linux/arch/arm/kernel/vdso.c
Linus Torvalds 82fa407da0 Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM updates from Russell King:

 - Correct ARMs dma-mapping to use the correct printk format strings.

 - Avoid defining OBJCOPYFLAGS globally which upsets lkdtm rodata
   testing.

 - Cleanups to ARMs asm/memory.h include.

 - L2 cache cleanups.

 - Allow flat nommu binaries to be executed on ARM MMU systems.

 - Kernel hardening - add more read-only after init annotations,
   including making some kernel vdso variables const.

 - Ensure AMBA primecell clocks are appropriately defaulted.

 - ARM breakpoint cleanup.

 - Various StrongARM 11x0 and companion chip (SA1111) updates to bring
   this legacy platform to use more modern APIs for (eg) GPIOs and
   interrupts, which will allow us in the future to reduce some of the
   board-level driver clutter and elimate function callbacks into board
   code via platform data. There still appears to be interest in these
   platforms!

 - Remove the now redundant secure_flush_area() API.

 - Module PLT relocation optimisations. Ard says: This series of 4
   patches optimizes the ARM PLT generation code that is invoked at
   module load time, to get rid of the O(n^2) algorithm that results in
   pathological load times of 10 seconds or more for large modules on
   certain STB platforms.

 - ARMv7M cache maintanence support.

 - L2 cache PMU support

* 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (35 commits)
  ARM: sa1111: provide to_sa1111_device() macro
  ARM: sa1111: add sa1111_get_irq()
  ARM: sa1111: clean up duplication in IRQ chip implementation
  ARM: sa1111: implement a gpio_chip for SA1111 GPIOs
  ARM: sa1111: move irq cleanup to separate function
  ARM: sa1111: use devm_clk_get()
  ARM: sa1111: use devm_kzalloc()
  ARM: sa1111: ensure we only touch RAB bus type devices when removing
  ARM: 8611/1: l2x0: add PMU support
  ARM: 8610/1: V7M: Add dsb before jumping in handler mode
  ARM: 8609/1: V7M: Add support for the Cortex-M7 processor
  ARM: 8608/1: V7M: Indirect proc_info construction for V7M CPUs
  ARM: 8607/1: V7M: Wire up caches for V7M processors with cache support.
  ARM: 8606/1: V7M: introduce cache operations
  ARM: 8605/1: V7M: fix notrace variant of save_and_disable_irqs
  ARM: 8604/1: V7M: Add support for reading the CTR with read_cpuid_cachetype()
  ARM: 8603/1: V7M: Add addresses for mem-mapped V7M cache operations
  ARM: 8602/1: factor out CSSELR/CCSIDR operations that use cp15 directly
  ARM: kernel: avoid brute force search on PLT generation
  ARM: kernel: sort relocation sections before allocating PLTs
  ...
2016-10-06 07:59:37 -07:00

338 lines
8.4 KiB
C

/*
* Adapted from arm64 version.
*
* Copyright (C) 2012 ARM Limited
* Copyright (C) 2015 Mentor Graphics Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/cache.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>
#include <linux/vmalloc.h>
#include <asm/arch_timer.h>
#include <asm/barrier.h>
#include <asm/cacheflush.h>
#include <asm/page.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>
#include <clocksource/arm_arch_timer.h>
#define MAX_SYMNAME 64
static struct page **vdso_text_pagelist;
/* 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;
static 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 struct vm_special_mapping vdso_text_mapping __ro_after_init = {
.name = "[vdso]",
};
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.
*/
static 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)
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");
}
}
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;
pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
/* 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_sem 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;
}
static void vdso_write_begin(struct vdso_data *vdata)
{
++vdso_data->seq_count;
smp_wmb(); /* Pairs with smp_rmb in vdso_read_retry */
}
static void vdso_write_end(struct vdso_data *vdata)
{
smp_wmb(); /* Pairs with smp_rmb in vdso_read_begin */
++vdso_data->seq_count;
}
static bool tk_is_cntvct(const struct timekeeper *tk)
{
if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
return false;
if (!tk->tkr_mono.clock->archdata.vdso_direct)
return false;
return true;
}
/**
* update_vsyscall - update the vdso data page
*
* Increment the sequence counter, making it odd, indicating to
* userspace that an update is in progress. Update the fields used
* for coarse clocks and, if the architected system timer is in use,
* the fields used for high precision clocks. Increment the sequence
* counter again, making it even, indicating to userspace that the
* update is finished.
*
* Userspace is expected to sample seq_count before reading any other
* fields from the data page. If seq_count is odd, userspace is
* expected to wait until it becomes even. After copying data from
* the page, userspace must sample seq_count again; if it has changed
* from its previous value, userspace must retry the whole sequence.
*
* Calls to update_vsyscall are serialized by the timekeeping core.
*/
void update_vsyscall(struct timekeeper *tk)
{
struct timespec64 *wtm = &tk->wall_to_monotonic;
if (!cntvct_ok) {
/* The entry points have been zeroed, so there is no
* point in updating the data page.
*/
return;
}
vdso_write_begin(vdso_data);
vdso_data->tk_is_cntvct = tk_is_cntvct(tk);
vdso_data->xtime_coarse_sec = tk->xtime_sec;
vdso_data->xtime_coarse_nsec = (u32)(tk->tkr_mono.xtime_nsec >>
tk->tkr_mono.shift);
vdso_data->wtm_clock_sec = wtm->tv_sec;
vdso_data->wtm_clock_nsec = wtm->tv_nsec;
if (vdso_data->tk_is_cntvct) {
vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
vdso_data->xtime_clock_sec = tk->xtime_sec;
vdso_data->xtime_clock_snsec = tk->tkr_mono.xtime_nsec;
vdso_data->cs_mult = tk->tkr_mono.mult;
vdso_data->cs_shift = tk->tkr_mono.shift;
vdso_data->cs_mask = tk->tkr_mono.mask;
}
vdso_write_end(vdso_data);
flush_dcache_page(virt_to_page(vdso_data));
}
void update_vsyscall_tz(void)
{
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
flush_dcache_page(virt_to_page(vdso_data));
}