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authorMax Filippov2012-12-22 06:35:04 +0400
committerChris Zankel2013-02-23 19:12:53 -0800
commitde73b6b1bd7480301c8e8fbe58184448b1757945 (patch)
tree9aca0e26cfa96e18e1d353777349ee30cc25718d /arch/xtensa/kernel/syscall.c
parent475c32d0a1b836fc3798ea96cc334a4bfffec2cf (diff)
xtensa: avoid mmap cache aliasing
Provide arch_get_unmapped_area function aligning shared memory mapping addresses to the biggest of the page size or the cache way size. That guarantees that corresponding virtual addresses of shared mappings are cached by the same cache sets. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
Diffstat (limited to 'arch/xtensa/kernel/syscall.c')
-rw-r--r--arch/xtensa/kernel/syscall.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index 54fa8425cee2..5d3f7a119ed1 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -36,6 +36,10 @@ syscall_t sys_call_table[__NR_syscall_count] /* FIXME __cacheline_aligned */= {
#include <uapi/asm/unistd.h>
};
+#define COLOUR_ALIGN(addr, pgoff) \
+ ((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) + \
+ (((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
+
asmlinkage long xtensa_shmat(int shmid, char __user *shmaddr, int shmflg)
{
unsigned long ret;
@@ -52,3 +56,40 @@ asmlinkage long xtensa_fadvise64_64(int fd, int advice,
{
return sys_fadvise64_64(fd, offset, len, advice);
}
+
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ struct vm_area_struct *vmm;
+
+ if (flags & MAP_FIXED) {
+ /* We do not accept a shared mapping if it would violate
+ * cache aliasing constraints.
+ */
+ if ((flags & MAP_SHARED) &&
+ ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
+ return -EINVAL;
+ return addr;
+ }
+
+ if (len > TASK_SIZE)
+ return -ENOMEM;
+ if (!addr)
+ addr = TASK_UNMAPPED_BASE;
+
+ if (flags & MAP_SHARED)
+ addr = COLOUR_ALIGN(addr, pgoff);
+ else
+ addr = PAGE_ALIGN(addr);
+
+ for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
+ /* At this point: (!vmm || addr < vmm->vm_end). */
+ if (TASK_SIZE - len < addr)
+ return -ENOMEM;
+ if (!vmm || addr + len <= vmm->vm_start)
+ return addr;
+ addr = vmm->vm_end;
+ if (flags & MAP_SHARED)
+ addr = COLOUR_ALIGN(addr, pgoff);
+ }
+}