s390/maccess: fix semantics of memcpy_real() and its callers

There is a confusion with regard to the source address of
memcpy_real() and calling functions. While the declared
type for a source assumes a virtual address, in fact it
always called with physical address of the source.

This confusion led to bugs in copy_oldmem_kernel() and
copy_oldmem_user() functions, where __pa() macro applied
mistakenly to physical addresses. It does not lead to a
real issue, since virtual and physical addresses are
currently the same.

Fix both the bugs and memcpy_real() prototype by making
type of source address consistent to the function name
and the way it actually used.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/os_info.h

@@ -39,7 +39,7 @@ u32 os_info_csum(struct os_info *os_info);
 
 #ifdef CONFIG_CRASH_DUMP
 void *os_info_old_entry(int nr, unsigned long *size);
-int copy_oldmem_kernel(void *dst, void *src, size_t count);
+int copy_oldmem_kernel(void *dst, unsigned long src, size_t count);
 #else
 static inline void *os_info_old_entry(int nr, unsigned long *size)
 {

arch/s390/include/asm/processor.h

@@ -317,7 +317,7 @@ extern void (*s390_base_pgm_handler_fn)(void);
 
 #define ARCH_LOW_ADDRESS_LIMIT	0x7fffffffUL
 
-extern int memcpy_real(void *, void *, size_t);
+extern int memcpy_real(void *, unsigned long, size_t);
 extern void memcpy_absolute(void *, void *, size_t);
 
 #define mem_assign_absolute(dest, val) do {			\

arch/s390/include/asm/uaccess.h

@@ -279,7 +279,7 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo
 	return __clear_user(to, n);
 }
 
-int copy_to_user_real(void __user *dest, void *src, unsigned long count);
+int copy_to_user_real(void __user *dest, unsigned long src, unsigned long count);
 void *s390_kernel_write(void *dst, const void *src, size_t size);
 
 #define HAVE_GET_KERNEL_NOFAULT

arch/s390/kernel/crash_dump.c

@@ -132,28 +132,27 @@ static inline void *load_real_addr(void *addr)
 /*
  * Copy memory of the old, dumped system to a kernel space virtual address
  */
-int copy_oldmem_kernel(void *dst, void *src, size_t count)
+int copy_oldmem_kernel(void *dst, unsigned long src, size_t count)
 {
-	unsigned long from, len;
+	unsigned long len;
 	void *ra;
 	int rc;
 
 	while (count) {
-		from = __pa(src);
-		if (!oldmem_data.start && from < sclp.hsa_size) {
+		if (!oldmem_data.start && src < sclp.hsa_size) {
 			/* Copy from zfcp/nvme dump HSA area */
-			len = min(count, sclp.hsa_size - from);
-			rc = memcpy_hsa_kernel(dst, from, len);
+			len = min(count, sclp.hsa_size - src);
+			rc = memcpy_hsa_kernel(dst, src, len);
 			if (rc)
 				return rc;
 		} else {
 			/* Check for swapped kdump oldmem areas */
-			if (oldmem_data.start && from - oldmem_data.start < oldmem_data.size) {
-				from -= oldmem_data.start;
-				len = min(count, oldmem_data.size - from);
-			} else if (oldmem_data.start && from < oldmem_data.size) {
-				len = min(count, oldmem_data.size - from);
-				from += oldmem_data.start;
+			if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
+				src -= oldmem_data.start;
+				len = min(count, oldmem_data.size - src);
+			} else if (oldmem_data.start && src < oldmem_data.size) {
+				len = min(count, oldmem_data.size - src);
+				src += oldmem_data.start;
 			} else {
 				len = count;
 			}
@@ -163,7 +162,7 @@ int copy_oldmem_kernel(void *dst, void *src, size_t count)
 			} else {
 				ra = dst;
 			}
-			if (memcpy_real(ra, (void *) from, len))
+			if (memcpy_real(ra, src, len))
 				return -EFAULT;
 		}
 		dst += len;
@@ -176,31 +175,30 @@ int copy_oldmem_kernel(void *dst, void *src, size_t count)
 /*
  * Copy memory of the old, dumped system to a user space virtual address
  */
-static int copy_oldmem_user(void __user *dst, void *src, size_t count)
+static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
 {
-	unsigned long from, len;
+	unsigned long len;
 	int rc;
 
 	while (count) {
-		from = __pa(src);
-		if (!oldmem_data.start && from < sclp.hsa_size) {
+		if (!oldmem_data.start && src < sclp.hsa_size) {
 			/* Copy from zfcp/nvme dump HSA area */
-			len = min(count, sclp.hsa_size - from);
-			rc = memcpy_hsa_user(dst, from, len);
+			len = min(count, sclp.hsa_size - src);
+			rc = memcpy_hsa_user(dst, src, len);
 			if (rc)
 				return rc;
 		} else {
 			/* Check for swapped kdump oldmem areas */
-			if (oldmem_data.start && from - oldmem_data.start < oldmem_data.size) {
-				from -= oldmem_data.start;
-				len = min(count, oldmem_data.size - from);
-			} else if (oldmem_data.start && from < oldmem_data.size) {
-				len = min(count, oldmem_data.size - from);
-				from += oldmem_data.start;
+			if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
+				src -= oldmem_data.start;
+				len = min(count, oldmem_data.size - src);
+			} else if (oldmem_data.start && src < oldmem_data.size) {
+				len = min(count, oldmem_data.size - src);
+				src += oldmem_data.start;
 			} else {
 				len = count;
 			}
-			rc = copy_to_user_real(dst, (void *) from, count);
+			rc = copy_to_user_real(dst, src, count);
 			if (rc)
 				return rc;
 		}
@@ -217,12 +215,12 @@ static int copy_oldmem_user(void __user *dst, void *src, size_t count)
 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
 			 unsigned long offset, int userbuf)
 {
-	void *src;
+	unsigned long src;
 	int rc;
 
 	if (!csize)
 		return 0;
-	src = (void *) (pfn << PAGE_SHIFT) + offset;
+	src = pfn_to_phys(pfn) + offset;
 	if (userbuf)
 		rc = copy_oldmem_user((void __force __user *) buf, src, csize);
 	else
@@ -429,10 +427,10 @@ static void *nt_prpsinfo(void *ptr)
 static void *get_vmcoreinfo_old(unsigned long *size)
 {
 	char nt_name[11], *vmcoreinfo;
+	unsigned long addr;
 	Elf64_Nhdr note;
-	void *addr;
 
-	if (copy_oldmem_kernel(&addr, (void *)__LC_VMCORE_INFO, sizeof(addr)))
+	if (copy_oldmem_kernel(&addr, __LC_VMCORE_INFO, sizeof(addr)))
 		return NULL;
 	memset(nt_name, 0, sizeof(nt_name));
 	if (copy_oldmem_kernel(&note, addr, sizeof(note)))

arch/s390/kernel/os_info.c

@@ -91,7 +91,7 @@ static void os_info_old_alloc(int nr, int align)
 		goto fail;
 	}
 	buf_align = PTR_ALIGN(buf, align);
-	if (copy_oldmem_kernel(buf_align, (void *) addr, size)) {
+	if (copy_oldmem_kernel(buf_align, addr, size)) {
 		msg = "copy failed";
 		goto fail_free;
 	}
@@ -124,15 +124,14 @@ static void os_info_old_init(void)
 		return;
 	if (!oldmem_data.start)
 		goto fail;
-	if (copy_oldmem_kernel(&addr, (void *)__LC_OS_INFO, sizeof(addr)))
+	if (copy_oldmem_kernel(&addr, __LC_OS_INFO, sizeof(addr)))
 		goto fail;
 	if (addr == 0 || addr % PAGE_SIZE)
 		goto fail;
 	os_info_old = kzalloc(sizeof(*os_info_old), GFP_KERNEL);
 	if (!os_info_old)
 		goto fail;
-	if (copy_oldmem_kernel(os_info_old, (void *) addr,
-			       sizeof(*os_info_old)))
+	if (copy_oldmem_kernel(os_info_old, addr, sizeof(*os_info_old)))
 		goto fail_free;
 	if (os_info_old->magic != OS_INFO_MAGIC)
 		goto fail_free;

arch/s390/kernel/smp.c

@@ -670,7 +670,7 @@ static __init void smp_save_cpu_regs(struct save_area *sa, u16 addr,
 				     bool is_boot_cpu, void *regs)
 {
 	if (is_boot_cpu)
-		copy_oldmem_kernel(regs, (void *) __LC_FPREGS_SAVE_AREA, 512);
+		copy_oldmem_kernel(regs, __LC_FPREGS_SAVE_AREA, 512);
 	else
 		__pcpu_sigp_relax(addr, SIGP_STORE_STATUS_AT_ADDRESS, __pa(regs));
 	save_area_add_regs(sa, regs);

arch/s390/mm/maccess.c

@@ -121,7 +121,7 @@ static unsigned long __no_sanitize_address _memcpy_real(unsigned long dest,
 /*
  * Copy memory in real mode (kernel to kernel)
  */
-int memcpy_real(void *dest, void *src, size_t count)
+int memcpy_real(void *dest, unsigned long src, size_t count)
 {
 	unsigned long _dest  = (unsigned long)dest;
 	unsigned long _src   = (unsigned long)src;
@@ -173,7 +173,7 @@ void memcpy_absolute(void *dest, void *src, size_t count)
 /*
  * Copy memory from kernel (real) to user (virtual)
  */
-int copy_to_user_real(void __user *dest, void *src, unsigned long count)
+int copy_to_user_real(void __user *dest, unsigned long src, unsigned long count)
 {
 	int offs = 0, size, rc;
 	char *buf;

drivers/s390/char/zcore.c

@@ -229,8 +229,7 @@ static int __init zcore_reipl_init(void)
 		rc = memcpy_hsa_kernel(zcore_ipl_block, ipib_info.ipib,
 				       PAGE_SIZE);
 	else
-		rc = memcpy_real(zcore_ipl_block, (void *) ipib_info.ipib,
-				 PAGE_SIZE);
+		rc = memcpy_real(zcore_ipl_block, ipib_info.ipib, PAGE_SIZE);
 	if (rc || (__force u32)csum_partial(zcore_ipl_block, zcore_ipl_block->hdr.len, 0) !=
 	    ipib_info.checksum) {
 		TRACE("Checksum does not match\n");