ARM: 7408/1: cacheflush: return error to userspace when flushing syscall fails

The cacheflush syscall can fail for two reasons:

(1) The arguments are invalid (nonsensical address range or no VMA)

(2) The region generates a translation fault on a VIPT or PIPT cache

This patch allows do_cache_op to return an error code to userspace in
the case of the above. The various coherent_user_range implementations
are modified to return 0 in the case of VIVT caches or -EFAULT in the
case of an abort on v6/v7 cores.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 5 insertions, 6 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 63d402f75e2..3647170e9a1 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -479,14 +479,14 @@ static int bad_syscall(int n, struct pt_regs *regs)
         return regs->ARM_r0;
 }
 
-static inline void
+static inline int
 do_cache_op(unsigned long start, unsigned long end, int flags)
 {
         struct mm_struct *mm = current->active_mm;
         struct vm_area_struct *vma;
 
         if (end < start || flags)
-                return;
+                return -EINVAL;
 
         down_read(&mm->mmap_sem);
         vma = find_vma(mm, start);
@@ -497,10 +497,10 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
                         end = vma->vm_end;
 
                 up_read(&mm->mmap_sem);
-                flush_cache_user_range(start, end);
-                return;
+                return flush_cache_user_range(start, end);
         }
         up_read(&mm->mmap_sem);
+        return -EINVAL;
 }
 
 /*
@@ -546,8 +546,7 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
          * the specified region).
          */
         case NR(cacheflush):
-                do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
-                return 0;
+                return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
 
         case NR(usr26):
                 if (!(elf_hwcap & HWCAP_26BIT))