Re: [tip:x86/boot] x86/boot: Early parse RSDP and save it in boot_params

From: Borislav Petkov
Date: Mon Feb 11 2019 - 06:20:18 EST


On Mon, Feb 11, 2019 at 10:46:18AM +0000, Ard Biesheuvel wrote:
> As I pointed out in my previous reply, systab will be the wrong type
> on 32-bit firmware, it needs to be efi_system_table_32_t

This seems to work. Chao, please run it too.

Thx.

---
diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index c5a949335d8b..0d97aa8bd01f 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -50,7 +50,8 @@ static acpi_physical_address efi_get_rsdp_addr(void)
acpi_physical_address rsdp_addr = 0;

#ifdef CONFIG_EFI
- efi_system_table_t *systab;
+ unsigned long systab, systab_tables, config_tables;
+ unsigned int nr_tables;
struct efi_info *ei;
bool efi_64;
int size, i;
@@ -70,13 +71,13 @@ static acpi_physical_address efi_get_rsdp_addr(void)

/* Get systab from boot params. */
#ifdef CONFIG_X86_64
- systab = (efi_system_table_t *)(ei->efi_systab | ((__u64)ei->efi_systab_hi<<32));
+ systab = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
#else
if (ei->efi_systab_hi || ei->efi_memmap_hi) {
debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n");
return 0;
}
- systab = (efi_system_table_t *)ei->efi_systab;
+ systab = ei->efi_systab;
#endif
if (!systab)
error("EFI system table not found.");
@@ -87,16 +88,30 @@ static acpi_physical_address efi_get_rsdp_addr(void)
size = efi_64 ? sizeof(efi_config_table_64_t) :
sizeof(efi_config_table_32_t);

- for (i = 0; i < systab->nr_tables; i++) {
+ if (efi_64) {
+ efi_system_table_64_t *st_tbl = (efi_system_table_64_t *)systab;
+
+ config_tables = st_tbl->tables;
+ nr_tables = st_tbl->nr_tables;
+ } else {
+ efi_system_table_32_t *st_tbl = (efi_system_table_32_t *)systab;
+
+ config_tables = st_tbl->tables;
+ nr_tables = st_tbl->nr_tables;
+ }
+
+ if (!config_tables)
+ error("EFI config tables not found.");
+
+ for (i = 0; i < nr_tables; i++) {
acpi_physical_address table;
- void *config_tables;
efi_guid_t guid;

- config_tables = (void *)(systab->tables + size * i);
+ config_tables += size * i;
+
if (efi_64) {
- efi_config_table_64_t *tmp_table;
+ efi_config_table_64_t *tmp_table = (efi_config_table_64_t *)config_tables;

- tmp_table = config_tables;
guid = tmp_table->guid;
table = tmp_table->table;

@@ -105,9 +120,8 @@ static acpi_physical_address efi_get_rsdp_addr(void)
return 0;
}
} else {
- efi_config_table_32_t *tmp_table;
+ efi_config_table_32_t *tmp_table = (efi_config_table_32_t *)config_tables;

- tmp_table = config_tables;
guid = tmp_table->guid;
table = tmp_table->table;
}

--
Regards/Gruss,
Boris.

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