* [PATCH] powerpc/perf/hv-gpci: bound sysfs formatting with sysfs_emit_at()
@ 2026-04-17 7:48 Pengpeng Hou
2026-04-17 7:58 ` Christophe Leroy (CS GROUP)
0 siblings, 1 reply; 2+ messages in thread
From: Pengpeng Hou @ 2026-04-17 7:48 UTC (permalink / raw)
To: Madhavan Srinivasan, Michael Ellerman
Cc: Nicholas Piggin, Christophe Leroy (CS GROUP), Kees Cook,
linuxppc-dev, linux-kernel, Pengpeng Hou, stable
systeminfo_gpci_request() and
affinity_domain_via_partition_result_parse() hex-encode hypervisor data
into the single-page sysfs read buffer with sprintf(buf + *n, ...).
Both helpers only check PAGE_SIZE after the formatting loops have already
advanced past the end of the buffer.
Switch these appends to sysfs_emit_at() and stop once the sysfs buffer is
full.
Fixes: 71f1c39647d8 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor bus topology information")
Fixes: a15e0d6a6929 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via partition information")
Cc: stable@vger.kernel.org
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
arch/powerpc/perf/hv-gpci.c | 56 +++++++++++++++++++++++++++++++------
1 file changed, 47 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
index 5cac2cf3bd1e..325b80f01629 100644
--- a/arch/powerpc/perf/hv-gpci.c
+++ b/arch/powerpc/perf/hv-gpci.c
@@ -11,6 +11,7 @@
#include <linux/init.h>
#include <linux/perf_event.h>
+#include <linux/sysfs.h>
#include <asm/firmware.h>
#include <asm/hvcall.h>
#include <asm/io.h>
@@ -134,6 +135,7 @@ static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,
size_t *n, struct hv_gpci_request_buffer *arg)
{
unsigned long ret;
+ int len;
size_t i, j;
arg->params.counter_request = cpu_to_be32(req);
@@ -176,9 +178,17 @@ static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,
for (i = 0; i < be16_to_cpu(arg->params.returned_values); i++) {
j = i * be16_to_cpu(arg->params.cv_element_size);
- for (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size); j++)
- *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[j]);
- *n += sprintf(buf + *n, "\n");
+ for (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size);
+ j++) {
+ len = sysfs_emit_at(buf, *n, "%02x", (u8)arg->bytes[j]);
+ if (!len)
+ return -EFBIG;
+ *n += len;
+ }
+ len = sysfs_emit_at(buf, *n, "\n");
+ if (!len)
+ return -EFBIG;
+ *n += len;
}
if (*n >= PAGE_SIZE) {
@@ -465,6 +475,7 @@ static void affinity_domain_via_partition_result_parse(int returned_values,
int element_size, char *buf, size_t *last_element,
size_t *n, struct hv_gpci_request_buffer *arg)
{
+ int len;
size_t i = 0, j = 0;
size_t k, l, m;
uint16_t total_affinity_domain_ele, size_of_each_affinity_domain_ele;
@@ -483,22 +494,49 @@ static void affinity_domain_via_partition_result_parse(int returned_values,
*/
while (i < returned_values) {
k = j;
- for (; k < j + element_size; k++)
- *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[k]);
- *n += sprintf(buf + *n, "\n");
+ for (; k < j + element_size; k++) {
+ len = sysfs_emit_at(buf, *n, "%02x", (u8)arg->bytes[k]);
+ if (!len) {
+ *n = PAGE_SIZE;
+ return;
+ }
+ *n += len;
+ }
+ len = sysfs_emit_at(buf, *n, "\n");
+ if (!len) {
+ *n = PAGE_SIZE;
+ return;
+ }
+ *n += len;
total_affinity_domain_ele = (u8)arg->bytes[k - 2] << 8 | (u8)arg->bytes[k - 3];
size_of_each_affinity_domain_ele = (u8)arg->bytes[k] << 8 | (u8)arg->bytes[k - 1];
for (l = 0; l < total_affinity_domain_ele; l++) {
for (m = 0; m < size_of_each_affinity_domain_ele; m++) {
- *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[k]);
+ len = sysfs_emit_at(buf, *n, "%02x",
+ (u8)arg->bytes[k]);
+ if (!len) {
+ *n = PAGE_SIZE;
+ return;
+ }
+ *n += len;
k++;
}
- *n += sprintf(buf + *n, "\n");
+ len = sysfs_emit_at(buf, *n, "\n");
+ if (!len) {
+ *n = PAGE_SIZE;
+ return;
+ }
+ *n += len;
}
- *n += sprintf(buf + *n, "\n");
+ len = sysfs_emit_at(buf, *n, "\n");
+ if (!len) {
+ *n = PAGE_SIZE;
+ return;
+ }
+ *n += len;
i++;
j = k;
}
--
2.50.1 (Apple Git-155)
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] powerpc/perf/hv-gpci: bound sysfs formatting with sysfs_emit_at()
2026-04-17 7:48 [PATCH] powerpc/perf/hv-gpci: bound sysfs formatting with sysfs_emit_at() Pengpeng Hou
@ 2026-04-17 7:58 ` Christophe Leroy (CS GROUP)
0 siblings, 0 replies; 2+ messages in thread
From: Christophe Leroy (CS GROUP) @ 2026-04-17 7:58 UTC (permalink / raw)
To: Pengpeng Hou, Madhavan Srinivasan, Michael Ellerman
Cc: Nicholas Piggin, Kees Cook, linuxppc-dev, linux-kernel, stable
Le 17/04/2026 à 09:48, Pengpeng Hou a écrit :
> systeminfo_gpci_request() and
> affinity_domain_via_partition_result_parse() hex-encode hypervisor data
> into the single-page sysfs read buffer with sprintf(buf + *n, ...).
> Both helpers only check PAGE_SIZE after the formatting loops have already
> advanced past the end of the buffer.
>
> Switch these appends to sysfs_emit_at() and stop once the sysfs buffer is
> full.
You are changing several time a single lines by multiples lines that
look pretty similar. Can you refactor in a helper function ?
>
> Fixes: 71f1c39647d8 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show processor bus topology information")
> Fixes: a15e0d6a6929 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via partition information")
> Cc: stable@vger.kernel.org
>
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
> arch/powerpc/perf/hv-gpci.c | 56 +++++++++++++++++++++++++++++++------
> 1 file changed, 47 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c
> index 5cac2cf3bd1e..325b80f01629 100644
> --- a/arch/powerpc/perf/hv-gpci.c
> +++ b/arch/powerpc/perf/hv-gpci.c
> @@ -11,6 +11,7 @@
>
> #include <linux/init.h>
> #include <linux/perf_event.h>
> +#include <linux/sysfs.h>
> #include <asm/firmware.h>
> #include <asm/hvcall.h>
> #include <asm/io.h>
> @@ -134,6 +135,7 @@ static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,
> size_t *n, struct hv_gpci_request_buffer *arg)
> {
> unsigned long ret;
> + int len;
> size_t i, j;
>
> arg->params.counter_request = cpu_to_be32(req);
> @@ -176,9 +178,17 @@ static unsigned long systeminfo_gpci_request(u32 req, u32 starting_index,
> for (i = 0; i < be16_to_cpu(arg->params.returned_values); i++) {
> j = i * be16_to_cpu(arg->params.cv_element_size);
>
> - for (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size); j++)
> - *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[j]);
> - *n += sprintf(buf + *n, "\n");
> + for (; j < (i + 1) * be16_to_cpu(arg->params.cv_element_size);
> + j++) {
> + len = sysfs_emit_at(buf, *n, "%02x", (u8)arg->bytes[j]);
> + if (!len)
> + return -EFBIG;
> + *n += len;
> + }
> + len = sysfs_emit_at(buf, *n, "\n");
> + if (!len)
> + return -EFBIG;
> + *n += len;
> }
>
> if (*n >= PAGE_SIZE) {
> @@ -465,6 +475,7 @@ static void affinity_domain_via_partition_result_parse(int returned_values,
> int element_size, char *buf, size_t *last_element,
> size_t *n, struct hv_gpci_request_buffer *arg)
> {
> + int len;
> size_t i = 0, j = 0;
> size_t k, l, m;
> uint16_t total_affinity_domain_ele, size_of_each_affinity_domain_ele;
> @@ -483,22 +494,49 @@ static void affinity_domain_via_partition_result_parse(int returned_values,
> */
> while (i < returned_values) {
> k = j;
> - for (; k < j + element_size; k++)
> - *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[k]);
> - *n += sprintf(buf + *n, "\n");
> + for (; k < j + element_size; k++) {
> + len = sysfs_emit_at(buf, *n, "%02x", (u8)arg->bytes[k]);
> + if (!len) {
> + *n = PAGE_SIZE;
> + return;
> + }
> + *n += len;
> + }
> + len = sysfs_emit_at(buf, *n, "\n");
> + if (!len) {
> + *n = PAGE_SIZE;
> + return;
> + }
> + *n += len;
>
> total_affinity_domain_ele = (u8)arg->bytes[k - 2] << 8 | (u8)arg->bytes[k - 3];
> size_of_each_affinity_domain_ele = (u8)arg->bytes[k] << 8 | (u8)arg->bytes[k - 1];
>
> for (l = 0; l < total_affinity_domain_ele; l++) {
> for (m = 0; m < size_of_each_affinity_domain_ele; m++) {
> - *n += sprintf(buf + *n, "%02x", (u8)arg->bytes[k]);
> + len = sysfs_emit_at(buf, *n, "%02x",
> + (u8)arg->bytes[k]);
> + if (!len) {
> + *n = PAGE_SIZE;
> + return;
> + }
> + *n += len;
> k++;
> }
> - *n += sprintf(buf + *n, "\n");
> + len = sysfs_emit_at(buf, *n, "\n");
> + if (!len) {
> + *n = PAGE_SIZE;
> + return;
> + }
> + *n += len;
> }
>
> - *n += sprintf(buf + *n, "\n");
> + len = sysfs_emit_at(buf, *n, "\n");
> + if (!len) {
> + *n = PAGE_SIZE;
> + return;
> + }
> + *n += len;
> i++;
> j = k;
> }
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-04-17 7:58 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-04-17 7:48 [PATCH] powerpc/perf/hv-gpci: bound sysfs formatting with sysfs_emit_at() Pengpeng Hou
2026-04-17 7:58 ` Christophe Leroy (CS GROUP)
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox