On 5/29/25 06:05, Ying-Chun Liu (PaulLiu) wrote:
From: "Ying-Chun Liu (PaulLiu)" <[email protected]>
Add EFI_SYSTEM_TABLE_POINTER structure for remote debugger to locate
the address of EFI_SYSTEM_TABLE.
This feature is described in UEFI SPEC version 2.10. Section 18.4.2.
The implementation ensures support for hardware-assisted debugging and
provides a standardized mechanism for debuggers to discover the EFI
system table.
Signed-off-by: Ying-Chun Liu (PaulLiu) <[email protected]>
Cc: Heinrich Schuchardt <[email protected]>
Cc: Ilias Apalodimas <[email protected]>
Cc: Peter Robinson <[email protected]>
Cc: Simon Glass <[email protected]>
---
V2: add Kconfig options to turn on/off this feature.
V3: make efi_initialize_system_table_pointer() do the job as described.
V4: use efi_alloc_aligned_pages() for system_table_pointer.
---
include/efi_api.h | 16 +++++++++++++++
include/efi_loader.h | 2 ++
lib/efi_loader/Kconfig | 7 +++++++
lib/efi_loader/efi_boottime.c | 37 +++++++++++++++++++++++++++++++++++
lib/efi_loader/efi_setup.c | 8 ++++++++
5 files changed, 70 insertions(+)
diff --git a/include/efi_api.h b/include/efi_api.h
index eb61eafa028..6c4c1a0cc7b 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -259,6 +259,22 @@ struct efi_capsule_result_variable_header {
efi_status_t capsule_status;
} __packed;
+/**
+ * struct efi_system_table_pointer - struct to store the pointer of system
+ * table.
+ * @signature: The signature of this struct.
+ * @efi_system_table_base: The physical address of System Table.
+ * @crc32: CRC32 checksum
+ *
+ * This struct is design for hardware debugger to search through memory to
+ * get the address of EFI System Table.
+ */
+struct efi_system_table_pointer {
+ u64 signature;
+ efi_physical_addr_t efi_system_table_base;
+ u32 crc32;
+};
+
struct efi_memory_range {
efi_physical_addr_t address;
u64 length;
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 8f9f2bcf1cb..8f065244d8e 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -646,6 +646,8 @@ efi_status_t efi_tcg2_measure_dtb(void *dtb);
efi_status_t efi_root_node_register(void);
/* Called by bootefi to initialize runtime */
efi_status_t efi_initialize_system_table(void);
+/* Called by bootefi to initialize debug */
+efi_status_t efi_initialize_system_table_pointer(void);
/* efi_runtime_detach() - detach unimplemented runtime functions */
void efi_runtime_detach(void);
/* efi_convert_pointer() - convert pointer to virtual address */
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 7f02a83e2a2..d878fc9021d 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -71,6 +71,13 @@ config EFI_SECURE_BOOT
config EFI_SIGNATURE_SUPPORT
bool
+config EFI_DEBUG_SUPPORT_TABLE
+ bool "EFI Debug Support Table"
+ help
+ Select this option if you want to setup the EFI Debug Support
+ Table which is used by the debug agent or an external debugger to
+ determine loaded image information in a quiescent manner.
+
menu "UEFI services"
config EFI_GET_TIME
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index dbebb37dc04..16e921781e9 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -4001,6 +4001,8 @@ struct efi_system_table __efi_runtime_data systab = {
.tables = NULL,
};
+struct efi_system_table_pointer __efi_runtime_data * systab_pointer = NULL;
+
/**
* efi_initialize_system_table() - Initialize system table
*
@@ -4035,3 +4037,38 @@ efi_status_t efi_initialize_system_table(void)
return ret;
}
+
+/**
+ * efi_initialize_system_table() - Initialize system table pointer
+ *
+ * Return: status code
+ */
+efi_status_t efi_initialize_system_table_pointer(void)
+{
+ const int size_4MB = 0x00400000;
+ u64 addr;
+ u32 crc32_value;
+
+ /* Allocate configuration table array */
+ addr = (u64)efi_alloc_aligned_pages(sizeof(struct
efi_system_table_pointer),
+ EFI_RUNTIME_SERVICES_DATA,
+ size_4MB);
We expect the code to compile after each individual step. Function
efi_alloc_aligned_pages() does not exist when this step is applied.
Even if I apply all patches your code does not compile on 32bit systems:
+lib/efi_loader/efi_boottime.c:4072:16: error: cast from pointer to
integer of different size [-Werror=pointer-to-int-cast]
+ 4072 | addr = (u64)efi_alloc_aligned_pages(sizeof(struct
efi_system_table_pointer),
+ |
Use (uintptr_t) here.
Best regards
Heinrich
+
+ if (!addr) {
+ log_err("Installing EFI system table pointer failed\n");
+ return EFI_OUT_OF_RESOURCES;
+ }
+
+ systab_pointer = (struct efi_system_table_pointer *)addr;
+ memset(systab_pointer, 0, sizeof(struct efi_system_table_pointer));
+
+ systab_pointer->signature = EFI_SYSTEM_TABLE_SIGNATURE;
+ systab_pointer->efi_system_table_base = (efi_physical_addr_t)&systab;
+
+ crc32_value = crc32(0,
+ (const unsigned char *)systab_pointer,
+ sizeof(struct efi_system_table_pointer));
+ systab_pointer->crc32 = crc32_value;
+
+ return EFI_SUCCESS;
+}
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index 48f91da5df7..a6b37d994f6 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -278,6 +278,14 @@ efi_status_t efi_init_obj_list(void)
if (ret != EFI_SUCCESS)
goto out;
+ /* Initialize system table pointer */
+ if (IS_ENABLED(CONFIG_EFI_DEBUG_SUPPORT_TABLE)) {
+ ret = efi_initialize_system_table_pointer();
+ if (ret != EFI_SUCCESS) {
+ goto out;
+ }
+ }
+
if (IS_ENABLED(CONFIG_EFI_ECPT)) {
ret = efi_ecpt_register();
if (ret != EFI_SUCCESS)
