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 70 0: 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 105 .set .Lalias\@, TRAMP_VALIAS + \sym - .entry.tramp.text 106 movz \dst, :abs_g2_s:.Lalias\@ 107 movk \dst, :abs_g1_nc:.Lalias\@ 108 movk \dst, :abs_g0_nc:.Lalias\@ 109 .endm 110 111 /* 112 * This macro corrupts x0-x3. It is the caller's duty to save/restore 113 * them if required. 114 */ 115 .macro apply_ssbd, state, tmp1, tmp2 116 alternative_cb ARM64_ALWAYS_SYSTEM, spectre_v4_patch_fw_mitigation_enable 117 b .L__asm_ssbd_skip\@ // Patched to NOP 118 alternative_cb_end 119 ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 120 cbz \tmp2, .L__asm_ssbd_skip\@ 121 ldr \tmp2, [tsk, #TSK_TI_FLAGS] 122 tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@ 123 mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 124 mov w1, #\state 125 alternative_cb ARM64_ALWAYS_SYSTEM, smccc_patch_fw_mitigation_conduit 126 nop // Patched to SMC/HVC #0 127 alternative_cb_end 128 .L__asm_ssbd_skip\@: 129 .endm 130 131 /* Check for MTE asynchronous tag check faults */ 132 .macro check_mte_async_tcf, tmp, ti_flags, thread_sctlr 133 #ifdef CONFIG_ARM64_MTE 134 .arch_extension lse 135 alternative_if_not ARM64_MTE 136 b 1f 137 alternative_else_nop_endif 138 /* 139 * Asynchronous tag check faults are only possible in ASYNC (2) or 140 * ASYM (3) modes. In each of these modes bit 1 of SCTLR_EL1.TCF0 is 141 * set, so skip the check if it is unset. 142 */ 143 tbz \thread_sctlr, #(SCTLR_EL1_TCF0_SHIFT + 1), 1f 144 mrs_s \tmp, SYS_TFSRE0_EL1 145 tbz \tmp, #SYS_TFSR_EL1_TF0_SHIFT, 1f 146 /* Asynchronous TCF occurred for TTBR0 access, set the TI flag */ 147 mov \tmp, #_TIF_MTE_ASYNC_FAULT 148 add \ti_flags, tsk, #TSK_TI_FLAGS 149 stset \tmp, [\ti_flags] 150 1: 151 #endif 152 .endm 153 154 /* Clear the MTE asynchronous tag check faults */ 155 .macro clear_mte_async_tcf thread_sctlr 156 #ifdef CONFIG_ARM64_MTE 157 alternative_if ARM64_MTE 158 /* See comment in check_mte_async_tcf above. */ 159 tbz \thread_sctlr, #(SCTLR_EL1_TCF0_SHIFT + 1), 1f 160 dsb ish 161 msr_s SYS_TFSRE0_EL1, xzr 162 1: 163 alternative_else_nop_endif 164 #endif 165 .endm 166 167 .macro mte_set_gcr, mte_ctrl, tmp 168 #ifdef CONFIG_ARM64_MTE 169 ubfx \tmp, \mte_ctrl, #MTE_CTRL_GCR_USER_EXCL_SHIFT, #16 170 orr \tmp, \tmp, #SYS_GCR_EL1_RRND 171 msr_s SYS_GCR_EL1, \tmp 172 #endif 173 .endm 174 175 .macro mte_set_kernel_gcr, tmp, tmp2 176 #ifdef CONFIG_KASAN_HW_TAGS 177 alternative_cb ARM64_ALWAYS_SYSTEM, kasan_hw_tags_enable 178 b 1f 179 alternative_cb_end 180 mov \tmp, KERNEL_GCR_EL1 181 msr_s SYS_GCR_EL1, \tmp 182 1: 183 #endif 184 .endm 185 186 .macro mte_set_user_gcr, tsk, tmp, tmp2 187 #ifdef CONFIG_KASAN_HW_TAGS 188 alternative_cb ARM64_ALWAYS_SYSTEM, kasan_hw_tags_enable 189 b 1f 190 alternative_cb_end 191 ldr \tmp, [\tsk, #THREAD_MTE_CTRL] 192 193 mte_set_gcr \tmp, \tmp2 194 1: 195 #endif 196 .endm 197 198 .macro kernel_entry, el, regsize = 64 199 .if \el == 0 200 alternative_insn nop, SET_PSTATE_DIT(1), ARM64_HAS_DIT 201 .endif 202 .if \regsize == 32 203 mov w0, w0 // zero upper 32 bits of x0 204 .endif 205 stp x0, x1, [sp, #16 * 0] 206 stp x2, x3, [sp, #16 * 1] 207 stp x4, x5, [sp, #16 * 2] 208 stp x6, x7, [sp, #16 * 3] 209 stp x8, x9, [sp, #16 * 4] 210 stp x10, x11, [sp, #16 * 5] 211 stp x12, x13, [sp, #16 * 6] 212 stp x14, x15, [sp, #16 * 7] 213 stp x16, x17, [sp, #16 * 8] 214 stp x18, x19, [sp, #16 * 9] 215 stp x20, x21, [sp, #16 * 10] 216 stp x22, x23, [sp, #16 * 11] 217 stp x24, x25, [sp, #16 * 12] 218 stp x26, x27, [sp, #16 * 13] 219 stp x28, x29, [sp, #16 * 14] 220 221 .if \el == 0 222 clear_gp_regs 223 mrs x21, sp_el0 224 ldr_this_cpu tsk, __entry_task, x20 225 msr sp_el0, tsk 226 227 /* 228 * Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions 229 * when scheduling. 230 */ 231 ldr x19, [tsk, #TSK_TI_FLAGS] 232 disable_step_tsk x19, x20 233 234 /* Check for asynchronous tag check faults in user space */ 235 ldr x0, [tsk, THREAD_SCTLR_USER] 236 check_mte_async_tcf x22, x23, x0 237 238 #ifdef CONFIG_ARM64_PTR_AUTH 239 alternative_if ARM64_HAS_ADDRESS_AUTH 240 /* 241 * Enable IA for in-kernel PAC if the task had it disabled. Although 242 * this could be implemented with an unconditional MRS which would avoid 243 * a load, this was measured to be slower on Cortex-A75 and Cortex-A76. 244 * 245 * Install the kernel IA key only if IA was enabled in the task. If IA 246 * was disabled on kernel exit then we would have left the kernel IA 247 * installed so there is no need to install it again. 248 */ 249 tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f 250 __ptrauth_keys_install_kernel_nosync tsk, x20, x22, x23 251 b 2f 252 1: 253 mrs x0, sctlr_el1 254 orr x0, x0, SCTLR_ELx_ENIA 255 msr sctlr_el1, x0 256 2: 257 alternative_else_nop_endif 258 #endif 259 260 apply_ssbd 1, x22, x23 261 262 mte_set_kernel_gcr x22, x23 263 264 /* 265 * Any non-self-synchronizing system register updates required for 266 * kernel entry should be placed before this point. 267 */ 268 alternative_if ARM64_MTE 269 isb 270 b 1f 271 alternative_else_nop_endif 272 alternative_if ARM64_HAS_ADDRESS_AUTH 273 isb 274 alternative_else_nop_endif 275 1: 276 277 scs_load_current 278 .else 279 add x21, sp, #PT_REGS_SIZE 280 get_current_task tsk 281 .endif /* \el == 0 */ 282 mrs x22, elr_el1 283 mrs x23, spsr_el1 284 stp lr, x21, [sp, #S_LR] 285 286 /* 287 * For exceptions from EL0, create a final frame record. 288 * For exceptions from EL1, create a synthetic frame record so the 289 * interrupted code shows up in the backtrace. 290 */ 291 .if \el == 0 292 stp xzr, xzr, [sp, #S_STACKFRAME] 293 .else 294 stp x29, x22, [sp, #S_STACKFRAME] 295 .endif 296 add x29, sp, #S_STACKFRAME 297 298 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 299 alternative_if_not ARM64_HAS_PAN 300 bl __swpan_entry_el\el 301 alternative_else_nop_endif 302 #endif 303 304 stp x22, x23, [sp, #S_PC] 305 306 /* Not in a syscall by default (el0_svc overwrites for real syscall) */ 307 .if \el == 0 308 mov w21, #NO_SYSCALL 309 str w21, [sp, #S_SYSCALLNO] 310 .endif 311 312 #ifdef CONFIG_ARM64_PSEUDO_NMI 313 alternative_if_not ARM64_HAS_GIC_PRIO_MASKING 314 b .Lskip_pmr_save\@ 315 alternative_else_nop_endif 316 317 mrs_s x20, SYS_ICC_PMR_EL1 318 str x20, [sp, #S_PMR_SAVE] 319 mov x20, #GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET 320 msr_s SYS_ICC_PMR_EL1, x20 321 322 .Lskip_pmr_save\@: 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 #ifdef CONFIG_ARM64_PSEUDO_NMI 341 alternative_if_not ARM64_HAS_GIC_PRIO_MASKING 342 b .Lskip_pmr_restore\@ 343 alternative_else_nop_endif 344 345 ldr x20, [sp, #S_PMR_SAVE] 346 msr_s SYS_ICC_PMR_EL1, x20 347 348 /* Ensure priority change is seen by redistributor */ 349 alternative_if_not ARM64_HAS_GIC_PRIO_RELAXED_SYNC 350 dsb sy 351 alternative_else_nop_endif 352 353 .Lskip_pmr_restore\@: 354 #endif 355 356 ldp x21, x22, [sp, #S_PC] // load ELR, SPSR 357 358 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 359 alternative_if_not ARM64_HAS_PAN 360 bl __swpan_exit_el\el 361 alternative_else_nop_endif 362 #endif 363 364 .if \el == 0 365 ldr x23, [sp, #S_SP] // load return stack pointer 366 msr sp_el0, x23 367 tst x22, #PSR_MODE32_BIT // native task? 368 b.eq 3f 369 370 #ifdef CONFIG_ARM64_ERRATUM_845719 371 alternative_if ARM64_WORKAROUND_845719 372 #ifdef CONFIG_PID_IN_CONTEXTIDR 373 mrs x29, contextidr_el1 374 msr contextidr_el1, x29 375 #else 376 msr contextidr_el1, xzr 377 #endif 378 alternative_else_nop_endif 379 #endif 380 3: 381 scs_save tsk 382 383 /* Ignore asynchronous tag check faults in the uaccess routines */ 384 ldr x0, [tsk, THREAD_SCTLR_USER] 385 clear_mte_async_tcf x0 386 387 #ifdef CONFIG_ARM64_PTR_AUTH 388 alternative_if ARM64_HAS_ADDRESS_AUTH 389 /* 390 * IA was enabled for in-kernel PAC. Disable it now if needed, or 391 * alternatively install the user's IA. All other per-task keys and 392 * SCTLR bits were updated on task switch. 393 * 394 * No kernel C function calls after this. 395 */ 396 tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f 397 __ptrauth_keys_install_user tsk, x0, x1, x2 398 b 2f 399 1: 400 mrs x0, sctlr_el1 401 bic x0, x0, SCTLR_ELx_ENIA 402 msr sctlr_el1, x0 403 2: 404 alternative_else_nop_endif 405 #endif 406 407 mte_set_user_gcr tsk, x0, x1 408 409 apply_ssbd 0, x0, x1 410 .endif 411 412 msr elr_el1, x21 // set up the return data 413 msr spsr_el1, x22 414 ldp x0, x1, [sp, #16 * 0] 415 ldp x2, x3, [sp, #16 * 1] 416 ldp x4, x5, [sp, #16 * 2] 417 ldp x6, x7, [sp, #16 * 3] 418 ldp x8, x9, [sp, #16 * 4] 419 ldp x10, x11, [sp, #16 * 5] 420 ldp x12, x13, [sp, #16 * 6] 421 ldp x14, x15, [sp, #16 * 7] 422 ldp x16, x17, [sp, #16 * 8] 423 ldp x18, x19, [sp, #16 * 9] 424 ldp x20, x21, [sp, #16 * 10] 425 ldp x22, x23, [sp, #16 * 11] 426 ldp x24, x25, [sp, #16 * 12] 427 ldp x26, x27, [sp, #16 * 13] 428 ldp x28, x29, [sp, #16 * 14] 429 430 .if \el == 0 431 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 432 alternative_insn "b .L_skip_tramp_exit_\@", nop, ARM64_UNMAP_KERNEL_AT_EL0 433 434 msr far_el1, x29 435 436 ldr_this_cpu x30, this_cpu_vector, x29 437 tramp_alias x29, tramp_exit 438 msr vbar_el1, x30 // install vector table 439 ldr lr, [sp, #S_LR] // restore x30 440 add sp, sp, #PT_REGS_SIZE // restore sp 441 br x29 442 443 .L_skip_tramp_exit_\@: 444 #endif 445 .endif 446 447 ldr lr, [sp, #S_LR] 448 add sp, sp, #PT_REGS_SIZE // restore sp 449 450 .if \el == 0 451 /* This must be after the last explicit memory access */ 452 alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD 453 tlbi vale1, xzr 454 dsb nsh 455 alternative_else_nop_endif 456 .else 457 /* Ensure any device/NC reads complete */ 458 alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 459 .endif 460 461 eret 462 sb 463 .endm 464 465 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 466 /* 467 * Set the TTBR0 PAN bit in SPSR. When the exception is taken from 468 * EL0, there is no need to check the state of TTBR0_EL1 since 469 * accesses are always enabled. 470 * Note that the meaning of this bit differs from the ARMv8.1 PAN 471 * feature as all TTBR0_EL1 accesses are disabled, not just those to 472 * user mappings. 473 */ 474 SYM_CODE_START_LOCAL(__swpan_entry_el1) 475 mrs x21, ttbr0_el1 476 tst x21, #TTBR_ASID_MASK // Check for the reserved ASID 477 orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR 478 b.eq 1f // TTBR0 access already disabled 479 and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR 480 SYM_INNER_LABEL(__swpan_entry_el0, SYM_L_LOCAL) 481 __uaccess_ttbr0_disable x21 482 1: ret 483 SYM_CODE_END(__swpan_entry_el1) 484 485 /* 486 * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR 487 * PAN bit checking. 488 */ 489 SYM_CODE_START_LOCAL(__swpan_exit_el1) 490 tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set 491 __uaccess_ttbr0_enable x0, x1 492 1: and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit 493 ret 494 SYM_CODE_END(__swpan_exit_el1) 495 496 SYM_CODE_START_LOCAL(__swpan_exit_el0) 497 __uaccess_ttbr0_enable x0, x1 498 /* 499 * Enable errata workarounds only if returning to user. The only 500 * workaround currently required for TTBR0_EL1 changes are for the 501 * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache 502 * corruption). 503 */ 504 b post_ttbr_update_workaround 505 SYM_CODE_END(__swpan_exit_el0) 506 #endif 507 508 /* GPRs used by entry code */ 509 tsk .req x28 // current thread_info 510 511 .text 512 513 /* 514 * Exception vectors. 515 */ 516 .pushsection ".entry.text", "ax" 517 518 .align 11 519 SYM_CODE_START(vectors) 520 kernel_ventry 1, t, 64, sync // Synchronous EL1t 521 kernel_ventry 1, t, 64, irq // IRQ EL1t 522 kernel_ventry 1, t, 64, fiq // FIQ EL1t 523 kernel_ventry 1, t, 64, error // Error EL1t 524 525 kernel_ventry 1, h, 64, sync // Synchronous EL1h 526 kernel_ventry 1, h, 64, irq // IRQ EL1h 527 kernel_ventry 1, h, 64, fiq // FIQ EL1h 528 kernel_ventry 1, h, 64, error // Error EL1h 529 530 kernel_ventry 0, t, 64, sync // Synchronous 64-bit EL0 531 kernel_ventry 0, t, 64, irq // IRQ 64-bit EL0 532 kernel_ventry 0, t, 64, fiq // FIQ 64-bit EL0 533 kernel_ventry 0, t, 64, error // Error 64-bit EL0 534 535 kernel_ventry 0, t, 32, sync // Synchronous 32-bit EL0 536 kernel_ventry 0, t, 32, irq // IRQ 32-bit EL0 537 kernel_ventry 0, t, 32, fiq // FIQ 32-bit EL0 538 kernel_ventry 0, t, 32, error // Error 32-bit EL0 539 SYM_CODE_END(vectors) 540 541 #ifdef CONFIG_VMAP_STACK 542 SYM_CODE_START_LOCAL(__bad_stack) 543 /* 544 * We detected an overflow in kernel_ventry, which switched to the 545 * overflow stack. Stash the exception regs, and head to our overflow 546 * handler. 547 */ 548 549 /* Restore the original x0 value */ 550 mrs x0, tpidrro_el0 551 552 /* 553 * Store the original GPRs to the new stack. The orginal SP (minus 554 * PT_REGS_SIZE) was stashed in tpidr_el0 by kernel_ventry. 555 */ 556 sub sp, sp, #PT_REGS_SIZE 557 kernel_entry 1 558 mrs x0, tpidr_el0 559 add x0, x0, #PT_REGS_SIZE 560 str x0, [sp, #S_SP] 561 562 /* Stash the regs for handle_bad_stack */ 563 mov x0, sp 564 565 /* Time to die */ 566 bl handle_bad_stack 567 ASM_BUG() 568 SYM_CODE_END(__bad_stack) 569 #endif /* CONFIG_VMAP_STACK */ 570 571 572 .macro entry_handler el:req, ht:req, regsize:req, label:req 573 SYM_CODE_START_LOCAL(el\el\ht\()_\regsize\()_\label) 574 kernel_entry \el, \regsize 575 mov x0, sp 576 bl el\el\ht\()_\regsize\()_\label\()_handler 577 .if \el == 0 578 b ret_to_user 579 .else 580 b ret_to_kernel 581 .endif 582 SYM_CODE_END(el\el\ht\()_\regsize\()_\label) 583 .endm 584 585 /* 586 * Early exception handlers 587 */ 588 entry_handler 1, t, 64, sync 589 entry_handler 1, t, 64, irq 590 entry_handler 1, t, 64, fiq 591 entry_handler 1, t, 64, error 592 593 entry_handler 1, h, 64, sync 594 entry_handler 1, h, 64, irq 595 entry_handler 1, h, 64, fiq 596 entry_handler 1, h, 64, error 597 598 entry_handler 0, t, 64, sync 599 entry_handler 0, t, 64, irq 600 entry_handler 0, t, 64, fiq 601 entry_handler 0, t, 64, error 602 603 entry_handler 0, t, 32, sync 604 entry_handler 0, t, 32, irq 605 entry_handler 0, t, 32, fiq 606 entry_handler 0, t, 32, error 607 608 SYM_CODE_START_LOCAL(ret_to_kernel) 609 kernel_exit 1 610 SYM_CODE_END(ret_to_kernel) 611 612 SYM_CODE_START_LOCAL(ret_to_user) 613 ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step 614 enable_step_tsk x19, x2 615 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK 616 bl stackleak_erase_on_task_stack 617 #endif 618 kernel_exit 0 619 SYM_CODE_END(ret_to_user) 620 621 .popsection // .entry.text 622 623 // Move from tramp_pg_dir to swapper_pg_dir 624 .macro tramp_map_kernel, tmp 625 mrs \tmp, ttbr1_el1 626 add \tmp, \tmp, #TRAMP_SWAPPER_OFFSET 627 bic \tmp, \tmp, #USER_ASID_FLAG 628 msr ttbr1_el1, \tmp 629 #ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003 630 alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003 631 /* ASID already in \tmp[63:48] */ 632 movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12) 633 movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12) 634 /* 2MB boundary containing the vectors, so we nobble the walk cache */ 635 movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12) 636 isb 637 tlbi vae1, \tmp 638 dsb nsh 639 alternative_else_nop_endif 640 #endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */ 641 .endm 642 643 // Move from swapper_pg_dir to tramp_pg_dir 644 .macro tramp_unmap_kernel, tmp 645 mrs \tmp, ttbr1_el1 646 sub \tmp, \tmp, #TRAMP_SWAPPER_OFFSET 647 orr \tmp, \tmp, #USER_ASID_FLAG 648 msr ttbr1_el1, \tmp 649 /* 650 * We avoid running the post_ttbr_update_workaround here because 651 * it's only needed by Cavium ThunderX, which requires KPTI to be 652 * disabled. 653 */ 654 .endm 655 656 .macro tramp_data_read_var dst, var 657 #ifdef CONFIG_RELOCATABLE 658 ldr \dst, .L__tramp_data_\var 659 .ifndef .L__tramp_data_\var 660 .pushsection ".entry.tramp.rodata", "a", %progbits 661 .align 3 662 .L__tramp_data_\var: 663 .quad \var 664 .popsection 665 .endif 666 #else 667 /* 668 * As !RELOCATABLE implies !RANDOMIZE_BASE the address is always a 669 * compile time constant (and hence not secret and not worth hiding). 670 * 671 * As statically allocated kernel code and data always live in the top 672 * 47 bits of the address space we can sign-extend bit 47 and avoid an 673 * instruction to load the upper 16 bits (which must be 0xFFFF). 674 */ 675 movz \dst, :abs_g2_s:\var 676 movk \dst, :abs_g1_nc:\var 677 movk \dst, :abs_g0_nc:\var 678 #endif 679 .endm 680 681 #define BHB_MITIGATION_NONE 0 682 #define BHB_MITIGATION_LOOP 1 683 #define BHB_MITIGATION_FW 2 684 #define BHB_MITIGATION_INSN 3 685 686 .macro tramp_ventry, vector_start, regsize, kpti, bhb 687 .align 7 688 1: 689 .if \regsize == 64 690 msr tpidrro_el0, x30 // Restored in kernel_ventry 691 .endif 692 693 .if \bhb == BHB_MITIGATION_LOOP 694 /* 695 * This sequence must appear before the first indirect branch. i.e. the 696 * ret out of tramp_ventry. It appears here because x30 is free. 697 */ 698 __mitigate_spectre_bhb_loop x30 699 .endif // \bhb == BHB_MITIGATION_LOOP 700 701 .if \bhb == BHB_MITIGATION_INSN 702 clearbhb 703 isb 704 .endif // \bhb == BHB_MITIGATION_INSN 705 706 .if \kpti == 1 707 /* 708 * Defend against branch aliasing attacks by pushing a dummy 709 * entry onto the return stack and using a RET instruction to 710 * enter the full-fat kernel vectors. 711 */ 712 bl 2f 713 b . 714 2: 715 tramp_map_kernel x30 716 alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 717 tramp_data_read_var x30, vectors 718 alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM 719 prfm plil1strm, [x30, #(1b - \vector_start)] 720 alternative_else_nop_endif 721 722 msr vbar_el1, x30 723 isb 724 .else 725 adr_l x30, vectors 726 .endif // \kpti == 1 727 728 .if \bhb == BHB_MITIGATION_FW 729 /* 730 * The firmware sequence must appear before the first indirect branch. 731 * i.e. the ret out of tramp_ventry. But it also needs the stack to be 732 * mapped to save/restore the registers the SMC clobbers. 733 */ 734 __mitigate_spectre_bhb_fw 735 .endif // \bhb == BHB_MITIGATION_FW 736 737 add x30, x30, #(1b - \vector_start + 4) 738 ret 739 .org 1b + 128 // Did we overflow the ventry slot? 740 .endm 741 742 .macro generate_tramp_vector, kpti, bhb 743 .Lvector_start\@: 744 .space 0x400 745 746 .rept 4 747 tramp_ventry .Lvector_start\@, 64, \kpti, \bhb 748 .endr 749 .rept 4 750 tramp_ventry .Lvector_start\@, 32, \kpti, \bhb 751 .endr 752 .endm 753 754 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 755 /* 756 * Exception vectors trampoline. 757 * The order must match __bp_harden_el1_vectors and the 758 * arm64_bp_harden_el1_vectors enum. 759 */ 760 .pushsection ".entry.tramp.text", "ax" 761 .align 11 762 SYM_CODE_START_LOCAL_NOALIGN(tramp_vectors) 763 #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY 764 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP 765 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW 766 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_INSN 767 #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ 768 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE 769 SYM_CODE_END(tramp_vectors) 770 771 SYM_CODE_START_LOCAL(tramp_exit) 772 tramp_unmap_kernel x29 773 mrs x29, far_el1 // restore x29 774 eret 775 sb 776 SYM_CODE_END(tramp_exit) 777 .popsection // .entry.tramp.text 778 #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ 779 780 /* 781 * Exception vectors for spectre mitigations on entry from EL1 when 782 * kpti is not in use. 783 */ 784 .macro generate_el1_vector, bhb 785 .Lvector_start\@: 786 kernel_ventry 1, t, 64, sync // Synchronous EL1t 787 kernel_ventry 1, t, 64, irq // IRQ EL1t 788 kernel_ventry 1, t, 64, fiq // FIQ EL1h 789 kernel_ventry 1, t, 64, error // Error EL1t 790 791 kernel_ventry 1, h, 64, sync // Synchronous EL1h 792 kernel_ventry 1, h, 64, irq // IRQ EL1h 793 kernel_ventry 1, h, 64, fiq // FIQ EL1h 794 kernel_ventry 1, h, 64, error // Error EL1h 795 796 .rept 4 797 tramp_ventry .Lvector_start\@, 64, 0, \bhb 798 .endr 799 .rept 4 800 tramp_ventry .Lvector_start\@, 32, 0, \bhb 801 .endr 802 .endm 803 804 /* The order must match tramp_vecs and the arm64_bp_harden_el1_vectors enum. */ 805 .pushsection ".entry.text", "ax" 806 .align 11 807 SYM_CODE_START(__bp_harden_el1_vectors) 808 #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY 809 generate_el1_vector bhb=BHB_MITIGATION_LOOP 810 generate_el1_vector bhb=BHB_MITIGATION_FW 811 generate_el1_vector bhb=BHB_MITIGATION_INSN 812 #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */ 813 SYM_CODE_END(__bp_harden_el1_vectors) 814 .popsection 815 816 817 /* 818 * Register switch for AArch64. The callee-saved registers need to be saved 819 * and restored. On entry: 820 * x0 = previous task_struct (must be preserved across the switch) 821 * x1 = next task_struct 822 * Previous and next are guaranteed not to be the same. 823 * 824 */ 825 SYM_FUNC_START(cpu_switch_to) 826 mov x10, #THREAD_CPU_CONTEXT 827 add x8, x0, x10 828 mov x9, sp 829 stp x19, x20, [x8], #16 // store callee-saved registers 830 stp x21, x22, [x8], #16 831 stp x23, x24, [x8], #16 832 stp x25, x26, [x8], #16 833 stp x27, x28, [x8], #16 834 stp x29, x9, [x8], #16 835 str lr, [x8] 836 add x8, x1, x10 837 ldp x19, x20, [x8], #16 // restore callee-saved registers 838 ldp x21, x22, [x8], #16 839 ldp x23, x24, [x8], #16 840 ldp x25, x26, [x8], #16 841 ldp x27, x28, [x8], #16 842 ldp x29, x9, [x8], #16 843 ldr lr, [x8] 844 mov sp, x9 845 msr sp_el0, x1 846 ptrauth_keys_install_kernel x1, x8, x9, x10 847 scs_save x0 848 scs_load_current 849 ret 850 SYM_FUNC_END(cpu_switch_to) 851 NOKPROBE(cpu_switch_to) 852 853 /* 854 * This is how we return from a fork. 855 */ 856 SYM_CODE_START(ret_from_fork) 857 bl schedule_tail 858 cbz x19, 1f // not a kernel thread 859 mov x0, x20 860 blr x19 861 1: get_current_task tsk 862 mov x0, sp 863 bl asm_exit_to_user_mode 864 b ret_to_user 865 SYM_CODE_END(ret_from_fork) 866 NOKPROBE(ret_from_fork) 867 868 /* 869 * void call_on_irq_stack(struct pt_regs *regs, 870 * void (*func)(struct pt_regs *)); 871 * 872 * Calls func(regs) using this CPU's irq stack and shadow irq stack. 873 */ 874 SYM_FUNC_START(call_on_irq_stack) 875 #ifdef CONFIG_SHADOW_CALL_STACK 876 get_current_task x16 877 scs_save x16 878 ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x17 879 #endif 880 881 /* Create a frame record to save our LR and SP (implicit in FP) */ 882 stp x29, x30, [sp, #-16]! 883 mov x29, sp 884 885 ldr_this_cpu x16, irq_stack_ptr, x17 886 887 /* Move to the new stack and call the function there */ 888 add sp, x16, #IRQ_STACK_SIZE 889 blr x1 890 891 /* 892 * Restore the SP from the FP, and restore the FP and LR from the frame 893 * record. 894 */ 895 mov sp, x29 896 ldp x29, x30, [sp], #16 897 scs_load_current 898 ret 899 SYM_FUNC_END(call_on_irq_stack) 900 NOKPROBE(call_on_irq_stack) 901 902 #ifdef CONFIG_ARM_SDE_INTERFACE 903 904 #include <asm/sdei.h> 905 #include <uapi/linux/arm_sdei.h> 906 907 .macro sdei_handler_exit exit_mode 908 /* On success, this call never returns... */ 909 cmp \exit_mode, #SDEI_EXIT_SMC 910 b.ne 99f 911 smc #0 912 b . 913 99: hvc #0 914 b . 915 .endm 916 917 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 918 /* 919 * The regular SDEI entry point may have been unmapped along with the rest of 920 * the kernel. This trampoline restores the kernel mapping to make the x1 memory 921 * argument accessible. 922 * 923 * This clobbers x4, __sdei_handler() will restore this from firmware's 924 * copy. 925 */ 926 .pushsection ".entry.tramp.text", "ax" 927 SYM_CODE_START(__sdei_asm_entry_trampoline) 928 mrs x4, ttbr1_el1 929 tbz x4, #USER_ASID_BIT, 1f 930 931 tramp_map_kernel tmp=x4 932 isb 933 mov x4, xzr 934 935 /* 936 * Remember whether to unmap the kernel on exit. 937 */ 938 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] 939 tramp_data_read_var x4, __sdei_asm_handler 940 br x4 941 SYM_CODE_END(__sdei_asm_entry_trampoline) 942 NOKPROBE(__sdei_asm_entry_trampoline) 943 944 /* 945 * Make the exit call and restore the original ttbr1_el1 946 * 947 * x0 & x1: setup for the exit API call 948 * x2: exit_mode 949 * x4: struct sdei_registered_event argument from registration time. 950 */ 951 SYM_CODE_START(__sdei_asm_exit_trampoline) 952 ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] 953 cbnz x4, 1f 954 955 tramp_unmap_kernel tmp=x4 956 957 1: sdei_handler_exit exit_mode=x2 958 SYM_CODE_END(__sdei_asm_exit_trampoline) 959 NOKPROBE(__sdei_asm_exit_trampoline) 960 .popsection // .entry.tramp.text 961 #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ 962 963 /* 964 * Software Delegated Exception entry point. 965 * 966 * x0: Event number 967 * x1: struct sdei_registered_event argument from registration time. 968 * x2: interrupted PC 969 * x3: interrupted PSTATE 970 * x4: maybe clobbered by the trampoline 971 * 972 * Firmware has preserved x0->x17 for us, we must save/restore the rest to 973 * follow SMC-CC. We save (or retrieve) all the registers as the handler may 974 * want them. 975 */ 976 SYM_CODE_START(__sdei_asm_handler) 977 stp x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC] 978 stp x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2] 979 stp x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3] 980 stp x8, x9, [x1, #SDEI_EVENT_INTREGS + 16 * 4] 981 stp x10, x11, [x1, #SDEI_EVENT_INTREGS + 16 * 5] 982 stp x12, x13, [x1, #SDEI_EVENT_INTREGS + 16 * 6] 983 stp x14, x15, [x1, #SDEI_EVENT_INTREGS + 16 * 7] 984 stp x16, x17, [x1, #SDEI_EVENT_INTREGS + 16 * 8] 985 stp x18, x19, [x1, #SDEI_EVENT_INTREGS + 16 * 9] 986 stp x20, x21, [x1, #SDEI_EVENT_INTREGS + 16 * 10] 987 stp x22, x23, [x1, #SDEI_EVENT_INTREGS + 16 * 11] 988 stp x24, x25, [x1, #SDEI_EVENT_INTREGS + 16 * 12] 989 stp x26, x27, [x1, #SDEI_EVENT_INTREGS + 16 * 13] 990 stp x28, x29, [x1, #SDEI_EVENT_INTREGS + 16 * 14] 991 mov x4, sp 992 stp lr, x4, [x1, #SDEI_EVENT_INTREGS + S_LR] 993 994 mov x19, x1 995 996 /* Store the registered-event for crash_smp_send_stop() */ 997 ldrb w4, [x19, #SDEI_EVENT_PRIORITY] 998 cbnz w4, 1f 999 adr_this_cpu dst=x5, sym=sdei_active_normal_event, tmp=x6 1000 b 2f 1001 1: adr_this_cpu dst=x5, sym=sdei_active_critical_event, tmp=x6 1002 2: str x19, [x5] 1003 1004 #ifdef CONFIG_VMAP_STACK 1005 /* 1006 * entry.S may have been using sp as a scratch register, find whether 1007 * this is a normal or critical event and switch to the appropriate 1008 * stack for this CPU. 1009 */ 1010 cbnz w4, 1f 1011 ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6 1012 b 2f 1013 1: ldr_this_cpu dst=x5, sym=sdei_stack_critical_ptr, tmp=x6 1014 2: mov x6, #SDEI_STACK_SIZE 1015 add x5, x5, x6 1016 mov sp, x5 1017 #endif 1018 1019 #ifdef CONFIG_SHADOW_CALL_STACK 1020 /* Use a separate shadow call stack for normal and critical events */ 1021 cbnz w4, 3f 1022 ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6 1023 b 4f 1024 3: ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6 1025 4: 1026 #endif 1027 1028 /* 1029 * We may have interrupted userspace, or a guest, or exit-from or 1030 * return-to either of these. We can't trust sp_el0, restore it. 1031 */ 1032 mrs x28, sp_el0 1033 ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1 1034 msr sp_el0, x0 1035 1036 /* If we interrupted the kernel point to the previous stack/frame. */ 1037 and x0, x3, #0xc 1038 mrs x1, CurrentEL 1039 cmp x0, x1 1040 csel x29, x29, xzr, eq // fp, or zero 1041 csel x4, x2, xzr, eq // elr, or zero 1042 1043 stp x29, x4, [sp, #-16]! 1044 mov x29, sp 1045 1046 add x0, x19, #SDEI_EVENT_INTREGS 1047 mov x1, x19 1048 bl __sdei_handler 1049 1050 msr sp_el0, x28 1051 /* restore regs >x17 that we clobbered */ 1052 mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline 1053 ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14] 1054 ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9] 1055 ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR] 1056 mov sp, x1 1057 1058 mov x1, x0 // address to complete_and_resume 1059 /* x0 = (x0 <= SDEI_EV_FAILED) ? 1060 * EVENT_COMPLETE:EVENT_COMPLETE_AND_RESUME 1061 */ 1062 cmp x0, #SDEI_EV_FAILED 1063 mov_q x2, SDEI_1_0_FN_SDEI_EVENT_COMPLETE 1064 mov_q x3, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME 1065 csel x0, x2, x3, ls 1066 1067 ldr_l x2, sdei_exit_mode 1068 1069 /* Clear the registered-event seen by crash_smp_send_stop() */ 1070 ldrb w3, [x4, #SDEI_EVENT_PRIORITY] 1071 cbnz w3, 1f 1072 adr_this_cpu dst=x5, sym=sdei_active_normal_event, tmp=x6 1073 b 2f 1074 1: adr_this_cpu dst=x5, sym=sdei_active_critical_event, tmp=x6 1075 2: str xzr, [x5] 1076 1077 alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 1078 sdei_handler_exit exit_mode=x2 1079 alternative_else_nop_endif 1080 1081 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 1082 tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline 1083 br x5 1084 #endif 1085 SYM_CODE_END(__sdei_asm_handler) 1086 NOKPROBE(__sdei_asm_handler) 1087 1088 SYM_CODE_START(__sdei_handler_abort) 1089 mov_q x0, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME 1090 adr x1, 1f 1091 ldr_l x2, sdei_exit_mode 1092 sdei_handler_exit exit_mode=x2 1093 // exit the handler and jump to the next instruction. 1094 // Exit will stomp x0-x17, PSTATE, ELR_ELx, and SPSR_ELx. 1095 1: ret 1096 SYM_CODE_END(__sdei_handler_abort) 1097 NOKPROBE(__sdei_handler_abort) 1098 #endif /* CONFIG_ARM_SDE_INTERFACE */
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