From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/arm/kernel/vdso.c | 260 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 260 insertions(+) create mode 100644 arch/arm/kernel/vdso.c (limited to 'arch/arm/kernel/vdso.c') diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c new file mode 100644 index 000000000..3408269d1 --- /dev/null +++ b/arch/arm/kernel/vdso.c @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Adapted from arm64 version. + * + * Copyright (C) 2012 ARM Limited + * Copyright (C) 2015 Mentor Graphics Corporation. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define MAX_SYMNAME 64 + +static struct page **vdso_text_pagelist; + +extern char vdso_start[], vdso_end[]; + +/* Total number of pages needed for the data and text portions of the VDSO. */ +unsigned int vdso_total_pages __ro_after_init; + +/* + * The VDSO data page. + */ +static union vdso_data_store vdso_data_store __page_aligned_data; +struct vdso_data *vdso_data = vdso_data_store.data; + +static struct page *vdso_data_page __ro_after_init; +static const struct vm_special_mapping vdso_data_mapping = { + .name = "[vvar]", + .pages = &vdso_data_page, +}; + +static int vdso_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) +{ + current->mm->context.vdso = new_vma->vm_start; + + return 0; +} + +static struct vm_special_mapping vdso_text_mapping __ro_after_init = { + .name = "[vdso]", + .mremap = vdso_mremap, +}; + +struct elfinfo { + Elf32_Ehdr *hdr; /* ptr to ELF */ + Elf32_Sym *dynsym; /* ptr to .dynsym section */ + unsigned long dynsymsize; /* size of .dynsym section */ + char *dynstr; /* ptr to .dynstr section */ +}; + +/* Cached result of boot-time check for whether the arch timer exists, + * and if so, whether the virtual counter is useable. + */ +bool cntvct_ok __ro_after_init; + +static bool __init cntvct_functional(void) +{ + struct device_node *np; + bool ret = false; + + if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER)) + goto out; + + /* The arm_arch_timer core should export + * arch_timer_use_virtual or similar so we don't have to do + * this. + */ + np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer"); + if (!np) + np = of_find_compatible_node(NULL, NULL, "arm,armv8-timer"); + if (!np) + goto out_put; + + if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured")) + goto out_put; + + ret = true; + +out_put: + of_node_put(np); +out: + return ret; +} + +static void * __init find_section(Elf32_Ehdr *ehdr, const char *name, + unsigned long *size) +{ + Elf32_Shdr *sechdrs; + unsigned int i; + char *secnames; + + /* Grab section headers and strings so we can tell who is who */ + sechdrs = (void *)ehdr + ehdr->e_shoff; + secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset; + + /* Find the section they want */ + for (i = 1; i < ehdr->e_shnum; i++) { + if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) { + if (size) + *size = sechdrs[i].sh_size; + return (void *)ehdr + sechdrs[i].sh_offset; + } + } + + if (size) + *size = 0; + return NULL; +} + +static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname) +{ + unsigned int i; + + for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) { + char name[MAX_SYMNAME], *c; + + if (lib->dynsym[i].st_name == 0) + continue; + strlcpy(name, lib->dynstr + lib->dynsym[i].st_name, + MAX_SYMNAME); + c = strchr(name, '@'); + if (c) + *c = 0; + if (strcmp(symname, name) == 0) + return &lib->dynsym[i]; + } + return NULL; +} + +static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname) +{ + Elf32_Sym *sym; + + sym = find_symbol(lib, symname); + if (!sym) + return; + + sym->st_name = 0; +} + +static void __init patch_vdso(void *ehdr) +{ + struct elfinfo einfo; + + einfo = (struct elfinfo) { + .hdr = ehdr, + }; + + einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize); + einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL); + + /* If the virtual counter is absent or non-functional we don't + * want programs to incur the slight additional overhead of + * dispatching through the VDSO only to fall back to syscalls. + */ + if (!cntvct_ok) { + vdso_nullpatch_one(&einfo, "__vdso_gettimeofday"); + vdso_nullpatch_one(&einfo, "__vdso_clock_gettime"); + vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64"); + } +} + +static int __init vdso_init(void) +{ + unsigned int text_pages; + int i; + + if (memcmp(vdso_start, "\177ELF", 4)) { + pr_err("VDSO is not a valid ELF object!\n"); + return -ENOEXEC; + } + + text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; + + /* Allocate the VDSO text pagelist */ + vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *), + GFP_KERNEL); + if (vdso_text_pagelist == NULL) + return -ENOMEM; + + /* Grab the VDSO data page. */ + vdso_data_page = virt_to_page(vdso_data); + + /* Grab the VDSO text pages. */ + for (i = 0; i < text_pages; i++) { + struct page *page; + + page = virt_to_page(vdso_start + i * PAGE_SIZE); + vdso_text_pagelist[i] = page; + } + + vdso_text_mapping.pages = vdso_text_pagelist; + + vdso_total_pages = 1; /* for the data/vvar page */ + vdso_total_pages += text_pages; + + cntvct_ok = cntvct_functional(); + + patch_vdso(vdso_start); + + return 0; +} +arch_initcall(vdso_init); + +static int install_vvar(struct mm_struct *mm, unsigned long addr) +{ + struct vm_area_struct *vma; + + vma = _install_special_mapping(mm, addr, PAGE_SIZE, + VM_READ | VM_MAYREAD, + &vdso_data_mapping); + + return PTR_ERR_OR_ZERO(vma); +} + +/* assumes mmap_lock is write-locked */ +void arm_install_vdso(struct mm_struct *mm, unsigned long addr) +{ + struct vm_area_struct *vma; + unsigned long len; + + mm->context.vdso = 0; + + if (vdso_text_pagelist == NULL) + return; + + if (install_vvar(mm, addr)) + return; + + /* Account for vvar page. */ + addr += PAGE_SIZE; + len = (vdso_total_pages - 1) << PAGE_SHIFT; + + vma = _install_special_mapping(mm, addr, len, + VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, + &vdso_text_mapping); + + if (!IS_ERR(vma)) + mm->context.vdso = addr; +} + -- cgit v1.2.3