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/asm_pointer_auth.h> 18#include <asm/bug.h> 19#include <asm/cpufeature.h> 20#include <asm/errno.h> 21#include <asm/esr.h> 22#include <asm/irq.h> 23#include <asm/memory.h> 24#include <asm/mmu.h> 25#include <asm/processor.h> 26#include <asm/ptrace.h> 27#include <asm/scs.h> 28#include <asm/thread_info.h> 29#include <asm/asm-uaccess.h> 30#include <asm/unistd.h> 31 32 .macro clear_gp_regs 33 .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 34 mov x\n, xzr 35 .endr 36 .endm 37 38 .macro kernel_ventry, el:req, ht:req, regsize:req, label:req 39 .align 7 40.Lventry_start\@: 41 .if \el == 0 42 /* 43 * This must be the first instruction of the EL0 vector entries. It is 44 * skipped by the trampoline vectors, to trigger the cleanup. 45 */ 46 b .Lskip_tramp_vectors_cleanup\@ 47 .if \regsize == 64 48 mrs x30, tpidrro_el0 49 msr tpidrro_el0, xzr 50 .else 51 mov x30, xzr 52 .endif 53.Lskip_tramp_vectors_cleanup\@: 54 .endif 55 56 sub sp, sp, #PT_REGS_SIZE 57#ifdef CONFIG_VMAP_STACK 58 /* 59 * Test whether the SP has overflowed, without corrupting a GPR. 60 * Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT) 61 * should always be zero. 62 */ 63 add sp, sp, x0 // sp' = sp + x0 64 sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp 65 tbnz x0, #THREAD_SHIFT, 0f 66 sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0 67 sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp 68 b el\el\ht\()_\regsize\()_\label 69 700: 71 /* 72 * Either we've just detected an overflow, or we've taken an exception 73 * while on the overflow stack. Either way, we won't return to 74 * userspace, and can clobber EL0 registers to free up GPRs. 75 */ 76 77 /* Stash the original SP (minus PT_REGS_SIZE) in tpidr_el0. */ 78 msr tpidr_el0, x0 79 80 /* Recover the original x0 value and stash it in tpidrro_el0 */ 81 sub x0, sp, x0 82 msr tpidrro_el0, x0 83 84 /* Switch to the overflow stack */ 85 adr_this_cpu sp, overflow_stack + OVERFLOW_STACK_SIZE, x0 86 87 /* 88 * Check whether we were already on the overflow stack. This may happen 89 * after panic() re-enables interrupts. 90 */ 91 mrs x0, tpidr_el0 // sp of interrupted context 92 sub x0, sp, x0 // delta with top of overflow stack 93 tst x0, #~(OVERFLOW_STACK_SIZE - 1) // within range? 94 b.ne __bad_stack // no? -> bad stack pointer 95 96 /* We were already on the overflow stack. Restore sp/x0 and carry on. */ 97 sub sp, sp, x0 98 mrs x0, tpidrro_el0 99#endif 100 b el\el\ht\()_\regsize\()_\label 101.org .Lventry_start\@ + 128 // Did we overflow the ventry slot? 102 .endm 103 104 .macro tramp_alias, dst, sym, tmp 105 mov_q \dst, TRAMP_VALIAS 106 adr_l \tmp, \sym 107 add \dst, \dst, \tmp 108 adr_l \tmp, .entry.tramp.text 109 sub \dst, \dst, \tmp 110 .endm 111 112 /* 113 * This macro corrupts x0-x3. It is the caller's duty to save/restore 114 * them if required. 115 */ 116 .macro apply_ssbd, state, tmp1, tmp2 117alternative_cb spectre_v4_patch_fw_mitigation_enable 118 b .L__asm_ssbd_skip\@ // Patched to NOP 119alternative_cb_end 120 ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 121 cbz \tmp2, .L__asm_ssbd_skip\@ 122 ldr \tmp2, [tsk, #TSK_TI_FLAGS] 123 tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@ 124 mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 125 mov w1, #\state 126alternative_cb smccc_patch_fw_mitigation_conduit 127 nop // Patched to SMC/HVC #0 128alternative_cb_end 129.L__asm_ssbd_skip\@: 130 .endm 131 132 /* Check for MTE asynchronous tag check faults */ 133 .macro check_mte_async_tcf, tmp, ti_flags, thread_sctlr 134#ifdef CONFIG_ARM64_MTE 135 .arch_extension lse 136alternative_if_not ARM64_MTE 137 b 1f 138alternative_else_nop_endif 139 /* 140 * Asynchronous tag check faults are only possible in ASYNC (2) or 141 * ASYM (3) modes. In each of these modes bit 1 of SCTLR_EL1.TCF0 is 142 * set, so skip the check if it is unset. 143 */ 144 tbz \thread_sctlr, #(SCTLR_EL1_TCF0_SHIFT + 1), 1f 145 mrs_s \tmp, SYS_TFSRE0_EL1 146 tbz \tmp, #SYS_TFSR_EL1_TF0_SHIFT, 1f 147 /* Asynchronous TCF occurred for TTBR0 access, set the TI flag */ 148 mov \tmp, #_TIF_MTE_ASYNC_FAULT 149 add \ti_flags, tsk, #TSK_TI_FLAGS 150 stset \tmp, [\ti_flags] 1511: 152#endif 153 .endm 154 155 /* Clear the MTE asynchronous tag check faults */ 156 .macro clear_mte_async_tcf thread_sctlr 157#ifdef CONFIG_ARM64_MTE 158alternative_if ARM64_MTE 159 /* See comment in check_mte_async_tcf above. */ 160 tbz \thread_sctlr, #(SCTLR_EL1_TCF0_SHIFT + 1), 1f 161 dsb ish 162 msr_s SYS_TFSRE0_EL1, xzr 1631: 164alternative_else_nop_endif 165#endif 166 .endm 167 168 .macro mte_set_gcr, mte_ctrl, tmp 169#ifdef CONFIG_ARM64_MTE 170 ubfx \tmp, \mte_ctrl, #MTE_CTRL_GCR_USER_EXCL_SHIFT, #16 171 orr \tmp, \tmp, #SYS_GCR_EL1_RRND 172 msr_s SYS_GCR_EL1, \tmp 173#endif 174 .endm 175 176 .macro mte_set_kernel_gcr, tmp, tmp2 177#ifdef CONFIG_KASAN_HW_TAGS 178alternative_cb kasan_hw_tags_enable 179 b 1f 180alternative_cb_end 181 mov \tmp, KERNEL_GCR_EL1 182 msr_s SYS_GCR_EL1, \tmp 1831: 184#endif 185 .endm 186 187 .macro mte_set_user_gcr, tsk, tmp, tmp2 188#ifdef CONFIG_KASAN_HW_TAGS 189alternative_cb kasan_hw_tags_enable 190 b 1f 191alternative_cb_end 192 ldr \tmp, [\tsk, #THREAD_MTE_CTRL] 193 194 mte_set_gcr \tmp, \tmp2 1951: 196#endif 197 .endm 198 199 .macro kernel_entry, el, regsize = 64 200 .if \regsize == 32 201 mov w0, w0 // zero upper 32 bits of x0 202 .endif 203 stp x0, x1, [sp, #16 * 0] 204 stp x2, x3, [sp, #16 * 1] 205 stp x4, x5, [sp, #16 * 2] 206 stp x6, x7, [sp, #16 * 3] 207 stp x8, x9, [sp, #16 * 4] 208 stp x10, x11, [sp, #16 * 5] 209 stp x12, x13, [sp, #16 * 6] 210 stp x14, x15, [sp, #16 * 7] 211 stp x16, x17, [sp, #16 * 8] 212 stp x18, x19, [sp, #16 * 9] 213 stp x20, x21, [sp, #16 * 10] 214 stp x22, x23, [sp, #16 * 11] 215 stp x24, x25, [sp, #16 * 12] 216 stp x26, x27, [sp, #16 * 13] 217 stp x28, x29, [sp, #16 * 14] 218 219 .if \el == 0 220 clear_gp_regs 221 mrs x21, sp_el0 222 ldr_this_cpu tsk, __entry_task, x20 223 msr sp_el0, tsk 224 225 /* 226 * Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions 227 * when scheduling. 228 */ 229 ldr x19, [tsk, #TSK_TI_FLAGS] 230 disable_step_tsk x19, x20 231 232 /* Check for asynchronous tag check faults in user space */ 233 ldr x0, [tsk, THREAD_SCTLR_USER] 234 check_mte_async_tcf x22, x23, x0 235 236#ifdef CONFIG_ARM64_PTR_AUTH 237alternative_if ARM64_HAS_ADDRESS_AUTH 238 /* 239 * Enable IA for in-kernel PAC if the task had it disabled. Although 240 * this could be implemented with an unconditional MRS which would avoid 241 * a load, this was measured to be slower on Cortex-A75 and Cortex-A76. 242 * 243 * Install the kernel IA key only if IA was enabled in the task. If IA 244 * was disabled on kernel exit then we would have left the kernel IA 245 * installed so there is no need to install it again. 246 */ 247 tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f 248 __ptrauth_keys_install_kernel_nosync tsk, x20, x22, x23 249 b 2f 2501: 251 mrs x0, sctlr_el1 252 orr x0, x0, SCTLR_ELx_ENIA 253 msr sctlr_el1, x0 2542: 255alternative_else_nop_endif 256#endif 257 258 apply_ssbd 1, x22, x23 259 260 mte_set_kernel_gcr x22, x23 261 262 /* 263 * Any non-self-synchronizing system register updates required for 264 * kernel entry should be placed before this point. 265 */ 266alternative_if ARM64_MTE 267 isb 268 b 1f 269alternative_else_nop_endif 270alternative_if ARM64_HAS_ADDRESS_AUTH 271 isb 272alternative_else_nop_endif 2731: 274 275 scs_load tsk 276 .else 277 add x21, sp, #PT_REGS_SIZE 278 get_current_task tsk 279 .endif /* \el == 0 */ 280 mrs x22, elr_el1 281 mrs x23, spsr_el1 282 stp lr, x21, [sp, #S_LR] 283 284 /* 285 * For exceptions from EL0, create a final frame record. 286 * For exceptions from EL1, create a synthetic frame record so the 287 * interrupted code shows up in the backtrace. 288 */ 289 .if \el == 0 290 stp xzr, xzr, [sp, #S_STACKFRAME] 291 .else 292 stp x29, x22, [sp, #S_STACKFRAME] 293 .endif 294 add x29, sp, #S_STACKFRAME 295 296#ifdef CONFIG_ARM64_SW_TTBR0_PAN 297alternative_if_not ARM64_HAS_PAN 298 bl __swpan_entry_el\el 299alternative_else_nop_endif 300#endif 301 302 stp x22, x23, [sp, #S_PC] 303 304 /* Not in a syscall by default (el0_svc overwrites for real syscall) */ 305 .if \el == 0 306 mov w21, #NO_SYSCALL 307 str w21, [sp, #S_SYSCALLNO] 308 .endif 309 310 /* Save pmr */ 311alternative_if ARM64_HAS_IRQ_PRIO_MASKING 312 mrs_s x20, SYS_ICC_PMR_EL1 313 str x20, [sp, #S_PMR_SAVE] 314 mov x20, #GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET 315 msr_s SYS_ICC_PMR_EL1, x20 316alternative_else_nop_endif 317 318 /* Re-enable tag checking (TCO set on exception entry) */ 319#ifdef CONFIG_ARM64_MTE 320alternative_if ARM64_MTE 321 SET_PSTATE_TCO(0) 322alternative_else_nop_endif 323#endif 324 325 /* 326 * Registers that may be useful after this macro is invoked: 327 * 328 * x20 - ICC_PMR_EL1 329 * x21 - aborted SP 330 * x22 - aborted PC 331 * x23 - aborted PSTATE 332 */ 333 .endm 334 335 .macro kernel_exit, el 336 .if \el != 0 337 disable_daif 338 .endif 339 340 /* Restore pmr */ 341alternative_if ARM64_HAS_IRQ_PRIO_MASKING 342 ldr x20, [sp, #S_PMR_SAVE] 343 msr_s SYS_ICC_PMR_EL1, x20 344 mrs_s x21, SYS_ICC_CTLR_EL1 345 tbz x21, #6, .L__skip_pmr_sync\@ // Check for ICC_CTLR_EL1.PMHE 346 dsb sy // Ensure priority change is seen by redistributor 347.L__skip_pmr_sync\@: 348alternative_else_nop_endif 349 350 ldp x21, x22, [sp, #S_PC] // load ELR, SPSR 351 352#ifdef CONFIG_ARM64_SW_TTBR0_PAN 353alternative_if_not ARM64_HAS_PAN 354 bl __swpan_exit_el\el 355alternative_else_nop_endif 356#endif 357 358 .if \el == 0 359 ldr x23, [sp, #S_SP] // load return stack pointer 360 msr sp_el0, x23 361 tst x22, #PSR_MODE32_BIT // native task? 362 b.eq 3f 363 364#ifdef CONFIG_ARM64_ERRATUM_845719 365alternative_if ARM64_WORKAROUND_845719 366#ifdef CONFIG_PID_IN_CONTEXTIDR 367 mrs x29, contextidr_el1 368 msr contextidr_el1, x29 369#else 370 msr contextidr_el1, xzr 371#endif 372alternative_else_nop_endif 373#endif 3743: 375 scs_save tsk 376 377 /* Ignore asynchronous tag check faults in the uaccess routines */ 378 ldr x0, [tsk, THREAD_SCTLR_USER] 379 clear_mte_async_tcf x0 380 381#ifdef CONFIG_ARM64_PTR_AUTH 382alternative_if ARM64_HAS_ADDRESS_AUTH 383 /* 384 * IA was enabled for in-kernel PAC. Disable it now if needed, or 385 * alternatively install the user's IA. All other per-task keys and 386 * SCTLR bits were updated on task switch. 387 * 388 * No kernel C function calls after this. 389 */ 390 tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f 391 __ptrauth_keys_install_user tsk, x0, x1, x2 392 b 2f 3931: 394 mrs x0, sctlr_el1 395 bic x0, x0, SCTLR_ELx_ENIA 396 msr sctlr_el1, x0 3972: 398alternative_else_nop_endif 399#endif 400 401 mte_set_user_gcr tsk, x0, x1 402 403 apply_ssbd 0, x0, x1 404 .endif 405 406 msr elr_el1, x21 // set up the return data 407 msr spsr_el1, x22 408 ldp x0, x1, [sp, #16 * 0] 409 ldp x2, x3, [sp, #16 * 1] 410 ldp x4, x5, [sp, #16 * 2] 411 ldp x6, x7, [sp, #16 * 3] 412 ldp x8, x9, [sp, #16 * 4] 413 ldp x10, x11, [sp, #16 * 5] 414 ldp x12, x13, [sp, #16 * 6] 415 ldp x14, x15, [sp, #16 * 7] 416 ldp x16, x17, [sp, #16 * 8] 417 ldp x18, x19, [sp, #16 * 9] 418 ldp x20, x21, [sp, #16 * 10] 419 ldp x22, x23, [sp, #16 * 11] 420 ldp x24, x25, [sp, #16 * 12] 421 ldp x26, x27, [sp, #16 * 13] 422 ldp x28, x29, [sp, #16 * 14] 423 424 .if \el == 0 425alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 426 ldr lr, [sp, #S_LR] 427 add sp, sp, #PT_REGS_SIZE // restore sp 428 eret 429alternative_else_nop_endif 430#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 431 bne 4f 432 msr far_el1, x29 433 tramp_alias x30, tramp_exit_native, x29 434 br x30 4354: 436 tramp_alias x30, tramp_exit_compat, x29 437 br x30 438#endif 439 .else 440 ldr lr, [sp, #S_LR] 441 add sp, sp, #PT_REGS_SIZE // restore sp 442 443 /* Ensure any device/NC reads complete */ 444 alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 445 446 eret 447 .endif 448 sb 449 .endm 450 451#ifdef CONFIG_ARM64_SW_TTBR0_PAN 452 /* 453 * Set the TTBR0 PAN bit in SPSR. When the exception is taken from 454 * EL0, there is no need to check the state of TTBR0_EL1 since 455 * accesses are always enabled. 456 * Note that the meaning of this bit differs from the ARMv8.1 PAN 457 * feature as all TTBR0_EL1 accesses are disabled, not just those to 458 * user mappings. 459 */ 460SYM_CODE_START_LOCAL(__swpan_entry_el1) 461 mrs x21, ttbr0_el1 462 tst x21, #TTBR_ASID_MASK // Check for the reserved ASID 463 orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR 464 b.eq 1f // TTBR0 access already disabled 465 and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR 466SYM_INNER_LABEL(__swpan_entry_el0, SYM_L_LOCAL) 467 __uaccess_ttbr0_disable x21 4681: ret 469SYM_CODE_END(__swpan_entry_el1) 470 471 /* 472 * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR 473 * PAN bit checking. 474 */ 475SYM_CODE_START_LOCAL(__swpan_exit_el1) 476 tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set 477 __uaccess_ttbr0_enable x0, x1 4781: and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit 479 ret 480SYM_CODE_END(__swpan_exit_el1) 481 482SYM_CODE_START_LOCAL(__swpan_exit_el0) 483 __uaccess_ttbr0_enable x0, x1 484 /* 485 * Enable errata workarounds only if returning to user. The only 486 * workaround currently required for TTBR0_EL1 changes are for the 487 * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache 488 * corruption). 489 */ 490 b post_ttbr_update_workaround 491SYM_CODE_END(__swpan_exit_el0) 492#endif 493 494/* GPRs used by entry code */ 495tsk .req x28 // current thread_info 496 497 .text 498 499/* 500 * Exception vectors. 501 */ 502 .pushsection ".entry.text", "ax" 503 504 .align 11 505SYM_CODE_START(vectors) 506 kernel_ventry 1, t, 64, sync // Synchronous EL1t 507 kernel_ventry 1, t, 64, irq // IRQ EL1t 508 kernel_ventry 1, t, 64, fiq // FIQ EL1h 509 kernel_ventry 1, t, 64, error // Error EL1t 510 511 kernel_ventry 1, h, 64, sync // Synchronous EL1h 512 kernel_ventry 1, h, 64, irq // IRQ EL1h 513 kernel_ventry 1, h, 64, fiq // FIQ EL1h 514 kernel_ventry 1, h, 64, error // Error EL1h 515 516 kernel_ventry 0, t, 64, sync // Synchronous 64-bit EL0 517 kernel_ventry 0, t, 64, irq // IRQ 64-bit EL0 518 kernel_ventry 0, t, 64, fiq // FIQ 64-bit EL0 519 kernel_ventry 0, t, 64, error // Error 64-bit EL0 520 521 kernel_ventry 0, t, 32, sync // Synchronous 32-bit EL0 522 kernel_ventry 0, t, 32, irq // IRQ 32-bit EL0 523 kernel_ventry 0, t, 32, fiq // FIQ 32-bit EL0 524 kernel_ventry 0, t, 32, error // Error 32-bit EL0 525SYM_CODE_END(vectors) 526 527#ifdef CONFIG_VMAP_STACK 528SYM_CODE_START_LOCAL(__bad_stack) 529 /* 530 * We detected an overflow in kernel_ventry, which switched to the 531 * overflow stack. Stash the exception regs, and head to our overflow 532 * handler. 533 */ 534 535 /* Restore the original x0 value */ 536 mrs x0, tpidrro_el0 537 538 /* 539 * Store the original GPRs to the new stack. The orginal SP (minus 540 * PT_REGS_SIZE) was stashed in tpidr_el0 by kernel_ventry. 541 */ 542 sub sp, sp, #PT_REGS_SIZE 543 kernel_entry 1 544 mrs x0, tpidr_el0 545 add x0, x0, #PT_REGS_SIZE 546 str x0, [sp, #S_SP] 547 548 /* Stash the regs for handle_bad_stack */ 549 mov x0, sp 550 551 /* Time to die */ 552 bl handle_bad_stack 553 ASM_BUG() 554SYM_CODE_END(__bad_stack) 555#endif /* CONFIG_VMAP_STACK */ 556 557 558 .macro entry_handler el:req, ht:req, regsize:req, label:req 559SYM_CODE_START_LOCAL(el\el\ht\()_\regsize\()_\label) 560 kernel_entry \el, \regsize 561 mov x0, sp 562 bl el\el\ht\()_\regsize\()_\label\()_handler 563 .if \el == 0 564 b ret_to_user 565 .else 566 b ret_to_kernel 567 .endif 568SYM_CODE_END(el\el\ht\()_\regsize\()_\label) 569 .endm 570 571/* 572 * Early exception handlers 573 */ 574 entry_handler 1, t, 64, sync 575 entry_handler 1, t, 64, irq 576 entry_handler 1, t, 64, fiq 577 entry_handler 1, t, 64, error 578 579 entry_handler 1, h, 64, sync 580 entry_handler 1, h, 64, irq 581 entry_handler 1, h, 64, fiq 582 entry_handler 1, h, 64, error 583 584 entry_handler 0, t, 64, sync 585 entry_handler 0, t, 64, irq 586 entry_handler 0, t, 64, fiq 587 entry_handler 0, t, 64, error 588 589 entry_handler 0, t, 32, sync 590 entry_handler 0, t, 32, irq 591 entry_handler 0, t, 32, fiq 592 entry_handler 0, t, 32, error 593 594SYM_CODE_START_LOCAL(ret_to_kernel) 595 kernel_exit 1 596SYM_CODE_END(ret_to_kernel) 597 598SYM_CODE_START_LOCAL(ret_to_user) 599 ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step 600 enable_step_tsk x19, x2 601#ifdef CONFIG_GCC_PLUGIN_STACKLEAK 602 bl stackleak_erase 603#endif 604 kernel_exit 0 605SYM_CODE_END(ret_to_user) 606 607 .popsection // .entry.text 608 609 // Move from tramp_pg_dir to swapper_pg_dir 610 .macro tramp_map_kernel, tmp 611 mrs \tmp, ttbr1_el1 612 add \tmp, \tmp, #TRAMP_SWAPPER_OFFSET 613 bic \tmp, \tmp, #USER_ASID_FLAG 614 msr ttbr1_el1, \tmp 615#ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003 616alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003 617 /* ASID already in \tmp[63:48] */ 618 movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12) 619 movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12) 620 /* 2MB boundary containing the vectors, so we nobble the walk cache */ 621 movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12) 622 isb 623 tlbi vae1, \tmp 624 dsb nsh 625alternative_else_nop_endif 626#endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */ 627 .endm 628 629 // Move from swapper_pg_dir to tramp_pg_dir 630 .macro tramp_unmap_kernel, tmp 631 mrs \tmp, ttbr1_el1 632 sub \tmp, \tmp, #TRAMP_SWAPPER_OFFSET 633 orr \tmp, \tmp, #USER_ASID_FLAG 634 msr ttbr1_el1, \tmp 635 /* 636 * We avoid running the post_ttbr_update_workaround here because 637 * it's only needed by Cavium ThunderX, which requires KPTI to be 638 * disabled. 639 */ 640 .endm 641 642 .macro tramp_data_page dst 643 adr_l \dst, .entry.tramp.text 644 sub \dst, \dst, PAGE_SIZE 645 .endm 646 647 .macro tramp_data_read_var dst, var 648#ifdef CONFIG_RANDOMIZE_BASE 649 tramp_data_page \dst 650 add \dst, \dst, #:lo12:__entry_tramp_data_\var 651 ldr \dst, [\dst] 652#else 653 ldr \dst, =\var 654#endif 655 .endm 656 657#define BHB_MITIGATION_NONE 0 658#define BHB_MITIGATION_LOOP 1 659#define BHB_MITIGATION_FW 2 660#define BHB_MITIGATION_INSN 3 661 662 .macro tramp_ventry, vector_start, regsize, kpti, bhb 663 .align 7 6641: 665 .if \regsize == 64 666 msr tpidrro_el0, x30 // Restored in kernel_ventry 667 .endif 668 669 .if \bhb == BHB_MITIGATION_LOOP 670 /* 671 * This sequence must appear before the first indirect branch. i.e. the 672 * ret out of tramp_ventry. It appears here because x30 is free. 673 */ 674 __mitigate_spectre_bhb_loop x30 675 .endif // \bhb == BHB_MITIGATION_LOOP 676 677 .if \bhb == BHB_MITIGATION_INSN 678 clearbhb 679 isb 680 .endif // \bhb == BHB_MITIGATION_INSN 681 682 .if \kpti == 1 683 /* 684 * Defend against branch aliasing attacks by pushing a dummy 685 * entry onto the return stack and using a RET instruction to 686 * enter the full-fat kernel vectors. 687 */ 688 bl 2f 689 b . 6902: 691 tramp_map_kernel x30 692alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 693 tramp_data_read_var x30, vectors 694alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM 695 prfm plil1strm, [x30, #(1b - \vector_start)] 696alternative_else_nop_endif 697 698 msr vbar_el1, x30 699 isb 700 .else 701 ldr x30, =vectors 702 .endif // \kpti == 1 703 704 .if \bhb == BHB_MITIGATION_FW 705 /* 706 * The firmware sequence must appear before the first indirect branch. 707 * i.e. the ret out of tramp_ventry. But it also needs the stack to be 708 * mapped to save/restore the registers the SMC clobbers. 709 */ 710 __mitigate_spectre_bhb_fw 711 .endif // \bhb == BHB_MITIGATION_FW 712 713 add x30, x30, #(1b - \vector_start + 4) 714 ret 715.org 1b + 128 // Did we overflow the ventry slot? 716 .endm 717 718 .macro tramp_exit, regsize = 64 719 tramp_data_read_var x30, this_cpu_vector 720 get_this_cpu_offset x29 721 ldr x30, [x30, x29] 722 723 msr vbar_el1, x30 724 ldr lr, [sp, #S_LR] 725 tramp_unmap_kernel x29 726 .if \regsize == 64 727 mrs x29, far_el1 728 .endif 729 add sp, sp, #PT_REGS_SIZE // restore sp 730 eret 731 sb 732 .endm 733 734 .macro generate_tramp_vector, kpti, bhb 735.Lvector_start\@: 736 .space 0x400 737 738 .rept 4 739 tramp_ventry .Lvector_start\@, 64, \kpti, \bhb 740 .endr 741 .rept 4 742 tramp_ventry .Lvector_start\@, 32, \kpti, \bhb 743 .endr 744 .endm 745 746#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 747/* 748 * Exception vectors trampoline. 749 * The order must match __bp_harden_el1_vectors and the 750 * arm64_bp_harden_el1_vectors enum. 751 */ 752 .pushsection ".entry.tramp.text", "ax" 753 .align 11 754SYM_CODE_START_NOALIGN(tramp_vectors) 755#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY 756 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP 757 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW 758 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_INSN 759#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ 760 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE 761SYM_CODE_END(tramp_vectors) 762 763SYM_CODE_START(tramp_exit_native) 764 tramp_exit 765SYM_CODE_END(tramp_exit_native) 766 767SYM_CODE_START(tramp_exit_compat) 768 tramp_exit 32 769SYM_CODE_END(tramp_exit_compat) 770 771 .ltorg 772 .popsection // .entry.tramp.text 773#ifdef CONFIG_RANDOMIZE_BASE 774 .pushsection ".rodata", "a" 775 .align PAGE_SHIFT 776SYM_DATA_START(__entry_tramp_data_start) 777__entry_tramp_data_vectors: 778 .quad vectors 779#ifdef CONFIG_ARM_SDE_INTERFACE 780__entry_tramp_data___sdei_asm_handler: 781 .quad __sdei_asm_handler 782#endif /* CONFIG_ARM_SDE_INTERFACE */ 783__entry_tramp_data_this_cpu_vector: 784 .quad this_cpu_vector 785SYM_DATA_END(__entry_tramp_data_start) 786 .popsection // .rodata 787#endif /* CONFIG_RANDOMIZE_BASE */ 788#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ 789 790/* 791 * Exception vectors for spectre mitigations on entry from EL1 when 792 * kpti is not in use. 793 */ 794 .macro generate_el1_vector, bhb 795.Lvector_start\@: 796 kernel_ventry 1, t, 64, sync // Synchronous EL1t 797 kernel_ventry 1, t, 64, irq // IRQ EL1t 798 kernel_ventry 1, t, 64, fiq // FIQ EL1h 799 kernel_ventry 1, t, 64, error // Error EL1t 800 801 kernel_ventry 1, h, 64, sync // Synchronous EL1h 802 kernel_ventry 1, h, 64, irq // IRQ EL1h 803 kernel_ventry 1, h, 64, fiq // FIQ EL1h 804 kernel_ventry 1, h, 64, error // Error EL1h 805 806 .rept 4 807 tramp_ventry .Lvector_start\@, 64, 0, \bhb 808 .endr 809 .rept 4 810 tramp_ventry .Lvector_start\@, 32, 0, \bhb 811 .endr 812 .endm 813 814/* The order must match tramp_vecs and the arm64_bp_harden_el1_vectors enum. */ 815 .pushsection ".entry.text", "ax" 816 .align 11 817SYM_CODE_START(__bp_harden_el1_vectors) 818#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY 819 generate_el1_vector bhb=BHB_MITIGATION_LOOP 820 generate_el1_vector bhb=BHB_MITIGATION_FW 821 generate_el1_vector bhb=BHB_MITIGATION_INSN 822#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ 823SYM_CODE_END(__bp_harden_el1_vectors) 824 .popsection 825 826 827/* 828 * Register switch for AArch64. The callee-saved registers need to be saved 829 * and restored. On entry: 830 * x0 = previous task_struct (must be preserved across the switch) 831 * x1 = next task_struct 832 * Previous and next are guaranteed not to be the same. 833 * 834 */ 835SYM_FUNC_START(cpu_switch_to) 836 mov x10, #THREAD_CPU_CONTEXT 837 add x8, x0, x10 838 mov x9, sp 839 stp x19, x20, [x8], #16 // store callee-saved registers 840 stp x21, x22, [x8], #16 841 stp x23, x24, [x8], #16 842 stp x25, x26, [x8], #16 843 stp x27, x28, [x8], #16 844 stp x29, x9, [x8], #16 845 str lr, [x8] 846 add x8, x1, x10 847 ldp x19, x20, [x8], #16 // restore callee-saved registers 848 ldp x21, x22, [x8], #16 849 ldp x23, x24, [x8], #16 850 ldp x25, x26, [x8], #16 851 ldp x27, x28, [x8], #16 852 ldp x29, x9, [x8], #16 853 ldr lr, [x8] 854 mov sp, x9 855 msr sp_el0, x1 856 ptrauth_keys_install_kernel x1, x8, x9, x10 857 scs_save x0 858 scs_load x1 859 ret 860SYM_FUNC_END(cpu_switch_to) 861NOKPROBE(cpu_switch_to) 862 863/* 864 * This is how we return from a fork. 865 */ 866SYM_CODE_START(ret_from_fork) 867 bl schedule_tail 868 cbz x19, 1f // not a kernel thread 869 mov x0, x20 870 blr x19 8711: get_current_task tsk 872 mov x0, sp 873 bl asm_exit_to_user_mode 874 b ret_to_user 875SYM_CODE_END(ret_from_fork) 876NOKPROBE(ret_from_fork) 877 878/* 879 * void call_on_irq_stack(struct pt_regs *regs, 880 * void (*func)(struct pt_regs *)); 881 * 882 * Calls func(regs) using this CPU's irq stack and shadow irq stack. 883 */ 884SYM_FUNC_START(call_on_irq_stack) 885#ifdef CONFIG_SHADOW_CALL_STACK 886 stp scs_sp, xzr, [sp, #-16]! 887 ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x17 888#endif 889 /* Create a frame record to save our LR and SP (implicit in FP) */ 890 stp x29, x30, [sp, #-16]! 891 mov x29, sp 892 893 ldr_this_cpu x16, irq_stack_ptr, x17 894 mov x15, #IRQ_STACK_SIZE 895 add x16, x16, x15 896 897 /* Move to the new stack and call the function there */ 898 mov sp, x16 899 blr x1 900 901 /* 902 * Restore the SP from the FP, and restore the FP and LR from the frame 903 * record. 904 */ 905 mov sp, x29 906 ldp x29, x30, [sp], #16 907#ifdef CONFIG_SHADOW_CALL_STACK 908 ldp scs_sp, xzr, [sp], #16 909#endif 910 ret 911SYM_FUNC_END(call_on_irq_stack) 912NOKPROBE(call_on_irq_stack) 913 914#ifdef CONFIG_ARM_SDE_INTERFACE 915 916#include <asm/sdei.h> 917#include <uapi/linux/arm_sdei.h> 918 919.macro sdei_handler_exit exit_mode 920 /* On success, this call never returns... */ 921 cmp \exit_mode, #SDEI_EXIT_SMC 922 b.ne 99f 923 smc #0 924 b . 92599: hvc #0 926 b . 927.endm 928 929#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 930/* 931 * The regular SDEI entry point may have been unmapped along with the rest of 932 * the kernel. This trampoline restores the kernel mapping to make the x1 memory 933 * argument accessible. 934 * 935 * This clobbers x4, __sdei_handler() will restore this from firmware's 936 * copy. 937 */ 938.ltorg 939.pushsection ".entry.tramp.text", "ax" 940SYM_CODE_START(__sdei_asm_entry_trampoline) 941 mrs x4, ttbr1_el1 942 tbz x4, #USER_ASID_BIT, 1f 943 944 tramp_map_kernel tmp=x4 945 isb 946 mov x4, xzr 947 948 /* 949 * Remember whether to unmap the kernel on exit. 950 */ 9511: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] 952 tramp_data_read_var x4, __sdei_asm_handler 953 br x4 954SYM_CODE_END(__sdei_asm_entry_trampoline) 955NOKPROBE(__sdei_asm_entry_trampoline) 956 957/* 958 * Make the exit call and restore the original ttbr1_el1 959 * 960 * x0 & x1: setup for the exit API call 961 * x2: exit_mode 962 * x4: struct sdei_registered_event argument from registration time. 963 */ 964SYM_CODE_START(__sdei_asm_exit_trampoline) 965 ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] 966 cbnz x4, 1f 967 968 tramp_unmap_kernel tmp=x4 969 9701: sdei_handler_exit exit_mode=x2 971SYM_CODE_END(__sdei_asm_exit_trampoline) 972NOKPROBE(__sdei_asm_exit_trampoline) 973 .ltorg 974.popsection // .entry.tramp.text 975#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ 976 977/* 978 * Software Delegated Exception entry point. 979 * 980 * x0: Event number 981 * x1: struct sdei_registered_event argument from registration time. 982 * x2: interrupted PC 983 * x3: interrupted PSTATE 984 * x4: maybe clobbered by the trampoline 985 * 986 * Firmware has preserved x0->x17 for us, we must save/restore the rest to 987 * follow SMC-CC. We save (or retrieve) all the registers as the handler may 988 * want them. 989 */ 990SYM_CODE_START(__sdei_asm_handler) 991 stp x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC] 992 stp x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2] 993 stp x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3] 994 stp x8, x9, [x1, #SDEI_EVENT_INTREGS + 16 * 4] 995 stp x10, x11, [x1, #SDEI_EVENT_INTREGS + 16 * 5] 996 stp x12, x13, [x1, #SDEI_EVENT_INTREGS + 16 * 6] 997 stp x14, x15, [x1, #SDEI_EVENT_INTREGS + 16 * 7] 998 stp x16, x17, [x1, #SDEI_EVENT_INTREGS + 16 * 8] 999 stp x18, x19, [x1, #SDEI_EVENT_INTREGS + 16 * 9] 1000 stp x20, x21, [x1, #SDEI_EVENT_INTREGS + 16 * 10] 1001 stp x22, x23, [x1, #SDEI_EVENT_INTREGS + 16 * 11] 1002 stp x24, x25, [x1, #SDEI_EVENT_INTREGS + 16 * 12] 1003 stp x26, x27, [x1, #SDEI_EVENT_INTREGS + 16 * 13] 1004 stp x28, x29, [x1, #SDEI_EVENT_INTREGS + 16 * 14] 1005 mov x4, sp 1006 stp lr, x4, [x1, #SDEI_EVENT_INTREGS + S_LR] 1007 1008 mov x19, x1 1009 1010#if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK) 1011 ldrb w4, [x19, #SDEI_EVENT_PRIORITY] 1012#endif 1013 1014#ifdef CONFIG_VMAP_STACK 1015 /* 1016 * entry.S may have been using sp as a scratch register, find whether 1017 * this is a normal or critical event and switch to the appropriate 1018 * stack for this CPU. 1019 */ 1020 cbnz w4, 1f 1021 ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6 1022 b 2f 10231: ldr_this_cpu dst=x5, sym=sdei_stack_critical_ptr, tmp=x6 10242: mov x6, #SDEI_STACK_SIZE 1025 add x5, x5, x6 1026 mov sp, x5 1027#endif 1028 1029#ifdef CONFIG_SHADOW_CALL_STACK 1030 /* Use a separate shadow call stack for normal and critical events */ 1031 cbnz w4, 3f 1032 ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6 1033 b 4f 10343: ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6 10354: 1036#endif 1037 1038 /* 1039 * We may have interrupted userspace, or a guest, or exit-from or 1040 * return-to either of these. We can't trust sp_el0, restore it. 1041 */ 1042 mrs x28, sp_el0 1043 ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1 1044 msr sp_el0, x0 1045 1046 /* If we interrupted the kernel point to the previous stack/frame. */ 1047 and x0, x3, #0xc 1048 mrs x1, CurrentEL 1049 cmp x0, x1 1050 csel x29, x29, xzr, eq // fp, or zero 1051 csel x4, x2, xzr, eq // elr, or zero 1052 1053 stp x29, x4, [sp, #-16]! 1054 mov x29, sp 1055 1056 add x0, x19, #SDEI_EVENT_INTREGS 1057 mov x1, x19 1058 bl __sdei_handler 1059 1060 msr sp_el0, x28 1061 /* restore regs >x17 that we clobbered */ 1062 mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline 1063 ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14] 1064 ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9] 1065 ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR] 1066 mov sp, x1 1067 1068 mov x1, x0 // address to complete_and_resume 1069 /* x0 = (x0 <= SDEI_EV_FAILED) ? 1070 * EVENT_COMPLETE:EVENT_COMPLETE_AND_RESUME 1071 */ 1072 cmp x0, #SDEI_EV_FAILED 1073 mov_q x2, SDEI_1_0_FN_SDEI_EVENT_COMPLETE 1074 mov_q x3, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME 1075 csel x0, x2, x3, ls 1076 1077 ldr_l x2, sdei_exit_mode 1078 1079alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 1080 sdei_handler_exit exit_mode=x2 1081alternative_else_nop_endif 1082 1083#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 1084 tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline, tmp=x3 1085 br x5 1086#endif 1087SYM_CODE_END(__sdei_asm_handler) 1088NOKPROBE(__sdei_asm_handler) 1089#endif /* CONFIG_ARM_SDE_INTERFACE */ 1090