1 files changed, 31 insertions, 26 deletions

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 515a3c44c11..d37ed3501e5 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -537,6 +537,17 @@ static int arch_build_bp_info(struct perf_event *bp)
                 return -EINVAL;
         }
 
+        /*
+         * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes.
+         * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported
+         * by the hardware and must be aligned to the appropriate number of
+         * bytes.
+         */
+        if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
+            info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
+            info->ctrl.len != ARM_BREAKPOINT_LEN_4)
+                return -EINVAL;
+
         /* Address */
         info->address = bp->attr.bp_addr;
 
@@ -561,7 +572,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 {
         struct arch_hw_breakpoint *info = counter_arch_bp(bp);
         int ret = 0;
-        u32 bytelen, max_len, offset, alignment_mask = 0x3;
+        u32 offset, alignment_mask = 0x3;
 
         /* Build the arch_hw_breakpoint. */
         ret = arch_build_bp_info(bp);
@@ -571,32 +582,27 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
         /* Check address alignment. */
         if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
                 alignment_mask = 0x7;
-        if (info->address & alignment_mask) {
-                /*
-                 * Try to fix the alignment. This may result in a length
-                 * that is too large, so we must check for that.
-                 */
-                bytelen = get_hbp_len(info->ctrl.len);
-                max_len = info->ctrl.type == ARM_BREAKPOINT_EXECUTE ? 4 :
-                                max_watchpoint_len;
-
-                if (max_len >= 8)
-                        offset = info->address & 0x7;
-                else
-                        offset = info->address & 0x3;
-
-                if (bytelen > (1 << ((max_len - (offset + 1)) >> 1))) {
-                        ret = -EFBIG;
-                        goto out;
-                }
-
-                info->ctrl.len <<= offset;
-                info->address &= ~offset;
-
-                pr_debug("breakpoint alignment fixup: length = 0x%x, "
-                        "address = 0x%x\n", info->ctrl.len, info->address);
+        offset = info->address & alignment_mask;
+        switch (offset) {
+        case 0:
+                /* Aligned */
+                break;
+        case 1:
+                /* Allow single byte watchpoint. */
+                if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
+                        break;
+        case 2:
+                /* Allow halfword watchpoints and breakpoints. */
+                if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
+                        break;
+        default:
+                ret = -EINVAL;
+                goto out;
         }
 
+        info->address &= ~alignment_mask;
+        info->ctrl.len <<= offset;
+
         /*
          * Currently we rely on an overflow handler to take
          * care of single-stepping the breakpoint when it fires.
@@ -607,7 +613,6 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
                 (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_bps()),
                         "overflow handler required but none found")) {
                 ret = -EINVAL;
-                goto out;
         }
 out:
         return ret;