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acpi: Update acpi_find_table() to verify checksums

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The RSP is not valid unless the checksums are corrrect, so add a test
for this.

Add a few blank lines for readability while here.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass
2025-07-08 05:06:56 +02:00
parent d0b607221f
commit 9d4aa656de
2 changed files with 28 additions and 1 deletions
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25
lib/acpi/acpi.c
View File

@@ -5,6 +5,8 @@
* Copyright 2023 Google LLC
*/
#define LOG_CATEGORY LOGC_ACPI
#include <mapmem.h>
#include <tables_csum.h>
#include <acpi/acpi_table.h>
@@ -18,6 +20,25 @@ void acpi_update_checksum(struct acpi_table_header *header)
header->checksum = table_compute_checksum(header, header->length);
}
static bool acpi_valid_rsdp(struct acpi_rsdp *rsdp)
{
if (strncmp((char *)rsdp, RSDP_SIG, sizeof(RSDP_SIG) - 1) != 0)
return false;
debug("Looking on %p for valid checksum\n", rsdp);
if (table_compute_checksum((void *)rsdp, 20) != 0)
return false;
debug("acpi rsdp checksum 1 passed\n");
if (rsdp->revision > 1 &&
table_compute_checksum((void *)rsdp, rsdp->length))
return false;
debug("acpi rsdp checksum 2 passed\n");
return true;
}
struct acpi_table_header *acpi_find_table(const char *sig)
{
struct acpi_rsdp *rsdp;
@@ -26,8 +47,9 @@ struct acpi_table_header *acpi_find_table(const char *sig)
int len, i, count;
rsdp = map_sysmem(gd_acpi_start(), 0);
if (!rsdp)
if (!rsdp || !acpi_valid_rsdp(rsdp))
return NULL;
if (rsdp->xsdt_address) {
xsdt = nomap_sysmem(rsdp->xsdt_address, 0);
len = xsdt->header.length - sizeof(xsdt->header);
@@ -39,6 +61,7 @@ struct acpi_table_header *acpi_find_table(const char *sig)
len = rsdt->header.length - sizeof(rsdt->header);
count = len / sizeof(u32);
}
for (i = 0; i < count; i++) {
struct acpi_table_header *hdr;