[U-Boot] [RFC 1/1] efi_loader: refactor switch to hypervisor mode

[Heinrich Schuchardt]

Refactor the switch from supervisor to hypervisor to a new function called at
the beginning of do_bootefi().

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
With this patch I am just moving around the switch from supervisor to
hypervisor mode within the EFI subsystem. Similar switching also occurs
in all other boot commands (cf. arch/arm/lib/bootm.c).

Why are we running the U-Boot console in supervisor mode at all? Wouldn't
it be advisable for security reasons to switch to hypervisor mode before
entering the console?

Best regards

Heinrich
---
 cmd/bootefi.c | 109 ++++++++++++++++++++++----------------------------
 1 file changed, 47 insertions(+), 62 deletions(-)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 1aaf5319e13..277d4863953 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -31,9 +31,9 @@ DECLARE_GLOBAL_DATA_PTR;
 #define OBJ_LIST_NOT_INITIALIZED 1
 
 static efi_status_t efi_obj_list_initialized = OBJ_LIST_NOT_INITIALIZED;
-
 static struct efi_device_path *bootefi_image_path;
 static struct efi_device_path *bootefi_device_path;
+struct jmp_buf_data hyp_jmp;
 
 /* Initialize and populate EFI object list */
 efi_status_t efi_init_obj_list(void)
@@ -122,6 +122,50 @@ void __weak allow_unaligned(void)
 {
 }
 
+/**
+ * entry_hyp() - entry point when switching to hypervisor mode
+ */
+static void entry_hyp(void)
+{
+	dcache_enable();
+	debug("Reached HYP mode\n");
+	longjmp(&hyp_jmp, 1);
+}
+
+/**
+ * leave_supervisor() - switch to hypervisor mode
+ */
+static void leave_supervisor(void)
+{
+#ifdef CONFIG_ARMV7_NONSEC
+	static bool is_nonsec;
+
+	if (armv7_boot_nonsec() && !is_nonsec) {
+		if (setjmp(&hyp_jmp))
+			return;
+		dcache_disable();	/* flush cache before switch to HYP */
+		armv7_init_nonsec();
+		is_nonsec = true;
+		secure_ram_addr(_do_nonsec_entry)(entry_hyp, 0, 0, 0);
+	}
+#endif
+
+#ifdef CONFIG_ARM64
+	/* On AArch64 we need to make sure we call our payload in < EL3 */
+	if (current_el() == 3) {
+		if (setjmp(&hyp_jmp))
+			return;
+		smp_kick_all_cpus();
+		dcache_disable();	/* flush cache before switch to EL2 */
+
+		/* Move into EL2 and keep running there */
+		armv8_switch_to_el2(0, 0, 0, 0, (uintptr_t)entry_hyp,
+				    ES_TO_AARCH64);
+	}
+#endif
+	return;
+}
+
 /*
  * Set the load options of an image from an environment variable.
  *
@@ -233,34 +277,6 @@ static efi_status_t efi_do_enter(
 	return ret;
 }
 
-#ifdef CONFIG_ARM64
-static efi_status_t efi_run_in_el2(EFIAPI efi_status_t (*entry)(
-			efi_handle_t image_handle, struct efi_system_table *st),
-			efi_handle_t image_handle, struct efi_system_table *st)
-{
-	/* Enable caches again */
-	dcache_enable();
-
-	return efi_do_enter(image_handle, st, entry);
-}
-#endif
-
-#ifdef CONFIG_ARMV7_NONSEC
-static bool is_nonsec;
-
-static efi_status_t efi_run_in_hyp(EFIAPI efi_status_t (*entry)(
-			efi_handle_t image_handle, struct efi_system_table *st),
-			efi_handle_t image_handle, struct efi_system_table *st)
-{
-	/* Enable caches again */
-	dcache_enable();
-
-	is_nonsec = true;
-
-	return efi_do_enter(image_handle, st, entry);
-}
-#endif
-
 /*
  * efi_carve_out_dt_rsv() - Carve out DT reserved memory ranges
  *
@@ -440,39 +456,6 @@ static efi_status_t do_bootefi_exec(void *efi,
 		goto err_prepare;
 	}
 
-#ifdef CONFIG_ARM64
-	/* On AArch64 we need to make sure we call our payload in < EL3 */
-	if (current_el() == 3) {
-		smp_kick_all_cpus();
-		dcache_disable();	/* flush cache before switch to EL2 */
-
-		/* Move into EL2 and keep running there */
-		armv8_switch_to_el2((ulong)entry,
-				    (ulong)&image_obj->header,
-				    (ulong)&systab, 0, (ulong)efi_run_in_el2,
-				    ES_TO_AARCH64);
-
-		/* Should never reach here, efi exits with longjmp */
-		while (1) { }
-	}
-#endif
-
-#ifdef CONFIG_ARMV7_NONSEC
-	if (armv7_boot_nonsec() && !is_nonsec) {
-		dcache_disable();	/* flush cache before switch to HYP */
-
-		armv7_init_nonsec();
-		secure_ram_addr(_do_nonsec_entry)(
-					efi_run_in_hyp,
-					(uintptr_t)entry,
-					(uintptr_t)&image_obj->header,
-					(uintptr_t)&systab);
-
-		/* Should never reach here, efi exits with longjmp */
-		while (1) { }
-	}
-#endif
-
 	ret = efi_do_enter(&image_obj->header, &systab, entry);
 
 err_prepare:
@@ -558,6 +541,8 @@ static int do_bootefi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	/* Allow unaligned memory access */
 	allow_unaligned();
 
+	leave_supervisor();
+
 	/* Initialize EFI drivers */
 	r = efi_init_obj_list();
 	if (r != EFI_SUCCESS) {
-- 
2.19.2