* Chao Fan <fanc.f...@cn.fujitsu.com> wrote:
> Memory information in SRAT is necessary to fix the conflict between
> KASLR and memory-hotremove. So RSDP and SRAT should be parsed.
>
> When booting form KEXEC/EFI/BIOS, the methods to compute RSDP
> are different. When booting from EFI, EFI table points to RSDP.
> So parse the EFI table and find the RSDP.
>
> Signed-off-by: Chao Fan <fanc.f...@cn.fujitsu.com>
> ---
> arch/x86/boot/compressed/acpi.c | 79 +++++++++++++++++++++++++++++++++
> 1 file changed, 79 insertions(+)
>
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> index 44f19546c169..4151881d8713 100644
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -28,3 +28,82 @@ static acpi_physical_address get_acpi_rsdp(void)
> #endif
> return 0;
> }
> +
> +/* Search EFI table for RSDP. */
> +static acpi_physical_address efi_get_rsdp_addr(void)
> +{
> + acpi_physical_address rsdp_addr = 0;
> +#ifdef CONFIG_EFI
> + efi_system_table_t *systab;
> + struct efi_info *e;
'e' is pretty meaningless, the canonical name for efi_info local
variables is typically 'ei' (although this is not consistent across the
code).
> + bool efi_64;
Is this a flag that shows whether the EFI loader is 64-bit?
> + char *sig;
> + int size;
> + int i;
> +
> + e = &boot_params->efi_info;
> + sig = (char *)&e->efi_loader_signature;
> +
> + if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
> + efi_64 = true;
> + } else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {
> + efi_64 = false;
> + } else {
> + debug_putstr("Wrong EFI loader signature.\n");
> + return 0;
> + }
> +
> + /* Get systab from boot params. Based on efi_init(). */
> +#ifdef CONFIG_X86_64
> + systab = (efi_system_table_t *)(e->efi_systab |
> ((__u64)e->efi_systab_hi<<32));
> +#else
> + if (e->efi_systab_hi || e->efi_memmap_hi) {
> + debug_putstr("Error getting RSDP address: EFI system table
> located above 4GB.\n");
> + return 0;
> + }
> + systab = (efi_system_table_t *)e->efi_systab;
> +#endif
> +
> + if (!systab)
> + return 0;
Is it normal that EFI provides no 'systab'?
> + /*
> + * Get EFI tables from systab. Based on efi_config_init() and
> + * efi_config_parse_tables().
> + */
> + size = efi_64 ? sizeof(efi_config_table_64_t) :
> + sizeof(efi_config_table_32_t);
> +
> + for (i = 0; i < systab->nr_tables; i++) {
> + void *config_tables;
> + unsigned long table;
> + efi_guid_t guid;
> +
> + config_tables = (void *)(systab->tables + size * i);
> + if (efi_64) {
> + efi_config_table_64_t *tmp_table;
> +
> + tmp_table = (efi_config_table_64_t *)config_tables;
Since 'config_tables' is a void * there's no need to cast the type.
> + guid = tmp_table->guid;
> + table = tmp_table->table;
> +
> + if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) {
> + debug_putstr("Error getting RSDP address: EFI
> config table located above 4GB.\n");
> + return 0;
> + }
> + } else {
> + efi_config_table_32_t *tmp_table;
> +
> + tmp_table = (efi_config_table_32_t *)config_tables;
Ditto.
> + guid = tmp_table->guid;
> + table = tmp_table->table;
> + }
So it looks like
> +
> + if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
> + rsdp_addr = (acpi_physical_address)table;
> + else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
> + return (acpi_physical_address)table;
'return' is not a function.
Thanks,
Ingo
