[kvm-unit-tests PATCH v3 17/18] arm64: efi: Switch to our own stack

[Andrew Jones <andrew.jones@linux.dev>]

We don't want to map EFI_BOOT_SERVICES_DATA regions, so move the
stack from its EFI_BOOT_SERVICES_DATA region to EFI_LOADER_CODE,
which we always map. We'll still map the stack as R/W instead of
R/X because we split EFI_LOADER_CODE regions on the _etext boundary
and map addresses before _etext as R/X and the rest as R/W.

Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
---
 arm/efi/crt0-efi-aarch64.S | 22 +++++++++++++++++-----
 lib/arm/setup.c            |  4 ----
 lib/memregions.c           |  6 ------
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/arm/efi/crt0-efi-aarch64.S b/arm/efi/crt0-efi-aarch64.S
index 5fd3dc94dae8..71ce2794f059 100644
--- a/arm/efi/crt0-efi-aarch64.S
+++ b/arm/efi/crt0-efi-aarch64.S
@@ -125,12 +125,18 @@ _start:
 
 	ldp		x0, x1, [sp, #16]
 
-	/* Align sp; this is necessary due to way we store cpu0's thread_info */
+	/*
+	 * Switch to our own stack and align sp; this is necessary due
+	 * to way we store cpu0's thread_info
+	 */
+	adrp		x2, stacktop
+	add		x2, x2, :lo12:stacktop
+	and		x2, x2, #THREAD_MASK
+	mov		x3, sp
+	mov		sp, x2
+	stp		xzr, xzr, [sp, #-16]!
 	mov		x29, sp
-	mov		x30, sp
-	and		x30, x30, #THREAD_MASK
-	mov		sp, x30
-	str		x29, [sp, #-16]!
+	str		x3, [sp, #-16]!
 
 	bl		efi_main
 
@@ -140,3 +146,9 @@ _start:
 
 0:	ldp		x29, x30, [sp], #32
 	ret
+
+	.section	.data
+
+.balign 65536
+.space 65536
+stacktop:
diff --git a/lib/arm/setup.c b/lib/arm/setup.c
index 50a3bb65d865..2f649aff5551 100644
--- a/lib/arm/setup.c
+++ b/lib/arm/setup.c
@@ -340,10 +340,6 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
 {
 	efi_status_t status;
 
-	struct thread_info *ti = current_thread_info();
-
-	memset(ti, 0, sizeof(*ti));
-
 	exceptions_init();
 
 	memregions_init(arm_mem_regions, NR_MEM_REGIONS);
diff --git a/lib/memregions.c b/lib/memregions.c
index 3c6f751eb4f2..53fc0c7cfc58 100644
--- a/lib/memregions.c
+++ b/lib/memregions.c
@@ -114,12 +114,6 @@ void memregions_efi_init(struct efi_boot_memmap *mem_map,
 			break;
 		case EFI_LOADER_DATA:
 			break;
-		case EFI_BOOT_SERVICES_DATA:
-			/*
-			 * FIXME: This would ideally be MR_F_RESERVED, but the
-			 * primary stack is in a region of this EFI type.
-			 */
-			break;
 		case EFI_PERSISTENT_MEMORY:
 			r.flags = MR_F_PERSISTENT;
 			break;
-- 
2.44.0