diff options
Diffstat (limited to 'arch/mips/kernel/vdso.c')
| -rw-r--r-- | arch/mips/kernel/vdso.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c new file mode 100644 index 000000000..5fd9bf1d5 --- /dev/null +++ b/arch/mips/kernel/vdso.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Alex Smith <alex.smith@imgtec.com> + */ + +#include <linux/binfmts.h> +#include <linux/elf.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/ioport.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/random.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/timekeeper_internal.h> + +#include <asm/abi.h> +#include <asm/mips-cps.h> +#include <asm/page.h> +#include <asm/vdso.h> +#include <vdso/helpers.h> +#include <vdso/vsyscall.h> + +/* Kernel-provided data used by the VDSO. */ +static union mips_vdso_data mips_vdso_data __page_aligned_data; +struct vdso_data *vdso_data = mips_vdso_data.data; + +/* + * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as + * what we map and where within the area they are mapped is determined at + * runtime. + */ +static struct page *no_pages[] = { NULL }; +static struct vm_special_mapping vdso_vvar_mapping = { + .name = "[vvar]", + .pages = no_pages, +}; + +static void __init init_vdso_image(struct mips_vdso_image *image) +{ + unsigned long num_pages, i; + unsigned long data_pfn; + + BUG_ON(!PAGE_ALIGNED(image->data)); + BUG_ON(!PAGE_ALIGNED(image->size)); + + num_pages = image->size / PAGE_SIZE; + + data_pfn = __phys_to_pfn(__pa_symbol(image->data)); + for (i = 0; i < num_pages; i++) + image->mapping.pages[i] = pfn_to_page(data_pfn + i); +} + +static int __init init_vdso(void) +{ + init_vdso_image(&vdso_image); + +#ifdef CONFIG_MIPS32_O32 + init_vdso_image(&vdso_image_o32); +#endif + +#ifdef CONFIG_MIPS32_N32 + init_vdso_image(&vdso_image_n32); +#endif + + return 0; +} +subsys_initcall(init_vdso); + +static unsigned long vdso_base(void) +{ + unsigned long base = STACK_TOP; + + if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { + /* Skip the delay slot emulation page */ + base += PAGE_SIZE; + } + + if (current->flags & PF_RANDOMIZE) { + base += prandom_u32_max(VDSO_RANDOMIZE_SIZE); + base = PAGE_ALIGN(base); + } + + return base; +} + +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + struct mips_vdso_image *image = current->thread.abi->vdso; + struct mm_struct *mm = current->mm; + unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base; + struct vm_area_struct *vma; + int ret; + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { + /* Map delay slot emulation page */ + base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, + VM_READ | VM_EXEC | + VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, + 0, NULL); + if (IS_ERR_VALUE(base)) { + ret = base; + goto out; + } + } + + /* + * Determine total area size. This includes the VDSO data itself, the + * data page, and the GIC user page if present. Always create a mapping + * for the GIC user area if the GIC is present regardless of whether it + * is the current clocksource, in case it comes into use later on. We + * only map a page even though the total area is 64K, as we only need + * the counter registers at the start. + */ + gic_size = mips_gic_present() ? PAGE_SIZE : 0; + vvar_size = gic_size + PAGE_SIZE; + size = vvar_size + image->size; + + /* + * Find a region that's large enough for us to perform the + * colour-matching alignment below. + */ + if (cpu_has_dc_aliases) + size += shm_align_mask + 1; + + base = get_unmapped_area(NULL, vdso_base(), size, 0, 0); + if (IS_ERR_VALUE(base)) { + ret = base; + goto out; + } + + /* + * If we suffer from dcache aliasing, ensure that the VDSO data page + * mapping is coloured the same as the kernel's mapping of that memory. + * This ensures that when the kernel updates the VDSO data userland + * will observe it without requiring cache invalidations. + */ + if (cpu_has_dc_aliases) { + base = __ALIGN_MASK(base, shm_align_mask); + base += ((unsigned long)vdso_data - gic_size) & shm_align_mask; + } + + data_addr = base + gic_size; + vdso_addr = data_addr + PAGE_SIZE; + + vma = _install_special_mapping(mm, base, vvar_size, + VM_READ | VM_MAYREAD, + &vdso_vvar_mapping); + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); + goto out; + } + + /* Map GIC user page. */ + if (gic_size) { + gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS; + gic_pfn = PFN_DOWN(__pa(gic_base)); + + ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size, + pgprot_noncached(vma->vm_page_prot)); + if (ret) + goto out; + } + + /* Map data page. */ + ret = remap_pfn_range(vma, data_addr, + virt_to_phys(vdso_data) >> PAGE_SHIFT, + PAGE_SIZE, vma->vm_page_prot); + if (ret) + goto out; + + /* Map VDSO image. */ + vma = _install_special_mapping(mm, vdso_addr, image->size, + VM_READ | VM_EXEC | + VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, + &image->mapping); + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); + goto out; + } + + mm->context.vdso = (void *)vdso_addr; + ret = 0; + +out: + mmap_write_unlock(mm); + return ret; +} |