From 41ba11229a80eb19d97c8052aff1861478ee2486 Mon Sep 17 00:00:00 2001 From: David Milosevic Date: Thu, 27 Apr 2023 02:12:31 +0200 Subject: arch/arm64: Add EL1/EL2/EL3 support for arm64 Currently, arch/arm64 requires coreboot to run on EL3 due to EL3 register access. This might be an issue when, for example, one boots into TF-A first and drops into EL2 for coreboot afterwards. This patch aims at making arch/arm64 more versatile by removing the current EL3 constraint and allowing arm64 coreboot to run on EL1, EL2 and EL3. The strategy here, is to add a Kconfig option (ARM64_CURRENT_EL) which lets us specify coreboot's EL upon entry. Based on that, we access the appropriate ELx registers. So, for example, when running coreboot on EL1, we would not access vbar_el3 or vbar_el2 but instead vbar_el1. This way, we don't generate faults when accessing higher-EL registers. Currently only tested on the qemu-aarch64 target. Exceptions were tested by enabling FATAL_ASSERTS. Signed-off-by: David Milosevic Change-Id: Iae1c57f0846c8d0585384f7e54102a837e701e7e Reviewed-on: https://review.coreboot.org/c/coreboot/+/74798 Reviewed-by: Werner Zeh Reviewed-by: ron minnich Tested-by: build bot (Jenkins) Reviewed-by: Julius Werner --- src/arch/arm64/armv8/cpu.S | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'src/arch/arm64/armv8/cpu.S') diff --git a/src/arch/arm64/armv8/cpu.S b/src/arch/arm64/armv8/cpu.S index 04bf6a7021..a40ee64536 100644 --- a/src/arch/arm64/armv8/cpu.S +++ b/src/arch/arm64/armv8/cpu.S @@ -77,10 +77,10 @@ ENDPROC(dcache_clean_invalidate_all) memory (e.g. the stack) in between disabling and flushing the cache. */ ENTRY(mmu_disable) str x30, [sp, #-0x8] - mrs x0, sctlr_el3 + mrs x0, CURRENT_EL(sctlr) mov x1, #~(SCTLR_C | SCTLR_M) and x0, x0, x1 - msr sctlr_el3, x0 + msr CURRENT_EL(sctlr), x0 isb bl dcache_clean_invalidate_all ldr x30, [sp, #-0x8] @@ -102,12 +102,11 @@ ENTRY(arm64_init_cpu) /* x22: SCTLR, return address: x23 (callee-saved by subroutine) */ mov x23, x30 - /* TODO: Assert that we always start running at EL3 */ - mrs x22, sctlr_el3 + mrs x22, CURRENT_EL(sctlr) /* Activate ICache already for speed during cache flush below. */ orr x22, x22, #SCTLR_I - msr sctlr_el3, x22 + msr CURRENT_EL(sctlr), x22 isb /* Invalidate dcache */ @@ -116,13 +115,15 @@ ENTRY(arm64_init_cpu) /* Reinitialize SCTLR from scratch to known-good state. This may disable MMU or DCache. */ ldr w22, =(SCTLR_RES1 | SCTLR_I | SCTLR_SA) - msr sctlr_el3, x22 + msr CURRENT_EL(sctlr), x22 +#if CONFIG_ARM64_CURRENT_EL == EL3 /* Initialize SCR to unmask all interrupts (so that if we get a spurious IRQ/SError we'll see it when it happens, not hang in BL31). This will only have an effect after we DAIFClr in exception_init(). */ mov x22, #SCR_RES1 | SCR_IRQ | SCR_FIQ | SCR_EA msr scr_el3, x22 +#endif /* Invalidate icache and TLB for good measure */ ic iallu -- cgit v1.2.3