On 4/11/25 12:00, Ilias Apalodimas wrote:
Hi Heinrich,
[...]
+
+/**
+ * current_exception_level()
+ *
+ * Return: current exception level, 0 - 3
+ */
+static unsigned int current_exception_level(void)
+{
+ unsigned long el;
+
+ asm volatile (
+ "MRS %0, CurrentEL"
+ : "=r" (el) : : );
+
+ return (el >> 2) & 0x3;
+}
+
We have an identical function in arch/arm/include/asm/system.h, can we
use that? It's static inline so you may be able to just include the
header file directly. Also, that function adds a 'cc,' which tells the
compiler that the instruction might change the condition code flags. I
don't remember if this is needed, but it doesn't hurt to have it.
The function current_el() in arch/arm/include/asm/system.h is already
used in switch_to_non_secure_mode() when determining if U-Boot should
switch the exception state. Including the same function both in the code
under test and in the test should be avoided.
https://developer.arm.com/documentation/ddi0597/2025-03/Base-Instructions/MRS--Move-Special-register-to-general-purpose-register-
does not describe any side effects when reading the CurrentEL flags?
Best regards
Heinrich
+/**
+ * execute() - execute test
+ *
+ * Check that the exception level is not EL3.
+ */
+static int execute(void)
+{
+ unsigned int el = current_exception_level();
+
+ efi_st_printf("Exception level EL%u\n", el);
+ if (el != 1 && el != 2) {
+ efi_st_error("EL1 or EL2 expected");
+ return EFI_ST_FAILURE;
+ }
+
+ return EFI_ST_SUCCESS;
+}
+
+EFI_UNIT_TEST(el) = {
+ .name = "exception level",
+ .phase = EFI_EXECUTE_BEFORE_BOOTTIME_EXIT,
+ .execute = execute,
+};
--
2.48.1
Other than that LGTM
/Ilias
