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SubjectRe: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel
Something like this based on your v3. I still need to figure out a
reliable way to check in kexec_get_rsdp_addr() whether we're a kexec-ed
kernel but other than that, it should look something like this:

---
diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 0ef4ad55b29b..039d91258171 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -8,6 +8,8 @@
#include <linux/efi.h>
#include <asm/efi.h>

+#define EFI_SETUP_DATA_INVALID -1ULL
+
/*
* Longest parameter of 'acpi=' is 'copy_dsdt', plus an extra '\0'
* for termination.
@@ -44,17 +46,108 @@ static acpi_physical_address get_acpi_rsdp(void)
return addr;
}

-/* Search EFI system tables for RSDP. */
-static acpi_physical_address efi_get_rsdp_addr(void)
+static struct efi_setup_data *get_kexec_setup_data_addr(void)
+{
+ 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 (struct efi_setup_data *)(pa_data + sizeof(struct setup_data));
+
+ pa_data = data->next;
+ }
+ return NULL;
+}
+
+#ifdef CONFIG_EFI
+/*
+ * Search EFI system tables for RSDP. If both ACPI_20_TABLE_GUID and
+ * ACPI_TABLE_GUID are found, take the former, which has more features.
+ */
+static acpi_physical_address
+__efi_get_rsdp_addr(unsigned long config_tables, unsigned int nr_tables,
+ bool efi_64)
{
acpi_physical_address rsdp_addr = 0;
+ int i;
+
+ /* Get EFI tables from systab. */
+ for (i = 0; i < nr_tables; i++) {
+ acpi_physical_address table;
+ efi_guid_t guid;
+
+ if (efi_64) {
+ efi_config_table_64_t *tbl = (efi_config_table_64_t *) config_tables + i;
+
+ 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 + i;
+
+ 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 rsdp_addr;
+}
+#endif
+
+/* EFI/kexec support is 64-bit only. */
+static acpi_physical_address kexec_get_rsdp_addr(void)
+{
+ efi_system_table_64_t *systab;
+ struct efi_setup_data *esd;
+ struct efi_info *ei;
+ char *sig;
+
+ if (!IS_ENABLED(CONFIG_X86_64))
+ return 0;
+
+ esd = get_kexec_setup_data_addr();
+ if (!esd)
+ return EFI_SETUP_DATA_INVALID;

+ 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 kexec 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 in kexec boot_params.");
+
+ return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables, true);
+}
+
+static acpi_physical_address efi_get_rsdp_addr(void)
+{
#ifdef CONFIG_EFI
- unsigned long systab, systab_tables, config_tables;
+ unsigned long systab, config_tables;
unsigned int nr_tables;
struct efi_info *ei;
bool efi_64;
- int size, i;
char *sig;

ei = &boot_params->efi_info;
@@ -88,49 +181,20 @@ static acpi_physical_address efi_get_rsdp_addr(void)

config_tables = stbl->tables;
nr_tables = stbl->nr_tables;
- size = sizeof(efi_config_table_64_t);
} else {
efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab;

config_tables = stbl->tables;
nr_tables = stbl->nr_tables;
- size = sizeof(efi_config_table_32_t);
}

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, efi_64);
+#else
+ return 0;
#endif
- return rsdp_addr;
}

static u8 compute_checksum(u8 *buffer, u32 length)
@@ -220,6 +284,12 @@ acpi_physical_address get_rsdp_addr(void)
if (!pa)
pa = boot_params->acpi_rsdp_addr;

+ if (!pa)
+ pa = kexec_get_rsdp_addr();
+
+ if (pa == EFI_SETUP_DATA_INVALID)
+ return 0;
+
if (!pa)
pa = efi_get_rsdp_addr();


--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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