vmcore: Convert copy_oldmem_page() to take an iov_iter

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.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

arch/arm/kernel/crash_dump.c

@@ -27,9 +27,8 @@
  * @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 +39,7 @@ 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

@@ -25,9 +25,8 @@
  * @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 +37,7 @@ 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

@@ -31,21 +31,15 @@
  * 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

@@ -15,23 +15,16 @@
  * 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;
 
 	if (!csize)
 		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

@@ -68,18 +68,6 @@ 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
@@ -93,8 +81,8 @@ static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  * 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 +95,10 @@ 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);
 	}
 

arch/riscv/kernel/crash_dump.c

@@ -20,9 +20,8 @@
  * @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 +32,7 @@ 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;

arch/s390/kernel/crash_dump.c

@@ -214,19 +214,21 @@ static int copy_oldmem_user(void __user *dst, void *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)
 {
 	void *src;
 	int rc;
 
 	if (!csize)
 		return 0;
 	src = (void *) (pfn << PAGE_SHIFT) + 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;
 }
 

arch/sh/kernel/crash_dump.c

@@ -23,24 +23,17 @@
  * 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;
 
 	if (!csize)
 		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;
 }

arch/x86/kernel/crash_dump_32.c

@@ -42,8 +42,8 @@ static inline bool is_crashed_pfn_valid(unsigned long pfn)
  * 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 +54,7 @@ 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;

arch/x86/kernel/crash_dump_64.c

@@ -12,8 +12,8 @@
 #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;
@@ -29,13 +29,7 @@ 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);
 
 	set_iounmap_nonlazy();
 	iounmap((void __iomem *)vaddr);
@@ -55,21 +49,21 @@ static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
  * 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)