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1e338f4d99
Patch series "kasan: unify kasan_enabled() and remove arch-specific
implementations", v6.
This patch series addresses the fragmentation in KASAN initialization
across architectures by introducing a unified approach that eliminates
duplicate static keys and arch-specific kasan_arch_is_ready()
implementations.
The core issue is that different architectures have inconsistent approaches
to KASAN readiness tracking:
- PowerPC, LoongArch, and UML arch, each implement own kasan_arch_is_ready()
- Only HW_TAGS mode had a unified static key (kasan_flag_enabled)
- Generic and SW_TAGS modes relied on arch-specific solutions
or always-on behavior
This patch (of 2):
Introduce CONFIG_ARCH_DEFER_KASAN to identify architectures [1] that need
to defer KASAN initialization until shadow memory is properly set up, and
unify the static key infrastructure across all KASAN modes.
[1] PowerPC, UML, LoongArch selects ARCH_DEFER_KASAN.
The core issue is that different architectures haveinconsistent approaches
to KASAN readiness tracking:
- PowerPC, LoongArch, and UML arch, each implement own
kasan_arch_is_ready()
- Only HW_TAGS mode had a unified static key (kasan_flag_enabled)
- Generic and SW_TAGS modes relied on arch-specific solutions or always-on
behavior
This patch addresses the fragmentation in KASAN initialization across
architectures by introducing a unified approach that eliminates duplicate
static keys and arch-specific kasan_arch_is_ready() implementations.
Let's replace kasan_arch_is_ready() with existing kasan_enabled() check,
which examines the static key being enabled if arch selects
ARCH_DEFER_KASAN or has HW_TAGS mode support. For other arch,
kasan_enabled() checks the enablement during compile time.
Now KASAN users can use a single kasan_enabled() check everywhere.
Link: https://lkml.kernel.org/r/20250810125746.1105476-1-snovitoll@gmail.com
Link: https://lkml.kernel.org/r/20250810125746.1105476-2-snovitoll@gmail.com
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> #powerpc
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: David Gow <davidgow@google.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Marco Elver <elver@google.com>
Cc: Qing Zhang <zhangqing@loongson.cn>
Cc: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
101 lines
3.0 KiB
C
101 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* KASAN for 64-bit Book3S powerpc
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*
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* Copyright 2019-2022, Daniel Axtens, IBM Corporation.
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*/
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/*
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* ppc64 turns on virtual memory late in boot, after calling into generic code
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* like the device-tree parser, so it uses this in conjunction with a hook in
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* outline mode to avoid invalid access early in boot.
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*/
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#define DISABLE_BRANCH_PROFILING
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#include <linux/kasan.h>
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#include <linux/printk.h>
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#include <linux/sched/task.h>
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#include <linux/memblock.h>
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#include <asm/pgalloc.h>
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static void __init kasan_init_phys_region(void *start, void *end)
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{
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unsigned long k_start, k_end, k_cur;
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void *va;
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if (start >= end)
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return;
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k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
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k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
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va = memblock_alloc_or_panic(k_end - k_start, PAGE_SIZE);
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for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE)
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map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
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}
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void __init kasan_init(void)
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{
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/*
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* We want to do the following things:
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* 1) Map real memory into the shadow for all physical memblocks
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* This takes us from c000... to c008...
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* 2) Leave a hole over the shadow of vmalloc space. KASAN_VMALLOC
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* will manage this for us.
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* This takes us from c008... to c00a...
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* 3) Map the 'early shadow'/zero page over iomap and vmemmap space.
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* This takes us up to where we start at c00e...
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*/
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void *k_start = kasan_mem_to_shadow((void *)RADIX_VMALLOC_END);
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void *k_end = kasan_mem_to_shadow((void *)RADIX_VMEMMAP_END);
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phys_addr_t start, end;
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u64 i;
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pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);
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if (!early_radix_enabled()) {
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pr_warn("KASAN not enabled as it requires radix!");
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return;
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}
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for_each_mem_range(i, &start, &end)
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kasan_init_phys_region(phys_to_virt(start), phys_to_virt(end));
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for (i = 0; i < PTRS_PER_PTE; i++)
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__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
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&kasan_early_shadow_pte[i], zero_pte, 0);
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for (i = 0; i < PTRS_PER_PMD; i++)
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pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i],
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kasan_early_shadow_pte);
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for (i = 0; i < PTRS_PER_PUD; i++)
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pud_populate(&init_mm, &kasan_early_shadow_pud[i],
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kasan_early_shadow_pmd);
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/* map the early shadow over the iomap and vmemmap space */
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kasan_populate_early_shadow(k_start, k_end);
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/* mark early shadow region as RO and wipe it */
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zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);
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for (i = 0; i < PTRS_PER_PTE; i++)
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__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
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&kasan_early_shadow_pte[i], zero_pte, 0);
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/*
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* clear_page relies on some cache info that hasn't been set up yet.
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* It ends up looping ~forever and blows up other data.
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* Use memset instead.
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*/
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memset(kasan_early_shadow_page, 0, PAGE_SIZE);
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/* Enable error messages */
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init_task.kasan_depth = 0;
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kasan_init_generic();
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}
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void __init kasan_early_init(void) { }
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void __init kasan_late_init(void) { }
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