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arm64/cpuinfo: only show one cpu's info in c_show()

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Currently, when ARM64 displays CPU information, every call to c_show()
assembles all CPU information. However, as the number of CPUs increases,
this can lead to insufficient buffer space due to excessive assembly in
a single call, causing repeated expansion and multiple calls to c_show().

To prevent this invalid c_show() call, only one CPU's information is
assembled each time c_show() is called.

Signed-off-by: Ye Bin <yebin10@huawei.com>
Link: https://lore.kernel.org/r/20250421062947.4072855-1-yebin@huaweicloud.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ye Bin 2025-04-21 14:29:47 +08:00 committed by Will Deacon
parent 83a39eccdf
commit 7bb797757b
1 changed files with 52 additions and 53 deletions
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105
arch/arm64/kernel/cpuinfo.c
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@ -209,80 +209,79 @@ static const char *const compat_hwcap2_str[] = {
static int c_show(struct seq_file *m, void *v)
{
int i, j;
int j;
int cpu = m->index;
bool compat = personality(current->personality) == PER_LINUX32;
struct cpuinfo_arm64 *cpuinfo = v;
u32 midr = cpuinfo->reg_midr;
for_each_online_cpu(i) {
struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, i);
u32 midr = cpuinfo->reg_midr;
/*
* glibc reads /proc/cpuinfo to determine the number of
* online processors, looking for lines beginning with
* "processor". Give glibc what it expects.
*/
seq_printf(m, "processor\t: %d\n", cpu);
if (compat)
seq_printf(m, "model name\t: ARMv8 Processor rev %d (%s)\n",
MIDR_REVISION(midr), COMPAT_ELF_PLATFORM);
/*
* glibc reads /proc/cpuinfo to determine the number of
* online processors, looking for lines beginning with
* "processor". Give glibc what it expects.
*/
seq_printf(m, "processor\t: %d\n", i);
if (compat)
seq_printf(m, "model name\t: ARMv8 Processor rev %d (%s)\n",
MIDR_REVISION(midr), COMPAT_ELF_PLATFORM);
seq_printf(m, "BogoMIPS\t: %lu.%02lu\n",
loops_per_jiffy / (500000UL/HZ),
loops_per_jiffy / (5000UL/HZ) % 100);
seq_printf(m, "BogoMIPS\t: %lu.%02lu\n",
loops_per_jiffy / (500000UL/HZ),
loops_per_jiffy / (5000UL/HZ) % 100);
/*
* Dump out the common processor features in a single line.
* Userspace should read the hwcaps with getauxval(AT_HWCAP)
* rather than attempting to parse this, but there's a body of
* software which does already (at least for 32-bit).
*/
seq_puts(m, "Features\t:");
if (compat) {
/*
* Dump out the common processor features in a single line.
* Userspace should read the hwcaps with getauxval(AT_HWCAP)
* rather than attempting to parse this, but there's a body of
* software which does already (at least for 32-bit).
*/
seq_puts(m, "Features\t:");
if (compat) {
#ifdef CONFIG_COMPAT
for (j = 0; j < ARRAY_SIZE(compat_hwcap_str); j++) {
if (compat_elf_hwcap & (1 << j)) {
/*
* Warn once if any feature should not
* have been present on arm64 platform.
*/
if (WARN_ON_ONCE(!compat_hwcap_str[j]))
continue;
for (j = 0; j < ARRAY_SIZE(compat_hwcap_str); j++) {
if (compat_elf_hwcap & (1 << j)) {
/*
* Warn once if any feature should not
* have been present on arm64 platform.
*/
if (WARN_ON_ONCE(!compat_hwcap_str[j]))
continue;
seq_printf(m, " %s", compat_hwcap_str[j]);
}
seq_printf(m, " %s", compat_hwcap_str[j]);
}
for (j = 0; j < ARRAY_SIZE(compat_hwcap2_str); j++)
if (compat_elf_hwcap2 & (1 << j))
seq_printf(m, " %s", compat_hwcap2_str[j]);
#endif /* CONFIG_COMPAT */
} else {
for (j = 0; j < ARRAY_SIZE(hwcap_str); j++)
if (cpu_have_feature(j))
seq_printf(m, " %s", hwcap_str[j]);
}
seq_puts(m, "\n");
seq_printf(m, "CPU implementer\t: 0x%02x\n",
MIDR_IMPLEMENTOR(midr));
seq_printf(m, "CPU architecture: 8\n");
seq_printf(m, "CPU variant\t: 0x%x\n", MIDR_VARIANT(midr));
seq_printf(m, "CPU part\t: 0x%03x\n", MIDR_PARTNUM(midr));
seq_printf(m, "CPU revision\t: %d\n\n", MIDR_REVISION(midr));
for (j = 0; j < ARRAY_SIZE(compat_hwcap2_str); j++)
if (compat_elf_hwcap2 & (1 << j))
seq_printf(m, " %s", compat_hwcap2_str[j]);
#endif /* CONFIG_COMPAT */
} else {
for (j = 0; j < ARRAY_SIZE(hwcap_str); j++)
if (cpu_have_feature(j))
seq_printf(m, " %s", hwcap_str[j]);
}
seq_puts(m, "\n");
seq_printf(m, "CPU implementer\t: 0x%02x\n",
MIDR_IMPLEMENTOR(midr));
seq_puts(m, "CPU architecture: 8\n");
seq_printf(m, "CPU variant\t: 0x%x\n", MIDR_VARIANT(midr));
seq_printf(m, "CPU part\t: 0x%03x\n", MIDR_PARTNUM(midr));
seq_printf(m, "CPU revision\t: %d\n\n", MIDR_REVISION(midr));
return 0;
}
static void *c_start(struct seq_file *m, loff_t *pos)
{
return *pos < 1 ? (void *)1 : NULL;
*pos = cpumask_next(*pos - 1, cpu_online_mask);
return *pos < nr_cpu_ids ? &per_cpu(cpu_data, *pos) : NULL;
}
static void *c_next(struct seq_file *m, void *v, loff_t *pos)
{
++*pos;
return NULL;
return c_start(m, pos);
}
static void c_stop(struct seq_file *m, void *v)