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eb3d8ea3e1
In arm64_relocate_new_kernel() we load some fields out of the kimage
structure after relocation has occurred. As the kimage structure isn't
allocated to be relocation-safe, it may be clobbered during relocation,
and we may load junk values out of the structure.
Due to this, kexec may fail when the kimage allocation happens to fall
within a PA range that an object will be relocated to. This has been
observed to occur for regular kexec on a QEMU TCG 'virt' machine with
2GiB of RAM, where the PA range of the new kernel image overlaps the
kimage structure.
Avoid this by ensuring we load all values from the kimage structure
prior to relocation.
I've tested this atop v5.16 and v5.18-rc6.
Fixes: 878fdbd704 ("arm64: kexec: pass kimage as the only argument to relocation function")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/r/20220516160735.731404-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
100 lines
3 KiB
ArmAsm
100 lines
3 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* kexec for arm64
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*
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* Copyright (C) Linaro.
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* Copyright (C) Huawei Futurewei Technologies.
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* Copyright (C) 2021, Microsoft Corporation.
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* Pasha Tatashin <pasha.tatashin@soleen.com>
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*/
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#include <linux/kexec.h>
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/kexec.h>
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#include <asm/page.h>
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#include <asm/sysreg.h>
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#include <asm/virt.h>
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.macro turn_off_mmu tmp1, tmp2
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mov_q \tmp1, INIT_SCTLR_EL1_MMU_OFF
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pre_disable_mmu_workaround
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msr sctlr_el1, \tmp1
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isb
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.endm
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.section ".kexec_relocate.text", "ax"
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/*
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* arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it.
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*
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* The memory that the old kernel occupies may be overwritten when copying the
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* new image to its final location. To assure that the
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* arm64_relocate_new_kernel routine which does that copy is not overwritten,
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* all code and data needed by arm64_relocate_new_kernel must be between the
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* symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end. The
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* machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec
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* safe memory that has been set up to be preserved during the copy operation.
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*/
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SYM_CODE_START(arm64_relocate_new_kernel)
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/*
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* The kimage structure isn't allocated specially and may be clobbered
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* during relocation. We must load any values we need from it prior to
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* any relocation occurring.
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*/
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ldr x28, [x0, #KIMAGE_START]
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ldr x27, [x0, #KIMAGE_ARCH_EL2_VECTORS]
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ldr x26, [x0, #KIMAGE_ARCH_DTB_MEM]
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/* Setup the list loop variables. */
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ldr x18, [x0, #KIMAGE_ARCH_ZERO_PAGE] /* x18 = zero page for BBM */
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ldr x17, [x0, #KIMAGE_ARCH_TTBR1] /* x17 = linear map copy */
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ldr x16, [x0, #KIMAGE_HEAD] /* x16 = kimage_head */
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ldr x22, [x0, #KIMAGE_ARCH_PHYS_OFFSET] /* x22 phys_offset */
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raw_dcache_line_size x15, x1 /* x15 = dcache line size */
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break_before_make_ttbr_switch x18, x17, x1, x2 /* set linear map */
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.Lloop:
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and x12, x16, PAGE_MASK /* x12 = addr */
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sub x12, x12, x22 /* Convert x12 to virt */
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/* Test the entry flags. */
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.Ltest_source:
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tbz x16, IND_SOURCE_BIT, .Ltest_indirection
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/* Invalidate dest page to PoC. */
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mov x19, x13
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copy_page x13, x12, x1, x2, x3, x4, x5, x6, x7, x8
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add x1, x19, #PAGE_SIZE
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dcache_by_myline_op civac, sy, x19, x1, x15, x20
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b .Lnext
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.Ltest_indirection:
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tbz x16, IND_INDIRECTION_BIT, .Ltest_destination
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mov x14, x12 /* ptr = addr */
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b .Lnext
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.Ltest_destination:
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tbz x16, IND_DESTINATION_BIT, .Lnext
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mov x13, x12 /* dest = addr */
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.Lnext:
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ldr x16, [x14], #8 /* entry = *ptr++ */
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tbz x16, IND_DONE_BIT, .Lloop /* while (!(entry & DONE)) */
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/* wait for writes from copy_page to finish */
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dsb nsh
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ic iallu
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dsb nsh
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isb
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turn_off_mmu x12, x13
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/* Start new image. */
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cbz x27, .Lel1
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mov x1, x28 /* kernel entry point */
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mov x2, x26 /* dtb address */
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mov x3, xzr
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mov x4, xzr
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mov x0, #HVC_SOFT_RESTART
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hvc #0 /* Jumps from el2 */
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.Lel1:
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mov x0, x26 /* dtb address */
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mov x1, xzr
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mov x2, xzr
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mov x3, xzr
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br x28 /* Jumps from el1 */
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SYM_CODE_END(arm64_relocate_new_kernel)
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