ARM: Add an empty secure stack section

Until now we've been using memory beyond psci_text_end as stack space
for the secure monitor or PSCI implementation, even if space was not
allocated for it.

This was partially fixed in ("ARM: allocate extra space for PSCI stack
in secure section during link phase"). However, calculating stack space
from psci_text_end in one place, while allocating the space in another
is error prone.

This patch adds a separate empty secure stack section, with space for
CONFIG_ARMV7_PSCI_NR_CPUS stacks, each 1 KB. There's also
__secure_stack_start and __secure_stack_end symbols. The linker script
handles calculating the correct VMAs for the stack section. For
platforms that relocate/copy the secure monitor before using it, the
space is not allocated in the executable, saving space.

For platforms that do not define CONFIG_ARMV7_PSCI_NR_CPUS, a whole page
of stack space for 4 CPUs is allocated, matching the previous behavior.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/lib/sections.c b/arch/arm/lib/sections.c
index 6a94522..952e8ae 100644
--- a/arch/arm/lib/sections.c
+++ b/arch/arm/lib/sections.c
@@ -27,6 +27,8 @@ char __rel_dyn_start[0] __attribute__((section(".__rel_dyn_start")));
 char __rel_dyn_end[0] __attribute__((section(".__rel_dyn_end")));
 char __secure_start[0] __attribute__((section(".__secure_start")));
 char __secure_end[0] __attribute__((section(".__secure_end")));
+char __secure_stack_start[0] __attribute__((section(".__secure_stack_start")));
+char __secure_stack_end[0] __attribute__((section(".__secure_stack_end")));
 char __efi_runtime_start[0] __attribute__((section(".__efi_runtime_start")));
 char __efi_runtime_stop[0] __attribute__((section(".__efi_runtime_stop")));
 char __efi_runtime_rel_start[0] __attribute__((section(".__efi_runtime_rel_start")));