x86: Fix instruction breakpoint encoding

[mv-sheeva.git] / arch / x86 / kernel / hw_breakpoint.c

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index a8f1b803d2fd916c7aacf4952ff33b620f790852..ff15c9dcc25de8be8144fd4d15f1dfd3069314e4 100644 (file)
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -206,6 +206,25 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp)
 int arch_bp_generic_fields(int x86_len, int x86_type,
                           int *gen_len, int *gen_type)
 {
+       /* Type */
+       switch (x86_type) {
+       case X86_BREAKPOINT_EXECUTE:
+               if (x86_len != X86_BREAKPOINT_LEN_X)
+                       return -EINVAL;
+
+               *gen_type = HW_BREAKPOINT_X;
+               *gen_len = sizeof(long);
+               return 0;
+       case X86_BREAKPOINT_WRITE:
+               *gen_type = HW_BREAKPOINT_W;
+               break;
+       case X86_BREAKPOINT_RW:
+               *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
+               break;
+       default:
+               return -EINVAL;
+       }
+
        /* Len */
        switch (x86_len) {
        case X86_BREAKPOINT_LEN_1:
@@ -226,21 +245,6 @@ int arch_bp_generic_fields(int x86_len, int x86_type,
                return -EINVAL;
        }
 
-       /* Type */
-       switch (x86_type) {
-       case X86_BREAKPOINT_EXECUTE:
-               *gen_type = HW_BREAKPOINT_X;
-               break;
-       case X86_BREAKPOINT_WRITE:
-               *gen_type = HW_BREAKPOINT_W;
-               break;
-       case X86_BREAKPOINT_RW:
-               *gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
-               break;
-       default:
-               return -EINVAL;
-       }
-
        return 0;
 }
 
@@ -251,6 +255,29 @@ static int arch_build_bp_info(struct perf_event *bp)
 
        info->address = bp->attr.bp_addr;
 
+       /* Type */
+       switch (bp->attr.bp_type) {
+       case HW_BREAKPOINT_W:
+               info->type = X86_BREAKPOINT_WRITE;
+               break;
+       case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+               info->type = X86_BREAKPOINT_RW;
+               break;
+       case HW_BREAKPOINT_X:
+               info->type = X86_BREAKPOINT_EXECUTE;
+               /*
+                * x86 inst breakpoints need to have a specific undefined len.
+                * But we still need to check userspace is not trying to setup
+                * an unsupported length, to get a range breakpoint for example.
+                */
+               if (bp->attr.bp_len == sizeof(long)) {
+                       info->len = X86_BREAKPOINT_LEN_X;
+                       return 0;
+               }
+       default:
+               return -EINVAL;
+       }
+
        /* Len */
        switch (bp->attr.bp_len) {
        case HW_BREAKPOINT_LEN_1:
@@ -271,21 +298,6 @@ static int arch_build_bp_info(struct perf_event *bp)
                return -EINVAL;
        }
 
-       /* Type */
-       switch (bp->attr.bp_type) {
-       case HW_BREAKPOINT_W:
-               info->type = X86_BREAKPOINT_WRITE;
-               break;
-       case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
-               info->type = X86_BREAKPOINT_RW;
-               break;
-       case HW_BREAKPOINT_X:
-               info->type = X86_BREAKPOINT_EXECUTE;
-               break;
-       default:
-               return -EINVAL;
-       }
-
        return 0;
 }
 /*
@@ -466,6 +478,13 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
 
                perf_bp_event(bp, args->regs);
 
+               /*
+                * Set up resume flag to avoid breakpoint recursion when
+                * returning back to origin.
+                */
+               if (bp->hw.info.type == X86_BREAKPOINT_EXECUTE)
+                       args->regs->flags |= X86_EFLAGS_RF;
+
                rcu_read_unlock();
        }
        /*