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https://github.com/torvalds/linux
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8ec4198743
The arm64 booting document requires that the bootloader has cleaned the kernel image to the PoC. However, when a CPU re-enters the kernel due to either a CPU hotplug "on" event or resuming from a low-power state (e.g. cpuidle), the kernel text may in-fact be dirty at the PoU due to things like alternative patching or even module loading. Thanks to I-cache speculation with the MMU off, stale instructions could be fetched prior to enabling the MMU, potentially leading to crashes when executing regions of code that have been modified at runtime. This patch addresses the issue by ensuring that the local I-cache is invalidated immediately after a CPU has enabled its MMU but before jumping out of the identity mapping. Any stale instructions fetched from the PoC will then be discarded and refetched correctly from the PoU. Patching kernel text executed prior to the MMU being enabled is prohibited, so the early entry code will always be clean. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
227 lines
5.3 KiB
ArmAsm
227 lines
5.3 KiB
ArmAsm
/*
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* Based on arch/arm/mm/proc.S
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*
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* Copyright (C) 2001 Deep Blue Solutions Ltd.
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* Copyright (C) 2012 ARM Ltd.
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* Author: Catalin Marinas <catalin.marinas@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/asm-offsets.h>
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#include <asm/hwcap.h>
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#include <asm/pgtable-hwdef.h>
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#include <asm/pgtable.h>
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#include "proc-macros.S"
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#ifdef CONFIG_ARM64_64K_PAGES
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#define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K
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#else
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#define TCR_TG_FLAGS TCR_TG0_4K | TCR_TG1_4K
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#endif
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#define TCR_SMP_FLAGS TCR_SHARED
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/* PTWs cacheable, inner/outer WBWA */
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#define TCR_CACHE_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA
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#define MAIR(attr, mt) ((attr) << ((mt) * 8))
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/*
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* cpu_do_idle()
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*
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* Idle the processor (wait for interrupt).
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*/
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ENTRY(cpu_do_idle)
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dsb sy // WFI may enter a low-power mode
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wfi
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ret
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ENDPROC(cpu_do_idle)
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#ifdef CONFIG_CPU_PM
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/**
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* cpu_do_suspend - save CPU registers context
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*
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* x0: virtual address of context pointer
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*/
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ENTRY(cpu_do_suspend)
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mrs x2, tpidr_el0
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mrs x3, tpidrro_el0
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mrs x4, contextidr_el1
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mrs x5, mair_el1
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mrs x6, cpacr_el1
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mrs x7, ttbr1_el1
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mrs x8, tcr_el1
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mrs x9, vbar_el1
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mrs x10, mdscr_el1
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mrs x11, oslsr_el1
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mrs x12, sctlr_el1
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stp x2, x3, [x0]
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stp x4, x5, [x0, #16]
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stp x6, x7, [x0, #32]
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stp x8, x9, [x0, #48]
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stp x10, x11, [x0, #64]
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str x12, [x0, #80]
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ret
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ENDPROC(cpu_do_suspend)
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/**
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* cpu_do_resume - restore CPU register context
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*
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* x0: Physical address of context pointer
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* x1: ttbr0_el1 to be restored
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*
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* Returns:
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* sctlr_el1 value in x0
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*/
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ENTRY(cpu_do_resume)
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/*
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* Invalidate local tlb entries before turning on MMU
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*/
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tlbi vmalle1
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ldp x2, x3, [x0]
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ldp x4, x5, [x0, #16]
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ldp x6, x7, [x0, #32]
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ldp x8, x9, [x0, #48]
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ldp x10, x11, [x0, #64]
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ldr x12, [x0, #80]
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msr tpidr_el0, x2
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msr tpidrro_el0, x3
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msr contextidr_el1, x4
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msr mair_el1, x5
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msr cpacr_el1, x6
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msr ttbr0_el1, x1
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msr ttbr1_el1, x7
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tcr_set_idmap_t0sz x8, x7
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msr tcr_el1, x8
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msr vbar_el1, x9
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msr mdscr_el1, x10
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/*
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* Restore oslsr_el1 by writing oslar_el1
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*/
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ubfx x11, x11, #1, #1
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msr oslar_el1, x11
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mov x0, x12
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dsb nsh // Make sure local tlb invalidation completed
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isb
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ret
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ENDPROC(cpu_do_resume)
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#endif
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/*
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* cpu_do_switch_mm(pgd_phys, tsk)
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*
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* Set the translation table base pointer to be pgd_phys.
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*
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* - pgd_phys - physical address of new TTB
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*/
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ENTRY(cpu_do_switch_mm)
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mmid w1, x1 // get mm->context.id
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bfi x0, x1, #48, #16 // set the ASID
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msr ttbr0_el1, x0 // set TTBR0
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isb
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ret
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ENDPROC(cpu_do_switch_mm)
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.section ".text.init", #alloc, #execinstr
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/*
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* __cpu_setup
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*
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* Initialise the processor for turning the MMU on. Return in x0 the
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* value of the SCTLR_EL1 register.
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*/
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ENTRY(__cpu_setup)
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tlbi vmalle1is // invalidate I + D TLBs
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dsb ish
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mov x0, #3 << 20
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msr cpacr_el1, x0 // Enable FP/ASIMD
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msr mdscr_el1, xzr // Reset mdscr_el1
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/*
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* Memory region attributes for LPAE:
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*
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* n = AttrIndx[2:0]
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* n MAIR
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* DEVICE_nGnRnE 000 00000000
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* DEVICE_nGnRE 001 00000100
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* DEVICE_GRE 010 00001100
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* NORMAL_NC 011 01000100
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* NORMAL 100 11111111
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*/
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ldr x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
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MAIR(0x04, MT_DEVICE_nGnRE) | \
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MAIR(0x0c, MT_DEVICE_GRE) | \
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MAIR(0x44, MT_NORMAL_NC) | \
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MAIR(0xff, MT_NORMAL)
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msr mair_el1, x5
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/*
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* Prepare SCTLR
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*/
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adr x5, crval
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ldp w5, w6, [x5]
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mrs x0, sctlr_el1
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bic x0, x0, x5 // clear bits
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orr x0, x0, x6 // set bits
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/*
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* Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
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* both user and kernel.
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*/
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ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
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TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0
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tcr_set_idmap_t0sz x10, x9
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/*
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* Read the PARange bits from ID_AA64MMFR0_EL1 and set the IPS bits in
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* TCR_EL1.
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*/
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mrs x9, ID_AA64MMFR0_EL1
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bfi x10, x9, #32, #3
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#ifdef CONFIG_ARM64_HW_AFDBM
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/*
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* Hardware update of the Access and Dirty bits.
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*/
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mrs x9, ID_AA64MMFR1_EL1
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and x9, x9, #0xf
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cbz x9, 2f
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cmp x9, #2
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b.lt 1f
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orr x10, x10, #TCR_HD // hardware Dirty flag update
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1: orr x10, x10, #TCR_HA // hardware Access flag update
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2:
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#endif /* CONFIG_ARM64_HW_AFDBM */
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msr tcr_el1, x10
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ret // return to head.S
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ENDPROC(__cpu_setup)
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/*
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* We set the desired value explicitly, including those of the
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* reserved bits. The values of bits EE & E0E were set early in
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* el2_setup, which are left untouched below.
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*
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* n n T
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* U E WT T UD US IHBS
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* CE0 XWHW CZ ME TEEA S
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* .... .IEE .... NEAI TE.I ..AD DEN0 ACAM
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* 0011 0... 1101 ..0. ..0. 10.. .0.. .... < hardware reserved
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* .... .1.. .... 01.1 11.1 ..01 0.01 1101 < software settings
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*/
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.type crval, #object
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crval:
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.word 0xfcffffff // clear
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.word 0x34d5d91d // set
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