plat/kvm/arm: Make the earliest bootstack be part of the image

In order to make it easier for the paging API to not invalidate the
stack, make it part of the image (.bss), so that it is automatically
ignored.

Signed-off-by: Sergiu Moga <sergiu.moga@protonmail.com>
Reviewed-by: Michalis Pappas <michalis@unikraft.io>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #848

diff --git a/plat/kvm/arm/entry64.S b/plat/kvm/arm/entry64.S
index 52df96647949aa25f6d28b87edbac355cdec3b91..abf2c01dcc80bbeae8976289c666435c5cbd417e 100644 (file)
--- a/plat/kvm/arm/entry64.S
+++ b/plat/kvm/arm/entry64.S
@@ -36,6 +36,13 @@
 #include <uk/config.h>
 #include <uk/reloc.h>
 
+/* Prefer using in-image stack, to avoid conflicts when unmapping is done by
+ * paging_init (it invalidates our stack)
+ */
+.section .bss
+.space 4096
+lcpu_bootstack:
+
 /*
  * The registers used by _libkvmplat_start:
  * x0 - FDT pointer
@@ -45,8 +52,6 @@
 ENTRY(_libkvmplat_entry)
        ur_ldr  x25, _dtb
 
-       ur_ldr  x26, _end
-
 #ifdef CONFIG_FPSIMD
        /* Enable fp/simd support */
        ldr        x0, =(3 << 20)
@@ -63,10 +68,8 @@ ENTRY(_libkvmplat_entry)
         * just need to invalidate what we are going to use:
         * DTB, TEXT, DATA, BSS, and bootstack.
         */
-       ur_ldr  x0, _start_ram_addr
-
-       add x27, x26, #__STACK_SIZE
-       sub x1, x27, x25
+       ur_ldr  x0, _start_ram_addr
+       ur_ldr  x1, _end
        bl clean_and_invalidate_dcache_range
 
        /* Disable the MMU and D-Cache. */
@@ -78,7 +81,8 @@ ENTRY(_libkvmplat_entry)
        isb
 
        /* Set the boot stack */
-       mov sp, x27
+       ur_ldr x26, lcpu_bootstack
+       mov sp, x26
 
        /* Set the context id */
        msr contextidr_el1, xzr