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aarch64: Enhanced CPU diagnostics for ld.so

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This prints some information from struct cpu_features, and the midr_el1
and dczid_el0 system register contents on every CPU.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
This commit is contained in:
Florian Weimer 2024-04-08 16:48:55 +02:00
parent 7a430f40c4
commit f8d8b1b1e6
2 changed files with 118 additions and 0 deletions
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34
manual/dynlink.texi
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@ -224,6 +224,40 @@ reflect adjustment by @theglibc{}.
These Linux-specific items show the values of @code{struct utsname}, as
reported by the @code{uname} function. @xref{Platform Type}.
@item aarch64.cpu_features.@dots{}
These items are specific to the AArch64 architectures. They report data
@theglibc{} uses to activate conditionally supported features such as
BTI and MTE, and to select alternative function implementations.
@item aarch64.processor[@var{index}].@dots{}
These are additional items for the AArch64 architecture and are
described below.
@item aarch64.processor[@var{index}].requested=@var{kernel-cpu}
The kernel is told to run the subsequent probing on the CPU numbered
@var{kernel-cpu}. The values @var{kernel-cpu} and @var{index} can be
distinct if there are gaps in the process CPU affinity mask. This line
is not included if CPU affinity mask information is not available.
@item aarch64.processor[@var{index}].observed=@var{kernel-cpu}
This line reports the kernel CPU number @var{kernel-cpu} on which the
probing code initially ran. If the CPU number cannot be obtained,
this line is not printed.
@item aarch64.processor[@var{index}].observed_node=@var{node}
This reports the observed NUMA node number, as reported by the
@code{getcpu} system call. If this information cannot be obtained, this
line is not printed.
@item aarch64.processor[@var{index}].midr_el1=@var{value}
The value of the @code{midr_el1} system register on the processor
@var{index}. This line is only printed if the kernel indicates that
this system register is supported.
@item aarch64.processor[@var{index}].dczid_el0=@var{value}
The value of the @code{dczid_el0} system register on the processor
@var{index}.
@cindex CPUID (diagnostics)
@item x86.cpu_features.@dots{}
These items are specific to the i386 and x86-64 architectures. They

84
sysdeps/aarch64/dl-diagnostics-cpu.c Normal file
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@ -0,0 +1,84 @@
/* Print CPU diagnostics data in ld.so. AArch64 version.
Copyright (C) 2021-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dl-diagnostics.h>
#include <cpu-features.h>
#include <dl-iterate_cpu.h>
#include <ldsodefs.h>
#include <sys/auxv.h>
static void
print_cpu_features_value (const char *label, uint64_t value)
{
_dl_printf ("aarch64.cpu_features.");
_dl_diagnostics_print_labeled_value (label, value);
}
static void
print_per_cpu_value (const struct dl_iterate_cpu *dic,
const char *label, uint64_t value)
{
_dl_printf ("aarch64.processor[0x%x].", dic->processor_index);
_dl_diagnostics_print_labeled_value (label, value);
}
void
_dl_diagnostics_cpu (void)
{
print_cpu_features_value ("bti", GLRO (dl_aarch64_cpu_features).bti);
print_cpu_features_value ("midr_el1",
GLRO (dl_aarch64_cpu_features).midr_el1);
print_cpu_features_value ("mops", GLRO (dl_aarch64_cpu_features).mops);
print_cpu_features_value ("mte_state",
GLRO (dl_aarch64_cpu_features).mte_state);
print_cpu_features_value ("prefer_sve_ifuncs",
GLRO (dl_aarch64_cpu_features).prefer_sve_ifuncs);
print_cpu_features_value ("sve", GLRO (dl_aarch64_cpu_features).sve);
print_cpu_features_value ("zva_size",
GLRO (dl_aarch64_cpu_features).zva_size);
struct dl_iterate_cpu dic;
_dl_iterate_cpu_init (&dic);
while (_dl_iterate_cpu_next (&dic))
{
if (dic.requested_cpu >= 0)
_dl_printf ("aarch64.processor[0x%x].requested=0x%x\n",
dic.processor_index, dic.requested_cpu);
if (dic.actual_cpu >= 0)
_dl_printf ("aarch64.processor[0x%x].observed=0x%x\n",
dic.processor_index, dic.actual_cpu);
if (dic.actual_node >= 0)
_dl_printf ("aarch64.processor[0x%x].observed_node=0x%x\n",
dic.processor_index, dic.actual_node);
if (GLRO (dl_hwcap) & HWCAP_CPUID)
{
uint64_t midr_el1;
asm ("mrs %0, midr_el1" : "=r" (midr_el1));
print_per_cpu_value (&dic, "midr_el1", midr_el1);
}
{
uint64_t dczid_el0;
asm ("mrs %0, dczid_el0" : "=r" (dczid_el0));
print_per_cpu_value (&dic, "dczid_el0", dczid_el0);
}
}
}