From: Mike Rapoport <rppt@xxxxxxxxxxxxx> Subject: set_memory: allow querying whether set_direct_map_*() is actually enabled On arm64, set_direct_map_*() functions may return 0 without actually changing the linear map. This behaviour can be controlled using kernel parameters, so we need a way to determine at runtime whether calls to set_direct_map_invalid_noflush() and set_direct_map_default_noflush() have any effect. Extend set_memory API with can_set_direct_map() function that allows checking if calling set_direct_map_*() will actually change the page table, replace several occurrences of open coded checks in arm64 with the new function and provide a generic stub for architectures that always modify page tables upon calls to set_direct_map APIs. [arnd@xxxxxxxx: arm64: kfence: fix header inclusion ] Link: https://lkml.kernel.org/r/20210518072034.31572-4-rppt@xxxxxxxxxx Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Acked-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Christopher Lameter <cl@xxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Elena Reshetova <elena.reshetova@xxxxxxxxx> Cc: Hagen Paul Pfeifer <hagen@xxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: James Bottomley <jejb@xxxxxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> Cc: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Tycho Andersen <tycho@xxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: kernel test robot <lkp@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm64/include/asm/Kbuild | 1 - arch/arm64/include/asm/cacheflush.h | 6 ------ arch/arm64/include/asm/kfence.h | 2 +- arch/arm64/include/asm/set_memory.h | 17 +++++++++++++++++ arch/arm64/kernel/machine_kexec.c | 1 + arch/arm64/mm/mmu.c | 7 +++---- arch/arm64/mm/pageattr.c | 13 +++++++++---- include/linux/set_memory.h | 12 ++++++++++++ 8 files changed, 43 insertions(+), 16 deletions(-) --- a/arch/arm64/include/asm/cacheflush.h~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/arch/arm64/include/asm/cacheflush.h @@ -144,12 +144,6 @@ static __always_inline void icache_inval dsb(ish); } -int set_memory_valid(unsigned long addr, int numpages, int enable); - -int set_direct_map_invalid_noflush(struct page *page); -int set_direct_map_default_noflush(struct page *page); -bool kernel_page_present(struct page *page); - #include <asm-generic/cacheflush.h> #endif /* __ASM_CACHEFLUSH_H */ --- a/arch/arm64/include/asm/Kbuild~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/arch/arm64/include/asm/Kbuild @@ -3,7 +3,6 @@ generic-y += early_ioremap.h generic-y += mcs_spinlock.h generic-y += qrwlock.h generic-y += qspinlock.h -generic-y += set_memory.h generic-y += user.h generated-y += cpucaps.h --- a/arch/arm64/include/asm/kfence.h~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/arch/arm64/include/asm/kfence.h @@ -8,7 +8,7 @@ #ifndef __ASM_KFENCE_H #define __ASM_KFENCE_H -#include <asm/cacheflush.h> +#include <asm/set_memory.h> static inline bool arch_kfence_init_pool(void) { return true; } --- /dev/null +++ a/arch/arm64/include/asm/set_memory.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#ifndef _ASM_ARM64_SET_MEMORY_H +#define _ASM_ARM64_SET_MEMORY_H + +#include <asm-generic/set_memory.h> + +bool can_set_direct_map(void); +#define can_set_direct_map can_set_direct_map + +int set_memory_valid(unsigned long addr, int numpages, int enable); + +int set_direct_map_invalid_noflush(struct page *page); +int set_direct_map_default_noflush(struct page *page); +bool kernel_page_present(struct page *page); + +#endif /* _ASM_ARM64_SET_MEMORY_H */ --- a/arch/arm64/kernel/machine_kexec.c~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/arch/arm64/kernel/machine_kexec.c @@ -11,6 +11,7 @@ #include <linux/kernel.h> #include <linux/kexec.h> #include <linux/page-flags.h> +#include <linux/set_memory.h> #include <linux/smp.h> #include <asm/cacheflush.h> --- a/arch/arm64/mm/mmu.c~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/arch/arm64/mm/mmu.c @@ -22,6 +22,7 @@ #include <linux/io.h> #include <linux/mm.h> #include <linux/vmalloc.h> +#include <linux/set_memory.h> #include <asm/barrier.h> #include <asm/cputype.h> @@ -515,8 +516,7 @@ static void __init map_mem(pgd_t *pgdp) */ BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end)); - if (rodata_full || crash_mem_map || debug_pagealloc_enabled() || - IS_ENABLED(CONFIG_KFENCE)) + if (can_set_direct_map() || crash_mem_map || IS_ENABLED(CONFIG_KFENCE)) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; /* @@ -1489,8 +1489,7 @@ int arch_add_memory(int nid, u64 start, * KFENCE requires linear map to be mapped at page granularity, so that * it is possible to protect/unprotect single pages in the KFENCE pool. */ - if (rodata_full || debug_pagealloc_enabled() || - IS_ENABLED(CONFIG_KFENCE)) + if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), --- a/arch/arm64/mm/pageattr.c~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/arch/arm64/mm/pageattr.c @@ -19,6 +19,11 @@ struct page_change_data { bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED); +bool can_set_direct_map(void) +{ + return rodata_full || debug_pagealloc_enabled(); +} + static int change_page_range(pte_t *ptep, unsigned long addr, void *data) { struct page_change_data *cdata = data; @@ -155,7 +160,7 @@ int set_direct_map_invalid_noflush(struc .clear_mask = __pgprot(PTE_VALID), }; - if (!debug_pagealloc_enabled() && !rodata_full) + if (!can_set_direct_map()) return 0; return apply_to_page_range(&init_mm, @@ -170,7 +175,7 @@ int set_direct_map_default_noflush(struc .clear_mask = __pgprot(PTE_RDONLY), }; - if (!debug_pagealloc_enabled() && !rodata_full) + if (!can_set_direct_map()) return 0; return apply_to_page_range(&init_mm, @@ -181,7 +186,7 @@ int set_direct_map_default_noflush(struc #ifdef CONFIG_DEBUG_PAGEALLOC void __kernel_map_pages(struct page *page, int numpages, int enable) { - if (!debug_pagealloc_enabled() && !rodata_full) + if (!can_set_direct_map()) return; set_memory_valid((unsigned long)page_address(page), numpages, enable); @@ -206,7 +211,7 @@ bool kernel_page_present(struct page *pa pte_t *ptep; unsigned long addr = (unsigned long)page_address(page); - if (!debug_pagealloc_enabled() && !rodata_full) + if (!can_set_direct_map()) return true; pgdp = pgd_offset_k(addr); --- a/include/linux/set_memory.h~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled +++ a/include/linux/set_memory.h @@ -28,7 +28,19 @@ static inline bool kernel_page_present(s { return true; } +#else /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */ +/* + * Some architectures, e.g. ARM64 can disable direct map modifications at + * boot time. Let them overrive this query. + */ +#ifndef can_set_direct_map +static inline bool can_set_direct_map(void) +{ + return true; +} +#define can_set_direct_map can_set_direct_map #endif +#endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */ #ifndef set_mce_nospec static inline int set_mce_nospec(unsigned long pfn, bool unmap) _
