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Merge branch 'akpm' (patches from Andrew)

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Merge yet more updates from Andrew Morton:

 - various hotfixes

 - kexec_file updates and feature work

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (27 commits)
  kernel/kexec_file.c: move purgatories sha256 to common code
  kernel/kexec_file.c: allow archs to set purgatory load address
  kernel/kexec_file.c: remove mis-use of sh_offset field during purgatory load
  kernel/kexec_file.c: remove unneeded variables in kexec_purgatory_setup_sechdrs
  kernel/kexec_file.c: remove unneeded for-loop in kexec_purgatory_setup_sechdrs
  kernel/kexec_file.c: split up __kexec_load_puragory
  kernel/kexec_file.c: use read-only sections in arch_kexec_apply_relocations*
  kernel/kexec_file.c: search symbols in read-only kexec_purgatory
  kernel/kexec_file.c: make purgatory_info->ehdr const
  kernel/kexec_file.c: remove checks in kexec_purgatory_load
  include/linux/kexec.h: silence compile warnings
  kexec_file, x86: move re-factored code to generic side
  x86: kexec_file: clean up prepare_elf64_headers()
  x86: kexec_file: lift CRASH_MAX_RANGES limit on crash_mem buffer
  x86: kexec_file: remove X86_64 dependency from prepare_elf64_headers()
  x86: kexec_file: purge system-ram walking from prepare_elf64_headers()
  kexec_file,x86,powerpc: factor out kexec_file_ops functions
  kexec_file: make use of purgatory optional
  proc: revalidate misc dentries
  mm, slab: reschedule cache_reap() on the same CPU
  ...
This commit is contained in:
Linus Torvalds 2018-04-14 08:50:50 -07:00
commit 18b7fd1c93
29 changed files with 684 additions and 657 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/mips/mm/gup.c
View File

@ -178,6 +178,8 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
/*
* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
* back to the regular GUP.
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)

3
arch/powerpc/Kconfig
View File

@ -552,6 +552,9 @@ config KEXEC_FILE
for kernel and initramfs as opposed to a list of segments as is the
case for the older kexec call.
config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE
config RELOCATABLE
bool "Build a relocatable kernel"
depends on PPC64 || (FLATMEM && (44x || FSL_BOOKE))

2
arch/powerpc/include/asm/kexec.h
View File

@ -95,7 +95,7 @@ static inline bool kdump_in_progress(void)
}
#ifdef CONFIG_KEXEC_FILE
extern struct kexec_file_ops kexec_elf64_ops;
extern const struct kexec_file_ops kexec_elf64_ops;
#ifdef CONFIG_IMA_KEXEC
#define ARCH_HAS_KIMAGE_ARCH

11
arch/powerpc/kernel/kexec_elf_64.c
View File

@ -572,7 +572,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
{
int ret;
unsigned int fdt_size;
unsigned long kernel_load_addr, purgatory_load_addr;
unsigned long kernel_load_addr;
unsigned long initrd_load_addr = 0, fdt_load_addr;
void *fdt;
const void *slave_code;
@ -580,6 +580,8 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
struct elf_info elf_info;
struct kexec_buf kbuf = { .image = image, .buf_min = 0,
.buf_max = ppc64_rma_size };
struct kexec_buf pbuf = { .image = image, .buf_min = 0,
.buf_max = ppc64_rma_size, .top_down = true };
ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
if (ret)
@ -591,14 +593,13 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
pr_debug("Loaded the kernel at 0x%lx\n", kernel_load_addr);
ret = kexec_load_purgatory(image, 0, ppc64_rma_size, true,
&purgatory_load_addr);
ret = kexec_load_purgatory(image, &pbuf);
if (ret) {
pr_err("Loading purgatory failed.\n");
goto out;
}
pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
if (initrd != NULL) {
kbuf.buffer = initrd;
@ -657,7 +658,7 @@ out:
return ret ? ERR_PTR(ret) : fdt;
}
struct kexec_file_ops kexec_elf64_ops = {
const struct kexec_file_ops kexec_elf64_ops = {
.probe = elf64_probe,
.load = elf64_load,
};

39
arch/powerpc/kernel/machine_kexec_file_64.c
View File

@ -31,52 +31,19 @@
#define SLAVE_CODE_SIZE 256
static struct kexec_file_ops *kexec_file_loaders[] = {
const struct kexec_file_ops * const kexec_file_loaders[] = {
&kexec_elf64_ops,
NULL
};
int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len)
{
int i, ret = -ENOEXEC;
struct kexec_file_ops *fops;
/* We don't support crash kernels yet. */
if (image->type == KEXEC_TYPE_CRASH)
return -EOPNOTSUPP;
for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
fops = kexec_file_loaders[i];
if (!fops || !fops->probe)
continue;
ret = fops->probe(buf, buf_len);
if (!ret) {
image->fops = fops;
return ret;
}
}
return ret;
}
void *arch_kexec_kernel_image_load(struct kimage *image)
{
if (!image->fops || !image->fops->load)
return ERR_PTR(-ENOEXEC);
return image->fops->load(image, image->kernel_buf,
image->kernel_buf_len, image->initrd_buf,
image->initrd_buf_len, image->cmdline_buf,
image->cmdline_buf_len);
}
int arch_kimage_file_post_load_cleanup(struct kimage *image)
{
if (!image->fops || !image->fops->cleanup)
return 0;
return image->fops->cleanup(image->image_loader_data);
return kexec_image_probe_default(image, buf, buf_len);
}
/**

2
arch/s390/mm/gup.c
View File

@ -220,6 +220,8 @@ static inline int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr,
/*
* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
* back to the regular GUP.
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)

2
arch/sh/mm/gup.c
View File

@ -160,6 +160,8 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
/*
* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
* back to the regular GUP.
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)

4
arch/sparc/mm/gup.c
View File

@ -193,6 +193,10 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end,
return 1;
}
/*
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
{

3
arch/x86/Kconfig
View File

@ -2008,6 +2008,9 @@ config KEXEC_FILE
for kernel and initramfs as opposed to list of segments as
accepted by previous system call.
config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE
config KEXEC_VERIFY_SIG
bool "Verify kernel signature during kexec_file_load() syscall"
depends on KEXEC_FILE

2
arch/x86/include/asm/kexec-bzimage64.h
View File

@ -2,6 +2,6 @@
#ifndef _ASM_KEXEC_BZIMAGE64_H
#define _ASM_KEXEC_BZIMAGE64_H
extern struct kexec_file_ops kexec_bzImage64_ops;
extern const struct kexec_file_ops kexec_bzImage64_ops;
#endif /* _ASM_KEXE_BZIMAGE64_H */

334
arch/x86/kernel/crash.c
View File

@ -38,37 +38,6 @@
#include <asm/virtext.h>
#include <asm/intel_pt.h>
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
/* This primarily represents number of split ranges due to exclusion */
#define CRASH_MAX_RANGES 16
struct crash_mem_range {
u64 start, end;
};
struct crash_mem {
unsigned int nr_ranges;
struct crash_mem_range ranges[CRASH_MAX_RANGES];
};
/* Misc data about ram ranges needed to prepare elf headers */
struct crash_elf_data {
struct kimage *image;
/*
* Total number of ram ranges we have after various adjustments for
* crash reserved region, etc.
*/
unsigned int max_nr_ranges;
/* Pointer to elf header */
void *ehdr;
/* Pointer to next phdr */
void *bufp;
struct crash_mem mem;
};
/* Used while preparing memory map entries for second kernel */
struct crash_memmap_data {
struct boot_params *params;
@ -218,124 +187,49 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
return 0;
}
/* Gather all the required information to prepare elf headers for ram regions */
static void fill_up_crash_elf_data(struct crash_elf_data *ced,
struct kimage *image)
static struct crash_mem *fill_up_crash_elf_data(void)
{
unsigned int nr_ranges = 0;
ced->image = image;
struct crash_mem *cmem;
walk_system_ram_res(0, -1, &nr_ranges,
get_nr_ram_ranges_callback);
if (!nr_ranges)
return NULL;
ced->max_nr_ranges = nr_ranges;
/*
* Exclusion of crash region and/or crashk_low_res may cause
* another range split. So add extra two slots here.
*/
nr_ranges += 2;
cmem = vzalloc(sizeof(struct crash_mem) +
sizeof(struct crash_mem_range) * nr_ranges);
if (!cmem)
return NULL;
/* Exclusion of crash region could split memory ranges */
ced->max_nr_ranges++;
cmem->max_nr_ranges = nr_ranges;
cmem->nr_ranges = 0;
/* If crashk_low_res is not 0, another range split possible */
if (crashk_low_res.end)
ced->max_nr_ranges++;
}
static int exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart, unsigned long long mend)
{
int i, j;
unsigned long long start, end;
struct crash_mem_range temp_range = {0, 0};
for (i = 0; i < mem->nr_ranges; i++) {
start = mem->ranges[i].start;
end = mem->ranges[i].end;
if (mstart > end || mend < start)
continue;
/* Truncate any area outside of range */
if (mstart < start)
mstart = start;
if (mend > end)
mend = end;
/* Found completely overlapping range */
if (mstart == start && mend == end) {
mem->ranges[i].start = 0;
mem->ranges[i].end = 0;
if (i < mem->nr_ranges - 1) {
/* Shift rest of the ranges to left */
for (j = i; j < mem->nr_ranges - 1; j++) {
mem->ranges[j].start =
mem->ranges[j+1].start;
mem->ranges[j].end =
mem->ranges[j+1].end;
}
}
mem->nr_ranges--;
return 0;
}
if (mstart > start && mend < end) {
/* Split original range */
mem->ranges[i].end = mstart - 1;
temp_range.start = mend + 1;
temp_range.end = end;
} else if (mstart != start)
mem->ranges[i].end = mstart - 1;
else
mem->ranges[i].start = mend + 1;
break;
}
/* If a split happend, add the split to array */
if (!temp_range.end)
return 0;
/* Split happened */
if (i == CRASH_MAX_RANGES - 1) {
pr_err("Too many crash ranges after split\n");
return -ENOMEM;
}
/* Location where new range should go */
j = i + 1;
if (j < mem->nr_ranges) {
/* Move over all ranges one slot towards the end */
for (i = mem->nr_ranges - 1; i >= j; i--)
mem->ranges[i + 1] = mem->ranges[i];
}
mem->ranges[j].start = temp_range.start;
mem->ranges[j].end = temp_range.end;
mem->nr_ranges++;
return 0;
return cmem;
}
/*
* Look for any unwanted ranges between mstart, mend and remove them. This
* might lead to split and split ranges are put in ced->mem.ranges[] array
* might lead to split and split ranges are put in cmem->ranges[] array
*/
static int elf_header_exclude_ranges(struct crash_elf_data *ced,
unsigned long long mstart, unsigned long long mend)
static int elf_header_exclude_ranges(struct crash_mem *cmem)
{
struct crash_mem *cmem = &ced->mem;
int ret = 0;
memset(cmem->ranges, 0, sizeof(cmem->ranges));
cmem->ranges[0].start = mstart;
cmem->ranges[0].end = mend;
cmem->nr_ranges = 1;
/* Exclude crashkernel region */
ret = exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
if (ret)
return ret;
if (crashk_low_res.end) {
ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
crashk_low_res.end);
if (ret)
return ret;
}
@ -345,144 +239,12 @@ static int elf_header_exclude_ranges(struct crash_elf_data *ced,
static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
struct crash_elf_data *ced = arg;
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
unsigned long mstart, mend;
struct kimage *image = ced->image;
struct crash_mem *cmem;
int ret, i;
struct crash_mem *cmem = arg;
ehdr = ced->ehdr;
cmem->ranges[cmem->nr_ranges].start = res->start;
cmem->ranges[cmem->nr_ranges].end = res->end;
cmem->nr_ranges++;
/* Exclude unwanted mem ranges */
ret = elf_header_exclude_ranges(ced, res->start, res->end);
if (ret)
return ret;
/* Go through all the ranges in ced->mem.ranges[] and prepare phdr */
cmem = &ced->mem;
for (i = 0; i < cmem->nr_ranges; i++) {
mstart = cmem->ranges[i].start;
mend = cmem->ranges[i].end;
phdr = ced->bufp;
ced->bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R|PF_W|PF_X;
phdr->p_offset = mstart;
/*
* If a range matches backup region, adjust offset to backup
* segment.
*/
if (mstart == image->arch.backup_src_start &&
(mend - mstart + 1) == image->arch.backup_src_sz)
phdr->p_offset = image->arch.backup_load_addr;
phdr->p_paddr = mstart;
phdr->p_vaddr = (unsigned long long) __va(mstart);
phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
phdr->p_align = 0;
ehdr->e_phnum++;
pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
ehdr->e_phnum, phdr->p_offset);
}
return ret;
}
static int prepare_elf64_headers(struct crash_elf_data *ced,
void **addr, unsigned long *sz)
{
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
unsigned char *buf, *bufp;
unsigned int cpu;
unsigned long long notes_addr;
int ret;
/* extra phdr for vmcoreinfo elf note */
nr_phdr = nr_cpus + 1;
nr_phdr += ced->max_nr_ranges;
/*
* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
* area on x86_64 (ffffffff80000000 - ffffffffa0000000).
* I think this is required by tools like gdb. So same physical
* memory will be mapped in two elf headers. One will contain kernel
* text virtual addresses and other will have __va(physical) addresses.
*/
nr_phdr++;
elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
buf = vzalloc(elf_sz);
if (!buf)
return -ENOMEM;
bufp = buf;
ehdr = (Elf64_Ehdr *)bufp;
bufp += sizeof(Elf64_Ehdr);
memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
ehdr->e_ident[EI_CLASS] = ELFCLASS64;
ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
ehdr->e_ident[EI_VERSION] = EV_CURRENT;
ehdr->e_ident[EI_OSABI] = ELF_OSABI;
memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
ehdr->e_type = ET_CORE;
ehdr->e_machine = ELF_ARCH;
ehdr->e_version = EV_CURRENT;
ehdr->e_phoff = sizeof(Elf64_Ehdr);
ehdr->e_ehsize = sizeof(Elf64_Ehdr);
ehdr->e_phentsize = sizeof(Elf64_Phdr);
/* Prepare one phdr of type PT_NOTE for each present cpu */
for_each_present_cpu(cpu) {
phdr = (Elf64_Phdr *)bufp;
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_NOTE;
notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
phdr->p_offset = phdr->p_paddr = notes_addr;
phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
(ehdr->e_phnum)++;
}
/* Prepare one PT_NOTE header for vmcoreinfo */
phdr = (Elf64_Phdr *)bufp;
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_NOTE;
phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
(ehdr->e_phnum)++;
#ifdef CONFIG_X86_64
/* Prepare PT_LOAD type program header for kernel text region */
phdr = (Elf64_Phdr *)bufp;
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R|PF_W|PF_X;
phdr->p_vaddr = (Elf64_Addr)_text;
phdr->p_filesz = phdr->p_memsz = _end - _text;
phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
(ehdr->e_phnum)++;
#endif
/* Prepare PT_LOAD headers for system ram chunks. */
ced->ehdr = ehdr;
ced->bufp = bufp;
ret = walk_system_ram_res(0, -1, ced,
prepare_elf64_ram_headers_callback);
if (ret < 0)
return ret;
*addr = buf;
*sz = elf_sz;
return 0;
}
@ -490,18 +252,46 @@ static int prepare_elf64_headers(struct crash_elf_data *ced,
static int prepare_elf_headers(struct kimage *image, void **addr,
unsigned long *sz)
{
struct crash_elf_data *ced;
int ret;
struct crash_mem *cmem;
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
int ret, i;
ced = kzalloc(sizeof(*ced), GFP_KERNEL);
if (!ced)
cmem = fill_up_crash_elf_data();
if (!cmem)
return -ENOMEM;
fill_up_crash_elf_data(ced, image);
ret = walk_system_ram_res(0, -1, cmem,
prepare_elf64_ram_headers_callback);
if (ret)
goto out;
/* Exclude unwanted mem ranges */
ret = elf_header_exclude_ranges(cmem);
if (ret)
goto out;
/* By default prepare 64bit headers */
ret = prepare_elf64_headers(ced, addr, sz);
kfree(ced);
ret = crash_prepare_elf64_headers(cmem,
IS_ENABLED(CONFIG_X86_64), addr, sz);
if (ret)
goto out;
/*
* If a range matches backup region, adjust offset to backup
* segment.
*/
ehdr = (Elf64_Ehdr *)*addr;
phdr = (Elf64_Phdr *)(ehdr + 1);
for (i = 0; i < ehdr->e_phnum; phdr++, i++)
if (phdr->p_type == PT_LOAD &&
phdr->p_paddr == image->arch.backup_src_start &&
phdr->p_memsz == image->arch.backup_src_sz) {
phdr->p_offset = image->arch.backup_load_addr;
break;
}
out:
vfree(cmem);
return ret;
}
@ -547,14 +337,14 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
/* Exclude Backup region */
start = image->arch.backup_load_addr;
end = start + image->arch.backup_src_sz - 1;
ret = exclude_mem_range(cmem, start, end);
ret = crash_exclude_mem_range(cmem, start, end);
if (ret)
return ret;
/* Exclude elf header region */
start = image->arch.elf_load_addr;
end = start + image->arch.elf_headers_sz - 1;
return exclude_mem_range(cmem, start, end);
return crash_exclude_mem_range(cmem, start, end);
}
/* Prepare memory map for crash dump kernel */

10
arch/x86/kernel/kexec-bzimage64.c
View File

@ -334,7 +334,6 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
unsigned long setup_header_size, params_cmdline_sz;
struct boot_params *params;
unsigned long bootparam_load_addr, kernel_load_addr, initrd_load_addr;
unsigned long purgatory_load_addr;
struct bzimage64_data *ldata;
struct kexec_entry64_regs regs64;
void *stack;
@ -342,6 +341,8 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
unsigned int efi_map_offset, efi_map_sz, efi_setup_data_offset;
struct kexec_buf kbuf = { .image = image, .buf_max = ULONG_MAX,
.top_down = true };
struct kexec_buf pbuf = { .image = image, .buf_min = MIN_PURGATORY_ADDR,
.buf_max = ULONG_MAX, .top_down = true };
header = (struct setup_header *)(kernel + setup_hdr_offset);
setup_sects = header->setup_sects;
@ -379,14 +380,13 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
* Load purgatory. For 64bit entry point, purgatory code can be
* anywhere.
*/
ret = kexec_load_purgatory(image, MIN_PURGATORY_ADDR, ULONG_MAX, 1,
&purgatory_load_addr);
ret = kexec_load_purgatory(image, &pbuf);
if (ret) {
pr_err("Loading purgatory failed\n");
return ERR_PTR(ret);
}
pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
/*
@ -538,7 +538,7 @@ static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
}
#endif
struct kexec_file_ops kexec_bzImage64_ops = {
const struct kexec_file_ops kexec_bzImage64_ops = {
.probe = bzImage64_probe,
.load = bzImage64_load,
.cleanup = bzImage64_cleanup,

111
arch/x86/kernel/machine_kexec_64.c
View File

@ -30,8 +30,9 @@
#include <asm/set_memory.h>
#ifdef CONFIG_KEXEC_FILE
static struct kexec_file_ops *kexec_file_loaders[] = {
const struct kexec_file_ops * const kexec_file_loaders[] = {
&kexec_bzImage64_ops,
NULL
};
#endif
@ -364,27 +365,6 @@ void arch_crash_save_vmcoreinfo(void)
/* arch-dependent functionality related to kexec file-based syscall */
#ifdef CONFIG_KEXEC_FILE
int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len)
{
int i, ret = -ENOEXEC;
struct kexec_file_ops *fops;
for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
fops = kexec_file_loaders[i];
if (!fops || !fops->probe)
continue;
ret = fops->probe(buf, buf_len);
if (!ret) {
image->fops = fops;
return ret;
}
}
return ret;
}
void *arch_kexec_kernel_image_load(struct kimage *image)
{
vfree(image->arch.elf_headers);
@ -399,88 +379,53 @@ void *arch_kexec_kernel_image_load(struct kimage *image)
image->cmdline_buf_len);
}
int arch_kimage_file_post_load_cleanup(struct kimage *image)
{
if (!image->fops || !image->fops->cleanup)
return 0;
return image->fops->cleanup(image->image_loader_data);
}
#ifdef CONFIG_KEXEC_VERIFY_SIG
int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
unsigned long kernel_len)
{
if (!image->fops || !image->fops->verify_sig) {
pr_debug("kernel loader does not support signature verification.");
return -EKEYREJECTED;
}
return image->fops->verify_sig(kernel, kernel_len);
}
#endif
/*
* Apply purgatory relocations.
*
* ehdr: Pointer to elf headers
* sechdrs: Pointer to section headers.
* relsec: section index of SHT_RELA section.
* @pi: Purgatory to be relocated.
* @section: Section relocations applying to.
* @relsec: Section containing RELAs.
* @symtabsec: Corresponding symtab.
*
* TODO: Some of the code belongs to generic code. Move that in kexec.c.
*/
int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
Elf64_Shdr *sechdrs, unsigned int relsec)
int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
Elf_Shdr *section, const Elf_Shdr *relsec,
const Elf_Shdr *symtabsec)
{
unsigned int i;
Elf64_Rela *rel;
Elf64_Sym *sym;
void *location;
Elf64_Shdr *section, *symtabsec;
unsigned long address, sec_base, value;
const char *strtab, *name, *shstrtab;
const Elf_Shdr *sechdrs;
/*
* ->sh_offset has been modified to keep the pointer to section
* contents in memory
*/
rel = (void *)sechdrs[relsec].sh_offset;
/* String & section header string table */
sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
/* Section to which relocations apply */
section = &sechdrs[sechdrs[relsec].sh_info];
rel = (void *)pi->ehdr + relsec->sh_offset;
pr_debug("Applying relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
pr_debug("Applying relocate section %s to %u\n",
shstrtab + relsec->sh_name, relsec->sh_info);
/* Associated symbol table */
symtabsec = &sechdrs[sechdrs[relsec].sh_link];
/* String table */
if (symtabsec->sh_link >= ehdr->e_shnum) {
/* Invalid strtab section number */
pr_err("Invalid string table section index %d\n",
symtabsec->sh_link);
return -ENOEXEC;
}
strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
/* section header string table */
shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {
/*
* rel[i].r_offset contains byte offset from beginning
* of section to the storage unit affected.
*
* This is location to update (->sh_offset). This is temporary
* buffer where section is currently loaded. This will finally
* be loaded to a different address later, pointed to by
* This is location to update. This is temporary buffer
* where section is currently loaded. This will finally be
* loaded to a different address later, pointed to by
* ->sh_addr. kexec takes care of moving it
* (kexec_load_segment()).
*/
location = (void *)(section->sh_offset + rel[i].r_offset);
location = pi->purgatory_buf;
location += section->sh_offset;
location += rel[i].r_offset;
/* Final address of the location */
address = section->sh_addr + rel[i].r_offset;
@ -491,8 +436,8 @@ int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
* to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
* these respectively.
*/
sym = (Elf64_Sym *)symtabsec->sh_offset +
ELF64_R_SYM(rel[i].r_info);
sym = (void *)pi->ehdr + symtabsec->sh_offset;
sym += ELF64_R_SYM(rel[i].r_info);
if (sym->st_name)
name = strtab + sym->st_name;
@ -515,12 +460,12 @@ int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
if (sym->st_shndx == SHN_ABS)
sec_base = 0;
else if (sym->st_shndx >= ehdr->e_shnum) {
else if (sym->st_shndx >= pi->ehdr->e_shnum) {
pr_err("Invalid section %d for symbol %s\n",
sym->st_shndx, name);
return -ENOEXEC;
} else
sec_base = sechdrs[sym->st_shndx].sh_addr;
sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
value = sym->st_value;
value += sec_base;

3
arch/x86/purgatory/Makefile
View File

@ -6,6 +6,9 @@ purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string
targets += $(purgatory-y)
PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
$(obj)/sha256.o: $(srctree)/lib/sha256.c
$(call if_changed_rule,cc_o_c)
LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
targets += purgatory.ro

2
arch/x86/purgatory/purgatory.c
View File

@ -11,9 +11,9 @@
*/
#include <linux/bug.h>
#include <linux/sha256.h>
#include <asm/purgatory.h>
#include "sha256.h"
#include "../boot/string.h"
unsigned long purgatory_backup_dest __section(.kexec-purgatory);

12
arch/x86/purgatory/string.c
View File

@ -10,4 +10,16 @@
* Version 2. See the file COPYING for more details.
*/
#include <linux/types.h>
#include "../boot/string.c"
void *memcpy(void *dst, const void *src, size_t len)
{
return __builtin_memcpy(dst, src, len);
}
void *memset(void *dst, int c, size_t len)
{
return __builtin_memset(dst, c, len);
}

23
fs/proc/generic.c
View File

@ -15,6 +15,7 @@
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <linux/printk.h>
#include <linux/mount.h>
@ -217,6 +218,26 @@ void proc_free_inum(unsigned int inum)
ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
}
static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
{
if (flags & LOOKUP_RCU)
return -ECHILD;
if (atomic_read(&PDE(d_inode(dentry))->in_use) < 0)
return 0; /* revalidate */
return 1;
}
static int proc_misc_d_delete(const struct dentry *dentry)
{
return atomic_read(&PDE(d_inode(dentry))->in_use) < 0;
}
static const struct dentry_operations proc_misc_dentry_ops = {
.d_revalidate = proc_misc_d_revalidate,
.d_delete = proc_misc_d_delete,
};
/*
* Don't create negative dentries here, return -ENOENT by hand
* instead.
@ -234,7 +255,7 @@ struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
inode = proc_get_inode(dir->i_sb, de);
if (!inode)
return ERR_PTR(-ENOMEM);
d_set_d_op(dentry, &simple_dentry_operations);
d_set_d_op(dentry, &proc_misc_dentry_ops);
d_add(dentry, inode);
return NULL;
}

81
include/linux/kexec.h
View File

@ -99,21 +99,25 @@ struct compat_kexec_segment {
#ifdef CONFIG_KEXEC_FILE
struct purgatory_info {
/* Pointer to elf header of read only purgatory */
Elf_Ehdr *ehdr;
/* Pointer to purgatory sechdrs which are modifiable */
/*
* Pointer to elf header at the beginning of kexec_purgatory.
* Note: kexec_purgatory is read only
*/
const Elf_Ehdr *ehdr;
/*
* Temporary, modifiable buffer for sechdrs used for relocation.
* This memory can be freed post image load.
*/
Elf_Shdr *sechdrs;
/*
* Temporary buffer location where purgatory is loaded and relocated
* This memory can be freed post image load
* Temporary, modifiable buffer for stripped purgatory used for
* relocation. This memory can be freed post image load.
*/
void *purgatory_buf;
/* Address where purgatory is finally loaded and is executed from */
unsigned long purgatory_load_addr;
};
struct kimage;
typedef int (kexec_probe_t)(const char *kernel_buf, unsigned long kernel_size);
typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf,
unsigned long kernel_len, char *initrd,
@ -135,6 +139,11 @@ struct kexec_file_ops {
#endif
};
extern const struct kexec_file_ops * const kexec_file_loaders[];
int kexec_image_probe_default(struct kimage *image, void *buf,
unsigned long buf_len);
/**
* struct kexec_buf - parameters for finding a place for a buffer in memory
* @image: kexec image in which memory to search.
@ -159,10 +168,44 @@ struct kexec_buf {
bool top_down;
};
int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf);
int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
void *buf, unsigned int size,
bool get_value);
void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name);
int __weak arch_kexec_apply_relocations_add(struct purgatory_info *pi,
Elf_Shdr *section,
const Elf_Shdr *relsec,
const Elf_Shdr *symtab);
int __weak arch_kexec_apply_relocations(struct purgatory_info *pi,
Elf_Shdr *section,
const Elf_Shdr *relsec,
const Elf_Shdr *symtab);
int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
int (*func)(struct resource *, void *));
extern int kexec_add_buffer(struct kexec_buf *kbuf);
int kexec_locate_mem_hole(struct kexec_buf *kbuf);
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
struct crash_mem_range {
u64 start, end;
};
struct crash_mem {
unsigned int max_nr_ranges;
unsigned int nr_ranges;
struct crash_mem_range ranges[0];
};
extern int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart,
unsigned long long mend);
extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
void **addr, unsigned long *sz);
#endif /* CONFIG_KEXEC_FILE */
struct kimage {
@ -209,7 +252,7 @@ struct kimage {
unsigned long cmdline_buf_len;
/* File operations provided by image loader */
struct kexec_file_ops *fops;
const struct kexec_file_ops *fops;
/* Image loader handling the kernel can store a pointer here */
void *image_loader_data;
@ -226,14 +269,6 @@ extern void machine_kexec_cleanup(struct kimage *image);
extern int kernel_kexec(void);
extern struct page *kimage_alloc_control_pages(struct kimage *image,
unsigned int order);
extern int kexec_load_purgatory(struct kimage *image, unsigned long min,
unsigned long max, int top_down,
unsigned long *load_addr);
extern int kexec_purgatory_get_set_symbol(struct kimage *image,
const char *name, void *buf,
unsigned int size, bool get_value);
extern void *kexec_purgatory_get_symbol_addr(struct kimage *image,
const char *name);
extern void __crash_kexec(struct pt_regs *);
extern void crash_kexec(struct pt_regs *);
int kexec_should_crash(struct task_struct *);
@ -273,16 +308,6 @@ int crash_shrink_memory(unsigned long new_size);
size_t crash_get_memory_size(void);
void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len);
void * __weak arch_kexec_kernel_image_load(struct kimage *image);
int __weak arch_kimage_file_post_load_cleanup(struct kimage *image);
int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
unsigned long buf_len);
int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
Elf_Shdr *sechdrs, unsigned int relsec);
int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec);
void arch_kexec_protect_crashkres(void);
void arch_kexec_unprotect_crashkres(void);

11
arch/x86/purgatory/sha256.h → include/linux/sha256.h
View File

@ -13,9 +13,18 @@
#include <linux/types.h>
#include <crypto/sha.h>
/*
* Stand-alone implementation of the SHA256 algorithm. It is designed to
* have as little dependencies as possible so it can be used in the
* kexec_file purgatory. In other cases you should use the implementation in
* crypto/.
*
* For details see lib/sha256.c
*/
extern int sha256_init(struct sha256_state *sctx);
extern int sha256_update(struct sha256_state *sctx, const u8 *input,
unsigned int length);
unsigned int length);
extern int sha256_final(struct sha256_state *sctx, u8 *hash);
#endif /* SHA256_H */

23
ipc/shm.c
View File

@ -225,6 +225,12 @@ static int __shm_open(struct vm_area_struct *vma)
if (IS_ERR(shp))
return PTR_ERR(shp);
if (shp->shm_file != sfd->file) {
/* ID was reused */
shm_unlock(shp);
return -EINVAL;
}
shp->shm_atim = ktime_get_real_seconds();
ipc_update_pid(&shp->shm_lprid, task_tgid(current));
shp->shm_nattch++;
@ -455,8 +461,9 @@ static int shm_mmap(struct file *file, struct vm_area_struct *vma)
int ret;
/*
* In case of remap_file_pages() emulation, the file can represent
* removed IPC ID: propogate shm_lock() error to caller.
* In case of remap_file_pages() emulation, the file can represent an
* IPC ID that was removed, and possibly even reused by another shm
* segment already. Propagate this case as an error to caller.
*/
ret = __shm_open(vma);
if (ret)
@ -480,6 +487,7 @@ static int shm_release(struct inode *ino, struct file *file)
struct shm_file_data *sfd = shm_file_data(file);
put_ipc_ns(sfd->ns);
fput(sfd->file);
shm_file_data(file) = NULL;
kfree(sfd);
return 0;
@ -1445,7 +1453,16 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
file->f_mapping = shp->shm_file->f_mapping;
sfd->id = shp->shm_perm.id;
sfd->ns = get_ipc_ns(ns);
sfd->file = shp->shm_file;
/*
* We need to take a reference to the real shm file to prevent the
* pointer from becoming stale in cases where the lifetime of the outer
* file extends beyond that of the shm segment. It's not usually
* possible, but it can happen during remap_file_pages() emulation as
* that unmaps the memory, then does ->mmap() via file reference only.
* We'll deny the ->mmap() if the shm segment was since removed, but to
* detect shm ID reuse we need to compare the file pointers.
*/
sfd->file = get_file(shp->shm_file);
sfd->vm_ops = NULL;
err = security_mmap_file(file, prot, flags);

1
kernel/crash_core.c
View File

@ -454,6 +454,7 @@ static int __init crash_save_vmcoreinfo_init(void)
VMCOREINFO_NUMBER(PG_lru);
VMCOREINFO_NUMBER(PG_private);
VMCOREINFO_NUMBER(PG_swapcache);
VMCOREINFO_NUMBER(PG_swapbacked);
VMCOREINFO_NUMBER(PG_slab);
#ifdef CONFIG_MEMORY_FAILURE
VMCOREINFO_NUMBER(PG_hwpoison);

625
kernel/kexec_file.c
View File

@ -22,50 +22,123 @@
#include <linux/ima.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/vmalloc.h>
#include "kexec_internal.h"
static int kexec_calculate_store_digests(struct kimage *image);
/*
* Currently this is the only default function that is exported as some
* architectures need it to do additional handlings.
* In the future, other default functions may be exported too if required.
*/
int kexec_image_probe_default(struct kimage *image, void *buf,
unsigned long buf_len)
{
const struct kexec_file_ops * const *fops;
int ret = -ENOEXEC;
for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
ret = (*fops)->probe(buf, buf_len);
if (!ret) {
image->fops = *fops;
return ret;
}
}
return ret;
}
/* Architectures can provide this probe function */
int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len)
{
return -ENOEXEC;
return kexec_image_probe_default(image, buf, buf_len);
}
static void *kexec_image_load_default(struct kimage *image)
{
if (!image->fops || !image->fops->load)
return ERR_PTR(-ENOEXEC);
return image->fops->load(image, image->kernel_buf,
image->kernel_buf_len, image->initrd_buf,
image->initrd_buf_len, image->cmdline_buf,
image->cmdline_buf_len);
}
void * __weak arch_kexec_kernel_image_load(struct kimage *image)
{
return ERR_PTR(-ENOEXEC);
return kexec_image_load_default(image);
}
static int kexec_image_post_load_cleanup_default(struct kimage *image)
{
if (!image->fops || !image->fops->cleanup)
return 0;
return image->fops->cleanup(image->image_loader_data);
}
int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
{
return -EINVAL;
return kexec_image_post_load_cleanup_default(image);
}
#ifdef CONFIG_KEXEC_VERIFY_SIG
static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
unsigned long buf_len)
{
if (!image->fops || !image->fops->verify_sig) {
pr_debug("kernel loader does not support signature verification.\n");
return -EKEYREJECTED;
}
return image->fops->verify_sig(buf, buf_len);
}
int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
unsigned long buf_len)
{
return -EKEYREJECTED;
return kexec_image_verify_sig_default(image, buf, buf_len);
}
#endif
/* Apply relocations of type RELA */
/*
* arch_kexec_apply_relocations_add - apply relocations of type RELA
* @pi: Purgatory to be relocated.
* @section: Section relocations applying to.
* @relsec: Section containing RELAs.
* @symtab: Corresponding symtab.
*
* Return: 0 on success, negative errno on error.
*/
int __weak
arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
arch_kexec_apply_relocations_add(struct purgatory_info *pi, Elf_Shdr *section,
const Elf_Shdr *relsec, const Elf_Shdr *symtab)
{
pr_err("RELA relocation unsupported.\n");
return -ENOEXEC;
}
/* Apply relocations of type REL */
/*
* arch_kexec_apply_relocations - apply relocations of type REL
* @pi: Purgatory to be relocated.
* @section: Section relocations applying to.
* @relsec: Section containing RELs.
* @symtab: Corresponding symtab.
*
* Return: 0 on success, negative errno on error.
*/
int __weak
arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section,
const Elf_Shdr *relsec, const Elf_Shdr *symtab)
{
pr_err("REL relocation unsupported.\n");
return -ENOEXEC;
@ -532,6 +605,9 @@ static int kexec_calculate_store_digests(struct kimage *image)
struct kexec_sha_region *sha_regions;
struct purgatory_info *pi = &image->purgatory_info;
if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY))
return 0;
zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
zero_buf_sz = PAGE_SIZE;
@ -633,87 +709,29 @@ out:
return ret;
}
/* Actually load purgatory. Lot of code taken from kexec-tools */
static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
unsigned long max, int top_down)
#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
/*
* kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
* @pi: Purgatory to be loaded.
* @kbuf: Buffer to setup.
*
* Allocates the memory needed for the buffer. Caller is responsible to free
* the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
struct kexec_buf *kbuf)
{
struct purgatory_info *pi = &image->purgatory_info;
unsigned long align, bss_align, bss_sz, bss_pad;
unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
unsigned char *buf_addr, *src;
int i, ret = 0, entry_sidx = -1;
const Elf_Shdr *sechdrs_c;
Elf_Shdr *sechdrs = NULL;
struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
.buf_min = min, .buf_max = max,
.top_down = top_down };
const Elf_Shdr *sechdrs;
unsigned long bss_align;
unsigned long bss_sz;
unsigned long align;
int i, ret;
/*
* sechdrs_c points to section headers in purgatory and are read
* only. No modifications allowed.
*/
sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
/*
* We can not modify sechdrs_c[] and its fields. It is read only.
* Copy it over to a local copy where one can store some temporary
* data and free it at the end. We need to modify ->sh_addr and
* ->sh_offset fields to keep track of permanent and temporary
* locations of sections.
*/
sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
if (!sechdrs)
return -ENOMEM;
memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
/*
* We seem to have multiple copies of sections. First copy is which
* is embedded in kernel in read only section. Some of these sections
* will be copied to a temporary buffer and relocated. And these
* sections will finally be copied to their final destination at
* segment load time.
*
* Use ->sh_offset to reflect section address in memory. It will
* point to original read only copy if section is not allocatable.
* Otherwise it will point to temporary copy which will be relocated.
*
* Use ->sh_addr to contain final address of the section where it
* will go during execution time.
*/
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (sechdrs[i].sh_type == SHT_NOBITS)
continue;
sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
sechdrs[i].sh_offset;
}
/*
* Identify entry point section and make entry relative to section
* start.
*/
entry = pi->ehdr->e_entry;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
continue;
/* Make entry section relative */
if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
pi->ehdr->e_entry)) {
entry_sidx = i;
entry -= sechdrs[i].sh_addr;
break;
}
}
/* Determine how much memory is needed to load relocatable object. */
bss_align = 1;
bss_sz = 0;
sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
kbuf->buf_align = bss_align = 1;
kbuf->bufsz = bss_sz = 0;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
@ -721,111 +739,124 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
align = sechdrs[i].sh_addralign;
if (sechdrs[i].sh_type != SHT_NOBITS) {
if (kbuf.buf_align < align)
kbuf.buf_align = align;
kbuf.bufsz = ALIGN(kbuf.bufsz, align);
kbuf.bufsz += sechdrs[i].sh_size;
if (kbuf->buf_align < align)
kbuf->buf_align = align;
kbuf->bufsz = ALIGN(kbuf->bufsz, align);
kbuf->bufsz += sechdrs[i].sh_size;
} else {
/* bss section */
if (bss_align < align)
bss_align = align;
bss_sz = ALIGN(bss_sz, align);
bss_sz += sechdrs[i].sh_size;
}
}
kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
kbuf->memsz = kbuf->bufsz + bss_sz;
if (kbuf->buf_align < bss_align)
kbuf->buf_align = bss_align;
/* Determine the bss padding required to align bss properly */
bss_pad = 0;
if (kbuf.bufsz & (bss_align - 1))
bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1));
kbuf->buffer = vzalloc(kbuf->bufsz);
if (!kbuf->buffer)
return -ENOMEM;
pi->purgatory_buf = kbuf->buffer;
kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz;
/* Allocate buffer for purgatory */
kbuf.buffer = vzalloc(kbuf.bufsz);
if (!kbuf.buffer) {
ret = -ENOMEM;
goto out;
}
if (kbuf.buf_align < bss_align)
kbuf.buf_align = bss_align;
/* Add buffer to segment list */
ret = kexec_add_buffer(&kbuf);
ret = kexec_add_buffer(kbuf);
if (ret)
goto out;
pi->purgatory_load_addr = kbuf.mem;
/* Load SHF_ALLOC sections */
buf_addr = kbuf.buffer;
load_addr = curr_load_addr = pi->purgatory_load_addr;
bss_addr = load_addr + kbuf.bufsz + bss_pad;
return 0;
out:
vfree(pi->purgatory_buf);
pi->purgatory_buf = NULL;
return ret;
}
/*
* kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
* @pi: Purgatory to be loaded.
* @kbuf: Buffer prepared to store purgatory.
*
* Allocates the memory needed for the buffer. Caller is responsible to free
* the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
struct kexec_buf *kbuf)
{
unsigned long bss_addr;
unsigned long offset;
Elf_Shdr *sechdrs;
int i;
/*
* The section headers in kexec_purgatory are read-only. In order to
* have them modifiable make a temporary copy.
*/
sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
if (!sechdrs)
return -ENOMEM;
memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
pi->ehdr->e_shnum * sizeof(Elf_Shdr));
pi->sechdrs = sechdrs;
offset = 0;
bss_addr = kbuf->mem + kbuf->bufsz;
kbuf->image->start = pi->ehdr->e_entry;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
unsigned long align;
void *src, *dst;
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
align = sechdrs[i].sh_addralign;
if (sechdrs[i].sh_type != SHT_NOBITS) {
curr_load_addr = ALIGN(curr_load_addr, align);
offset = curr_load_addr - load_addr;
/* We already modifed ->sh_offset to keep src addr */
src = (char *) sechdrs[i].sh_offset;
memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
/* Store load address and source address of section */
sechdrs[i].sh_addr = curr_load_addr;
/*
* This section got copied to temporary buffer. Update
* ->sh_offset accordingly.
*/
sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
/* Advance to the next address */
curr_load_addr += sechdrs[i].sh_size;
} else {
if (sechdrs[i].sh_type == SHT_NOBITS) {
bss_addr = ALIGN(bss_addr, align);
sechdrs[i].sh_addr = bss_addr;
bss_addr += sechdrs[i].sh_size;
continue;
}
offset = ALIGN(offset, align);
if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
pi->ehdr->e_entry < (sechdrs[i].sh_addr
+ sechdrs[i].sh_size)) {
kbuf->image->start -= sechdrs[i].sh_addr;
kbuf->image->start += kbuf->mem + offset;
}
src = (void *)pi->ehdr + sechdrs[i].sh_offset;
dst = pi->purgatory_buf + offset;
memcpy(dst, src, sechdrs[i].sh_size);
sechdrs[i].sh_addr = kbuf->mem + offset;
sechdrs[i].sh_offset = offset;
offset += sechdrs[i].sh_size;
}
/* Update entry point based on load address of text section */
if (entry_sidx >= 0)
entry += sechdrs[entry_sidx].sh_addr;
/* Make kernel jump to purgatory after shutdown */
image->start = entry;
/* Used later to get/set symbol values */
pi->sechdrs = sechdrs;
/*
* Used later to identify which section is purgatory and skip it
* from checksumming.
*/
pi->purgatory_buf = kbuf.buffer;
return ret;
out:
vfree(sechdrs);
vfree(kbuf.buffer);
return ret;
return 0;
}
static int kexec_apply_relocations(struct kimage *image)
{
int i, ret;
struct purgatory_info *pi = &image->purgatory_info;
Elf_Shdr *sechdrs = pi->sechdrs;
const Elf_Shdr *sechdrs;
sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
/* Apply relocations */
for (i = 0; i < pi->ehdr->e_shnum; i++) {
Elf_Shdr *section, *symtab;
const Elf_Shdr *relsec;
const Elf_Shdr *symtab;
Elf_Shdr *section;
if (sechdrs[i].sh_type != SHT_RELA &&
sechdrs[i].sh_type != SHT_REL)
relsec = sechdrs + i;
if (relsec->sh_type != SHT_RELA &&
relsec->sh_type != SHT_REL)
continue;
/*
@ -834,12 +865,12 @@ static int kexec_apply_relocations(struct kimage *image)
* symbol table. And ->sh_info contains section header
* index of section to which relocations apply.
*/
if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
sechdrs[i].sh_link >= pi->ehdr->e_shnum)
if (relsec->sh_info >= pi->ehdr->e_shnum ||
relsec->sh_link >= pi->ehdr->e_shnum)
return -ENOEXEC;
section = &sechdrs[sechdrs[i].sh_info];
symtab = &sechdrs[sechdrs[i].sh_link];
section = pi->sechdrs + relsec->sh_info;
symtab = sechdrs + relsec->sh_link;
if (!(section->sh_flags & SHF_ALLOC))
continue;
@ -856,12 +887,12 @@ static int kexec_apply_relocations(struct kimage *image)
* Respective architecture needs to provide support for applying
* relocations of type SHT_RELA/SHT_REL.
*/
if (sechdrs[i].sh_type == SHT_RELA)
ret = arch_kexec_apply_relocations_add(pi->ehdr,
sechdrs, i);
else if (sechdrs[i].sh_type == SHT_REL)
ret = arch_kexec_apply_relocations(pi->ehdr,
sechdrs, i);
if (relsec->sh_type == SHT_RELA)
ret = arch_kexec_apply_relocations_add(pi, section,
relsec, symtab);
else if (relsec->sh_type == SHT_REL)
ret = arch_kexec_apply_relocations(pi, section,
relsec, symtab);
if (ret)
return ret;
}
@ -869,10 +900,18 @@ static int kexec_apply_relocations(struct kimage *image)
return 0;
}
/* Load relocatable purgatory object and relocate it appropriately */
int kexec_load_purgatory(struct kimage *image, unsigned long min,
unsigned long max, int top_down,
unsigned long *load_addr)
/*
* kexec_load_purgatory - Load and relocate the purgatory object.
* @image: Image to add the purgatory to.
* @kbuf: Memory parameters to use.
*
* Allocates the memory needed for image->purgatory_info.sechdrs and
* image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
* to free the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
{
struct purgatory_info *pi = &image->purgatory_info;
int ret;
@ -880,55 +919,51 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
if (kexec_purgatory_size <= 0)
return -EINVAL;
if (kexec_purgatory_size < sizeof(Elf_Ehdr))
return -ENOEXEC;
pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
|| pi->ehdr->e_type != ET_REL
|| !elf_check_arch(pi->ehdr)
|| pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
return -ENOEXEC;
if (pi->ehdr->e_shoff >= kexec_purgatory_size
|| (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
kexec_purgatory_size - pi->ehdr->e_shoff))
return -ENOEXEC;
ret = __kexec_load_purgatory(image, min, max, top_down);
ret = kexec_purgatory_setup_kbuf(pi, kbuf);
if (ret)
return ret;
ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
if (ret)
goto out_free_kbuf;
ret = kexec_apply_relocations(image);
if (ret)
goto out;
*load_addr = pi->purgatory_load_addr;
return 0;
out:
vfree(pi->sechdrs);
pi->sechdrs = NULL;
out_free_kbuf:
vfree(pi->purgatory_buf);
pi->purgatory_buf = NULL;
return ret;
}
static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
const char *name)
/*
* kexec_purgatory_find_symbol - find a symbol in the purgatory
* @pi: Purgatory to search in.
* @name: Name of the symbol.
*
* Return: pointer to symbol in read-only symtab on success, NULL on error.
*/
static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
const char *name)
{
Elf_Sym *syms;
Elf_Shdr *sechdrs;
Elf_Ehdr *ehdr;
int i, k;
const Elf_Shdr *sechdrs;
const Elf_Ehdr *ehdr;
const Elf_Sym *syms;
const char *strtab;
int i, k;
if (!pi->sechdrs || !pi->ehdr)
if (!pi->ehdr)
return NULL;
sechdrs = pi->sechdrs;
ehdr = pi->ehdr;
sechdrs = (void *)ehdr + ehdr->e_shoff;
for (i = 0; i < ehdr->e_shnum; i++) {
if (sechdrs[i].sh_type != SHT_SYMTAB)
@ -937,8 +972,8 @@ static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
if (sechdrs[i].sh_link >= ehdr->e_shnum)
/* Invalid strtab section number */
continue;
strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
syms = (Elf_Sym *)sechdrs[i].sh_offset;
strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
syms = (void *)ehdr + sechdrs[i].sh_offset;
/* Go through symbols for a match */
for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
@ -966,7 +1001,7 @@ static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
{
struct purgatory_info *pi = &image->purgatory_info;
Elf_Sym *sym;
const Elf_Sym *sym;
Elf_Shdr *sechdr;
sym = kexec_purgatory_find_symbol(pi, name);
@ -989,9 +1024,9 @@ void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
void *buf, unsigned int size, bool get_value)
{
Elf_Sym *sym;
Elf_Shdr *sechdrs;
struct purgatory_info *pi = &image->purgatory_info;
const Elf_Sym *sym;
Elf_Shdr *sec;
char *sym_buf;
sym = kexec_purgatory_find_symbol(pi, name);
@ -1004,16 +1039,15 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
return -EINVAL;
}
sechdrs = pi->sechdrs;
sec = pi->sechdrs + sym->st_shndx;
if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
if (sec->sh_type == SHT_NOBITS) {
pr_err("symbol %s is in a bss section. Cannot %s\n", name,
get_value ? "get" : "set");
return -EINVAL;
}
sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
sym->st_value;
sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
if (get_value)
memcpy((void *)buf, sym_buf, size);
@ -1022,3 +1056,174 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
return 0;
}
#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart, unsigned long long mend)
{
int i, j;
unsigned long long start, end;
struct crash_mem_range temp_range = {0, 0};
for (i = 0; i < mem->nr_ranges; i++) {
start = mem->ranges[i].start;
end = mem->ranges[i].end;
if (mstart > end || mend < start)
continue;
/* Truncate any area outside of range */
if (mstart < start)
mstart = start;
if (mend > end)
mend = end;
/* Found completely overlapping range */
if (mstart == start && mend == end) {
mem->ranges[i].start = 0;
mem->ranges[i].end = 0;
if (i < mem->nr_ranges - 1) {
/* Shift rest of the ranges to left */
for (j = i; j < mem->nr_ranges - 1; j++) {
mem->ranges[j].start =
mem->ranges[j+1].start;
mem->ranges[j].end =
mem->ranges[j+1].end;
}
}
mem->nr_ranges--;
return 0;
}
if (mstart > start && mend < end) {
/* Split original range */
mem->ranges[i].end = mstart - 1;
temp_range.start = mend + 1;
temp_range.end = end;
} else if (mstart != start)
mem->ranges[i].end = mstart - 1;
else
mem->ranges[i].start = mend + 1;
break;
}
/* If a split happened, add the split to array */
if (!temp_range.end)
return 0;
/* Split happened */
if (i == mem->max_nr_ranges - 1)
return -ENOMEM;
/* Location where new range should go */
j = i + 1;
if (j < mem->nr_ranges) {
/* Move over all ranges one slot towards the end */
for (i = mem->nr_ranges - 1; i >= j; i--)
mem->ranges[i + 1] = mem->ranges[i];
}
mem->ranges[j].start = temp_range.start;
mem->ranges[j].end = temp_range.end;
mem->nr_ranges++;
return 0;
}
int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
void **addr, unsigned long *sz)
{
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
unsigned char *buf;
unsigned int cpu, i;
unsigned long long notes_addr;
unsigned long mstart, mend;
/* extra phdr for vmcoreinfo elf note */
nr_phdr = nr_cpus + 1;
nr_phdr += mem->nr_ranges;
/*
* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
* area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
* I think this is required by tools like gdb. So same physical
* memory will be mapped in two elf headers. One will contain kernel
* text virtual addresses and other will have __va(physical) addresses.
*/
nr_phdr++;
elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
buf = vzalloc(elf_sz);
if (!buf)
return -ENOMEM;
ehdr = (Elf64_Ehdr *)buf;
phdr = (Elf64_Phdr *)(ehdr + 1);
memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
ehdr->e_ident[EI_CLASS] = ELFCLASS64;
ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
ehdr->e_ident[EI_VERSION] = EV_CURRENT;
ehdr->e_ident[EI_OSABI] = ELF_OSABI;
memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
ehdr->e_type = ET_CORE;
ehdr->e_machine = ELF_ARCH;
ehdr->e_version = EV_CURRENT;
ehdr->e_phoff = sizeof(Elf64_Ehdr);
ehdr->e_ehsize = sizeof(Elf64_Ehdr);
ehdr->e_phentsize = sizeof(Elf64_Phdr);
/* Prepare one phdr of type PT_NOTE for each present cpu */
for_each_present_cpu(cpu) {
phdr->p_type = PT_NOTE;
notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
phdr->p_offset = phdr->p_paddr = notes_addr;
phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
(ehdr->e_phnum)++;
phdr++;
}
/* Prepare one PT_NOTE header for vmcoreinfo */
phdr->p_type = PT_NOTE;
phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
(ehdr->e_phnum)++;
phdr++;
/* Prepare PT_LOAD type program header for kernel text region */
if (kernel_map) {
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R|PF_W|PF_X;
phdr->p_vaddr = (Elf64_Addr)_text;
phdr->p_filesz = phdr->p_memsz = _end - _text;
phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
ehdr->e_phnum++;
phdr++;
}
/* Go through all the ranges in mem->ranges[] and prepare phdr */
for (i = 0; i < mem->nr_ranges; i++) {
mstart = mem->ranges[i].start;
mend = mem->ranges[i].end;
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R|PF_W|PF_X;
phdr->p_offset = mstart;
phdr->p_paddr = mstart;
phdr->p_vaddr = (unsigned long long) __va(mstart);
phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
phdr->p_align = 0;
ehdr->e_phnum++;
phdr++;
pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
ehdr->e_phnum, phdr->p_offset);
}
*addr = buf;
*sz = elf_sz;
return 0;
}

3
kernel/resource.c
View File

@ -651,7 +651,8 @@ static int __find_resource(struct resource *root, struct resource *old,
alloc.start = constraint->alignf(constraint->alignf_data, &avail,
size, constraint->align);
alloc.end = alloc.start + size - 1;
if (resource_contains(&avail, &alloc)) {
if (alloc.start <= alloc.end &&
resource_contains(&avail, &alloc)) {
new->start = alloc.start;
new->end = alloc.end;
return 0;

4
arch/x86/purgatory/sha256.c → lib/sha256.c
View File

@ -16,9 +16,9 @@
*/
#include <linux/bitops.h>
#include <linux/sha256.h>
#include <linux/string.h>
#include <asm/byteorder.h>
#include "sha256.h"
#include "../boot/string.h"
static inline u32 Ch(u32 x, u32 y, u32 z)
{

6
mm/filemap.c
View File

@ -2719,7 +2719,6 @@ out:
sb_end_pagefault(inode->i_sb);
return ret;
}
EXPORT_SYMBOL(filemap_page_mkwrite);
const struct vm_operations_struct generic_file_vm_ops = {
.fault = filemap_fault,
@ -2750,6 +2749,10 @@ int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
return generic_file_mmap(file, vma);
}
#else
int filemap_page_mkwrite(struct vm_fault *vmf)
{
return -ENOSYS;
}
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
{
return -ENOSYS;
@ -2760,6 +2763,7 @@ int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
}
#endif /* CONFIG_MMU */
EXPORT_SYMBOL(filemap_page_mkwrite);
EXPORT_SYMBOL(generic_file_mmap);
EXPORT_SYMBOL(generic_file_readonly_mmap);

9
mm/gup.c
View File

@ -1740,7 +1740,9 @@ bool gup_fast_permitted(unsigned long start, int nr_pages, int write)
/*
* Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
* the regular GUP. It will only return non-negative values.
* the regular GUP.
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
*/
int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
@ -1806,9 +1808,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
len = (unsigned long) nr_pages << PAGE_SHIFT;
end = start + len;
if (nr_pages <= 0)
return 0;
if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
(void __user *)start, len)))
return 0;
return -EFAULT;
if (gup_fast_permitted(start, nr_pages, write)) {
local_irq_disable();

4
mm/gup_benchmark.c
View File

@ -23,7 +23,7 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
struct page **pages;
nr_pages = gup->size / PAGE_SIZE;
pages = kvmalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
if (!pages)
return -ENOMEM;
@ -41,6 +41,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
}
nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
if (nr <= 0)
break;
i += nr;
}
end_time = ktime_get();

3
mm/slab.c
View File

@ -4086,7 +4086,8 @@ next:
next_reap_node();
out:
/* Set up the next iteration */
schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC));
schedule_delayed_work_on(smp_processor_id(), work,
round_jiffies_relative(REAPTIMEOUT_AC));
}
void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)

6
mm/util.c
View File

@ -297,8 +297,10 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
/*
* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
* back to the regular GUP.
* If the architecture not support this function, simply return with no
* page pinned
* Note a difference with get_user_pages_fast: this always returns the
* number of pages pinned, 0 if no pages were pinned.
* If the architecture does not support this function, simply return with no
* pages pinned.
*/
int __weak __get_user_pages_fast(unsigned long start,
int nr_pages, int write, struct page **pages)