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#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <linux/api.h>
#include <x86/linux/api.h>
#include <cpuinfo/log.h>
/*
* Size, in chars, of the on-stack buffer used for parsing lines of /proc/cpuinfo.
* This is also the limit on the length of a single line.
*/
#define BUFFER_SIZE 2048
static uint32_t parse_processor_number(
const char* processor_start,
const char* processor_end)
{
const size_t processor_length = (size_t) (processor_end - processor_start);
if (processor_length == 0) {
cpuinfo_log_warning("Processor number in /proc/cpuinfo is ignored: string is empty");
return 0;
}
uint32_t processor_number = 0;
for (const char* digit_ptr = processor_start; digit_ptr != processor_end; digit_ptr++) {
const uint32_t digit = (uint32_t) (*digit_ptr - '0');
if (digit > 10) {
cpuinfo_log_warning("non-decimal suffix %.*s in /proc/cpuinfo processor number is ignored",
(int) (processor_end - digit_ptr), digit_ptr);
break;
}
processor_number = processor_number * 10 + digit;
}
return processor_number;
}
/*
* Decode APIC ID reported by Linux kernel for x86/x86-64 architecture.
* Example of APIC ID reported in /proc/cpuinfo:
*
* apicid : 2
*/
static void parse_apic_id(
const char* apic_start,
const char* apic_end,
struct cpuinfo_x86_linux_processor processor[restrict static 1])
{
uint32_t apic_id = 0;
for (const char* digit_ptr = apic_start; digit_ptr != apic_end; digit_ptr++) {
const uint32_t digit = *digit_ptr - '0';
if (digit >= 10) {
cpuinfo_log_warning("APIC ID %.*s in /proc/cpuinfo is ignored due to unexpected non-digit character '%c' at offset %zu",
(int) (apic_end - apic_start), apic_start,
*digit_ptr, (size_t) (digit_ptr - apic_start));
return;
}
apic_id = apic_id * 10 + digit;
}
processor->apic_id = apic_id;
processor->flags |= CPUINFO_LINUX_FLAG_APIC_ID;
}
struct proc_cpuinfo_parser_state {
uint32_t processor_index;
uint32_t max_processors_count;
struct cpuinfo_x86_linux_processor* processors;
struct cpuinfo_x86_linux_processor dummy_processor;
};
/*
* Decode a single line of /proc/cpuinfo information.
* Lines have format <words-with-spaces>[ ]*:[ ]<space-separated words>
*/
static bool parse_line(
const char* line_start,
const char* line_end,
struct proc_cpuinfo_parser_state state[restrict static 1],
uint64_t line_number)
{
/* Empty line. Skip. */
if (line_start == line_end) {
return true;
}
/* Search for ':' on the line. */
const char* separator = line_start;
for (; separator != line_end; separator++) {
if (*separator == ':') {
break;
}
}
/* Skip line if no ':' separator was found. */
if (separator == line_end) {
cpuinfo_log_warning("Line %.*s in /proc/cpuinfo is ignored: key/value separator ':' not found",
(int) (line_end - line_start), line_start);
return true;
}
/* Skip trailing spaces in key part. */
const char* key_end = separator;
for (; key_end != line_start; key_end--) {
if (key_end[-1] != ' ' && key_end[-1] != '\t') {
break;
}
}
/* Skip line if key contains nothing but spaces. */
if (key_end == line_start) {
cpuinfo_log_warning("Line %.*s in /proc/cpuinfo is ignored: key contains only spaces",
(int) (line_end - line_start), line_start);
return true;
}
/* Skip leading spaces in value part. */
const char* value_start = separator + 1;
for (; value_start != line_end; value_start++) {
if (*value_start != ' ') {
break;
}
}
/* Value part contains nothing but spaces. Skip line. */
if (value_start == line_end) {
cpuinfo_log_warning("Line %.*s in /proc/cpuinfo is ignored: value contains only spaces",
(int) (line_end - line_start), line_start);
return true;
}
/* Skip trailing spaces in value part (if any) */
const char* value_end = line_end;
for (; value_end != value_start; value_end--) {
if (value_end[-1] != ' ') {
break;
}
}
const uint32_t processor_index = state->processor_index;
const uint32_t max_processors_count = state->max_processors_count;
struct cpuinfo_x86_linux_processor* processors = state->processors;
struct cpuinfo_x86_linux_processor* processor = &state->dummy_processor;
if (processor_index < max_processors_count) {
processor = &processors[processor_index];
}
const size_t key_length = key_end - line_start;
switch (key_length) {
case 6:
if (memcmp(line_start, "apicid", key_length) == 0) {
parse_apic_id(value_start, value_end, processor);
} else {
goto unknown;
}
break;
case 9:
if (memcmp(line_start, "processor", key_length) == 0) {
const uint32_t new_processor_index = parse_processor_number(value_start, value_end);
if (new_processor_index < processor_index) {
/* Strange: decreasing processor number */
cpuinfo_log_warning(
"unexpectedly low processor number %"PRIu32" following processor %"PRIu32" in /proc/cpuinfo",
new_processor_index, processor_index);
} else if (new_processor_index > processor_index + 1) {
/* Strange, but common: skipped processor $(processor_index + 1) */
cpuinfo_log_info(
"unexpectedly high processor number %"PRIu32" following processor %"PRIu32" in /proc/cpuinfo",
new_processor_index, processor_index);
}
if (new_processor_index >= max_processors_count) {
/* Log and ignore processor */
cpuinfo_log_warning("processor %"PRIu32" in /proc/cpuinfo is ignored: index exceeds system limit %"PRIu32,
new_processor_index, max_processors_count - 1);
}
state->processor_index = new_processor_index;
return true;
} else {
goto unknown;
}
break;
default:
unknown:
cpuinfo_log_debug("unknown /proc/cpuinfo key: %.*s", (int) key_length, line_start);
}
return true;
}
bool cpuinfo_x86_linux_parse_proc_cpuinfo(
uint32_t max_processors_count,
struct cpuinfo_x86_linux_processor processors[restrict static max_processors_count])
{
struct proc_cpuinfo_parser_state state = {
.processor_index = 0,
.max_processors_count = max_processors_count,
.processors = processors,
};
return cpuinfo_linux_parse_multiline_file("/proc/cpuinfo", BUFFER_SIZE,
(cpuinfo_line_callback) parse_line, &state);
}
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