Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR Signed-off-by: Prasanna Karthik <mkarthi3@visteon.com> Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
336 lines
8.4 KiB
C
336 lines
8.4 KiB
C
/*
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* Adapted from arm64 version.
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*
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* Copyright (C) 2012 ARM Limited
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* Copyright (C) 2015 Mentor Graphics Corporation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/elf.h>
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/of.h>
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#include <linux/printk.h>
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#include <linux/slab.h>
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#include <linux/timekeeper_internal.h>
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#include <linux/vmalloc.h>
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#include <asm/arch_timer.h>
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#include <asm/barrier.h>
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#include <asm/cacheflush.h>
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#include <asm/page.h>
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#include <asm/vdso.h>
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#include <asm/vdso_datapage.h>
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#include <clocksource/arm_arch_timer.h>
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#define MAX_SYMNAME 64
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static struct page **vdso_text_pagelist;
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/* Total number of pages needed for the data and text portions of the VDSO. */
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unsigned int vdso_total_pages __read_mostly;
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/*
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* The VDSO data page.
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*/
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static union vdso_data_store vdso_data_store __page_aligned_data;
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static struct vdso_data *vdso_data = &vdso_data_store.data;
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static struct page *vdso_data_page;
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static struct vm_special_mapping vdso_data_mapping = {
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.name = "[vvar]",
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.pages = &vdso_data_page,
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};
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static struct vm_special_mapping vdso_text_mapping = {
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.name = "[vdso]",
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};
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struct elfinfo {
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Elf32_Ehdr *hdr; /* ptr to ELF */
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Elf32_Sym *dynsym; /* ptr to .dynsym section */
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unsigned long dynsymsize; /* size of .dynsym section */
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char *dynstr; /* ptr to .dynstr section */
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};
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/* Cached result of boot-time check for whether the arch timer exists,
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* and if so, whether the virtual counter is useable.
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*/
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static bool cntvct_ok __read_mostly;
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static bool __init cntvct_functional(void)
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{
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struct device_node *np;
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bool ret = false;
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if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
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goto out;
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/* The arm_arch_timer core should export
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* arch_timer_use_virtual or similar so we don't have to do
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* this.
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*/
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np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
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if (!np)
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goto out_put;
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if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
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goto out_put;
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ret = true;
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out_put:
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of_node_put(np);
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out:
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return ret;
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}
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static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,
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unsigned long *size)
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{
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Elf32_Shdr *sechdrs;
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unsigned int i;
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char *secnames;
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/* Grab section headers and strings so we can tell who is who */
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sechdrs = (void *)ehdr + ehdr->e_shoff;
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secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
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/* Find the section they want */
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for (i = 1; i < ehdr->e_shnum; i++) {
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if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {
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if (size)
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*size = sechdrs[i].sh_size;
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return (void *)ehdr + sechdrs[i].sh_offset;
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}
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}
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if (size)
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*size = 0;
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return NULL;
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}
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static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
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{
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unsigned int i;
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for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
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char name[MAX_SYMNAME], *c;
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if (lib->dynsym[i].st_name == 0)
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continue;
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strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
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MAX_SYMNAME);
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c = strchr(name, '@');
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if (c)
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*c = 0;
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if (strcmp(symname, name) == 0)
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return &lib->dynsym[i];
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}
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return NULL;
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}
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static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname)
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{
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Elf32_Sym *sym;
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sym = find_symbol(lib, symname);
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if (!sym)
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return;
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sym->st_name = 0;
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}
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static void __init patch_vdso(void *ehdr)
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{
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struct elfinfo einfo;
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einfo = (struct elfinfo) {
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.hdr = ehdr,
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};
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einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);
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einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL);
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/* If the virtual counter is absent or non-functional we don't
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* want programs to incur the slight additional overhead of
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* dispatching through the VDSO only to fall back to syscalls.
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*/
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if (!cntvct_ok) {
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vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
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vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
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}
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}
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static int __init vdso_init(void)
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{
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unsigned int text_pages;
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int i;
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if (memcmp(&vdso_start, "\177ELF", 4)) {
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pr_err("VDSO is not a valid ELF object!\n");
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return -ENOEXEC;
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}
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text_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
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pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
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/* Allocate the VDSO text pagelist */
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vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
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GFP_KERNEL);
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if (vdso_text_pagelist == NULL)
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return -ENOMEM;
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/* Grab the VDSO data page. */
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vdso_data_page = virt_to_page(vdso_data);
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/* Grab the VDSO text pages. */
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for (i = 0; i < text_pages; i++) {
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struct page *page;
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page = virt_to_page(&vdso_start + i * PAGE_SIZE);
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vdso_text_pagelist[i] = page;
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}
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vdso_text_mapping.pages = vdso_text_pagelist;
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vdso_total_pages = 1; /* for the data/vvar page */
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vdso_total_pages += text_pages;
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cntvct_ok = cntvct_functional();
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patch_vdso(&vdso_start);
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return 0;
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}
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arch_initcall(vdso_init);
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static int install_vvar(struct mm_struct *mm, unsigned long addr)
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{
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struct vm_area_struct *vma;
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vma = _install_special_mapping(mm, addr, PAGE_SIZE,
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VM_READ | VM_MAYREAD,
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&vdso_data_mapping);
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return PTR_ERR_OR_ZERO(vma);
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}
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/* assumes mmap_sem is write-locked */
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void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
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{
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struct vm_area_struct *vma;
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unsigned long len;
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mm->context.vdso = 0;
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if (vdso_text_pagelist == NULL)
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return;
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if (install_vvar(mm, addr))
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return;
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/* Account for vvar page. */
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addr += PAGE_SIZE;
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len = (vdso_total_pages - 1) << PAGE_SHIFT;
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vma = _install_special_mapping(mm, addr, len,
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VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
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&vdso_text_mapping);
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if (!IS_ERR(vma))
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mm->context.vdso = addr;
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}
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static void vdso_write_begin(struct vdso_data *vdata)
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{
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++vdso_data->seq_count;
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smp_wmb(); /* Pairs with smp_rmb in vdso_read_retry */
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}
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static void vdso_write_end(struct vdso_data *vdata)
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{
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smp_wmb(); /* Pairs with smp_rmb in vdso_read_begin */
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++vdso_data->seq_count;
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}
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static bool tk_is_cntvct(const struct timekeeper *tk)
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{
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if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
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return false;
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if (strcmp(tk->tkr_mono.clock->name, "arch_sys_counter") != 0)
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return false;
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return true;
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}
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/**
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* update_vsyscall - update the vdso data page
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*
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* Increment the sequence counter, making it odd, indicating to
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* userspace that an update is in progress. Update the fields used
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* for coarse clocks and, if the architected system timer is in use,
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* the fields used for high precision clocks. Increment the sequence
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* counter again, making it even, indicating to userspace that the
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* update is finished.
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*
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* Userspace is expected to sample seq_count before reading any other
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* fields from the data page. If seq_count is odd, userspace is
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* expected to wait until it becomes even. After copying data from
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* the page, userspace must sample seq_count again; if it has changed
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* from its previous value, userspace must retry the whole sequence.
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*
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* Calls to update_vsyscall are serialized by the timekeeping core.
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*/
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void update_vsyscall(struct timekeeper *tk)
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{
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struct timespec64 *wtm = &tk->wall_to_monotonic;
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if (!cntvct_ok) {
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/* The entry points have been zeroed, so there is no
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* point in updating the data page.
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*/
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return;
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}
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vdso_write_begin(vdso_data);
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vdso_data->tk_is_cntvct = tk_is_cntvct(tk);
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vdso_data->xtime_coarse_sec = tk->xtime_sec;
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vdso_data->xtime_coarse_nsec = (u32)(tk->tkr_mono.xtime_nsec >>
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tk->tkr_mono.shift);
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vdso_data->wtm_clock_sec = wtm->tv_sec;
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vdso_data->wtm_clock_nsec = wtm->tv_nsec;
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if (vdso_data->tk_is_cntvct) {
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vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
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vdso_data->xtime_clock_sec = tk->xtime_sec;
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vdso_data->xtime_clock_snsec = tk->tkr_mono.xtime_nsec;
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vdso_data->cs_mult = tk->tkr_mono.mult;
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vdso_data->cs_shift = tk->tkr_mono.shift;
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vdso_data->cs_mask = tk->tkr_mono.mask;
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}
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vdso_write_end(vdso_data);
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flush_dcache_page(virt_to_page(vdso_data));
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}
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void update_vsyscall_tz(void)
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{
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vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
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vdso_data->tz_dsttime = sys_tz.tz_dsttime;
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flush_dcache_page(virt_to_page(vdso_data));
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}
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