Re: [PATCH v2] x86/boot: Use EFI setup data if provided

[Junichi Nomura]

On 2019/03/28 15:43, bhe@xxxxxxxxxx wrote:
> On 03/28/19 at 04:17am, Junichi Nomura wrote:
>> I still don't get it... We still need systab for kexec case as well
>> to get nr_tables. Don't we?
> 
> Yes, simpler.
> 
> As Dave replied in another mail, efi/kexec is only added for x86_64. See
> how it does in setup_linux_system_parameters() of kexec_tools utility,
> and we only have bzImage64 handling in kernel for kexec_file loading,
> see prepare_add_efi_setup_data().
> 
> You may only need to get kexec ei_info to use directly.

OK, let me try. How does this look?


Commit 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in
boot_params") broke kexec boot on EFI systems.  efi_get_rsdp_addr()
in the early parsing code tries to search RSDP from EFI table but
that will crash because the table address is virtual when the kernel
was booted by kexec.

Since kexec(1) provides physical address of the table via efi_setup_data,
early boot code of kexec-ed kernel should look for setup_data in the same
way as efi_systab_init() in arch/x86/platform/efi/efi.c does.

Fixes: 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in boot_params")
Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Cc: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -44,17 +44,106 @@ static acpi_physical_address get_acpi_rsdp(void)
 	return addr;
 }
 
+static unsigned long efi_get_kexec_setup_data_addr(void)
+{
+#ifdef CONFIG_EFI
+	struct setup_data *data;
+	u64 pa_data;
+
+	pa_data = boot_params->hdr.setup_data;
+	while (pa_data) {
+		data = (struct setup_data *) pa_data;
+		if (data->type == SETUP_EFI)
+			return pa_data + sizeof(struct setup_data);
+		pa_data = data->next;
+	}
+#endif
+	return 0;
+}
+
 /* Search EFI system tables for RSDP. */
-static acpi_physical_address efi_get_rsdp_addr(void)
+static acpi_physical_address __efi_get_rsdp_addr(unsigned long config_tables, unsigned int nr_tables, int size, bool efi_64)
 {
 	acpi_physical_address rsdp_addr = 0;
 
 #ifdef CONFIG_EFI
-	unsigned long systab, systab_tables, config_tables;
+	int i;
+
+	/* Get EFI tables from systab. */
+	for (i = 0; i < nr_tables; i++) {
+		acpi_physical_address table;
+		efi_guid_t guid;
+
+		config_tables += size;
+
+		if (efi_64) {
+			efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables;
+
+			guid  = tbl->guid;
+			table = tbl->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 *tbl = (efi_config_table_32_t *)config_tables;
+
+			guid  = tbl->guid;
+			table = tbl->table;
+		}
+
+		if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
+			rsdp_addr = table;
+		else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
+			return table;
+	}
+#endif
+	return rsdp_addr;
+}
+
+static acpi_physical_address kexec_get_rsdp_addr(void)
+{
+#ifdef CONFIG_EFI
+	struct efi_setup_data *esd;
+	efi_system_table_64_t *systab;
+	struct efi_info *ei;
+	char *sig;
+
+	esd = (struct efi_setup_data *) efi_get_kexec_setup_data_addr();
+	if (!esd)
+		return 0;
+	if (!esd->tables) {
+		debug_putstr("Wrong kexec SETUP_EFI data.\n");
+		return 0;
+	}
+
+	ei = &boot_params->efi_info;
+	sig = (char *)&ei->efi_loader_signature;
+	if (strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
+		debug_putstr("Wrong EFI loader signature.\n");
+		return 0;
+	}
+
+	/* Get systab from boot params. */
+	systab = (efi_system_table_64_t *) (ei->efi_systab | ((__u64)ei->efi_systab_hi << 32));
+	if (!systab)
+		error("EFI system table not found.");
+
+	return __efi_get_rsdp_addr((unsigned long) esd->tables, systab->nr_tables, sizeof(efi_config_table_64_t), true);
+#else
+	return 0;
+#endif
+}
+
+static acpi_physical_address efi_get_rsdp_addr(void)
+{
+#ifdef CONFIG_EFI
+	unsigned long systab, config_tables;
 	unsigned int nr_tables;
 	struct efi_info *ei;
 	bool efi_64;
-	int size, i;
+	int size;
 	char *sig;
 
 	ei = &boot_params->efi_info;
@@ -100,37 +189,10 @@ static acpi_physical_address efi_get_rsdp_addr(void)
 	if (!config_tables)
 		error("EFI config tables not found.");
 
-	/* Get EFI tables from systab. */
-	for (i = 0; i < nr_tables; i++) {
-		acpi_physical_address table;
-		efi_guid_t guid;
-
-		config_tables += size;
-
-		if (efi_64) {
-			efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables;
-
-			guid  = tbl->guid;
-			table = tbl->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 *tbl = (efi_config_table_32_t *)config_tables;
-
-			guid  = tbl->guid;
-			table = tbl->table;
-		}
-
-		if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
-			rsdp_addr = table;
-		else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
-			return table;
-	}
+	return __efi_get_rsdp_addr(config_tables, nr_tables, size, efi_64);
+#else
+	return 0;
 #endif
-	return rsdp_addr;
 }
 
 static u8 compute_checksum(u8 *buffer, u32 length)
@@ -221,6 +283,9 @@ acpi_physical_address get_rsdp_addr(void)
 		pa = boot_params->acpi_rsdp_addr;
 
 	if (!pa)
+		pa = kexec_get_rsdp_addr();
+
+	if (!pa)
 		pa = efi_get_rsdp_addr();
 
 	if (!pa)