um: Replace to_phys() and to_virt() with less generic function names

The UML function names to_virt() and to_phys() are exposed by UML
headers, and are very generic and may be defined by drivers.  As it
turns out, commit 9409c9b ("pmem: refactor pmem_clear_poison()")
did exactly that.

This results in build errors such as the following when trying to build
um:allmodconfig:

  drivers/nvdimm/pmem.c: In function ‘pmem_dax_zero_page_range’:
  ./arch/um/include/asm/page.h:105:20: error: too few arguments to function ‘to_phys’
    105 | #define __pa(virt) to_phys((void *) (unsigned long) (virt))
        |                    ^~~~~~~

Use less generic function names for the um specific to_phys() and
to_virt() functions to fix the problem and to avoid similar problems in
the future.

Fixes: 9409c9b ("pmem: refactor pmem_clear_poison()")
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: groeck

arch/um/include/asm/page.h

@@ -102,8 +102,8 @@ extern unsigned long uml_physmem;
  * casting is the right thing, but 32-bit UML can't have 64-bit virtual
  * addresses
  */
-#define __pa(virt) to_phys((void *) (unsigned long) (virt))
-#define __va(phys) to_virt((unsigned long) (phys))
+#define __pa(virt) uml_to_phys((void *) (unsigned long) (virt))
+#define __va(phys) uml_to_virt((unsigned long) (phys))
 
 #define phys_to_pfn(p) ((p) >> PAGE_SHIFT)
 #define pfn_to_phys(pfn) PFN_PHYS(pfn)

arch/um/include/shared/mem.h

@@ -9,12 +9,12 @@
 extern int phys_mapping(unsigned long phys, unsigned long long *offset_out);
 
 extern unsigned long uml_physmem;
-static inline unsigned long to_phys(void *virt)
+static inline unsigned long uml_to_phys(void *virt)
 {
 	return(((unsigned long) virt) - uml_physmem);
 }
 
-static inline void *to_virt(unsigned long phys)
+static inline void *uml_to_virt(unsigned long phys)
 {
 	return((void *) uml_physmem + phys);
 }

arch/um/os-Linux/skas/process.c

@@ -251,7 +251,7 @@ static int userspace_tramp(void *stack)
 	signal(SIGTERM, SIG_DFL);
 	signal(SIGWINCH, SIG_IGN);
 
-	fd = phys_mapping(to_phys(__syscall_stub_start), &offset);
+	fd = phys_mapping(uml_to_phys(__syscall_stub_start), &offset);
 	addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
 		      PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
 	if (addr == MAP_FAILED) {
@@ -261,7 +261,7 @@ static int userspace_tramp(void *stack)
 	}
 
 	if (stack != NULL) {
-		fd = phys_mapping(to_phys(stack), &offset);
+		fd = phys_mapping(uml_to_phys(stack), &offset);
 		addr = mmap((void *) STUB_DATA,
 			    UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
 			    MAP_FIXED | MAP_SHARED, fd, offset);
@@ -534,7 +534,7 @@ int copy_context_skas0(unsigned long new_stack, int pid)
 	struct stub_data *data = (struct stub_data *) current_stack;
 	struct stub_data *child_data = (struct stub_data *) new_stack;
 	unsigned long long new_offset;
-	int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
+	int new_fd = phys_mapping(uml_to_phys((void *)new_stack), &new_offset);
 
 	/*
 	 * prepare offset and fd of child's stack as argument for parent's