Commit faf4058b authored by Alexander Gordeev's avatar Alexander Gordeev Committed by Wen Zhiwei
Browse files

fs/proc/kcore.c: allow translation of physical memory addresses 

stable inclusion
from stable-v6.6.57
commit e5a0031c7965d7b61a898146adfc4fe375742e2d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IB2M97

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e5a0031c7965d7b61a898146adfc4fe375742e2d

--------------------------------

commit 3d5854d75e3187147613130561b58f0b06166172 upstream.

When /proc/kcore is read an attempt to read the first two pages results in
HW-specific page swap on s390 and another (so called prefix) pages are
accessed instead.  That leads to a wrong read.

Allow architecture-specific translation of memory addresses using
kc_xlate_dev_mem_ptr() and kc_unxlate_dev_mem_ptr() callbacks similarily
to /dev/mem xlate_dev_mem_ptr() and unxlate_dev_mem_ptr() callbacks.  That
way an architecture can deal with specific physical memory ranges.

Re-use the existing /dev/mem callback implementation on s390, which
handles the described prefix pages swapping correctly.

For other architectures the default callback is basically NOP.  It is
expected the condition (vaddr == __va(__pa(vaddr))) always holds true for
KCORE_RAM memory type.

Link: https://lkml.kernel.org/r/20240930122119.1651546-1-agordeev@linux.ibm.com


Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
Suggested-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarWen Zhiwei <wenzhiwei@kylinos.cn>
parent 6f27e5f7

arch/s390/include/asm/io.h

+2 −0
Original line number Diff line number Diff line
@@ -16,8 +16,10 @@ 
#include <asm/pci_io.h>



#define xlate_dev_mem_ptr xlate_dev_mem_ptr

#define kc_xlate_dev_mem_ptr xlate_dev_mem_ptr

void *xlate_dev_mem_ptr(phys_addr_t phys);

#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr

#define kc_unxlate_dev_mem_ptr unxlate_dev_mem_ptr

void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);



#define IO_SPACE_LIMIT 0

fs/proc/kcore.c

+34 −2
Original line number Diff line number Diff line
@@ -50,6 +50,20 @@ static struct proc_dir_entry *proc_root_kcore; 
#define	kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)

#endif



#ifndef kc_xlate_dev_mem_ptr

#define kc_xlate_dev_mem_ptr kc_xlate_dev_mem_ptr

static inline void *kc_xlate_dev_mem_ptr(phys_addr_t phys)

{

	return __va(phys);

}

#endif

#ifndef kc_unxlate_dev_mem_ptr

#define kc_unxlate_dev_mem_ptr kc_unxlate_dev_mem_ptr

static inline void kc_unxlate_dev_mem_ptr(phys_addr_t phys, void *virt)

{

}

#endif



static LIST_HEAD(kclist_head);

static DECLARE_RWSEM(kclist_lock);

static int kcore_need_update = 1;
@@ -471,6 +485,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) 
	while (buflen) {

		struct page *page;

		unsigned long pfn;

		phys_addr_t phys;

		void *__start;



		/*

		 * If this is the first iteration or the address is not within
@@ -537,7 +553,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) 
			}

			break;

		case KCORE_RAM:

			pfn = __pa(start) >> PAGE_SHIFT;

			phys = __pa(start);

			pfn =  phys >> PAGE_SHIFT;

			page = pfn_to_online_page(pfn);



			/*
@@ -556,13 +573,28 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) 
			fallthrough;

		case KCORE_VMEMMAP:

		case KCORE_TEXT:

			if (m->type == KCORE_RAM) {

				__start = kc_xlate_dev_mem_ptr(phys);

				if (!__start) {

					ret = -ENOMEM;

					if (iov_iter_zero(tsz, iter) != tsz)

						ret = -EFAULT;

					goto out;

				}

			} else {

				__start = (void *)start;

			}



			/*

			 * Sadly we must use a bounce buffer here to be able to

			 * make use of copy_from_kernel_nofault(), as these

			 * memory regions might not always be mapped on all

			 * architectures.

			 */

			if (copy_from_kernel_nofault(buf, (void *)start, tsz)) {

			ret = copy_from_kernel_nofault(buf, __start, tsz);

			if (m->type == KCORE_RAM)

				kc_unxlate_dev_mem_ptr(phys, __start);

			if (ret) {

				if (iov_iter_zero(tsz, iter) != tsz) {

					ret = -EFAULT;

					goto out;