um: Remove obsolete fixmap support

It was added to support highmem. But since the highmem support has
been removed by commit a98a6d8 ("um: Remove broken highmem
support"), it is no longer needed. Remove it to simplify the code.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20241128081939.2216246-3-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: btw616

arch/um/include/asm/fixmap.h

@@ -8,8 +8,6 @@
 #ifndef __UM_PGTABLE_H
 #define __UM_PGTABLE_H
 
-#include <asm/fixmap.h>
-
 #define _PAGE_PRESENT	0x001
 #define _PAGE_NEEDSYNC	0x002
 #define _PAGE_RW	0x020
@@ -48,8 +46,7 @@ extern unsigned long end_iomem;
 
 #define VMALLOC_OFFSET	(__va_space)
 #define VMALLOC_START ((end_iomem + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
-#define PKMAP_BASE ((FIXADDR_START - LAST_PKMAP * PAGE_SIZE) & PMD_MASK)
-#define VMALLOC_END	(FIXADDR_START-2*PAGE_SIZE)
+#define VMALLOC_END	(TASK_SIZE-2*PAGE_SIZE)
 #define MODULES_VADDR	VMALLOC_START
 #define MODULES_END	VMALLOC_END
 

arch/um/include/asm/pgtable.h

@@ -9,7 +9,6 @@
 #include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/slab.h>
-#include <asm/fixmap.h>
 #include <asm/page.h>
 #include <asm/pgalloc.h>
 #include <as-layout.h>
@@ -74,6 +73,7 @@ void __init mem_init(void)
 	kmalloc_ok = 1;
 }
 
+#if IS_ENABLED(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA)
 /*
  * Create a page table and place a pointer to it in a middle page
  * directory entry.
@@ -152,7 +152,6 @@ static void __init fixrange_init(unsigned long start, unsigned long end,
 
 static void __init fixaddr_user_init( void)
 {
-#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 	long size = FIXADDR_USER_END - FIXADDR_USER_START;
 	pte_t *pte;
 	phys_t p;
@@ -174,13 +173,12 @@ static void __init fixaddr_user_init( void)
 		pte = virt_to_kpte(vaddr);
 		pte_set_val(*pte, p, PAGE_READONLY);
 	}
-#endif
 }
+#endif
 
 void __init paging_init(void)
 {
 	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
-	unsigned long vaddr;
 
 	empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 							       PAGE_SIZE);
@@ -191,14 +189,9 @@ void __init paging_init(void)
 	max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
 	free_area_init(max_zone_pfn);
 
-	/*
-	 * Fixed mappings, only the page table structure has to be
-	 * created - mappings will be set by set_fixmap():
-	 */
-	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
-	fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
-
+#if IS_ENABLED(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA)
 	fixaddr_user_init();
+#endif
 }
 
 /*