Re: [PATCH -next 3/3] kasan: arm64: Fix pcpu_page_first_chunk crash with KASAN_VMALLOC
From: Marco Elver <elver@google.com>
Date: 2021-07-05 15:04:27
Also in:
linux-arm-kernel, lkml
On Mon, Jul 05, 2021 at 07:14PM +0800, Kefeng Wang wrote: [...]
+#ifdef CONFIG_KASAN_VMALLOC +void __init __weak kasan_populate_early_vm_area_shadow(void *start, + unsigned long size)
This should probably not be __weak, otherwise you now have 2 __weak functions.
+{
+ unsigned long shadow_start, shadow_end;
+
+ if (!is_vmalloc_or_module_addr(start))
+ return;
+
+ shadow_start = (unsigned long)kasan_mem_to_shadow(start);
+ shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
+ shadow_end = (unsigned long)kasan_mem_to_shadow(start + size);
+ shadow_end = ALIGN(shadow_end, PAGE_SIZE);
+ kasan_map_populate(shadow_start, shadow_end,
+ early_pfn_to_nid(virt_to_pfn(start)));
+}
+#endifThis function looks quite generic -- would any of this also apply to other architectures? I see that ppc and sparc at least also define CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK.
quoted hunk ↗ jump to hunk
void __init kasan_init(void) { kasan_init_shadow();diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 5310e217bd74..79d3895b0240 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h@@ -49,6 +49,8 @@ extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D]; int kasan_populate_early_shadow(const void *shadow_start, const void *shadow_end); +void kasan_populate_early_vm_area_shadow(void *start, unsigned long size); + static inline void *kasan_mem_to_shadow(const void *addr) { return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)diff --git a/mm/kasan/init.c b/mm/kasan/init.c index cc64ed6858c6..d39577d088a1 100644 --- a/mm/kasan/init.c +++ b/mm/kasan/init.c@@ -279,6 +279,11 @@ int __ref kasan_populate_early_shadow(const void *shadow_start, return 0; } +void __init __weak kasan_populate_early_vm_area_shadow(void *start, + unsigned long size) +{ +}
I'm just wondering if this could be a generic function, perhaps with an appropriate IS_ENABLED() check of a generic Kconfig option (CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK ?) to short-circuit it, if it's not only an arm64 problem. But I haven't looked much further, so would appeal to you to either confirm or reject this idea. Thanks, -- Marco