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vmcore: convert copy_oldmem_page() to take an iov_iter

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Patch series "Convert vmcore to use an iov_iter", v5.

For some reason several people have been sending bad patches to fix
compiler warnings in vmcore recently.  Here's how it should be done. 
Compile-tested only on x86.  As noted in the first patch, s390 should take
this conversion a bit further, but I'm not inclined to do that work
myself.


This patch (of 3):

Instead of passing in a 'buf' and 'userbuf' argument, pass in an iov_iter.
s390 needs more work to pass the iov_iter down further, or refactor, but
I'd be more comfortable if someone who can test on s390 did that work.

It's more convenient to convert the whole of read_from_oldmem() to take an
iov_iter at the same time, so rename it to read_from_oldmem_iter() and add
a temporary read_from_oldmem() wrapper that creates an iov_iter.

Link: https://lkml.kernel.org/r/20220408090636.560886-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20220408090636.560886-2-bhe@redhat.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-04-29 14:37:59 -07:00 committed by akpm
parent 04d168c6d4
commit 5d8de293c2
12 changed files with 91 additions and 260 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

27
arch/arm/kernel/crash_dump.c
View file

@ -14,22 +14,10 @@
#include <linux/crash_dump.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/uio.h>
/**
* copy_oldmem_page() - copy one page from old kernel memory
* @pfn: page frame number to be copied
* @buf: buffer where the copied page is placed
* @csize: number of bytes to copy
* @offset: offset in bytes into the page
* @userbuf: if set, @buf is int he user address space
*
* This function copies one page from old kernel memory into buffer pointed by
* @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
* copied or negative error in case of failure.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset,
int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void *vaddr;
@ -40,14 +28,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
if (!vaddr)
return -ENOMEM;
if (userbuf) {
if (copy_to_user(buf, vaddr + offset, csize)) {
iounmap(vaddr);
return -EFAULT;
}
} else {
memcpy(buf, vaddr + offset, csize);
}
csize = copy_to_iter(vaddr + offset, csize, iter);
iounmap(vaddr);
return csize;

29
arch/arm64/kernel/crash_dump.c
View file

@ -9,25 +9,11 @@
#include <linux/crash_dump.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <asm/memory.h>
/**
* copy_oldmem_page() - copy one page from old kernel memory
* @pfn: page frame number to be copied
* @buf: buffer where the copied page is placed
* @csize: number of bytes to copy
* @offset: offset in bytes into the page
* @userbuf: if set, @buf is in a user address space
*
* This function copies one page from old kernel memory into buffer pointed by
* @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
* copied or negative error in case of failure.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset,
int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void *vaddr;
@ -38,14 +24,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
if (!vaddr)
return -ENOMEM;
if (userbuf) {
if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
memunmap(vaddr);
return -EFAULT;
}
} else {
memcpy(buf, vaddr + offset, csize);
}
csize = copy_to_iter(vaddr + offset, csize, iter);
memunmap(vaddr);

32
arch/ia64/kernel/crash_dump.c
View file

@ -10,42 +10,18 @@
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/crash_dump.h>
#include <linux/uio.h>
#include <asm/page.h>
#include <linux/uaccess.h>
/**
* copy_oldmem_page - copy one page from "oldmem"
* @pfn: page frame number to be copied
* @buf: target memory address for the copy; this can be in kernel address
* space or user address space (see @userbuf)
* @csize: number of bytes to copy
* @offset: offset in bytes into the page (based on pfn) to begin the copy
* @userbuf: if set, @buf is in user address space, use copy_to_user(),
* otherwise @buf is in kernel address space, use memcpy().
*
* Copy a page from "oldmem". For this page, there is no pte mapped
* in the current kernel. We stitch up a pte, similar to kmap_atomic.
*
* Calling copy_to_user() in atomic context is not desirable. Hence first
* copying the data to a pre-allocated kernel page and then copying to user
* space in non-atomic context.
*/
ssize_t
copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void *vaddr;
if (!csize)
return 0;
vaddr = __va(pfn<<PAGE_SHIFT);
if (userbuf) {
if (copy_to_user(buf, (vaddr + offset), csize)) {
return -EFAULT;
}
} else
memcpy(buf, (vaddr + offset), csize);
csize = copy_to_iter(vaddr + offset, csize, iter);
return csize;
}

27
arch/mips/kernel/crash_dump.c
View file

@ -1,22 +1,10 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/highmem.h>
#include <linux/crash_dump.h>
#include <linux/uio.h>
/**
* copy_oldmem_page - copy one page from "oldmem"
* @pfn: page frame number to be copied
* @buf: target memory address for the copy; this can be in kernel address
* space or user address space (see @userbuf)
* @csize: number of bytes to copy
* @offset: offset in bytes into the page (based on pfn) to begin the copy
* @userbuf: if set, @buf is in user address space, use copy_to_user(),
* otherwise @buf is in kernel address space, use memcpy().
*
* Copy a page from "oldmem". For this page, there is no pte mapped
* in the current kernel.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void *vaddr;
@ -24,14 +12,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
return 0;
vaddr = kmap_local_pfn(pfn);
if (!userbuf) {
memcpy(buf, vaddr + offset, csize);
} else {
if (copy_to_user(buf, vaddr + offset, csize))
csize = -EFAULT;
}
csize = copy_to_iter(vaddr + offset, csize, iter);
kunmap_local(vaddr);
return csize;

35
arch/powerpc/kernel/crash_dump.c
View file

@ -16,7 +16,7 @@
#include <asm/kdump.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <asm/rtas.h>
#include <asm/inst.h>
@ -68,33 +68,8 @@ void __init setup_kdump_trampoline(void)
}
#endif /* CONFIG_NONSTATIC_KERNEL */
static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
unsigned long offset, int userbuf)
{
if (userbuf) {
if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
return -EFAULT;
} else
memcpy(buf, (vaddr + offset), csize);
return csize;
}
/**
* copy_oldmem_page - copy one page from "oldmem"
* @pfn: page frame number to be copied
* @buf: target memory address for the copy; this can be in kernel address
* space or user address space (see @userbuf)
* @csize: number of bytes to copy
* @offset: offset in bytes into the page (based on pfn) to begin the copy
* @userbuf: if set, @buf is in user address space, use copy_to_user(),
* otherwise @buf is in kernel address space, use memcpy().
*
* Copy a page from "oldmem". For this page, there is no pte mapped
* in the current kernel. We stitch up a pte, similar to kmap_atomic.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void *vaddr;
phys_addr_t paddr;
@ -107,10 +82,10 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
if (memblock_is_region_memory(paddr, csize)) {
vaddr = __va(paddr);
csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
csize = copy_to_iter(vaddr + offset, csize, iter);
} else {
vaddr = ioremap_cache(paddr, PAGE_SIZE);
csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
csize = copy_to_iter(vaddr + offset, csize, iter);
iounmap(vaddr);
}

26
arch/riscv/kernel/crash_dump.c
View file

@ -7,22 +7,10 @@
#include <linux/crash_dump.h>
#include <linux/io.h>
#include <linux/uio.h>
/**
* copy_oldmem_page() - copy one page from old kernel memory
* @pfn: page frame number to be copied
* @buf: buffer where the copied page is placed
* @csize: number of bytes to copy
* @offset: offset in bytes into the page
* @userbuf: if set, @buf is in a user address space
*
* This function copies one page from old kernel memory into buffer pointed by
* @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
* copied or negative error in case of failure.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset,
int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void *vaddr;
@ -33,13 +21,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
if (!vaddr)
return -ENOMEM;
if (userbuf) {
if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
memunmap(vaddr);
return -EFAULT;
}
} else
memcpy(buf, vaddr + offset, csize);
csize = copy_to_iter(vaddr + offset, csize, iter);
memunmap(vaddr);
return csize;

13
arch/s390/kernel/crash_dump.c
View file

@ -15,6 +15,7 @@
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/elf.h>
#include <linux/uio.h>
#include <asm/asm-offsets.h>
#include <asm/os_info.h>
#include <asm/elf.h>
@ -212,8 +213,8 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
/*
* Copy one page from "oldmem"
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
unsigned long offset)
{
unsigned long src;
int rc;
@ -221,10 +222,12 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
if (!csize)
return 0;
src = pfn_to_phys(pfn) + offset;
if (userbuf)
rc = copy_oldmem_user((void __force __user *) buf, src, csize);
/* XXX: pass the iov_iter down to a common function */
if (iter_is_iovec(iter))
rc = copy_oldmem_user(iter->iov->iov_base, src, csize);
else
rc = copy_oldmem_kernel((void *) buf, src, csize);
rc = copy_oldmem_kernel(iter->kvec->iov_base, src, csize);
return rc;
}

29
arch/sh/kernel/crash_dump.c
View file

@ -8,23 +8,11 @@
#include <linux/errno.h>
#include <linux/crash_dump.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
/**
* copy_oldmem_page - copy one page from "oldmem"
* @pfn: page frame number to be copied
* @buf: target memory address for the copy; this can be in kernel address
* space or user address space (see @userbuf)
* @csize: number of bytes to copy
* @offset: offset in bytes into the page (based on pfn) to begin the copy
* @userbuf: if set, @buf is in user address space, use copy_to_user(),
* otherwise @buf is in kernel address space, use memcpy().
*
* Copy a page from "oldmem". For this page, there is no pte mapped
* in the current kernel. We stitch up a pte, similar to kmap_atomic.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
void __iomem *vaddr;
@ -32,15 +20,8 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
return 0;
vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
if (userbuf) {
if (copy_to_user((void __user *)buf, (vaddr + offset), csize)) {
iounmap(vaddr);
return -EFAULT;
}
} else
memcpy(buf, (vaddr + offset), csize);
csize = copy_to_iter(vaddr + offset, csize, iter);
iounmap(vaddr);
return csize;
}

29
arch/x86/kernel/crash_dump_32.c
View file

@ -10,8 +10,7 @@
#include <linux/errno.h>
#include <linux/highmem.h>
#include <linux/crash_dump.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
static inline bool is_crashed_pfn_valid(unsigned long pfn)
{
@ -29,21 +28,8 @@ static inline bool is_crashed_pfn_valid(unsigned long pfn)
#endif
}
/**
* copy_oldmem_page - copy one page from "oldmem"
* @pfn: page frame number to be copied
* @buf: target memory address for the copy; this can be in kernel address
* space or user address space (see @userbuf)
* @csize: number of bytes to copy
* @offset: offset in bytes into the page (based on pfn) to begin the copy
* @userbuf: if set, @buf is in user address space, use copy_to_user(),
* otherwise @buf is in kernel address space, use memcpy().
*
* Copy a page from "oldmem". For this page, there might be no pte mapped
* in the current kernel.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
unsigned long offset)
{
void *vaddr;
@ -54,14 +40,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
return -EFAULT;
vaddr = kmap_local_pfn(pfn);
if (!userbuf) {
memcpy(buf, vaddr + offset, csize);
} else {
if (copy_to_user(buf, vaddr + offset, csize))
csize = -EFAULT;
}
csize = copy_to_iter(vaddr + offset, csize, iter);
kunmap_local(vaddr);
return csize;

41
arch/x86/kernel/crash_dump_64.c
View file

@ -8,12 +8,12 @@
#include <linux/errno.h>
#include <linux/crash_dump.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <linux/io.h>
#include <linux/cc_platform.h>
static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
unsigned long offset, int userbuf,
static ssize_t __copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset,
bool encrypted)
{
void *vaddr;
@ -29,46 +29,27 @@ static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
if (!vaddr)
return -ENOMEM;
if (userbuf) {
if (copy_to_user((void __user *)buf, vaddr + offset, csize)) {
iounmap((void __iomem *)vaddr);
return -EFAULT;
}
} else
memcpy(buf, vaddr + offset, csize);
csize = copy_to_iter(vaddr + offset, csize, iter);
iounmap((void __iomem *)vaddr);
return csize;
}
/**
* copy_oldmem_page - copy one page of memory
* @pfn: page frame number to be copied
* @buf: target memory address for the copy; this can be in kernel address
* space or user address space (see @userbuf)
* @csize: number of bytes to copy
* @offset: offset in bytes into the page (based on pfn) to begin the copy
* @userbuf: if set, @buf is in user address space, use copy_to_user(),
* otherwise @buf is in kernel address space, use memcpy().
*
* Copy a page from the old kernel's memory. For this page, there is no pte
* mapped in the current kernel. We stitch up a pte, similar to kmap_atomic.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
unsigned long offset, int userbuf)
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
unsigned long offset)
{
return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false);
return __copy_oldmem_page(iter, pfn, csize, offset, false);
}
/**
/*
* copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
* memory with the encryption mask set to accommodate kdump on SME-enabled
* machines.
*/
ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
unsigned long offset, int userbuf)
ssize_t copy_oldmem_page_encrypted(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset)
{
return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
return __copy_oldmem_page(iter, pfn, csize, offset, true);
}
ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)

54
fs/proc/vmcore.c
View file

@ -26,6 +26,7 @@
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <linux/cc_platform.h>
#include <asm/io.h>
#include "internal.h"
@ -128,9 +129,8 @@ static int open_vmcore(struct inode *inode, struct file *file)
}
/* Reads a page from the oldmem device from given offset. */
ssize_t read_from_oldmem(char *buf, size_t count,
u64 *ppos, int userbuf,
bool encrypted)
static ssize_t read_from_oldmem_iter(struct iov_iter *iter, size_t count,
u64 *ppos, bool encrypted)
{
unsigned long pfn, offset;
size_t nr_bytes;
@ -152,29 +152,23 @@ ssize_t read_from_oldmem(char *buf, size_t count,
/* If pfn is not ram, return zeros for sparse dump files */
if (!pfn_is_ram(pfn)) {
tmp = 0;
if (!userbuf)
memset(buf, 0, nr_bytes);
else if (clear_user(buf, nr_bytes))
tmp = -EFAULT;
tmp = iov_iter_zero(nr_bytes, iter);
} else {
if (encrypted)
tmp = copy_oldmem_page_encrypted(pfn, buf,
tmp = copy_oldmem_page_encrypted(iter, pfn,
nr_bytes,
offset,
userbuf);
offset);
else
tmp = copy_oldmem_page(pfn, buf, nr_bytes,
offset, userbuf);
tmp = copy_oldmem_page(iter, pfn, nr_bytes,
offset);
}
if (tmp < 0) {
if (tmp < nr_bytes) {
srcu_read_unlock(&vmcore_cb_srcu, idx);
return tmp;
return -EFAULT;
}
*ppos += nr_bytes;
count -= nr_bytes;
buf += nr_bytes;
read += nr_bytes;
++pfn;
offset = 0;
@ -184,6 +178,27 @@ ssize_t read_from_oldmem(char *buf, size_t count,
return read;
}
ssize_t read_from_oldmem(char *buf, size_t count,
u64 *ppos, int userbuf,
bool encrypted)
{
struct iov_iter iter;
struct iovec iov;
struct kvec kvec;
if (userbuf) {
iov.iov_base = (__force void __user *)buf;
iov.iov_len = count;
iov_iter_init(&iter, READ, &iov, 1, count);
} else {
kvec.iov_base = buf;
kvec.iov_len = count;
iov_iter_kvec(&iter, READ, &kvec, 1, count);
}
return read_from_oldmem_iter(&iter, count, ppos, encrypted);
}
/*
* Architectures may override this function to allocate ELF header in 2nd kernel
*/
@ -228,11 +243,10 @@ int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
/*
* Architectures which support memory encryption override this.
*/
ssize_t __weak
copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
unsigned long offset, int userbuf)
ssize_t __weak copy_oldmem_page_encrypted(struct iov_iter *iter,
unsigned long pfn, size_t csize, unsigned long offset)
{
return copy_oldmem_page(pfn, buf, csize, offset, userbuf);
return copy_oldmem_page(iter, pfn, csize, offset);
}
/*

9
include/linux/crash_dump.h
View file

@ -24,11 +24,10 @@ extern int remap_oldmem_pfn_range(struct vm_area_struct *vma,
unsigned long from, unsigned long pfn,
unsigned long size, pgprot_t prot);
extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
unsigned long, int);
extern ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf,
size_t csize, unsigned long offset,
int userbuf);
ssize_t copy_oldmem_page(struct iov_iter *i, unsigned long pfn, size_t csize,
unsigned long offset);
ssize_t copy_oldmem_page_encrypted(struct iov_iter *iter, unsigned long pfn,
size_t csize, unsigned long offset);
void vmcore_cleanup(void);