[XEN,v3,07/12] x86/hvm: address violations of MISRA C Rule 16.3

Commit Message

Federico Serafini June 26, 2024, 9:28 a.m. UTC

MISRA C Rule 16.3 states that "An unconditional `break' statement shall
terminate every switch-clause".

Add pseudo keyword fallthrough or missing break statement
to address violations of the rule.

As a defensive measure, return -EOPNOTSUPP in case an unreachable
return statement is reached.

Signed-off-by: Federico Serafini <[e-mail]>
---
Changes in v3:
- squashed here modifications of pmtimer.c;
- no blank line after fallthrough;
- better indentation of fallthrough.
---
 xen/arch/x86/hvm/emulate.c   | 9 ++++++---
 xen/arch/x86/hvm/hvm.c       | 5 +++++
 xen/arch/x86/hvm/hypercall.c | 1 +
 xen/arch/x86/hvm/irq.c       | 1 +
 xen/arch/x86/hvm/pmtimer.c   | 1 +
 5 files changed, 14 insertions(+), 3 deletions(-)

Comments

Stefano Stabellini June 27, 2024, 12:55 a.m. UTC | #1

On Wed, 26 Jun 2024, Federico Serafini wrote:
> MISRA C Rule 16.3 states that "An unconditional `break' statement shall
> terminate every switch-clause".
> 
> Add pseudo keyword fallthrough or missing break statement
> to address violations of the rule.
> 
> As a defensive measure, return -EOPNOTSUPP in case an unreachable
> return statement is reached.
> 
> Signed-off-by: Federico Serafini <[e-mail]>

Aside from the ASSERT_UNREACHABLE which is still under discussion:

Reviewed-by: Stefano Stabellini <[e-mail]>

Patch

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 02e378365b..f5dd08f510 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -339,7 +339,7 @@  static int hvmemul_do_io(
     }
     case X86EMUL_UNIMPLEMENTED:
         ASSERT_UNREACHABLE();
-        /* Fall-through */
+        fallthrough;
     default:
         BUG();
     }
@@ -2674,6 +2674,7 @@  static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
 
     default:
         ASSERT_UNREACHABLE();
+        break;
     }
 
     if ( hvmemul_ctxt->ctxt.retire.singlestep )
@@ -2764,6 +2765,7 @@  int hvm_emulate_one_mmio(unsigned long mfn, unsigned long gla)
         /* fallthrough */
     default:
         hvm_emulate_writeback(&ctxt);
+        break;
     }
 
     return rc;
@@ -2798,11 +2800,12 @@  void hvm_emulate_one_vm_event(enum emul_kind kind, unsigned int trapnr,
         hvio->mmio_insn_bytes = sizeof(hvio->mmio_insn);
         memcpy(hvio->mmio_insn, curr->arch.vm_event->emul.insn.data,
                hvio->mmio_insn_bytes);
+        fallthrough;
     }
-    /* Fall-through */
     default:
         ctx.set_context = (kind == EMUL_KIND_SET_CONTEXT_DATA);
         rc = hvm_emulate_one(&ctx, VIO_no_completion);
+        break;
     }
 
     switch ( rc )
@@ -2818,7 +2821,7 @@  void hvm_emulate_one_vm_event(enum emul_kind kind, unsigned int trapnr,
     case X86EMUL_UNIMPLEMENTED:
         if ( hvm_monitor_emul_unimplemented() )
             return;
-        /* fall-through */
+        fallthrough;
     case X86EMUL_UNHANDLEABLE:
         hvm_dump_emulation_state(XENLOG_G_DEBUG, "Mem event", &ctx, rc);
         hvm_inject_hw_exception(trapnr, errcode);
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 7f4b627b1f..d7f195ba9a 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4919,6 +4919,8 @@  static int do_altp2m_op(
 
     default:
         ASSERT_UNREACHABLE();
+        rc = -EOPNOTSUPP;
+        break;
     }
 
  out:
@@ -5020,6 +5022,8 @@  static int compat_altp2m_op(
 
     default:
         ASSERT_UNREACHABLE();
+        rc = -EOPNOTSUPP;
+        break;
     }
 
     return rc;
@@ -5283,6 +5287,7 @@  void hvm_get_segment_register(struct vcpu *v, enum x86_segment seg,
          * %cs and %tr are unconditionally present.  SVM ignores these present
          * bits and will happily run without them set.
          */
+        fallthrough;
     case x86_seg_cs:
         reg->p = 1;
         break;
diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index 7fb3136f0c..2271afe02a 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -111,6 +111,7 @@  int hvm_hypercall(struct cpu_user_regs *regs)
     case 8:
         eax = regs->rax;
         /* Fallthrough to permission check. */
+        fallthrough;
     case 4:
     case 2:
         if ( currd->arch.monitor.guest_request_userspace_enabled &&
diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c
index 210cebb0e6..1eab44defc 100644
--- a/xen/arch/x86/hvm/irq.c
+++ b/xen/arch/x86/hvm/irq.c
@@ -282,6 +282,7 @@  static void hvm_set_callback_irq_level(struct vcpu *v)
             __hvm_pci_intx_assert(d, pdev, pintx);
         else
             __hvm_pci_intx_deassert(d, pdev, pintx);
+        break;
     default:
         break;
     }
diff --git a/xen/arch/x86/hvm/pmtimer.c b/xen/arch/x86/hvm/pmtimer.c
index 97099ac305..87a7a01c9f 100644
--- a/xen/arch/x86/hvm/pmtimer.c
+++ b/xen/arch/x86/hvm/pmtimer.c
@@ -185,6 +185,7 @@  static int cf_check handle_evt_io(
                 gdprintk(XENLOG_WARNING, 
                          "Bad ACPI PM register write: %x bytes (%x) at %x\n", 
                          bytes, *val, port);
+                break;
             }
         }
         /* Fix up the SCI state to match the new register state */