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Re: [Xen-devel] [RFC PATCH 1/4] cert:arch/arm: Add missing default labels to switch statements
Hi Oleksandr,
On 22/02/2019 09:57, Oleksandr Andrushchenko wrote:
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
It is required by MISRA [1] that every switch statement has a default
label as a measure of defensive programming technique.
The changes in this patch are to match MISRA C:2012: Rule 16.4
requirements.
[1] https://www.misra.org.uk/
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
---
xen/arch/arm/decode.c | 3 +++
xen/arch/arm/domain.c | 10 ++++++++++
xen/arch/arm/guest_walk.c | 2 ++
xen/arch/arm/mm.c | 3 +++
xen/arch/arm/p2m.c | 7 +++++++
xen/arch/arm/traps.c | 6 ++++++
xen/arch/arm/vsmc.c | 9 +++++++++
7 files changed, 40 insertions(+)
diff --git a/xen/arch/arm/decode.c b/xen/arch/arm/decode.c
index 8b1e15d11892..1ed37696d678 100644
--- a/xen/arch/arm/decode.c
+++ b/xen/arch/arm/decode.c
@@ -112,6 +112,9 @@ static int decode_thumb(register_t pc, struct hsr_dabt
*dabt)
case 3: /* Signed byte */
update_dabt(dabt, reg, 0, true);
break;
+ default:
+ ASSERT_UNREACHABLE();
+ goto bad_thumb;
Here the switch can only have 4 value (see opB & 0x3). They are handled
correctly, so not only it does not make much sense to me and it adds more
confusion to it.
}
break;
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 6dc633ed5048..ecb43736a7c3 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -439,6 +439,11 @@ unsigned long hypercall_create_continuation(
case 3: regs->x3 = arg; break;
case 4: regs->x4 = arg; break;
case 5: regs->x5 = arg; break;
+ /*
+ * arm_abi Hypercall Calling Convention:
s/arm_abi/ARM ABI/
+ * A hypercall can take up to 5 arguments.
+ */
+ default: BUG(); break;
This should be an ASSERT_UNREACHABLE here.
}
}
@@ -462,6 +467,11 @@ unsigned long hypercall_create_continuation(
case 3: regs->r3 = arg; break;
case 4: regs->r4 = arg; break;
case 5: regs->r5 = arg; break;
+ /*
+ * arm_abi Hypercall Calling Convention:
Ditto.
+ * A hypercall can take up to 5 arguments.
+ */
+ default: BUG(); break;
Ditto.
}
}
diff --git a/xen/arch/arm/guest_walk.c b/xen/arch/arm/guest_walk.c
index 7db7a7321b20..8c4be32b7ef8 100644
--- a/xen/arch/arm/guest_walk.c
+++ b/xen/arch/arm/guest_walk.c
@@ -101,6 +101,8 @@ static bool guest_walk_sd(const struct vcpu *v,
switch ( pte.walk.dt )
{
+ default:
+ /* Fall through. */
Similar to the first switch, we cover all the values here. So what does it
really bring us?
case L1DESC_INVALID:
return false;
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 01ae2cccc068..ba5bf5b2b3ba 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1112,6 +1112,9 @@ static void set_pte_flags_on_range(const char *p,
unsigned long l, enum mg mg)
pte.pt.xn = 0;
pte.pt.ro = 1;
break;
+ default:
+ pte.pt.valid = 0;
+ break;
This one, ...
}
write_pte(xen_xenmap + i, pte);
}
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index c38bd7e16e26..1e12dc0fd482 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -540,6 +540,10 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t,
p2m_access_t a)
case p2m_max_real_type:
BUG();
break;
+
+ default:
+ BUG();
+ break;
... this one and...
}
/* Then restrict with access permissions */
@@ -574,6 +578,9 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t,
p2m_access_t a)
e->p2m.read = e->p2m.write = 0;
e->p2m.xn = 1;
break;
+ default:
+ BUG();
+ break;
... this one is going to make much harder to extend the enum. TBH, I don't see
the issue of initializing before the switch with default invalid value and don't
add the default here.
}
}
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 8741aa1d59ce..42e1bd54d31f 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1306,6 +1306,10 @@ int do_bug_frame(const struct cpu_user_regs *regs,
vaddr_t pc)
show_execution_state(regs);
panic("Assertion '%s' failed at %s%s:%d\n",
predicate, prefix, filename, lineno);
+ break;
+
+ default:
+ break;
As all the other case panic or return an error, you can move "return -EINVAL"
here.
}
return -EINVAL;
@@ -1972,6 +1976,8 @@ static void do_trap_stage2_abort_guest(struct
cpu_user_regs *regs,
advance_pc(regs, hsr);
return;
case IO_UNHANDLED:
+ /* Fall through. */
+ default:
/* IO unhandled, try another way to handle it. */
break;
}
diff --git a/xen/arch/arm/vsmc.c b/xen/arch/arm/vsmc.c
index c72b9a04ff76..9eabed89f9c5 100644
--- a/xen/arch/arm/vsmc.c
+++ b/xen/arch/arm/vsmc.c
@@ -109,6 +109,8 @@ static bool handle_arch(struct cpu_user_regs *regs)
case ARM_SMCCC_ARCH_WORKAROUND_2_FID:
switch ( get_ssbd_state() )
{
+ default:
+ /* Fall through. */
Similar question to the p2m case here.
case ARM_SSBD_UNKNOWN:
case ARM_SSBD_FORCE_DISABLE:
break;
@@ -123,6 +125,8 @@ static bool handle_arch(struct cpu_user_regs *regs)
break;
}
break;
+ default:
+ break;
This kind of construct is very questionable. It adds 2 lines for the only
benefits to tell MISRA tools to shut up.
}
set_user_reg(regs, 0, ret);
@@ -152,6 +156,9 @@ static bool handle_arch(struct cpu_user_regs *regs)
return true;
}
+
+ default:
+ break;
Same here.
}
return false;
@@ -276,6 +283,8 @@ static bool vsmccc_handle_call(struct cpu_user_regs *regs)
case ARM_SMCCC_OWNER_SIP:
handled = platform_smc(regs);
break;
+ default:
+ break;
Same here.
}
}
Cheers,
--
Julien Grall
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