From 13fc2ce4d5e3c0531962a701d02f514a21629078 Mon Sep 17 00:00:00 2001
From: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
Date: Fri, 8 Oct 2021 12:52:22 +1100
Subject: [PATCH] acpi: cleanup smbios lookup to use actual smbios structs

Signed-off-by: Andy-Python-Programmer <andypythonappdeveloper@gmail.com>
---
 stage23/lib/acpi.c | 34 ++++++++++++++++------------
 stage23/lib/acpi.h | 55 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 74 insertions(+), 15 deletions(-)

diff --git a/stage23/lib/acpi.c b/stage23/lib/acpi.c
index 5f02cc91..df7a4eef 100644
--- a/stage23/lib/acpi.c
+++ b/stage23/lib/acpi.c
@@ -54,19 +54,23 @@ void acpi_get_smbios(void **smbios32, void **smbios64) {
     *smbios64 = NULL;
 
     for (size_t i = 0xf0000; i < 0x100000; i += 16) {
-        if (!memcmp((char *)i, "_SM_", 4)
-         && !acpi_checksum((void *)i, *((uint8_t *)(i + 5)))) {
+        struct smbios_entry_point_32 *ptr = (struct smbios_entry_point_32 *)i;
+
+        if (!memcmp(ptr->anchor_str, "_SM_", 4) &&
+            !acpi_checksum((void *)ptr, ptr->length)) {
             printv("acpi: Found SMBIOS 32-bit entry point at %x\n", i);
-            *smbios32 = (void *)i;
+            *smbios32 = (void *)ptr;
             break;
         }
     }
 
     for (size_t i = 0xf0000; i < 0x100000; i += 16) {
-        if (!memcmp((char *)i, "_SM3_", 5)
-         && !acpi_checksum((void *)i, *((uint8_t *)(i + 6)))) {
+        struct smbios_entry_point_64 *ptr = (struct smbios_entry_point_64 *)i;
+
+        if (!memcmp(ptr->anchor_str, "_SM3_", 5) &&
+            !acpi_checksum((void *)ptr, ptr->length)) {
             printv("acpi: Found SMBIOS 64-bit entry point at %x\n", i);
-            *smbios64 = (void *)i;
+            *smbios64 = (void *)ptr;
             break;
         }
     }
@@ -150,13 +154,14 @@ void acpi_get_smbios(void **smbios32, void **smbios64) {
         if (memcmp(&cur_table->VendorGuid, &smbios_guid, sizeof(EFI_GUID)) != 0)
             continue;
 
-        if (acpi_checksum(cur_table->VendorTable,
-                          *((uint8_t *)(cur_table->VendorTable + 5))) != 0)
+        struct smbios_entry_point_32 *ptr = (struct smbios_entry_point_32 *)cur_table->VendorTable;
+
+        if (acpi_checksum((void *)ptr, ptr->length) != 0)
             continue;
 
-        printv("acpi: Found SMBIOS 32-bit entry point at %X\n", cur_table->VendorTable);
+        printv("acpi: Found SMBIOS 32-bit entry point at %X\n", ptr);
 
-        *smbios32 = cur_table->VendorTable;
+        *smbios32 = (void *)ptr;
 
         break;
     }
@@ -168,13 +173,14 @@ void acpi_get_smbios(void **smbios32, void **smbios64) {
         if (memcmp(&cur_table->VendorGuid, &smbios3_guid, sizeof(EFI_GUID)) != 0)
             continue;
 
-        if (acpi_checksum(cur_table->VendorTable,
-                          *((uint8_t *)(cur_table->VendorTable + 6))) != 0)
+        struct smbios_entry_point_64 *ptr = (struct smbios_entry_point_64 *)cur_table->VendorTable;
+
+        if (acpi_checksum((void *)ptr, ptr->length) != 0)
             continue;
 
-        printv("acpi: Found SMBIOS 64-bit entry point at %X\n", cur_table->VendorTable);
+        printv("acpi: Found SMBIOS 64-bit entry point at %X\n", ptr);
 
-        *smbios64 = cur_table->VendorTable;
+        *smbios64 = (void *)ptr;
 
         break;
     }
diff --git a/stage23/lib/acpi.h b/stage23/lib/acpi.h
index 0638344f..5686b186 100644
--- a/stage23/lib/acpi.h
+++ b/stage23/lib/acpi.h
@@ -24,7 +24,7 @@ struct rsdp {
     char     oem_id[6];
     uint8_t  rev;
     uint32_t rsdt_addr;
-    // Rev 2 only after this comment
+    // Revision 2 only after this comment
     uint32_t length;
     uint64_t xsdt_addr;
     uint8_t  ext_checksum;
@@ -36,6 +36,59 @@ struct rsdt {
     char ptrs_start[];
 } __attribute__((packed));
 
+struct smbios_entry_point_32 {
+    char anchor_str[4];
+    /// This value summed with all the values of the table.
+    uint8_t checksum;
+    /// Length of the entry point table.
+    uint8_t length;
+    /// Major version of SMBIOS.
+    uint8_t major_version;
+    /// Minor version of SMBIOS.
+    uint8_t minor_version;
+    /// Size of the largest SMBIOS structure, in bytes, and encompasses the
+    /// structure’s formatted area and text strings
+    uint16_t max_structure_size;
+    uint8_t entry_point_revision;
+    char formatted_area[5];
+
+    char intermediate_anchor_str[5];
+    /// Checksum for values from intermediate anchor str to the 
+    /// end of table.
+    uint8_t intermediate_checksum;
+    /// Total length of SMBIOS Structure Table, pointed to by the structure
+    /// table address, in bytes.
+    uint16_t table_length;
+    /// 32-bit physical starting address of the read-only SMBIOS Structure
+    /// Table.
+    uint32_t table_address;
+    /// Total number of structures present in the SMBIOS Structure Table.
+    uint16_t number_of_structures;
+    /// Indicates compliance with a revision of this specification.
+    uint8_t bcd_revision;
+} __attribute__((packed));
+
+struct smbios_entry_point_64 {
+    char anchor_str[5];
+    /// This value summed with all the values of the table.
+    uint8_t checksum;
+    /// Length of the entry point table.
+    uint8_t length;
+    /// Major version of SMBIOS.
+    uint8_t major_version;
+    /// Minor version of SMBIOS.
+    uint8_t minor_version;
+    uint8_t docrev;
+    uint8_t entry_point_revision;
+    uint8_t reserved;
+    /// Size of the largest SMBIOS structure, in bytes, and encompasses the
+    /// structure’s formatted area and text strings
+    uint16_t max_structure_size;
+    /// 64-bit physical starting address of the read-only SMBIOS Structure
+    /// Table.
+    uint64_t table_address;
+} __attribute__((packed));
+
 uint8_t acpi_checksum(void *ptr, size_t size);
 void   *acpi_get_rsdp(void);