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>

20 files changed, 35 insertions, 26 deletions

diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index 1252a2675ca..004c1bc95d2 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -101,7 +101,7 @@ struct cpu_cache_fns {
         void (*flush_user_range)(unsigned long, unsigned long, unsigned int);
 
         void (*coherent_kern_range)(unsigned long, unsigned long);
-        void (*coherent_user_range)(unsigned long, unsigned long);
+        int  (*coherent_user_range)(unsigned long, unsigned long);
         void (*flush_kern_dcache_area)(void *, size_t);
 
         void (*dma_map_area)(const void *, size_t, int);
@@ -142,7 +142,7 @@ extern void __cpuc_flush_kern_all(void);
 extern void __cpuc_flush_user_all(void);
 extern void __cpuc_flush_user_range(unsigned long, unsigned long, unsigned int);
 extern void __cpuc_coherent_kern_range(unsigned long, unsigned long);
-extern void __cpuc_coherent_user_range(unsigned long, unsigned long);
+extern int  __cpuc_coherent_user_range(unsigned long, unsigned long);
 extern void __cpuc_flush_dcache_area(void *, size_t);
 
 /*
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))
diff --git a/arch/arm/mm/cache-v3.S b/arch/arm/mm/cache-v3.S
index c2301f22610..52e35f32eef 100644
--- a/arch/arm/mm/cache-v3.S
+++ b/arch/arm/mm/cache-v3.S
@@ -78,6 +78,7 @@ ENTRY(v3_coherent_kern_range)
  *      - end    - virtual end address
  */
 ENTRY(v3_coherent_user_range)
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/cache-v4.S b/arch/arm/mm/cache-v4.S
index fd9bb7addc8..022135d2b7e 100644
--- a/arch/arm/mm/cache-v4.S
+++ b/arch/arm/mm/cache-v4.S
@@ -88,6 +88,7 @@ ENTRY(v4_coherent_kern_range)
  *      - end    - virtual end address
  */
 ENTRY(v4_coherent_user_range)
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/cache-v4wb.S b/arch/arm/mm/cache-v4wb.S
index 4f2c14151cc..8f1eeae340c 100644
--- a/arch/arm/mm/cache-v4wb.S
+++ b/arch/arm/mm/cache-v4wb.S
@@ -167,9 +167,9 @@ ENTRY(v4wb_coherent_user_range)
         add     r0, r0, #CACHE_DLINESIZE
         cmp     r0, r1
         blo     1b
-        mov     ip, #0
-        mcr     p15, 0, ip, c7, c5, 0           @ invalidate I cache
-        mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        mov     r0, #0
+        mcr     p15, 0, r0, c7, c5, 0           @ invalidate I cache
+        mcr     p15, 0, r0, c7, c10, 4          @ drain WB
         mov     pc, lr
 
 
diff --git a/arch/arm/mm/cache-v4wt.S b/arch/arm/mm/cache-v4wt.S
index 4d7b467631c..b34a5f908a8 100644
--- a/arch/arm/mm/cache-v4wt.S
+++ b/arch/arm/mm/cache-v4wt.S
@@ -125,6 +125,7 @@ ENTRY(v4wt_coherent_user_range)
         add     r0, r0, #CACHE_DLINESIZE
         cmp     r0, r1
         blo     1b
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/cache-v6.S b/arch/arm/mm/cache-v6.S
index 74c2e5a33a4..4b10760c56d 100644
--- a/arch/arm/mm/cache-v6.S
+++ b/arch/arm/mm/cache-v6.S
@@ -12,6 +12,7 @@
 #include <linux/linkage.h>
 #include <linux/init.h>
 #include <asm/assembler.h>
+#include <asm/errno.h>
 #include <asm/unwind.h>
 
 #include "proc-macros.S"
@@ -135,7 +136,6 @@ ENTRY(v6_coherent_user_range)
 1:
  USER(  mcr     p15, 0, r0, c7, c10, 1  )       @ clean D line
         add     r0, r0, #CACHE_LINE_SIZE
-2:
         cmp     r0, r1
         blo     1b
 #endif
@@ -154,13 +154,11 @@ ENTRY(v6_coherent_user_range)
 
 /*
  * Fault handling for the cache operation above. If the virtual address in r0
- * isn't mapped, just try the next page.
+ * isn't mapped, fail with -EFAULT.
  */
 9001:
-        mov     r0, r0, lsr #12
-        mov     r0, r0, lsl #12
-        add     r0, r0, #4096
-        b       2b
+        mov     r0, #-EFAULT
+        mov     pc, lr
  UNWIND(.fnend          )
 ENDPROC(v6_coherent_user_range)
 ENDPROC(v6_coherent_kern_range)
diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
index a655d3da386..39e3fb3db80 100644
--- a/arch/arm/mm/cache-v7.S
+++ b/arch/arm/mm/cache-v7.S
@@ -13,6 +13,7 @@
 #include <linux/linkage.h>
 #include <linux/init.h>
 #include <asm/assembler.h>
+#include <asm/errno.h>
 #include <asm/unwind.h>
 
 #include "proc-macros.S"
@@ -198,7 +199,6 @@ ENTRY(v7_coherent_user_range)
         add     r12, r12, r2
         cmp     r12, r1
         blo     2b
-3:
         mov     r0, #0
         ALT_SMP(mcr     p15, 0, r0, c7, c1, 6)  @ invalidate BTB Inner Shareable
         ALT_UP(mcr      p15, 0, r0, c7, c5, 6)  @ invalidate BTB
@@ -208,13 +208,11 @@ ENTRY(v7_coherent_user_range)
 
 /*
  * Fault handling for the cache operation above. If the virtual address in r0
- * isn't mapped, just try the next page.
+ * isn't mapped, fail with -EFAULT.
  */
 9001:
-        mov     r12, r12, lsr #12
-        mov     r12, r12, lsl #12
-        add     r12, r12, #4096
-        b       3b
+        mov     r0, #-EFAULT
+        mov     pc, lr
  UNWIND(.fnend          )
 ENDPROC(v7_coherent_kern_range)
 ENDPROC(v7_coherent_user_range)
diff --git a/arch/arm/mm/proc-arm1020.S b/arch/arm/mm/proc-arm1020.S
index 234951345eb..0650bb87c1e 100644
--- a/arch/arm/mm/proc-arm1020.S
+++ b/arch/arm/mm/proc-arm1020.S
@@ -241,6 +241,7 @@ ENTRY(arm1020_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm1020e.S b/arch/arm/mm/proc-arm1020e.S
index c244b06caac..4188478325a 100644
--- a/arch/arm/mm/proc-arm1020e.S
+++ b/arch/arm/mm/proc-arm1020e.S
@@ -235,6 +235,7 @@ ENTRY(arm1020e_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm1022.S b/arch/arm/mm/proc-arm1022.S
index 38fe22efd18..33c68824bff 100644
--- a/arch/arm/mm/proc-arm1022.S
+++ b/arch/arm/mm/proc-arm1022.S
@@ -224,6 +224,7 @@ ENTRY(arm1022_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm1026.S b/arch/arm/mm/proc-arm1026.S
index 3eb9c3c26c7..fbc1d5fc24d 100644
--- a/arch/arm/mm/proc-arm1026.S
+++ b/arch/arm/mm/proc-arm1026.S
@@ -218,6 +218,7 @@ ENTRY(arm1026_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm920.S b/arch/arm/mm/proc-arm920.S
index cb941ae95f6..1a8c138eb89 100644
--- a/arch/arm/mm/proc-arm920.S
+++ b/arch/arm/mm/proc-arm920.S
@@ -210,6 +210,7 @@ ENTRY(arm920_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm922.S b/arch/arm/mm/proc-arm922.S
index 4ec0e074dd5..4c44d7e1c3c 100644
--- a/arch/arm/mm/proc-arm922.S
+++ b/arch/arm/mm/proc-arm922.S
@@ -212,6 +212,7 @@ ENTRY(arm922_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm925.S b/arch/arm/mm/proc-arm925.S
index 9dccd9a365b..ec5b1180994 100644
--- a/arch/arm/mm/proc-arm925.S
+++ b/arch/arm/mm/proc-arm925.S
@@ -258,6 +258,7 @@ ENTRY(arm925_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm926.S b/arch/arm/mm/proc-arm926.S
index 820259b81a1..c31e62c606c 100644
--- a/arch/arm/mm/proc-arm926.S
+++ b/arch/arm/mm/proc-arm926.S
@@ -221,6 +221,7 @@ ENTRY(arm926_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm940.S b/arch/arm/mm/proc-arm940.S
index 9fdc0a17097..a613a7dd714 100644
--- a/arch/arm/mm/proc-arm940.S
+++ b/arch/arm/mm/proc-arm940.S
@@ -160,7 +160,7 @@ ENTRY(arm940_coherent_user_range)
  *      - size  - region size
  */
 ENTRY(arm940_flush_kern_dcache_area)
-        mov     ip, #0
+        mov     r0, #0
         mov     r1, #(CACHE_DSEGMENTS - 1) << 4 @ 4 segments
 1:      orr     r3, r1, #(CACHE_DENTRIES - 1) << 26 @ 64 entries
 2:      mcr     p15, 0, r3, c7, c14, 2          @ clean/flush D index
@@ -168,8 +168,8 @@ ENTRY(arm940_flush_kern_dcache_area)
         bcs     2b                              @ entries 63 to 0
         subs    r1, r1, #1 << 4
         bcs     1b                              @ segments 7 to 0
-        mcr     p15, 0, ip, c7, c5, 0           @ invalidate I cache
-        mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        mcr     p15, 0, r0, c7, c5, 0           @ invalidate I cache
+        mcr     p15, 0, r0, c7, c10, 4          @ drain WB
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-arm946.S b/arch/arm/mm/proc-arm946.S
index f684cfedcca..9f4f2999fdd 100644
--- a/arch/arm/mm/proc-arm946.S
+++ b/arch/arm/mm/proc-arm946.S
@@ -190,6 +190,7 @@ ENTRY(arm946_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-feroceon.S b/arch/arm/mm/proc-feroceon.S
index ba3c500584a..23a8e4c7f2b 100644
--- a/arch/arm/mm/proc-feroceon.S
+++ b/arch/arm/mm/proc-feroceon.S
@@ -232,6 +232,7 @@ ENTRY(feroceon_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*
diff --git a/arch/arm/mm/proc-mohawk.S b/arch/arm/mm/proc-mohawk.S
index cdfedc5b8ad..b0475468c71 100644
--- a/arch/arm/mm/proc-mohawk.S
+++ b/arch/arm/mm/proc-mohawk.S
@@ -193,6 +193,7 @@ ENTRY(mohawk_coherent_user_range)
         cmp     r0, r1
         blo     1b
         mcr     p15, 0, r0, c7, c10, 4          @ drain WB
+        mov     r0, #0
         mov     pc, lr
 
 /*