Commit 4a22fd20 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

vmcore: convert __read_vmcore to use an iov_iter 

This gets rid of copy_to() and let us use proc_read_iter() instead of
proc_read().

Link: https://lkml.kernel.org/r/20220408090636.560886-3-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>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5d8de293

fs/proc/vmcore.c

+30 −52
Original line number Diff line number Diff line
@@ -249,22 +249,8 @@ ssize_t __weak copy_oldmem_page_encrypted(struct iov_iter *iter, 
	return copy_oldmem_page(iter, pfn, csize, offset);

}



/*

 * Copy to either kernel or user space

 */

static int copy_to(void *target, void *src, size_t size, int userbuf)

{

	if (userbuf) {

		if (copy_to_user((char __user *) target, src, size))

			return -EFAULT;

	} else {

		memcpy(target, src, size);

	}

	return 0;

}



#ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP

static int vmcoredd_copy_dumps(void *dst, u64 start, size_t size, int userbuf)

static int vmcoredd_copy_dumps(struct iov_iter *iter, u64 start, size_t size)

{

	struct vmcoredd_node *dump;

	u64 offset = 0;
@@ -277,14 +263,13 @@ static int vmcoredd_copy_dumps(void *dst, u64 start, size_t size, int userbuf) 
		if (start < offset + dump->size) {

			tsz = min(offset + (u64)dump->size - start, (u64)size);

			buf = dump->buf + start - offset;

			if (copy_to(dst, buf, tsz, userbuf)) {

			if (copy_to_iter(buf, tsz, iter) < tsz) {

				ret = -EFAULT;

				goto out_unlock;

			}



			size -= tsz;

			start += tsz;

			dst += tsz;



			/* Leave now if buffer filled already */

			if (!size)
@@ -340,33 +325,28 @@ static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst, 
/* Read from the ELF header and then the crash dump. On error, negative value is

 * returned otherwise number of bytes read are returned.

 */

static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,

			     int userbuf)

static ssize_t __read_vmcore(struct iov_iter *iter, loff_t *fpos)

{

	ssize_t acc = 0, tmp;

	size_t tsz;

	u64 start;

	struct vmcore *m = NULL;



	if (buflen == 0 || *fpos >= vmcore_size)

	if (!iov_iter_count(iter) || *fpos >= vmcore_size)

		return 0;



	/* trim buflen to not go beyond EOF */

	if (buflen > vmcore_size - *fpos)

		buflen = vmcore_size - *fpos;

	iov_iter_truncate(iter, vmcore_size - *fpos);



	/* Read ELF core header */

	if (*fpos < elfcorebuf_sz) {

		tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen);

		if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf))

		tsz = min(elfcorebuf_sz - (size_t)*fpos, iov_iter_count(iter));

		if (copy_to_iter(elfcorebuf + *fpos, tsz, iter) < tsz)

			return -EFAULT;

		buflen -= tsz;

		*fpos += tsz;

		buffer += tsz;

		acc += tsz;



		/* leave now if filled buffer already */

		if (buflen == 0)

		if (!iov_iter_count(iter))

			return acc;

	}
@@ -387,35 +367,32 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos, 
		/* Read device dumps */

		if (*fpos < elfcorebuf_sz + vmcoredd_orig_sz) {

			tsz = min(elfcorebuf_sz + vmcoredd_orig_sz -

				  (size_t)*fpos, buflen);

				  (size_t)*fpos, iov_iter_count(iter));

			start = *fpos - elfcorebuf_sz;

			if (vmcoredd_copy_dumps(buffer, start, tsz, userbuf))

			if (vmcoredd_copy_dumps(iter, start, tsz))

				return -EFAULT;



			buflen -= tsz;

			*fpos += tsz;

			buffer += tsz;

			acc += tsz;



			/* leave now if filled buffer already */

			if (!buflen)

			if (!iov_iter_count(iter))

				return acc;

		}

#endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */



		/* Read remaining elf notes */

		tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen);

		tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos,

			  iov_iter_count(iter));

		kaddr = elfnotes_buf + *fpos - elfcorebuf_sz - vmcoredd_orig_sz;

		if (copy_to(buffer, kaddr, tsz, userbuf))

		if (copy_to_iter(kaddr, tsz, iter) < tsz)

			return -EFAULT;



		buflen -= tsz;

		*fpos += tsz;

		buffer += tsz;

		acc += tsz;



		/* leave now if filled buffer already */

		if (buflen == 0)

		if (!iov_iter_count(iter))

			return acc;

	}
@@ -423,19 +400,17 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos, 
		if (*fpos < m->offset + m->size) {

			tsz = (size_t)min_t(unsigned long long,

					    m->offset + m->size - *fpos,

					    buflen);

					    iov_iter_count(iter));

			start = m->paddr + *fpos - m->offset;

			tmp = read_from_oldmem(buffer, tsz, &start,

					       userbuf, cc_platform_has(CC_ATTR_MEM_ENCRYPT));

			tmp = read_from_oldmem_iter(iter, tsz, &start,

					cc_platform_has(CC_ATTR_MEM_ENCRYPT));

			if (tmp < 0)

				return tmp;

			buflen -= tsz;

			*fpos += tsz;

			buffer += tsz;

			acc += tsz;



			/* leave now if filled buffer already */

			if (buflen == 0)

			if (!iov_iter_count(iter))

				return acc;

		}

	}
@@ -443,15 +418,14 @@ static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos, 
	return acc;

}



static ssize_t read_vmcore(struct file *file, char __user *buffer,

			   size_t buflen, loff_t *fpos)

static ssize_t read_vmcore(struct kiocb *iocb, struct iov_iter *iter)

{

	return __read_vmcore((__force char *) buffer, buflen, fpos, 1);

	return __read_vmcore(iter, &iocb->ki_pos);

}



/*

 * The vmcore fault handler uses the page cache and fills data using the

 * standard __vmcore_read() function.

 * standard __read_vmcore() function.

 *

 * On s390 the fault handler is used for memory regions that can't be mapped

 * directly with remap_pfn_range().
@@ -461,9 +435,10 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf) 
#ifdef CONFIG_S390

	struct address_space *mapping = vmf->vma->vm_file->f_mapping;

	pgoff_t index = vmf->pgoff;

	struct iov_iter iter;

	struct kvec kvec;

	struct page *page;

	loff_t offset;

	char *buf;

	int rc;



	page = find_or_create_page(mapping, index, GFP_KERNEL);
@@ -471,8 +446,11 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf) 
		return VM_FAULT_OOM;

	if (!PageUptodate(page)) {

		offset = (loff_t) index << PAGE_SHIFT;

		buf = __va((page_to_pfn(page) << PAGE_SHIFT));

		rc = __read_vmcore(buf, PAGE_SIZE, &offset, 0);

		kvec.iov_base = page_address(page);

		kvec.iov_len = PAGE_SIZE;

		iov_iter_kvec(&iter, READ, &kvec, 1, PAGE_SIZE);



		rc = __read_vmcore(&iter, &offset);

		if (rc < 0) {

			unlock_page(page);

			put_page(page);
@@ -722,7 +700,7 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma) 


static const struct proc_ops vmcore_proc_ops = {

	.proc_open	= open_vmcore,

	.proc_read	= read_vmcore,

	.proc_read_iter	= read_vmcore,

	.proc_lseek	= default_llseek,

	.proc_mmap	= mmap_vmcore,

};