[U-Boot] [RFC 4/6] efi_loader: Patch non-runtime code out at ExitBootServices already

[AKASHI Takahiro]

From: Alexander Graf <agraf at suse.de>

While discussing something completely different, Ard pointed out
that it might be legal to omit calling SetVirtualAddressMap altogether.

There is even a patch on the Linux Kernel Mailing List that implements
such behavior by now:

  https://patchwork.kernel.org/patch/10782393/

While that sounds great, we currently rely on the SetVirtualAddressMap
call to remove all references to code that would not work outside of
boot services.

So let's patch out those bits already on the call to ExitBootServices,
so that we can successfully run even when an OS chooses to omit
any call to SetVirtualAddressMap.

Reported-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Signed-off-by: Alexander Graf <agraf at suse.de>

OpenBSD is not calling SetVirtualAddressMap on ARM 32 bit.

Adjust selftest: expect 'U-Boot' instead of 'resetting'.

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 include/efi_loader.h               |  2 ++
 lib/efi_loader/efi_boottime.c      |  1 +
 lib/efi_loader/efi_runtime.c       | 25 ++++++++++++++++++++-----
 test/py/tests/test_efi_selftest.py |  4 ++--
 4 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 7bd8002e303e..93f7ece814a0 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -381,6 +381,8 @@ void efi_save_gd(void);
 void efi_restore_gd(void);
 /* Call this to relocate the runtime section to an address space */
 void efi_runtime_relocate(ulong offset, struct efi_mem_desc *map);
+/* Call this when we start to live in a runtime only world */
+void efi_runtime_detach(ulong offset);
 /* Call this to set the current device name */
 void efi_set_bootdev(const char *dev, const char *devnr, const char *path);
 /* Add a new object to the object list. */
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 7d1d6e92138e..e4abaf3601d9 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -1932,6 +1932,7 @@ static efi_status_t EFIAPI efi_exit_boot_services(efi_handle_t image_handle,
 	bootm_disable_interrupts();
 
 	/* Disable boot time services */
+	efi_runtime_detach((ulong)gd->relocaddr);
 	systab.con_in_handle = NULL;
 	systab.con_in = NULL;
 	systab.con_out_handle = NULL;
diff --git a/lib/efi_loader/efi_runtime.c b/lib/efi_loader/efi_runtime.c
index ff3684a4b692..fc5bdee80e00 100644
--- a/lib/efi_loader/efi_runtime.c
+++ b/lib/efi_loader/efi_runtime.c
@@ -433,7 +433,7 @@ struct efi_runtime_detach_list_struct {
 	void *patchto;
 };
 
-static const struct efi_runtime_detach_list_struct efi_runtime_detach_list[] = {
+static struct efi_runtime_detach_list_struct efi_runtime_detach_list[] = {
 	{
 		/* do_reset is gone */
 		.ptr = &efi_runtime_services.reset_system,
@@ -490,7 +490,15 @@ static bool efi_runtime_tobedetached(void *p)
 	return false;
 }
 
-static void efi_runtime_detach(ulong offset)
+/**
+ * efi_runtime_detach() - Remove any dependency on non-runtime sections
+ *
+ * This function patches all remaining code to be self-sufficient inside
+ * runtime sections. Any calls to non-runtime will be removed after this.
+ *
+ * @offset:		relocaddr for pre-set_v_a_space, offset to VA after
+ */
+__efi_runtime void efi_runtime_detach(ulong offset)
 {
 	int i;
 	ulong patchoff = offset - (ulong)gd->relocaddr;
@@ -506,6 +514,8 @@ static void efi_runtime_detach(ulong offset)
 
 	/* Update CRC32 */
 	efi_update_table_header_crc32(&efi_runtime_services.hdr);
+
+	invalidate_icache_all();
 }
 
 /* Relocate EFI runtime to uboot_reloc_base = offset */
@@ -593,19 +603,25 @@ void efi_runtime_relocate(ulong offset, struct efi_mem_desc *map)
  * @virtmap:		virtual address mapping information
  * Return:		status code
  */
-static efi_status_t EFIAPI efi_set_virtual_address_map(
+static __efi_runtime efi_status_t EFIAPI efi_set_virtual_address_map(
 			unsigned long memory_map_size,
 			unsigned long descriptor_size,
 			uint32_t descriptor_version,
 			struct efi_mem_desc *virtmap)
 {
+	static __efi_runtime_data bool is_patched;
 	int n = memory_map_size / descriptor_size;
 	int i;
 	int rt_code_sections = 0;
 
+	if (is_patched)
+		return EFI_INVALID_PARAMETER;
+
 	EFI_ENTRY("%lx %lx %x %p", memory_map_size, descriptor_size,
 		  descriptor_version, virtmap);
 
+	is_patched = true;
+
 	/*
 	 * TODO:
 	 * Further down we are cheating. While really we should implement
@@ -681,8 +697,7 @@ static efi_status_t EFIAPI efi_set_virtual_address_map(
 					   map->physical_start + gd->relocaddr;
 
 			efi_runtime_relocate(new_offset, map);
-			/* Once we're virtual, we can no longer handle
-			   complex callbacks */
+			/* We need to repatch callbacks for their new VA */
 			efi_runtime_detach(new_offset);
 
 			/*
diff --git a/test/py/tests/test_efi_selftest.py b/test/py/tests/test_efi_selftest.py
index 07e4db045284..f950911655a3 100644
--- a/test/py/tests/test_efi_selftest.py
+++ b/test/py/tests/test_efi_selftest.py
@@ -20,7 +20,7 @@ def test_efi_selftest(u_boot_console):
 	if m != 0:
 		raise Exception('Failures occurred during the EFI selftest')
 	u_boot_console.run_command(cmd='', wait_for_echo=False, wait_for_prompt=False);
-	m = u_boot_console.p.expect(['resetting', 'U-Boot'])
+	m = u_boot_console.p.expect(['U-Boot'])
 	if m != 0:
 		raise Exception('Reset failed during the EFI selftest')
 	u_boot_console.restart_uboot();
@@ -47,7 +47,7 @@ def test_efi_selftest_watchdog_reboot(u_boot_console):
 	assert '\'watchdog reboot\'' in output
 	u_boot_console.run_command(cmd='setenv efi_selftest watchdog reboot')
 	u_boot_console.run_command(cmd='bootefi selftest', wait_for_prompt=False)
-	m = u_boot_console.p.expect(['resetting', 'U-Boot'])
+	m = u_boot_console.p.expect(['U-Boot'])
 	if m != 0:
 		raise Exception('Reset failed in \'watchdog reboot\' test')
 	u_boot_console.restart_uboot();
-- 
2.21.0