ARM/hw_breakpoint: Mark expected switch fall-throughs

Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_arch_parse':
arch/arm/kernel/hw_breakpoint.c:609:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
      ^
arch/arm/kernel/hw_breakpoint.c:611:2: note: here
  case 3:
  ^~~~
arch/arm/kernel/hw_breakpoint.c:613:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
      ^
arch/arm/kernel/hw_breakpoint.c:615:2: note: here
  default:
  ^~~~~~~
arch/arm/kernel/hw_breakpoint.c: In function 'arch_build_bp_info':
arch/arm/kernel/hw_breakpoint.c:544:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if ((hw->ctrl.type != ARM_BREAKPOINT_EXECUTE)
      ^
arch/arm/kernel/hw_breakpoint.c:547:2: note: here
  default:
  ^~~~~~~
In file included from include/linux/kernel.h:11,
                 from include/linux/list.h:9,
                 from include/linux/preempt.h:11,
                 from include/linux/hardirq.h:5,
                 from arch/arm/kernel/hw_breakpoint.c:16:
arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_pending':
include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
 # define unlikely(x) __builtin_expect(!!(x), 0)
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:136:2: note: in expansion of macro 'unlikely'
  unlikely(__ret_warn_on);     \
  ^~~~~~~~
arch/arm/kernel/hw_breakpoint.c:863:3: note: in expansion of macro 'WARN'
   WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
   ^~~~
arch/arm/kernel/hw_breakpoint.c:864:2: note: here
  case ARM_ENTRY_SYNC_WATCHPOINT:
  ^~~~
arch/arm/kernel/hw_breakpoint.c: In function 'core_has_os_save_restore':
arch/arm/kernel/hw_breakpoint.c:910:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (oslsr & ARM_OSLSR_OSLM0)
      ^
arch/arm/kernel/hw_breakpoint.c:912:2: note: here
  default:
  ^~~~~~~

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index af8b8e1..b0c195e 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -544,6 +544,7 @@ static int arch_build_bp_info(struct perf_event *bp,
                if ((hw->ctrl.type != ARM_BREAKPOINT_EXECUTE)
                        && max_watchpoint_len >= 8)
                        break;
+               /* Else, fall through */
        default:
                return -EINVAL;
        }
@@ -608,10 +609,12 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
                /* Allow halfword watchpoints and breakpoints. */
                if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
                        break;
+               /* Else, fall through */
        case 3:
                /* Allow single byte watchpoint. */
                if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
                        break;
+               /* Else, fall through */
        default:
                ret = -EINVAL;
                goto out;
@@ -861,6 +864,7 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
                break;
        case ARM_ENTRY_ASYNC_WATCHPOINT:
                WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
+               /* Fall through */
        case ARM_ENTRY_SYNC_WATCHPOINT:
                watchpoint_handler(addr, fsr, regs);
                break;
@@ -909,6 +913,7 @@ static bool core_has_os_save_restore(void)
                ARM_DBG_READ(c1, c1, 4, oslsr);
                if (oslsr & ARM_OSLSR_OSLM0)
                        return true;
+               /* Else, fall through */
        default:
                return false;
        }