Kfence only needs its pool to be mapped as page granularity, previous judgement was a bit over protected. Decouple it from judgement and do page granularity mapping for kfence pool only [1]. To implement this, also relocate the kfence pool allocation before the linear mapping setting up, kfence_alloc_pool is to allocate phys addr, __kfence_pool is to be set after linear mapping set up. LINK: [1] https://lore.kernel.org/linux-arm-kernel/1675750519-1064-1-git-send-email-quic_zhenhuah@xxxxxxxxxxx/T/ Suggested-by: Mark Rutland <mark.rutland@xxxxxxx> Signed-off-by: Zhenhua Huang <quic_zhenhuah@xxxxxxxxxxx> --- arch/arm64/mm/mmu.c | 24 ++++++++++++++++++++++++ arch/arm64/mm/pageattr.c | 5 ++--- include/linux/kfence.h | 10 ++++++++-- init/main.c | 1 - mm/kfence/core.c | 18 ++++++++++++++---- 5 files changed, 48 insertions(+), 10 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 6f9d889..bd79691 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -24,6 +24,7 @@ #include <linux/mm.h> #include <linux/vmalloc.h> #include <linux/set_memory.h> +#include <linux/kfence.h> #include <asm/barrier.h> #include <asm/cputype.h> @@ -532,6 +533,9 @@ static void __init map_mem(pgd_t *pgdp) phys_addr_t kernel_end = __pa_symbol(__init_begin); phys_addr_t start, end; int flags = NO_EXEC_MAPPINGS; +#ifdef CONFIG_KFENCE + phys_addr_t kfence_pool = 0; +#endif u64 i; /* @@ -564,6 +568,12 @@ static void __init map_mem(pgd_t *pgdp) } #endif +#ifdef CONFIG_KFENCE + kfence_pool = kfence_alloc_pool(); + if (kfence_pool) + memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE); +#endif + /* map all the memory banks */ for_each_mem_range(i, &start, &end) { if (start >= end) @@ -608,6 +618,20 @@ static void __init map_mem(pgd_t *pgdp) } } #endif + + /* Kfence pool needs page-level mapping */ +#ifdef CONFIG_KFENCE + if (kfence_pool) { + __map_memblock(pgdp, kfence_pool, + kfence_pool + KFENCE_POOL_SIZE, + pgprot_tagged(PAGE_KERNEL), + NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); + memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE); + /* kfence_pool really mapped now */ + kfence_set_pool(kfence_pool); + } +#endif + } void mark_rodata_ro(void) diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 79dd201..61156d0 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -22,12 +22,11 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED bool can_set_direct_map(void) { /* - * rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be + * rodata_full and DEBUG_PAGEALLOC require linear map to be * mapped at page granularity, so that it is possible to * protect/unprotect single pages. */ - return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() || - IS_ENABLED(CONFIG_KFENCE); + return (rodata_enabled && rodata_full) || debug_pagealloc_enabled(); } static int change_page_range(pte_t *ptep, unsigned long addr, void *data) diff --git a/include/linux/kfence.h b/include/linux/kfence.h index 726857a..0252e74 100644 --- a/include/linux/kfence.h +++ b/include/linux/kfence.h @@ -61,7 +61,12 @@ static __always_inline bool is_kfence_address(const void *addr) /** * kfence_alloc_pool() - allocate the KFENCE pool via memblock */ -void __init kfence_alloc_pool(void); +phys_addr_t __init kfence_alloc_pool(void); + +/** + * kfence_set_pool() - KFENCE pool mapped and can be used + */ +void __init kfence_set_pool(phys_addr_t addr); /** * kfence_init() - perform KFENCE initialization at boot time @@ -223,7 +228,8 @@ bool __kfence_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *sla #else /* CONFIG_KFENCE */ static inline bool is_kfence_address(const void *addr) { return false; } -static inline void kfence_alloc_pool(void) { } +static inline phys_addr_t kfence_alloc_pool(void) { return (phys_addr_t)NULL; } +static inline void kfence_set_pool(phys_addr_t addr) { } static inline void kfence_init(void) { } static inline void kfence_shutdown_cache(struct kmem_cache *s) { } static inline void *kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) { return NULL; } diff --git a/init/main.c b/init/main.c index 4425d17..9aaf217 100644 --- a/init/main.c +++ b/init/main.c @@ -839,7 +839,6 @@ static void __init mm_init(void) */ page_ext_init_flatmem(); init_mem_debugging_and_hardening(); - kfence_alloc_pool(); report_meminit(); kmsan_init_shadow(); stack_depot_early_init(); diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 5349c37..dd5cdd5 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -809,15 +809,25 @@ static void toggle_allocation_gate(struct work_struct *work) /* === Public interface ===================================================== */ -void __init kfence_alloc_pool(void) +phys_addr_t __init kfence_alloc_pool(void) { + phys_addr_t kfence_pool; if (!kfence_sample_interval) - return; + return 0; - __kfence_pool = memblock_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); + kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); - if (!__kfence_pool) + if (!kfence_pool) { pr_err("failed to allocate pool\n"); + return 0; + } + + return kfence_pool; +} + +void __init kfence_set_pool(phys_addr_t addr) +{ + __kfence_pool = phys_to_virt(addr); } static void kfence_init_enable(void) -- 2.7.4
