On 07/03/2019 10:32, Jan Beulich wrote:
> generic.c: In function ‘print_mtrr_state’:
> generic.c:210:11: error: ‘%0*lx’ directive output between 1 and 1073741823
> bytes may cause result to exceed
> ‘INT_MAX’ [-Werror=format-overflow=]
> 210 | printk("%s %u base %0*"PRIx64"000 mask %0*"PRIx64"000 %s\n",
> | ^~~~~~~~~~~~~~~~~
> generic.c:210:44: note: format string is defined here
> 210 | printk("%s %u base %0*"PRIx64"000 mask %0*"PRIx64"000 %s\n",
> generic.c:210:11: note: directive argument in the range [0, 4503599627370495]
> 210 | printk("%s %u base %0*"PRIx64"000 mask %0*"PRIx64"000 %s\n",
> | ^~~~~~~~~~~~~~~~~
> generic.c:210:11: note: assuming directive output of 1 byte
>
> Restrict the width of the variable "width" controlling the number of
> address digits output.
>
> Reported-by: Charles Arnold <carn...@suse.com>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
This is because GCC doesn't know the value of paddr_bits, and has
concluded that
width = (paddr_bits - PAGE_SHIFT + 3) / 4;
can result in some insane values, which is true.
However, this logic to unnecessarily complicated for something which is
only printed in a verbose or error case.
I'd prefer this as an alternative:
diff --git a/xen/arch/x86/cpu/mtrr/generic.c b/xen/arch/x86/cpu/mtrr/generic.c
index 8f9cf1b..566396f 100644
--- a/xen/arch/x86/cpu/mtrr/generic.c
+++ b/xen/arch/x86/cpu/mtrr/generic.c
@@ -182,7 +182,6 @@ static void __init print_fixed(unsigned int base, unsigned
int step,
static void __init print_mtrr_state(const char *level)
{
unsigned int i;
- int width;
printk("%sMTRR default type: %s\n", level,
mtrr_attrib_to_str(mtrr_state.def_type));
@@ -203,14 +202,13 @@ static void __init print_mtrr_state(const char *level)
}
printk("%sMTRR variable ranges %sabled:\n", level,
mtrr_state.enabled ? "en" : "dis");
- width = (paddr_bits - PAGE_SHIFT + 3) / 4;
for (i = 0; i < num_var_ranges; ++i) {
if (mtrr_state.var_ranges[i].mask & MTRR_PHYSMASK_VALID)
- printk("%s %u base %0*"PRIx64"000 mask %0*"PRIx64"000
%s\n",
+ printk("%s %u base %013"PRIx64"000 mask
%013"PRIx64"000 %s\n",
level, i,
- width, mtrr_state.var_ranges[i].base >> 12,
- width, mtrr_state.var_ranges[i].mask >> 12,
+ mtrr_state.var_ranges[i].base >> 12,
+ mtrr_state.var_ranges[i].mask >> 12,
mtrr_attrib_to_str(mtrr_state.var_ranges[i].base
&
MTRR_PHYSBASE_TYPE_MASK));
else
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