el0_sync_invalid: 541 inv_entry 0, BAD_SYNC 542ENDPROC(el0_sync_invalid) 543 544el0_irq_invalid: 545 inv_entry 0, BAD_IRQ 546ENDPROC(el0_irq_invalid) 547 548el0_fiq_invalid: 549 inv_entry 0, BAD_FIQ 550ENDPROC(el0_fiq_invalid) 551 552el0_error_invalid: 553 inv_entry 0, BAD_ERROR 554ENDPROC(el0_error_invalid) 555 556#ifdef CONFIG_COMPAT 557el0_fiq_invalid_compat: 558 inv_entry 0, BAD_FIQ, 32 559ENDPROC(el0_fiq_invalid_compat) 560#endif 561 562el1_sync_invalid: 563 inv_entry 1, BAD_SYNC 564ENDPROC(el1_sync_invalid) 565 566el1_irq_invalid: 567 inv_entry 1, BAD_IRQ 568ENDPROC(el1_irq_invalid) 569 570el1_fiq_invalid: 571 inv_entry 1, BAD_FIQ 572ENDPROC(el1_fiq_invalid) 573 574el1_error_invalid: 575 inv_entry 1, BAD_ERROR 576ENDPROC(el1_error_invalid) 577 578/* 579 * EL1 mode handlers. 580 */ 581 .align 6 582el1_sync: 583 kernel_entry 1 584 mov x0, sp 585 bl el1_sync_handler 586 kernel_exit 1 587ENDPROC(el1_sync) 588 589 .align 6 590el1_irq: 591 kernel_entry 1 592 gic_prio_irq_setup pmr=x20, tmp=x1 593 enable_da_f 594 595#ifdef CONFIG_ARM64_PSEUDO_NMI 596 test_irqs_unmasked res=x0, pmr=x20 597 cbz x0, 1f 598 bl asm_nmi_enter 5991: 600#endif 601 602#ifdef CONFIG_TRACE_IRQFLAGS 603 bl trace_hardirqs_off 604#endif 605 606 irq_handler 607 608#ifdef CONFIG_PREEMPT 609 ldr x24, [tsk, #TSK_TI_PREEMPT] // get preempt count 610alternative_if ARM64_HAS_IRQ_PRIO_MASKING 611 /* 612 * DA_F were cleared at start of handling. If anything is set in DAIF, 613 * we come back from an NMI, so skip preemption 614 */ 615 mrs x0, daif 616 orr x24, x24, x0 617alternative_else_nop_endif 618 cbnz x24, 1f // preempt count != 0 || NMI return path 619 bl arm64_preempt_schedule_irq // irq en/disable is done inside 6201: 621#endif 622 623#ifdef CONFIG_ARM64_PSEUDO_NMI 624 /* 625 * When using IRQ priority masking, we can get spurious interrupts while 626 * PMR is set to GIC_PRIO_IRQOFF. An NMI might also have occurred in a 627 * section with interrupts disabled. Skip tracing in those cases. 628 */ 629 test_irqs_unmasked res=x0, pmr=x20 630 cbz x0, 1f 631 bl asm_nmi_exit 6321: 633#endif 634 635#ifdef CONFIG_TRACE_IRQFLAGS 636#ifdef CONFIG_ARM64_PSEUDO_NMI 637 test_irqs_unmasked res=x0, pmr=x20 638 cbnz x0, 1f 639#endif 640 bl trace_hardirqs_on 6411: 642#endif 643 644 kernel_exit 1 645ENDPROC(el1_irq) 646 647/* 648 * EL0 mode handlers. 649 */ 650 .align 6 651el0_sync: 652 kernel_entry 0 653 mov x0, sp 654 bl el0_sync_handler 655 b ret_to_user 656 657#ifdef CONFIG_COMPAT 658 .align 6 659el0_sync_compat: 660 kernel_entry 0, 32 661 mov x0, sp 662 bl el0_sync_compat_handler 663 b ret_to_user 664ENDPROC(el0_sync) 665 666 .align 6 667el0_irq_compat: 668 kernel_entry 0, 32 669 b el0_irq_naked 670 671el0_error_compat: 672 kernel_entry 0, 32 673 b el0_error_naked 674#endif 675 676 .align 6 677el0_irq: 678 kernel_entry 0 679el0_irq_naked: 680 gic_prio_irq_setup pmr=x20, tmp=x0 681 ct_user_exit_irqoff 682 enable_da_f 683 684#ifdef CONFIG_TRACE_IRQFLAGS 685 bl trace_hardirqs_off 686#endif 687 688#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR 689 tbz x22, #55, 1f 690 bl do_el0_irq_bp_hardening 6911: 692#endif 693 irq_handler 694 695#ifdef CONFIG_TRACE_IRQFLAGS 696 bl trace_hardirqs_on 697#endif 698 b ret_to_user 699ENDPROC(el0_irq) 700 701el1_error: 702 kernel_entry 1 703 mrs x1, esr_el1 704 gic_prio_kentry_setup tmp=x2 705 enable_dbg 706 mov x0, sp 707 bl do_serror 708 kernel_exit 1 709ENDPROC(el1_error) 710 711el0_error: 712 kernel_entry 0 713el0_error_naked: 714 mrs x25, esr_el1 715 gic_prio_kentry_setup tmp=x2 716 ct_user_exit_irqoff 717 enable_dbg 718 mov x0, sp 719 mov x1, x25 720 bl do_serror 721 enable_da_f 722 b ret_to_user 723ENDPROC(el0_error) 724 725/* 726 * Ok, we need to do extra processing, enter the slow path. 727 */ 728work_pending: 729 mov x0, sp // 'regs' 730 bl do_notify_resume 731#ifdef CONFIG_TRACE_IRQFLAGS 732 bl trace_hardirqs_on // enabled while in userspace 733#endif 734 ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step 735 b finish_ret_to_user 736/* 737 * "slow" syscall return path. 738 */ 739ret_to_user: 740 disable_daif 741 gic_prio_kentry_setup tmp=x3 742 ldr x1, [tsk, #TSK_TI_FLAGS] 743 and x2, x1, #_TIF_WORK_MASK 744 cbnz x2, work_pending 745finish_ret_to_user: 746 enable_step_tsk x1, x2 747#ifdef CONFIG_GCC_PLUGIN_STACKLEAK 748 bl stackleak_erase 749#endif 750 kernel_exit 0 751ENDPROC(ret_to_user) 752 753 .popsection // .entry.text 754 755#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 756/* 757 * Exception vectors trampoline. 758 */ 759 .pushsection ".entry.tramp.text", "ax" 760 761 .macro tramp_map_kernel, tmp 762 mrs \tmp, ttbr1_el1 763 add \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE) 764 bic \tmp, \tmp, #USER_ASID_FLAG 765 msr ttbr1_el1, \tmp 766#ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003 767alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003 768 /* ASID already in \tmp[63:48] */ 769 movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12) 770 movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12) 771 /* 2MB boundary containing the vectors, so we nobble the walk cache */ 772 movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12) 773 isb 774 tlbi vae1, \tmp 775 dsb nsh 776alternative_else_nop_endif 777#endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */ 778 .endm 779 780 .macro tramp_unmap_kernel, tmp 781 mrs \tmp, ttbr1_el1 782 sub \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE) 783 orr \tmp, \tmp, #USER_ASID_FLAG 784 msr ttbr1_el1, \tmp 785 /* 786 * We avoid running the post_ttbr_update_workaround here because 787 * it's only needed by Cavium ThunderX, which requires KPTI to be 788 * disabled. 789 */ 790 .endm 791 792 .macro tramp_ventry, regsize = 64 793 .align 7 7941: 795 .if \regsize == 64 796 msr tpidrro_el0, x30 // Restored in kernel_ventry 797 .endif 798 /* 799 * Defend against branch aliasing attacks by pushing a dummy 800 * entry onto the return stack and using a RET instruction to 801 * enter the full-fat kernel vectors. 802 */ 803 bl 2f 804 b . 8052: 806 tramp_map_kernel x30 807#ifdef CONFIG_RANDOMIZE_BASE 808 adr x30, tramp_vectors + PAGE_SIZE 809alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 810 ldr x30, [x30] 811#else 812 ldr x30, =vectors 813#endif 814alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM 815 prfm plil1strm, [x30, #(1b - tramp_vectors)] 816alternative_else_nop_endif 817 msr vbar_el1, x30 818 add x30, x30, #(1b - tramp_vectors) 819 isb 820 ret 821 .endm 822 823 .macro tramp_exit, regsize = 64 824 adr x30, tramp_vectors 825 msr vbar_el1, x30 826 tramp_unmap_kernel x30 827 .if \regsize == 64 828 mrs x30, far_el1 829 .endif 830 eret 831 sb 832 .endm 833 834 .align 11 835ENTRY(tramp_vectors) 836 .space 0x400 837 838 tramp_ventry 839 tramp_ventry 840 tramp_ventry 841 tramp_ventry 842 843 tramp_ventry 32 844 tramp_ventry 32 845 tramp_ventry 32 846 tramp_ventry 32 847END(tramp_vectors) 848 849ENTRY(tramp_exit_native) 850 tramp_exit 851END(tramp_exit_native) 852 853ENTRY(tramp_exit_compat) 854 tramp_exit 32 855END(tramp_exit_compat) 856 857 .ltorg 858 .popsection // .entry.tramp.text 859#ifdef CONFIG_RANDOMIZE_BASE 860 .pushsection ".rodata", "a" 861 .align PAGE_SHIFT 862 .globl __entry_tramp_data_start 863__entry_tramp_data_start: 864 .quad vectors 865 .popsection // .rodata 866#endif /* CONFIG_RANDOMIZE_BASE */ 867#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ 868 869/* 870 * Register switch for AArch64. The callee-saved registers need to be saved 871 * and restored. On entry: 872 * x0 = previous task_struct (must be preserved across the switch) 873 * x1 = next task_struct 874 * Previous and next are guaranteed not to be the same. 875 * 876 */ 877ENTRY(cpu_switch_to) 878 mov x10, #THREAD_CPU_CONTEXT 879 add x8, x0, x10 880 mov x9, sp 881 stp x19, x20, [x8], #16 // store callee-saved registers 882 stp x21, x22, [x8], #16 883 stp x23, x24, [x8], #16 884 stp x25, x26, [x8], #16 885 stp x27, x28, [x8], #16 886 stp x29, x9, [x8], #16 887 str lr, [x8] 888 add x8, x1, x10 889 ldp x19, x20, [x8], #16 // restore callee-saved registers 890 ldp x21, x22, [x8], #16 891 ldp x23, x24, [x8], #16 892 ldp x25, x26, [x8], #16 893 ldp x27, x28, [x8], #16 894 ldp x29, x9, [x8], #16 895 ldr lr, [x8] 896 mov sp, x9 897 msr sp_el0, x1 898 ret 899ENDPROC(cpu_switch_to) 900NOKPROBE(cpu_switch_to) 901 902/* 903 * This is how we return from a fork. 904 */ 905ENTRY(ret_from_fork) 906 bl schedule_tail 907 cbz x19, 1f // not a kernel thread 908 mov x0, x20 909 blr x19 9101: get_current_task tsk 911 b ret_to_user 912ENDPROC(ret_from_fork) 913NOKPROBE(ret_from_fork) 914 915#ifdef CONFIG_ARM_SDE_INTERFACE 916 917#include <asm/sdei.h> 918#include <uapi/linux/arm_sdei.h> 919 920.macro sdei_handler_exit exit_mode 921 /* On success, this call never returns... */ 922 cmp \exit_mode, #SDEI_EXIT_SMC 923 b.ne 99f 924 smc #0 925 b . 92699: hvc #0 927 b . 928.endm 929 930#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 931/* 932 * The regular SDEI entry point may have been unmapped along with the rest of 933 * the kernel. This trampoline restores the kernel mapping to make the x1 memory 934 * argument accessible. 935 * 936 * This clobbers x4, __sdei_handler() will restore this from firmware's 937 * copy. 938 */ 939.ltorg 940.pushsection ".entry.tramp.text", "ax" 941ENTRY(__sdei_asm_entry_trampoline) 942 mrs x4, ttbr1_el1 943 tbz x4, #USER_ASID_BIT, 1f 944 945 tramp_map_kernel tmp=x4 946 isb 947 mov x4, xzr 948 949 /* 950 * Use reg->interrupted_regs.addr_limit to remember whether to unmap 951 * the kernel on exit. 952 */ 9531: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] 954 955#ifdef CONFIG_RANDOMIZE_BASE 956 adr x4, tramp_vectors + PAGE_SIZE 957 add x4, x4, #:lo12:__sdei_asm_trampoline_next_handler 958 ldr x4, [x4] 959#else 960 ldr x4, =__sdei_asm_handler 961#endif 962 br x4 963ENDPROC(__sdei_asm_entry_trampoline) 964NOKPROBE(__sdei_asm_entry_trampoline) 965 966/* 967 * Make the exit call and restore the original ttbr1_el1 968 * 969 * x0 & x1: setup for the exit API call 970 * x2: exit_mode 971 * x4: struct sdei_registered_event argument from registration time. 972 */ 973ENTRY(__sdei_asm_exit_trampoline) 974 ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] 975 cbnz x4, 1f 976 977 tramp_unmap_kernel tmp=x4 978 9791: sdei_handler_exit exit_mode=x2 980ENDPROC(__sdei_asm_exit_trampoline) 981NOKPROBE(__sdei_asm_exit_trampoline) 982 .ltorg 983.popsection // .entry.tramp.text 984#ifdef CONFIG_RANDOMIZE_BASE 985.pushsection ".rodata", "a" 986__sdei_asm_trampoline_next_handler: 987 .quad __sdei_asm_handler 988.popsection // .rodata 989#endif /* CONFIG_RANDOMIZE_BASE */ 990#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ 991 992/* 993 * Software Delegated Exception entry point. 994 * 995 * x0: Event number 996 * x1: struct sdei_registered_event argument from registration time. 997 * x2: interrupted PC 998 * x3: interrupted PSTATE 999 * x4: maybe clobbered by the trampoline 1000 * 1001 * Firmware has preserved x0->x17 for us, we must save/restore the rest to 1002 * follow SMC-CC. We save (or retrieve) all the registers as the handler may 1003 * want them. 1004 */ 1005ENTRY(__sdei_asm_handler) 1006 stp x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC] 1007 stp x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2] 1008 stp x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3] 1009 stp x8, x9, [x1, #SDEI_EVENT_INTREGS + 16 * 4] 1010 stp x10, x11, [x1, #SDEI_EVENT_INTREGS + 16 * 5] 1011 stp x12, x13, [x1, #SDEI_EVENT_INTREGS + 16 * 6] 1012 stp x14, x15, [x1, #SDEI_EVENT_INTREGS + 16 * 7] 1013 stp x16, x17, [x1, #SDEI_EVENT_INTREGS + 16 * 8] 1014 stp x18, x19, [x1, #SDEI_EVENT_INTREGS + 16 * 9] 1015 stp x20, x21, [x1, #SDEI_EVENT_INTREGS + 16 * 10] 1016 stp x22, x23, [x1, #SDEI_EVENT_INTREGS + 16 * 11] 1017 stp x24, x25, [x1, #SDEI_EVENT_INTREGS + 16 * 12] 1018 stp x26, x27, [x1, #SDEI_EVENT_INTREGS + 16 * 13] 1019 stp x28, x29, [x1, #SDEI_EVENT_INTREGS + 16 * 14] 1020 mov x4, sp 1021 stp lr, x4, [x1, #SDEI_EVENT_INTREGS + S_LR] 1022 1023 mov x19, x1 1024 1025#ifdef CONFIG_VMAP_STACK 1026 /* 1027 * entry.S may have been using sp as a scratch register, find whether 1028 * this is a normal or critical event and switch to the appropriate 1029 * stack for this CPU. 1030 */ 1031 ldrb w4, [x19, #SDEI_EVENT_PRIORITY] 1032 cbnz w4, 1f 1033 ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6 1034 b 2f 10351: ldr_this_cpu dst=x5, sym=sdei_stack_critical_ptr, tmp=x6 10362: mov x6, #SDEI_STACK_SIZE 1037 add x5, x5, x6 1038 mov sp, x5 1039#endif 1040 1041 /* 1042 * We may have interrupted userspace, or a guest, or exit-from or 1043 * return-to either of these. We can't trust sp_el0, restore it. 1044 */ 1045 mrs x28, sp_el0 1046 ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1 1047 msr sp_el0, x0 1048 1049 /* If we interrupted the kernel point to the previous stack/frame. */ 1050 and x0, x3, #0xc 1051 mrs x1, CurrentEL 1052 cmp x0, x1 1053 csel x29, x29, xzr, eq // fp, or zero 1054 csel x4, x2, xzr, eq // elr, or zero 1055 1056 stp x29, x4, [sp, #-16]! 1057 mov x29, sp 1058 1059 add x0, x19, #SDEI_EVENT_INTREGS 1060 mov x1, x19 1061 bl __sdei_handler 1062 1063 msr sp_el0, x28 1064 /* restore regs >x17 that we clobbered */ 1065 mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline 1066 ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14] 1067 ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9] 1068 ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR] 1069 mov sp, x1 1070 1071 mov x1, x0 // address to complete_and_resume 1072 /* x0 = (x0 <= 1) ? EVENT_COMPLETE:EVENT_COMPLETE_AND_RESUME */ 1073 cmp x0, #1 1074 mov_q x2, SDEI_1_0_FN_SDEI_EVENT_COMPLETE 1075 mov_q x3, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME 1076 csel x0, x2, x3, ls 1077 1078 ldr_l x2, sdei_exit_mode 1079 1080alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 1081 sdei_handler_exit exit_mode=x2 1082alternative_else_nop_endif 1083 1084#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 1085 tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline 1086 br x5 1087#endif 1088ENDPROC(__sdei_asm_handler) 1089NOKPROBE(__sdei_asm_handler) 1090#endif /* CONFIG_ARM_SDE_INTERFACE */ 1091