hw/intc/exynos4210_gic.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
exynos4210_gic_realize() prints the number of cpus into some temporary
buffers, but it only allows 3 bytes space for it. That's plenty:
existing machines will only ever set this value to EXYNOS4210_NCPUS
(2). But the compiler can't always figure that out, so some[*] gcc9
versions emit -Wformat-truncation warnings.
We can fix that by hinting the constraint to the compiler with a
suitably placed assert().
[*] The bizarre thing here, is that I've long gotten these warnings
compiling in a 32-bit x86 container as host - Fedora 30 with
gcc-9.2.1-1.fc30.i686 - but it compiles just fine on my normal
x86_64 host - Fedora 30 with and gcc-9.2.1-1.fc30.x86_64.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Peter, up to you if you squeeze this in for qemu-4.2 or leave it until 5.0
Changes since v2:
* Moved the assert outside the for loop using a trick suggested by
Richard Henderson
Changes since v1:
* Used an assert to hint the compiler, instead of increasing the
buffer size.
---
hw/intc/exynos4210_gic.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/hw/intc/exynos4210_gic.c b/hw/intc/exynos4210_gic.c
index a1b699b6ba..ddd006aca6 100644
--- a/hw/intc/exynos4210_gic.c
+++ b/hw/intc/exynos4210_gic.c
@@ -293,6 +293,7 @@ static void exynos4210_gic_realize(DeviceState *dev, Error **errp)
char cpu_alias_name[sizeof(cpu_prefix) + 3];
char dist_alias_name[sizeof(cpu_prefix) + 3];
SysBusDevice *gicbusdev;
+ uint32_t n = s->num_cpu;
uint32_t i;
s->gic = qdev_create(NULL, "arm_gic");
@@ -313,7 +314,14 @@ static void exynos4210_gic_realize(DeviceState *dev, Error **errp)
memory_region_init(&s->dist_container, obj, "exynos4210-dist-container",
EXYNOS4210_EXT_GIC_DIST_REGION_SIZE);
- for (i = 0; i < s->num_cpu; i++) {
+ /*
+ * This clues in gcc that our on-stack buffers do, in fact have
+ * enough room for the cpu numbers. gcc 9.2.1 on 32-bit x86
+ * doesn't figure this out, otherwise and gives spurious warnings.
+ */
+ assert(n <= EXYNOS4210_NCPUS);
+ for (i = 0; i < n; i++) {
+
/* Map CPU interface per SMP Core */
sprintf(cpu_alias_name, "%s%x", cpu_prefix, i);
memory_region_init_alias(&s->cpu_alias[i], obj,
--
2.23.0
On 12/1/19 6:08 AM, David Gibson wrote: > > - for (i = 0; i < s->num_cpu; i++) { > + /* > + * This clues in gcc that our on-stack buffers do, in fact have > + * enough room for the cpu numbers. gcc 9.2.1 on 32-bit x86 > + * doesn't figure this out, otherwise and gives spurious warnings. > + */ > + assert(n <= EXYNOS4210_NCPUS); > + for (i = 0; i < n; i++) { > + > /* Map CPU interface per SMP Core */ Watch out for the extra line added at the start of the block. Otherwise, Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Mon, 2 Dec 2019 at 16:08, Richard Henderson <richard.henderson@linaro.org> wrote: > > On 12/1/19 6:08 AM, David Gibson wrote: > > > > - for (i = 0; i < s->num_cpu; i++) { > > + /* > > + * This clues in gcc that our on-stack buffers do, in fact have > > + * enough room for the cpu numbers. gcc 9.2.1 on 32-bit x86 > > + * doesn't figure this out, otherwise and gives spurious warnings. > > + */ > > + assert(n <= EXYNOS4210_NCPUS); > > + for (i = 0; i < n; i++) { > > + > > /* Map CPU interface per SMP Core */ > > Watch out for the extra line added at the start of the block. Otherwise, > > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> I thought about putting this in rc4 but eventually decided against it. Queued for 5.0 (with the stray extra blank line removed). thanks -- PMM
On Mon, Dec 02, 2019 at 05:44:11PM +0000, Peter Maydell wrote: > On Mon, 2 Dec 2019 at 16:08, Richard Henderson > <richard.henderson@linaro.org> wrote: > > > > On 12/1/19 6:08 AM, David Gibson wrote: > > > > > > - for (i = 0; i < s->num_cpu; i++) { > > > + /* > > > + * This clues in gcc that our on-stack buffers do, in fact have > > > + * enough room for the cpu numbers. gcc 9.2.1 on 32-bit x86 > > > + * doesn't figure this out, otherwise and gives spurious warnings. > > > + */ > > > + assert(n <= EXYNOS4210_NCPUS); > > > + for (i = 0; i < n; i++) { > > > + > > > /* Map CPU interface per SMP Core */ > > > > Watch out for the extra line added at the start of the block. Otherwise, > > > > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> > > I thought about putting this in rc4 but eventually decided > against it. Queued for 5.0 (with the stray extra blank line > removed). Great! -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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