x86/kasan: Add helpers to align shadow addresses up and down

Add helpers to dedup code for aligning shadow address up/down to page
boundaries when translating an address to its shadow.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Link: https://lkml.kernel.org/r/20221110203504.1985010-5-seanjc@google.com

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index ad7872a..afc5e12 100644 (file)
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -316,22 +316,33 @@ void __init kasan_early_init(void)
        kasan_map_early_shadow(init_top_pgt);
 }
 
+static unsigned long kasan_mem_to_shadow_align_down(unsigned long va)
+{
+       unsigned long shadow = (unsigned long)kasan_mem_to_shadow((void *)va);
+
+       return round_down(shadow, PAGE_SIZE);
+}
+
+static unsigned long kasan_mem_to_shadow_align_up(unsigned long va)
+{
+       unsigned long shadow = (unsigned long)kasan_mem_to_shadow((void *)va);
+
+       return round_up(shadow, PAGE_SIZE);
+}
+
 void __init kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid)
 {
        unsigned long shadow_start, shadow_end;
 
-       shadow_start = (unsigned long)kasan_mem_to_shadow(va);
-       shadow_start = round_down(shadow_start, PAGE_SIZE);
-       shadow_end = (unsigned long)kasan_mem_to_shadow(va + size);
-       shadow_end = round_up(shadow_end, PAGE_SIZE);
-
+       shadow_start = kasan_mem_to_shadow_align_down((unsigned long)va);
+       shadow_end = kasan_mem_to_shadow_align_up((unsigned long)va + size);
        kasan_populate_shadow(shadow_start, shadow_end, nid);
 }
 
 void __init kasan_init(void)
 {
+       unsigned long shadow_cea_begin, shadow_cea_end;
        int i;
-       void *shadow_cea_begin, *shadow_cea_end;
 
        memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 
@@ -372,16 +383,9 @@ void __init kasan_init(void)
                map_range(&pfn_mapped[i]);
        }
 
-       shadow_cea_begin = (void *)CPU_ENTRY_AREA_BASE;
-       shadow_cea_begin = kasan_mem_to_shadow(shadow_cea_begin);
-       shadow_cea_begin = (void *)round_down(
-                       (unsigned long)shadow_cea_begin, PAGE_SIZE);
-
-       shadow_cea_end = (void *)(CPU_ENTRY_AREA_BASE +
-                                       CPU_ENTRY_AREA_MAP_SIZE);
-       shadow_cea_end = kasan_mem_to_shadow(shadow_cea_end);
-       shadow_cea_end = (void *)round_up(
-                       (unsigned long)shadow_cea_end, PAGE_SIZE);
+       shadow_cea_begin = kasan_mem_to_shadow_align_down(CPU_ENTRY_AREA_BASE);
+       shadow_cea_end = kasan_mem_to_shadow_align_up(CPU_ENTRY_AREA_BASE +
+                                                     CPU_ENTRY_AREA_MAP_SIZE);
 
        kasan_populate_early_shadow(
                kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
@@ -403,9 +407,9 @@ void __init kasan_init(void)
 
        kasan_populate_early_shadow(
                kasan_mem_to_shadow((void *)VMALLOC_END + 1),
-               shadow_cea_begin);
+               (void *)shadow_cea_begin);
 
-       kasan_populate_early_shadow(shadow_cea_end,
+       kasan_populate_early_shadow((void *)shadow_cea_end,
                        kasan_mem_to_shadow((void *)__START_KERNEL_map));
 
        kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),