x86/boot/compressed/64: Don't pre-map memory in KASLR code

With the page-fault handler in place, he identity mapping can be built
on-demand. So remove the code which manually creates the mappings and
unexport/remove the functions used for it.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-18-joro@8bytes.org

diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
index ecf9353..c63257b 100644 (file)
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -87,11 +87,9 @@ phys_addr_t physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
 static struct x86_mapping_info mapping_info;
 
 /*
- * Adds the specified range to what will become the new identity mappings.
- * Once all ranges have been added, the new mapping is activated by calling
- * finalize_identity_maps() below.
+ * Adds the specified range to the identity mappings.
  */
-void add_identity_map(unsigned long start, unsigned long size)
+static void add_identity_map(unsigned long start, unsigned long size)
 {
        unsigned long end = start + size;
 

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 8266286..b59547c 100644 (file)
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -397,8 +397,6 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
         */
        mem_avoid[MEM_AVOID_ZO_RANGE].start = input;
        mem_avoid[MEM_AVOID_ZO_RANGE].size = (output + init_size) - input;
-       add_identity_map(mem_avoid[MEM_AVOID_ZO_RANGE].start,
-                        mem_avoid[MEM_AVOID_ZO_RANGE].size);
 
        /* Avoid initrd. */
        initrd_start  = (u64)boot_params->ext_ramdisk_image << 32;
@@ -416,15 +414,11 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
                cmd_line_size = strnlen((char *)cmd_line, COMMAND_LINE_SIZE-1) + 1;
                mem_avoid[MEM_AVOID_CMDLINE].start = cmd_line;
                mem_avoid[MEM_AVOID_CMDLINE].size = cmd_line_size;
-               add_identity_map(mem_avoid[MEM_AVOID_CMDLINE].start,
-                                mem_avoid[MEM_AVOID_CMDLINE].size);
        }
 
        /* Avoid boot parameters. */
        mem_avoid[MEM_AVOID_BOOTPARAMS].start = (unsigned long)boot_params;
        mem_avoid[MEM_AVOID_BOOTPARAMS].size = sizeof(*boot_params);
-       add_identity_map(mem_avoid[MEM_AVOID_BOOTPARAMS].start,
-                        mem_avoid[MEM_AVOID_BOOTPARAMS].size);
 
        /* We don't need to set a mapping for setup_data. */
 
@@ -433,11 +427,6 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
 
        /* Enumerate the immovable memory regions */
        num_immovable_mem = count_immovable_mem_regions();
-
-#ifdef CONFIG_X86_VERBOSE_BOOTUP
-       /* Make sure video RAM can be used. */
-       add_identity_map(0, PMD_SIZE);
-#endif
 }
 
 /*
@@ -884,19 +873,8 @@ void choose_random_location(unsigned long input,
                warn("Physical KASLR disabled: no suitable memory region!");
        } else {
                /* Update the new physical address location. */
-               if (*output != random_addr) {
-                       add_identity_map(random_addr, output_size);
+               if (*output != random_addr)
                        *output = random_addr;
-               }
-
-               /*
-                * This loads the identity mapping page table.
-                * This should only be done if a new physical address
-                * is found for the kernel, otherwise we should keep
-                * the old page table to make it be like the "nokaslr"
-                * case.
-                */
-               finalize_identity_maps();
        }
 
 

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index f0e1991..9840c82 100644 (file)
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -98,17 +98,7 @@ static inline void choose_random_location(unsigned long input,
 #endif
 
 #ifdef CONFIG_X86_64
-void initialize_identity_maps(void);
-void add_identity_map(unsigned long start, unsigned long size);
-void finalize_identity_maps(void);
 extern unsigned char _pgtable[];
-#else
-static inline void initialize_identity_maps(void)
-{ }
-static inline void add_identity_map(unsigned long start, unsigned long size)
-{ }
-static inline void finalize_identity_maps(void)
-{ }
 #endif
 
 #ifdef CONFIG_EARLY_PRINTK