vmbase: Move stack to end of writable_data
Instead of imposing an arbitrary size for the stack, allows clients to
query a validated address range of a given size with boot_stack_range(),
which places the stack at the largest address possible, extending
downwards (common on AArch64).
Keep allocating 40 pages of stack in vmbase_example, rialto, and pvmfw.
Bug: 279209532
Bug: 270684188
Test: atest vmbase_example.integration_test
Test: atest rialto_test
Test: atest MicrodroidTests
Change-Id: If205ccd4fa408e32e5533b880a85f4cccbd3f005
diff --git a/pvmfw/src/helpers.rs b/pvmfw/src/helpers.rs
index 8c05217..1f0a764 100644
--- a/pvmfw/src/helpers.rs
+++ b/pvmfw/src/helpers.rs
@@ -22,6 +22,7 @@
pub const SIZE_4MB: usize = 4 << 20;
pub const GUEST_PAGE_SIZE: usize = SIZE_4KB;
+pub const PVMFW_PAGE_SIZE: usize = SIZE_4KB;
/// Read a value from a system register.
#[macro_export]