![Dmitry Safonov](/assets/img/avatar_default.png)
The result of in_compat_syscall() can be pictured as:
x86 platform:
---------------------------------------------------
| Arch\syscall | 64-bit | ia32 | x32 |
|-------------------------------------------------|
| x86_64 | false | true | true |
|-------------------------------------------------|
| i686 | | <true> | |
---------------------------------------------------
Other platforms:
-------------------------------------------
| Arch\syscall | 64-bit | compat |
|-----------------------------------------|
| 64-bit | false | true |
|-----------------------------------------|
| 32-bit(?) | | <false> |
-------------------------------------------
As seen, the result of in_compat_syscall() on generic 32-bit platform
differs from i686.
There is no reason for in_compat_syscall() == true on native i686. It also
easy to misread code if the result on native 32-bit platform differs
between arches.
Because of that non arch-specific code has many places with:
if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
in different variations.
It looks-like the only non-x86 code which uses in_compat_syscall() not
under CONFIG_COMPAT guard is in amd/amdkfd. But according to the commit
a18069c132
("amdkfd: Disable support for 32-bit user processes"), it
actually should be disabled on native i686.
Rename in_compat_syscall() to in_32bit_syscall() for x86-specific code
and make in_compat_syscall() false under !CONFIG_COMPAT.
A follow on patch will clean up generic users which were forced to check
IS_ENABLED(CONFIG_COMPAT) with in_compat_syscall().
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-efi@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: https://lkml.kernel.org/r/20181012134253.23266-2-dima@arista.com
217 lines
5.2 KiB
C
217 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* IA-32 Huge TLB Page Support for Kernel.
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*
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* Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
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*/
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/sched/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/err.h>
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#include <linux/sysctl.h>
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#include <linux/compat.h>
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#include <asm/mman.h>
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#include <asm/tlb.h>
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#include <asm/tlbflush.h>
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#include <asm/pgalloc.h>
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#include <asm/elf.h>
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#include <asm/mpx.h>
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#if 0 /* This is just for testing */
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struct page *
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follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
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{
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unsigned long start = address;
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int length = 1;
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int nr;
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struct page *page;
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struct vm_area_struct *vma;
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vma = find_vma(mm, addr);
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if (!vma || !is_vm_hugetlb_page(vma))
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return ERR_PTR(-EINVAL);
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pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
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/* hugetlb should be locked, and hence, prefaulted */
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WARN_ON(!pte || pte_none(*pte));
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page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
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WARN_ON(!PageHead(page));
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return page;
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}
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int pmd_huge(pmd_t pmd)
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{
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return 0;
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}
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int pud_huge(pud_t pud)
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{
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return 0;
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}
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#else
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/*
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* pmd_huge() returns 1 if @pmd is hugetlb related entry, that is normal
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* hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry.
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* Otherwise, returns 0.
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*/
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int pmd_huge(pmd_t pmd)
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{
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return !pmd_none(pmd) &&
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(pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT;
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}
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int pud_huge(pud_t pud)
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{
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return !!(pud_val(pud) & _PAGE_PSE);
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}
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#endif
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#ifdef CONFIG_HUGETLB_PAGE
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static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
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unsigned long addr, unsigned long len,
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unsigned long pgoff, unsigned long flags)
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{
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struct hstate *h = hstate_file(file);
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struct vm_unmapped_area_info info;
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info.flags = 0;
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info.length = len;
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info.low_limit = get_mmap_base(1);
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/*
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* If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
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* in the full address space.
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*/
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info.high_limit = in_32bit_syscall() ?
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task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);
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info.align_mask = PAGE_MASK & ~huge_page_mask(h);
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info.align_offset = 0;
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return vm_unmapped_area(&info);
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}
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static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
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unsigned long addr, unsigned long len,
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unsigned long pgoff, unsigned long flags)
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{
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struct hstate *h = hstate_file(file);
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struct vm_unmapped_area_info info;
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info.flags = VM_UNMAPPED_AREA_TOPDOWN;
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info.length = len;
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info.low_limit = PAGE_SIZE;
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info.high_limit = get_mmap_base(0);
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/*
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* If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
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* in the full address space.
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*/
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if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
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info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
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info.align_mask = PAGE_MASK & ~huge_page_mask(h);
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info.align_offset = 0;
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addr = vm_unmapped_area(&info);
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/*
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* A failed mmap() very likely causes application failure,
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* so fall back to the bottom-up function here. This scenario
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* can happen with large stack limits and large mmap()
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* allocations.
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*/
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if (addr & ~PAGE_MASK) {
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VM_BUG_ON(addr != -ENOMEM);
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info.flags = 0;
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info.low_limit = TASK_UNMAPPED_BASE;
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info.high_limit = TASK_SIZE_LOW;
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addr = vm_unmapped_area(&info);
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}
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return addr;
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}
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unsigned long
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hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
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unsigned long len, unsigned long pgoff, unsigned long flags)
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{
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struct hstate *h = hstate_file(file);
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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if (len & ~huge_page_mask(h))
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return -EINVAL;
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addr = mpx_unmapped_area_check(addr, len, flags);
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if (IS_ERR_VALUE(addr))
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return addr;
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if (len > TASK_SIZE)
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return -ENOMEM;
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/* No address checking. See comment at mmap_address_hint_valid() */
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if (flags & MAP_FIXED) {
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if (prepare_hugepage_range(file, addr, len))
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return -EINVAL;
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return addr;
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}
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if (addr) {
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addr &= huge_page_mask(h);
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if (!mmap_address_hint_valid(addr, len))
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goto get_unmapped_area;
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vma = find_vma(mm, addr);
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if (!vma || addr + len <= vm_start_gap(vma))
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return addr;
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}
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get_unmapped_area:
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if (mm->get_unmapped_area == arch_get_unmapped_area)
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return hugetlb_get_unmapped_area_bottomup(file, addr, len,
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pgoff, flags);
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else
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return hugetlb_get_unmapped_area_topdown(file, addr, len,
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pgoff, flags);
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}
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#endif /* CONFIG_HUGETLB_PAGE */
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#ifdef CONFIG_X86_64
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static __init int setup_hugepagesz(char *opt)
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{
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unsigned long ps = memparse(opt, &opt);
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if (ps == PMD_SIZE) {
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hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
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} else if (ps == PUD_SIZE && boot_cpu_has(X86_FEATURE_GBPAGES)) {
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hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
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} else {
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hugetlb_bad_size();
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printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
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ps >> 20);
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return 0;
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}
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return 1;
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}
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__setup("hugepagesz=", setup_hugepagesz);
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#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
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static __init int gigantic_pages_init(void)
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{
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/* With compaction or CMA we can allocate gigantic pages at runtime */
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if (boot_cpu_has(X86_FEATURE_GBPAGES) && !size_to_hstate(1UL << PUD_SHIFT))
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hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
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return 0;
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}
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arch_initcall(gigantic_pages_init);
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#endif
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#endif
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