Commit 5d8de293 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

vmcore: convert copy_oldmem_page() to take an iov_iter 

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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarBaoquan He <bhe@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 04d168c6

arch/arm/kernel/crash_dump.c

+4 −23
Original line number Diff line number Diff line
@@ -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;

arch/arm64/kernel/crash_dump.c

+4 −25
Original line number Diff line number Diff line
@@ -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);

arch/ia64/kernel/crash_dump.c

+4 −28
Original line number Diff line number Diff line
@@ -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;

}

arch/mips/kernel/crash_dump.c

+4 −23
Original line number Diff line number Diff line 
// 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;

arch/powerpc/kernel/crash_dump.c

+5 −30
Original line number Diff line number Diff line
@@ -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);

	}