LoongArch: Remove shm_align_mask and use SHMLBA instead

Both shm_align_mask and SHMLBA want to avoid cache alias. But they are
inconsistent: shm_align_mask is (PAGE_SIZE - 1) while SHMLBA is SZ_64K,
but PAGE_SIZE is not always equal to SZ_64K.

This may cause problems when shmat() twice. Fix this problem by removing
shm_align_mask and using SHMLBA (strictly SHMLBA - 1) instead.

Reported-by: Jiantao Shan <shanjiantao@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/mm/cache.c b/arch/loongarch/mm/cache.c
index 72685a48eaf084f61ce967bcd16fd0bb79bf9ce4..6be04d36ca0769658a2b52d25af50dd6ad7e07e0 100644 (file)
--- a/arch/loongarch/mm/cache.c
+++ b/arch/loongarch/mm/cache.c
@@ -156,7 +156,6 @@ void cpu_cache_init(void)
 
        current_cpu_data.cache_leaves_present = leaf;
        current_cpu_data.options |= LOONGARCH_CPU_PREFETCH;
-       shm_align_mask = PAGE_SIZE - 1;
 }
 
 static const pgprot_t protection_map[16] = {

diff --git a/arch/loongarch/mm/mmap.c b/arch/loongarch/mm/mmap.c
index fbe1a4856fc42d4f255d9e9c3a9e349c3fa09e9a..a9630a81b38abbfc575ea4174af049ccd5a9a888 100644 (file)
--- a/arch/loongarch/mm/mmap.c
+++ b/arch/loongarch/mm/mmap.c
@@ -8,12 +8,11 @@
 #include <linux/mm.h>
 #include <linux/mman.h>
 
-unsigned long shm_align_mask = PAGE_SIZE - 1;  /* Sane caches */
-EXPORT_SYMBOL(shm_align_mask);
+#define SHM_ALIGN_MASK (SHMLBA - 1)
 
-#define COLOUR_ALIGN(addr, pgoff)                              \
-       ((((addr) + shm_align_mask) & ~shm_align_mask) +        \
-        (((pgoff) << PAGE_SHIFT) & shm_align_mask))
+#define COLOUR_ALIGN(addr, pgoff)                      \
+       ((((addr) + SHM_ALIGN_MASK) & ~SHM_ALIGN_MASK)  \
+        + (((pgoff) << PAGE_SHIFT) & SHM_ALIGN_MASK))
 
 enum mmap_allocation_direction {UP, DOWN};
 
@@ -40,7 +39,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
                 * cache aliasing constraints.
                 */
                if ((flags & MAP_SHARED) &&
-                   ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask))
+                   ((addr - (pgoff << PAGE_SHIFT)) & SHM_ALIGN_MASK))
                        return -EINVAL;
                return addr;
        }
@@ -63,7 +62,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
        }
 
        info.length = len;
-       info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
+       info.align_mask = do_color_align ? (PAGE_MASK & SHM_ALIGN_MASK) : 0;
        info.align_offset = pgoff << PAGE_SHIFT;
 
        if (dir == DOWN) {