Quelle fw_table.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
*  fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
*                platform or device firmware
*
*  Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
*  Copyright (C) 2023 Intel Corp.
*/
#include <linux/errno.h>
#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/fw_table.h>

enum acpi_subtable_type {
ACPI_SUBTABLE_COMMON,
ACPI_SUBTABLE_HMAT,
ACPI_SUBTABLE_PRMT,
ACPI_SUBTABLE_CEDT,
CDAT_SUBTABLE,
};

struct acpi_subtable_entry {
union acpi_subtable_headers *hdr;
enum acpi_subtable_type type;
};

static unsigned long __init_or_fwtbl_lib
acpi_get_entry_type(struct acpi_subtable_entry *entry)
{
switch (entry->type) {
case ACPI_SUBTABLE_COMMON:
  return entry->hdr->common.type;
case ACPI_SUBTABLE_HMAT:
  return entry->hdr->hmat.type;
case ACPI_SUBTABLE_PRMT:
  return 0;
case ACPI_SUBTABLE_CEDT:
  return entry->hdr->cedt.type;
case CDAT_SUBTABLE:
  return entry->hdr->cdat.type;
}
return 0;
}

static unsigned long __init_or_fwtbl_lib
acpi_get_entry_length(struct acpi_subtable_entry *entry)
{
switch (entry->type) {
case ACPI_SUBTABLE_COMMON:
  return entry->hdr->common.length;
case ACPI_SUBTABLE_HMAT:
  return entry->hdr->hmat.length;
case ACPI_SUBTABLE_PRMT:
  return entry->hdr->prmt.length;
case ACPI_SUBTABLE_CEDT:
  return entry->hdr->cedt.length;
case CDAT_SUBTABLE: {
  __le16 length = (__force __le16)entry->hdr->cdat.length;

  return le16_to_cpu(length);
}
}
return 0;
}

static unsigned long __init_or_fwtbl_lib
acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
{
switch (entry->type) {
case ACPI_SUBTABLE_COMMON:
  return sizeof(entry->hdr->common);
case ACPI_SUBTABLE_HMAT:
  return sizeof(entry->hdr->hmat);
case ACPI_SUBTABLE_PRMT:
  return sizeof(entry->hdr->prmt);
case ACPI_SUBTABLE_CEDT:
  return sizeof(entry->hdr->cedt);
case CDAT_SUBTABLE:
  return sizeof(entry->hdr->cdat);
}
return 0;
}

static enum acpi_subtable_type __init_or_fwtbl_lib
acpi_get_subtable_type(char *id)
{
if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
  return ACPI_SUBTABLE_HMAT;
if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
  return ACPI_SUBTABLE_PRMT;
if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
  return ACPI_SUBTABLE_CEDT;
if (strncmp(id, ACPI_SIG_CDAT, 4) == 0)
  return CDAT_SUBTABLE;
return ACPI_SUBTABLE_COMMON;
}

static unsigned long __init_or_fwtbl_lib
acpi_table_get_length(enum acpi_subtable_type type,
        union fw_table_header *header)
{
if (type == CDAT_SUBTABLE) {
  __le32 length = (__force __le32)header->cdat.length;

  return le32_to_cpu(length);
}

return header->acpi.length;
}

static __init_or_fwtbl_lib int call_handler(struct acpi_subtable_proc *proc,
         union acpi_subtable_headers *hdr,
         unsigned long end)
{
if (proc->handler)
  return proc->handler(hdr, end);
if (proc->handler_arg)
  return proc->handler_arg(hdr, proc->arg, end);
return -EINVAL;
}

/**
* acpi_parse_entries_array - for each proc_num find a suitable subtable
*
* @id: table id (for debugging purposes)
* @table_size: size of the root table
* @max_length: maximum size of the table (ignore if 0)
* @table_header: where does the table start?
* @proc: array of acpi_subtable_proc struct containing entry id
*        and associated handler with it
* @proc_num: how big proc is?
* @max_entries: how many entries can we process?
*
* For each proc_num find a subtable with proc->id and run proc->handler
* on it. Assumption is that there's only single handler for particular
* entry id.
*
* The table_size is not the size of the complete ACPI table (the length
* field in the header struct), but only the size of the root table; i.e.,
* the offset from the very first byte of the complete ACPI table, to the
* first byte of the very first subtable.
*
* On success returns sum of all matching entries for all proc handlers.
* Otherwise, -ENODEV or -EINVAL is returned.
*/
int __init_or_fwtbl_lib
acpi_parse_entries_array(char *id, unsigned long table_size,
    union fw_table_header *table_header,
    unsigned long max_length,
    struct acpi_subtable_proc *proc,
    int proc_num, unsigned int max_entries)
{
unsigned long table_len, table_end, subtable_len, entry_len;
struct acpi_subtable_entry entry;
enum acpi_subtable_type type;
int count = 0;
int i;

type = acpi_get_subtable_type(id);
table_len = acpi_table_get_length(type, table_header);
if (max_length && max_length < table_len)
  table_len = max_length;
table_end = (unsigned long)table_header + table_len;

/* Parse all entries looking for a match. */

entry.type = type;
entry.hdr = (union acpi_subtable_headers *)
     ((unsigned long)table_header + table_size);
subtable_len = acpi_get_subtable_header_length(&entry);

while (((unsigned long)entry.hdr) + subtable_len < table_end) {
  for (i = 0; i < proc_num; i++) {
   if (acpi_get_entry_type(&entry) != proc[i].id)
    continue;

   if (!max_entries || count < max_entries)
    if (call_handler(&proc[i], entry.hdr, table_end))
     return -EINVAL;

   proc[i].count++;
   count++;
   break;
  }

  /*
* If entry->length is 0, break from this loop to avoid
* infinite loop.
*/
  entry_len = acpi_get_entry_length(&entry);
  if (entry_len == 0) {
   pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
   return -EINVAL;
  }

  entry.hdr = (union acpi_subtable_headers *)
      ((unsigned long)entry.hdr + entry_len);
}

if (max_entries && count > max_entries) {
  pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
   id, proc->id, count - max_entries, count);
}

return count;
}

int __init_or_fwtbl_lib
cdat_table_parse(enum acpi_cdat_type type,
   acpi_tbl_entry_handler_arg handler_arg,
   void *arg,
   struct acpi_table_cdat *table_header,
   unsigned long length)
{
struct acpi_subtable_proc proc = {
  .id  = type,
  .handler_arg = handler_arg,
  .arg  = arg,
};

if (!table_header)
  return -EINVAL;

return acpi_parse_entries_array(ACPI_SIG_CDAT,
     sizeof(struct acpi_table_cdat),
     (union fw_table_header *)table_header,
     length, &proc, 1, 0);
}
EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse);

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