Re: [PATCH] s390: add unreachable() to dump_fault_info() to fix -Wmaybe-uninitialized
On Fri, 17 May 2019 15:49:22 +0900
Masahiro Yamada wrote:
> When CONFIG_OPTIMIZE_INLINING is enabled for s390, I see this warning:
>
> arch/s390/mm/fault.c:127:15: warning: 'asce' may be used uninitialized in
> this function [-Wmaybe-uninitialized]
> switch (asce & _ASCE_TYPE_MASK) {
> arch/s390/mm/fault.c:177:16: note: 'asce' was declared here
> unsigned long asce;
> ^~~~
>
> If get_fault_type() is not inlined, the compiler cannot deduce that
> all the possible paths in the 'switch' statement are covered.
>
> Of course, we could mark get_fault_type() as __always_inline to get
> back the original behavior, but I do not think it sensible to force
> inlining just for the purpose of suppressing the warning. Since this
> is just a matter of warning, I want to keep as much room for compiler
> optimization as possible.
>
> I added unreachable() to teach the compiler that the 'default' label
> is unreachable.
>
> I got rid of the 'inline' marker. Even without the 'inline' hint,
> the compiler inlines functions based on its inlining heuristic.
>
> Fixes: 9012d011660e ("compiler: allow all arches to enable
> CONFIG_OPTIMIZE_INLINING")
> Signed-off-by: Masahiro Yamada
Added to our internal tree and I will add it to s390/linux soon. Thanks.
> ---
>
> arch/s390/mm/fault.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index c220399ae196..91ce03fd0c84 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -85,7 +85,7 @@ static inline int notify_page_fault(struct pt_regs *regs)
> * Find out which address space caused the exception.
> * Access register mode is impossible, ignore space == 3.
> */
> -static inline enum fault_type get_fault_type(struct pt_regs *regs)
> +static enum fault_type get_fault_type(struct pt_regs *regs)
> {
> unsigned long trans_exc_code;
>
> @@ -211,6 +211,8 @@ static void dump_fault_info(struct pt_regs *regs)
> asce = S390_lowcore.kernel_asce;
> pr_cont("kernel ");
> break;
> + default:
> + unreachable();
> }
> pr_cont("ASCE.\n");
> dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
Re: [PATCH] s390: add unreachable() to dump_fault_info() to fix -Wmaybe-uninitialized
On (05/17/19 15:49), Masahiro Yamada wrote:
[..]
> @@ -211,6 +211,8 @@ static void dump_fault_info(struct pt_regs *regs)
> asce = S390_lowcore.kernel_asce;
> pr_cont("kernel ");
> break;
> + default:
> + unreachable();
> }
> pr_cont("ASCE.\n");
> dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
Or have default fault type and asce?
Just an idea.
---
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index c220399ae196..876d71c31894 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -174,7 +174,8 @@ static void dump_pagetable(unsigned long asce, unsigned
long address)
static void dump_fault_info(struct pt_regs *regs)
{
- unsigned long asce;
+ unsigned long asce = S390_lowcore.kernel_asce;
+ char *type = "kernel ";
pr_alert("Failing address: %016lx TEID: %016lx\n",
regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
@@ -197,22 +198,18 @@ static void dump_fault_info(struct pt_regs *regs)
switch (get_fault_type(regs)) {
case USER_FAULT:
asce = S390_lowcore.user_asce;
- pr_cont("user ");
+ type = "user ";
break;
case VDSO_FAULT:
asce = S390_lowcore.vdso_asce;
- pr_cont("vdso ");
+ type = "vdso ";
break;
case GMAP_FAULT:
asce = ((struct gmap *) S390_lowcore.gmap)->asce;
- pr_cont("gmap ");
- break;
- case KERNEL_FAULT:
- asce = S390_lowcore.kernel_asce;
- pr_cont("kernel ");
+ type = "gmap ";
break;
}
- pr_cont("ASCE.\n");
+ pr_cont("%s ASCE.\n", type);
dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
}
[PATCH] s390: add unreachable() to dump_fault_info() to fix -Wmaybe-uninitialized
When CONFIG_OPTIMIZE_INLINING is enabled for s390, I see this warning:
arch/s390/mm/fault.c:127:15: warning: 'asce' may be used uninitialized in this
function [-Wmaybe-uninitialized]
switch (asce & _ASCE_TYPE_MASK) {
arch/s390/mm/fault.c:177:16: note: 'asce' was declared here
unsigned long asce;
^~~~
If get_fault_type() is not inlined, the compiler cannot deduce that
all the possible paths in the 'switch' statement are covered.
Of course, we could mark get_fault_type() as __always_inline to get
back the original behavior, but I do not think it sensible to force
inlining just for the purpose of suppressing the warning. Since this
is just a matter of warning, I want to keep as much room for compiler
optimization as possible.
I added unreachable() to teach the compiler that the 'default' label
is unreachable.
I got rid of the 'inline' marker. Even without the 'inline' hint,
the compiler inlines functions based on its inlining heuristic.
Fixes: 9012d011660e ("compiler: allow all arches to enable
CONFIG_OPTIMIZE_INLINING")
Signed-off-by: Masahiro Yamada
---
arch/s390/mm/fault.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index c220399ae196..91ce03fd0c84 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -85,7 +85,7 @@ static inline int notify_page_fault(struct pt_regs *regs)
* Find out which address space caused the exception.
* Access register mode is impossible, ignore space == 3.
*/
-static inline enum fault_type get_fault_type(struct pt_regs *regs)
+static enum fault_type get_fault_type(struct pt_regs *regs)
{
unsigned long trans_exc_code;
@@ -211,6 +211,8 @@ static void dump_fault_info(struct pt_regs *regs)
asce = S390_lowcore.kernel_asce;
pr_cont("kernel ");
break;
+ default:
+ unreachable();
}
pr_cont("ASCE.\n");
dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
--
2.17.1
