diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/mips/kernel/vdso.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c new file mode 100644 index 000000000..9df3ebdc7 --- /dev/null +++ b/arch/mips/kernel/vdso.c @@ -0,0 +1,217 @@ +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Alex Smith <alex.smith@imgtec.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#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> + +/* Kernel-provided data used by the VDSO. */ +static union mips_vdso_data vdso_data __page_aligned_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); + +void update_vsyscall(struct timekeeper *tk) +{ + vdso_data_write_begin(&vdso_data); + + vdso_data.xtime_sec = tk->xtime_sec; + vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec; + vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec; + vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec; + vdso_data.cs_shift = tk->tkr_mono.shift; + + vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode; + if (vdso_data.clock_mode != VDSO_CLOCK_NONE) { + vdso_data.cs_mult = tk->tkr_mono.mult; + vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last; + vdso_data.cs_mask = tk->tkr_mono.mask; + } + + vdso_data_write_end(&vdso_data); +} + +void update_vsyscall_tz(void) +{ + if (vdso_data.clock_mode != VDSO_CLOCK_NONE) { + vdso_data.tz_minuteswest = sys_tz.tz_minuteswest; + vdso_data.tz_dsttime = sys_tz.tz_dsttime; + } +} + +static unsigned long vdso_base(void) +{ + unsigned long base; + + /* Skip the delay slot emulation page */ + base = STACK_TOP + PAGE_SIZE; + + if (current->flags & PF_RANDOMIZE) { + base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1); + 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; + struct vm_area_struct *vma; + int ret; + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + /* 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_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT; + + ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size, + pgprot_noncached(PAGE_READONLY)); + if (ret) + goto out; + } + + /* Map data page. */ + ret = remap_pfn_range(vma, data_addr, + virt_to_phys(&vdso_data) >> PAGE_SHIFT, + PAGE_SIZE, PAGE_READONLY); + 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: + up_write(&mm->mmap_sem); + return ret; +} |