sh: Calculate shm alignment at runtime.

Set the SHM alignment at runtime, based off of probed cache desc.
Optimize get_unmapped_area() to only colour align shared mappings.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

2 files changed, 39 insertions, 20 deletions

diff --git a/arch/sh/kernel/cpu/init.c b/arch/sh/kernel/cpu/init.c
index 731dd61419dd..bfb90eb0b7a6 100644
--- a/arch/sh/kernel/cpu/init.c
+++ b/arch/sh/kernel/cpu/init.c
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <asm/processor.h>
 #include <asm/uaccess.h>
+#include <asm/page.h>
 #include <asm/system.h>
 #include <asm/cacheflush.h>
 #include <asm/cache.h>
@@ -198,6 +199,10 @@ asmlinkage void __init sh_cpu_init(void)
         /* Init the cache */
         cache_init();
 
+        shm_align_mask = max_t(unsigned long,
+                               cpu_data->dcache.way_size - 1,
+                               PAGE_SIZE - 1);
+
         /* Disable the FPU */
         if (fpu_disabled) {
                 printk("FPU Disabled\n");
diff --git a/arch/sh/kernel/sys_sh.c b/arch/sh/kernel/sys_sh.c
index 0ee7bf4cb238..b68ff705f067 100644
--- a/arch/sh/kernel/sys_sh.c
+++ b/arch/sh/kernel/sys_sh.c
@@ -21,6 +21,7 @@
 #include <linux/mman.h>
 #include <linux/file.h>
 #include <linux/utsname.h>
+#include <linux/module.h>
 #include <asm/cacheflush.h>
 #include <asm/uaccess.h>
 #include <asm/ipc.h>
@@ -44,11 +45,16 @@ asmlinkage int sys_pipe(unsigned long r4, unsigned long r5,
         return error;
 }
 
-#if defined(HAVE_ARCH_UNMAPPED_AREA) && defined(CONFIG_MMU)
+unsigned long shm_align_mask = PAGE_SIZE - 1;   /* Sane caches */
+
+EXPORT_SYMBOL(shm_align_mask);
+
 /*
- * To avoid cache alias, we map the shard page with same color.
+ * To avoid cache aliases, we map the shared page with same color.
  */
-#define COLOUR_ALIGN(addr)      (((addr)+SHMLBA-1)&~(SHMLBA-1))
+#define COLOUR_ALIGN(addr, pgoff)                               \
+        ((((addr) + shm_align_mask) & ~shm_align_mask) +        \
+         (((pgoff) << PAGE_SHIFT) & shm_align_mask))
 
 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
         unsigned long len, unsigned long pgoff, unsigned long flags)
@@ -56,43 +62,52 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
         unsigned long start_addr;
+        int do_colour_align;
 
         if (flags & MAP_FIXED) {
                 /* We do not accept a shared mapping if it would violate
                  * cache aliasing constraints.
                  */
-                if ((flags & MAP_SHARED) && (addr & (SHMLBA - 1)))
+                if ((flags & MAP_SHARED) && (addr & shm_align_mask))
                         return -EINVAL;
                 return addr;
         }
 
-        if (len > TASK_SIZE)
+        if (unlikely(len > TASK_SIZE))
                 return -ENOMEM;
 
+        do_colour_align = 0;
+        if (filp || (flags & MAP_SHARED))
+                do_colour_align = 1;
+
         if (addr) {
-                if (flags & MAP_PRIVATE)
-                        addr = PAGE_ALIGN(addr);
+                if (do_colour_align)
+                        addr = COLOUR_ALIGN(addr, pgoff);
                 else
-                        addr = COLOUR_ALIGN(addr);
+                        addr = PAGE_ALIGN(addr);
+
                 vma = find_vma(mm, addr);
                 if (TASK_SIZE - len >= addr &&
                     (!vma || addr + len <= vma->vm_start))
                         return addr;
         }
-        if (len <= mm->cached_hole_size) {
+
+        if (len > mm->cached_hole_size) {
+                start_addr = addr = mm->free_area_cache;
+        } else {
                 mm->cached_hole_size = 0;
-                mm->free_area_cache = TASK_UNMAPPED_BASE;
+                start_addr = addr = TASK_UNMAPPED_BASE;
         }
-        if (flags & MAP_PRIVATE)
-                addr = PAGE_ALIGN(mm->free_area_cache);
-        else
-                addr = COLOUR_ALIGN(mm->free_area_cache);
-        start_addr = addr;
 
 full_search:
+        if (do_colour_align)
+                addr = COLOUR_ALIGN(addr, pgoff);
+        else
+                addr = PAGE_ALIGN(mm->free_area_cache);
+
         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
                 /* At this point:  (!vma || addr < vma->vm_end). */
-                if (TASK_SIZE - len < addr) {
+                if (unlikely(TASK_SIZE - len < addr)) {
                         /*
                          * Start a new search - just in case we missed
                          * some holes.
@@ -104,7 +119,7 @@ full_search:
                         }
                         return -ENOMEM;
                 }
-                if (!vma || addr + len <= vma->vm_start) {
+                if (likely(!vma || addr + len <= vma->vm_start)) {
                         /*
                          * Remember the place where we stopped the search:
                          */
@@ -115,11 +130,10 @@ full_search:
                         mm->cached_hole_size = vma->vm_start - addr;
 
                 addr = vma->vm_end;
-                if (!(flags & MAP_PRIVATE))
-                        addr = COLOUR_ALIGN(addr);
+                if (do_colour_align)
+                        addr = COLOUR_ALIGN(addr, pgoff);
         }
 }
-#endif
 
 static inline long
 do_mmap2(unsigned long addr, unsigned long len, unsigned long prot,