The following commit has been merged into the x86/mm branch of tip: Commit-ID: 186525bd6b83efc592672e2d6185e4d7c810d2b4 Gitweb: https://git.kernel.org/tip/186525bd6b83efc592672e2d6185e4d7c810d2b4 Author: Ingo Molnar <mingo@xxxxxxxxxx> AuthorDate: Fri, 29 Nov 2019 08:17:25 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 10 Dec 2019 10:12:55 +01:00 mm, x86/mm: Untangle address space layout definitions from basic pgtable type definitions - Untangle the somewhat incestous way of how VMALLOC_START is used all across the kernel, but is, on x86, defined deep inside one of the lowest level page table headers. It doesn't help that vmalloc.h only includes a single asm header: #include <asm/page.h> /* pgprot_t */ So there was no existing cross-arch way to decouple address layout definitions from page.h details. I used this: #ifndef VMALLOC_START # include <asm/vmalloc.h> #endif This way every architecture that wants to simplify page.h can do so. - Also on x86 we had a couple of LDT related inline functions that used the late-stage address space layout positions - but these could be uninlined without real trouble - the end result is cleaner this way as well. Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/include/asm/cpu_entry_area.h | 10 +--- arch/x86/include/asm/mmu_context.h | 86 +----------------------- arch/x86/include/asm/pgtable_32_areas.h | 53 +++++++++++++++- arch/x86/include/asm/pgtable_32_types.h | 57 +---------------- arch/x86/include/asm/pgtable_areas.h | 16 ++++- arch/x86/include/asm/vmalloc.h | 2 +- arch/x86/kernel/ldt.c | 83 +++++++++++++++++++++++- arch/x86/kernel/setup.c | 1 +- arch/x86/mm/fault.c | 1 +- arch/x86/mm/init_32.c | 1 +- arch/x86/mm/pgtable_32.c | 1 +- arch/x86/mm/physaddr.c | 1 +- include/linux/mm.h | 15 +--- mm/highmem.c | 2 +- mm/vmalloc.c | 8 ++- 15 files changed, 183 insertions(+), 154 deletions(-) create mode 100644 arch/x86/include/asm/pgtable_32_areas.h create mode 100644 arch/x86/include/asm/pgtable_areas.h diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h index 8047340..02c0078 100644 --- a/arch/x86/include/asm/cpu_entry_area.h +++ b/arch/x86/include/asm/cpu_entry_area.h @@ -6,6 +6,7 @@ #include <linux/percpu-defs.h> #include <asm/processor.h> #include <asm/intel_ds.h> +#include <asm/pgtable_areas.h> #ifdef CONFIG_X86_64 @@ -134,15 +135,6 @@ DECLARE_PER_CPU(struct cea_exception_stacks *, cea_exception_stacks); extern void setup_cpu_entry_areas(void); extern void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags); -/* Single page reserved for the readonly IDT mapping: */ -#define CPU_ENTRY_AREA_RO_IDT CPU_ENTRY_AREA_BASE -#define CPU_ENTRY_AREA_PER_CPU (CPU_ENTRY_AREA_RO_IDT + PAGE_SIZE) - -#define CPU_ENTRY_AREA_RO_IDT_VADDR ((void *)CPU_ENTRY_AREA_RO_IDT) - -#define CPU_ENTRY_AREA_MAP_SIZE \ - (CPU_ENTRY_AREA_PER_CPU + CPU_ENTRY_AREA_ARRAY_SIZE - CPU_ENTRY_AREA_BASE) - extern struct cpu_entry_area *get_cpu_entry_area(int cpu); static inline struct entry_stack *cpu_entry_stack(int cpu) diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 5f33924..b243234 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -69,14 +69,6 @@ struct ldt_struct { int slot; }; -/* This is a multiple of PAGE_SIZE. */ -#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE) - -static inline void *ldt_slot_va(int slot) -{ - return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot); -} - /* * Used for LDT copy/destruction. */ @@ -99,87 +91,21 @@ static inline void destroy_context_ldt(struct mm_struct *mm) { } static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { } #endif -static inline void load_mm_ldt(struct mm_struct *mm) -{ #ifdef CONFIG_MODIFY_LDT_SYSCALL - struct ldt_struct *ldt; - - /* READ_ONCE synchronizes with smp_store_release */ - ldt = READ_ONCE(mm->context.ldt); - - /* - * Any change to mm->context.ldt is followed by an IPI to all - * CPUs with the mm active. The LDT will not be freed until - * after the IPI is handled by all such CPUs. This means that, - * if the ldt_struct changes before we return, the values we see - * will be safe, and the new values will be loaded before we run - * any user code. - * - * NB: don't try to convert this to use RCU without extreme care. - * We would still need IRQs off, because we don't want to change - * the local LDT after an IPI loaded a newer value than the one - * that we can see. - */ - - if (unlikely(ldt)) { - if (static_cpu_has(X86_FEATURE_PTI)) { - if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) { - /* - * Whoops -- either the new LDT isn't mapped - * (if slot == -1) or is mapped into a bogus - * slot (if slot > 1). - */ - clear_LDT(); - return; - } - - /* - * If page table isolation is enabled, ldt->entries - * will not be mapped in the userspace pagetables. - * Tell the CPU to access the LDT through the alias - * at ldt_slot_va(ldt->slot). - */ - set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries); - } else { - set_ldt(ldt->entries, ldt->nr_entries); - } - } else { - clear_LDT(); - } +extern void load_mm_ldt(struct mm_struct *mm); +extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next); #else +static inline void load_mm_ldt(struct mm_struct *mm) +{ clear_LDT(); -#endif } - static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next) { -#ifdef CONFIG_MODIFY_LDT_SYSCALL - /* - * Load the LDT if either the old or new mm had an LDT. - * - * An mm will never go from having an LDT to not having an LDT. Two - * mms never share an LDT, so we don't gain anything by checking to - * see whether the LDT changed. There's also no guarantee that - * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL, - * then prev->context.ldt will also be non-NULL. - * - * If we really cared, we could optimize the case where prev == next - * and we're exiting lazy mode. Most of the time, if this happens, - * we don't actually need to reload LDTR, but modify_ldt() is mostly - * used by legacy code and emulators where we don't need this level of - * performance. - * - * This uses | instead of || because it generates better code. - */ - if (unlikely((unsigned long)prev->context.ldt | - (unsigned long)next->context.ldt)) - load_mm_ldt(next); -#endif - DEBUG_LOCKS_WARN_ON(preemptible()); } +#endif -void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk); +extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk); /* * Init a new mm. Used on mm copies, like at fork() diff --git a/arch/x86/include/asm/pgtable_32_areas.h b/arch/x86/include/asm/pgtable_32_areas.h new file mode 100644 index 0000000..b635541 --- /dev/null +++ b/arch/x86/include/asm/pgtable_32_areas.h @@ -0,0 +1,53 @@ +#ifndef _ASM_X86_PGTABLE_32_AREAS_H +#define _ASM_X86_PGTABLE_32_AREAS_H + +#include <asm/cpu_entry_area.h> + +/* + * Just any arbitrary offset to the start of the vmalloc VM area: the + * current 8MB value just means that there will be a 8MB "hole" after the + * physical memory until the kernel virtual memory starts. That means that + * any out-of-bounds memory accesses will hopefully be caught. + * The vmalloc() routines leaves a hole of 4kB between each vmalloced + * area for the same reason. ;) + */ +#define VMALLOC_OFFSET (8 * 1024 * 1024) + +#ifndef __ASSEMBLY__ +extern bool __vmalloc_start_set; /* set once high_memory is set */ +#endif + +#define VMALLOC_START ((unsigned long)high_memory + VMALLOC_OFFSET) +#ifdef CONFIG_X86_PAE +#define LAST_PKMAP 512 +#else +#define LAST_PKMAP 1024 +#endif + +#define CPU_ENTRY_AREA_PAGES (NR_CPUS * DIV_ROUND_UP(sizeof(struct cpu_entry_area), PAGE_SIZE)) + +/* The +1 is for the readonly IDT page: */ +#define CPU_ENTRY_AREA_BASE \ + ((FIXADDR_TOT_START - PAGE_SIZE*(CPU_ENTRY_AREA_PAGES+1)) & PMD_MASK) + +#define LDT_BASE_ADDR \ + ((CPU_ENTRY_AREA_BASE - PAGE_SIZE) & PMD_MASK) + +#define LDT_END_ADDR (LDT_BASE_ADDR + PMD_SIZE) + +#define PKMAP_BASE \ + ((LDT_BASE_ADDR - PAGE_SIZE) & PMD_MASK) + +#ifdef CONFIG_HIGHMEM +# define VMALLOC_END (PKMAP_BASE - 2 * PAGE_SIZE) +#else +# define VMALLOC_END (LDT_BASE_ADDR - 2 * PAGE_SIZE) +#endif + +#define MODULES_VADDR VMALLOC_START +#define MODULES_END VMALLOC_END +#define MODULES_LEN (MODULES_VADDR - MODULES_END) + +#define MAXMEM (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE) + +#endif /* _ASM_X86_PGTABLE_32_AREAS_H */ diff --git a/arch/x86/include/asm/pgtable_32_types.h b/arch/x86/include/asm/pgtable_32_types.h index 0416d42..5356a46 100644 --- a/arch/x86/include/asm/pgtable_32_types.h +++ b/arch/x86/include/asm/pgtable_32_types.h @@ -1,6 +1,6 @@ /* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _ASM_X86_PGTABLE_32_DEFS_H -#define _ASM_X86_PGTABLE_32_DEFS_H +#ifndef _ASM_X86_PGTABLE_32_TYPES_H +#define _ASM_X86_PGTABLE_32_TYPES_H /* * The Linux x86 paging architecture is 'compile-time dual-mode', it @@ -20,55 +20,4 @@ #define PGDIR_SIZE (1UL << PGDIR_SHIFT) #define PGDIR_MASK (~(PGDIR_SIZE - 1)) -/* Just any arbitrary offset to the start of the vmalloc VM area: the - * current 8MB value just means that there will be a 8MB "hole" after the - * physical memory until the kernel virtual memory starts. That means that - * any out-of-bounds memory accesses will hopefully be caught. - * The vmalloc() routines leaves a hole of 4kB between each vmalloced - * area for the same reason. ;) - */ -#define VMALLOC_OFFSET (8 * 1024 * 1024) - -#ifndef __ASSEMBLY__ -extern bool __vmalloc_start_set; /* set once high_memory is set */ -#endif - -#define VMALLOC_START ((unsigned long)high_memory + VMALLOC_OFFSET) -#ifdef CONFIG_X86_PAE -#define LAST_PKMAP 512 -#else -#define LAST_PKMAP 1024 -#endif - -/* - * This is an upper bound on sizeof(struct cpu_entry_area) / PAGE_SIZE. - * Define this here and validate with BUILD_BUG_ON() in cpu_entry_area.c - * to avoid include recursion hell. - */ -#define CPU_ENTRY_AREA_PAGES (NR_CPUS * 43) - -/* The +1 is for the readonly IDT page: */ -#define CPU_ENTRY_AREA_BASE \ - ((FIXADDR_TOT_START - PAGE_SIZE*(CPU_ENTRY_AREA_PAGES+1)) & PMD_MASK) - -#define LDT_BASE_ADDR \ - ((CPU_ENTRY_AREA_BASE - PAGE_SIZE) & PMD_MASK) - -#define LDT_END_ADDR (LDT_BASE_ADDR + PMD_SIZE) - -#define PKMAP_BASE \ - ((LDT_BASE_ADDR - PAGE_SIZE) & PMD_MASK) - -#ifdef CONFIG_HIGHMEM -# define VMALLOC_END (PKMAP_BASE - 2 * PAGE_SIZE) -#else -# define VMALLOC_END (LDT_BASE_ADDR - 2 * PAGE_SIZE) -#endif - -#define MODULES_VADDR VMALLOC_START -#define MODULES_END VMALLOC_END -#define MODULES_LEN (MODULES_VADDR - MODULES_END) - -#define MAXMEM (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE) - -#endif /* _ASM_X86_PGTABLE_32_DEFS_H */ +#endif /* _ASM_X86_PGTABLE_32_TYPES_H */ diff --git a/arch/x86/include/asm/pgtable_areas.h b/arch/x86/include/asm/pgtable_areas.h new file mode 100644 index 0000000..d34cce1 --- /dev/null +++ b/arch/x86/include/asm/pgtable_areas.h @@ -0,0 +1,16 @@ +#ifndef _ASM_X86_PGTABLE_AREAS_H +#define _ASM_X86_PGTABLE_AREAS_H + +#ifdef CONFIG_X86_32 +# include <asm/pgtable_32_areas.h> +#endif + +/* Single page reserved for the readonly IDT mapping: */ +#define CPU_ENTRY_AREA_RO_IDT CPU_ENTRY_AREA_BASE +#define CPU_ENTRY_AREA_PER_CPU (CPU_ENTRY_AREA_RO_IDT + PAGE_SIZE) + +#define CPU_ENTRY_AREA_RO_IDT_VADDR ((void *)CPU_ENTRY_AREA_RO_IDT) + +#define CPU_ENTRY_AREA_MAP_SIZE (CPU_ENTRY_AREA_PER_CPU + CPU_ENTRY_AREA_ARRAY_SIZE - CPU_ENTRY_AREA_BASE) + +#endif /* _ASM_X86_PGTABLE_AREAS_H */ diff --git a/arch/x86/include/asm/vmalloc.h b/arch/x86/include/asm/vmalloc.h index ba6295f..2983774 100644 --- a/arch/x86/include/asm/vmalloc.h +++ b/arch/x86/include/asm/vmalloc.h @@ -1,4 +1,6 @@ #ifndef _ASM_X86_VMALLOC_H #define _ASM_X86_VMALLOC_H +#include <asm/pgtable_areas.h> + #endif /* _ASM_X86_VMALLOC_H */ diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index b2463fc..c57e1ca 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -28,6 +28,89 @@ #include <asm/desc.h> #include <asm/mmu_context.h> #include <asm/syscalls.h> +#include <asm/pgtable_areas.h> + +/* This is a multiple of PAGE_SIZE. */ +#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE) + +static inline void *ldt_slot_va(int slot) +{ + return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot); +} + +void load_mm_ldt(struct mm_struct *mm) +{ + struct ldt_struct *ldt; + + /* READ_ONCE synchronizes with smp_store_release */ + ldt = READ_ONCE(mm->context.ldt); + + /* + * Any change to mm->context.ldt is followed by an IPI to all + * CPUs with the mm active. The LDT will not be freed until + * after the IPI is handled by all such CPUs. This means that, + * if the ldt_struct changes before we return, the values we see + * will be safe, and the new values will be loaded before we run + * any user code. + * + * NB: don't try to convert this to use RCU without extreme care. + * We would still need IRQs off, because we don't want to change + * the local LDT after an IPI loaded a newer value than the one + * that we can see. + */ + + if (unlikely(ldt)) { + if (static_cpu_has(X86_FEATURE_PTI)) { + if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) { + /* + * Whoops -- either the new LDT isn't mapped + * (if slot == -1) or is mapped into a bogus + * slot (if slot > 1). + */ + clear_LDT(); + return; + } + + /* + * If page table isolation is enabled, ldt->entries + * will not be mapped in the userspace pagetables. + * Tell the CPU to access the LDT through the alias + * at ldt_slot_va(ldt->slot). + */ + set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries); + } else { + set_ldt(ldt->entries, ldt->nr_entries); + } + } else { + clear_LDT(); + } +} + +void switch_ldt(struct mm_struct *prev, struct mm_struct *next) +{ + /* + * Load the LDT if either the old or new mm had an LDT. + * + * An mm will never go from having an LDT to not having an LDT. Two + * mms never share an LDT, so we don't gain anything by checking to + * see whether the LDT changed. There's also no guarantee that + * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL, + * then prev->context.ldt will also be non-NULL. + * + * If we really cared, we could optimize the case where prev == next + * and we're exiting lazy mode. Most of the time, if this happens, + * we don't actually need to reload LDTR, but modify_ldt() is mostly + * used by legacy code and emulators where we don't need this level of + * performance. + * + * This uses | instead of || because it generates better code. + */ + if (unlikely((unsigned long)prev->context.ldt | + (unsigned long)next->context.ldt)) + load_mm_ldt(next); + + DEBUG_LOCKS_WARN_ON(preemptible()); +} static void refresh_ldt_segments(void) { diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index b5ac993..90296a0 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -41,6 +41,7 @@ #include <asm/proto.h> #include <asm/unwind.h> #include <asm/vsyscall.h> +#include <linux/vmalloc.h> /* * max_low_pfn_mapped: highest directly mapped pfn < 4 GB diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 304d31d..c9c8523 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -29,6 +29,7 @@ #include <asm/efi.h> /* efi_recover_from_page_fault()*/ #include <asm/desc.h> /* store_idt(), ... */ #include <asm/cpu_entry_area.h> /* exception stack */ +#include <asm/pgtable_areas.h> /* VMALLOC_START, ... */ #define CREATE_TRACE_POINTS #include <asm/trace/exceptions.h> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index 930edeb..16274a3 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -52,6 +52,7 @@ #include <asm/page_types.h> #include <asm/cpu_entry_area.h> #include <asm/init.h> +#include <asm/pgtable_areas.h> #include "mm_internal.h" diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c index 9bb7f0a..0e6700e 100644 --- a/arch/x86/mm/pgtable_32.c +++ b/arch/x86/mm/pgtable_32.c @@ -18,6 +18,7 @@ #include <asm/tlb.h> #include <asm/tlbflush.h> #include <asm/io.h> +#include <linux/vmalloc.h> unsigned int __VMALLOC_RESERVE = 128 << 20; diff --git a/arch/x86/mm/physaddr.c b/arch/x86/mm/physaddr.c index bdc9815..fc3f3d3 100644 --- a/arch/x86/mm/physaddr.c +++ b/arch/x86/mm/physaddr.c @@ -5,6 +5,7 @@ #include <linux/mm.h> #include <asm/page.h> +#include <linux/vmalloc.h> #include "physaddr.h" diff --git a/include/linux/mm.h b/include/linux/mm.h index c97ea3b..fb8f941 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -625,24 +625,19 @@ unsigned long vmalloc_to_pfn(const void *addr); * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there * is no special casing required. */ -static inline bool is_vmalloc_addr(const void *x) -{ -#ifdef CONFIG_MMU - unsigned long addr = (unsigned long)x; - - return addr >= VMALLOC_START && addr < VMALLOC_END; -#else - return false; -#endif -} #ifndef is_ioremap_addr #define is_ioremap_addr(x) is_vmalloc_addr(x) #endif #ifdef CONFIG_MMU +extern bool is_vmalloc_addr(const void *x); extern int is_vmalloc_or_module_addr(const void *x); #else +static inline bool is_vmalloc_addr(const void *x) +{ + return false; +} static inline int is_vmalloc_or_module_addr(const void *x) { return 0; diff --git a/mm/highmem.c b/mm/highmem.c index 107b10f..64d8dea 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -29,7 +29,7 @@ #include <linux/highmem.h> #include <linux/kgdb.h> #include <asm/tlbflush.h> - +#include <linux/vmalloc.h> #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32) DEFINE_PER_CPU(int, __kmap_atomic_idx); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 4d3b3d6..19cdbb1 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -41,6 +41,14 @@ #include "internal.h" +bool is_vmalloc_addr(const void *x) +{ + unsigned long addr = (unsigned long)x; + + return addr >= VMALLOC_START && addr < VMALLOC_END; +} +EXPORT_SYMBOL(is_vmalloc_addr); + struct vfree_deferred { struct llist_head list; struct work_struct wq;
