diff options
| author | David Milosevic <David.Milosevic@9elements.com> | 2023-04-27 02:12:31 +0200 |
|---|---|---|
| committer | Werner Zeh <werner.zeh@siemens.com> | 2024-04-22 07:35:36 +0000 |
| commit | 41ba11229a80eb19d97c8052aff1861478ee2486 (patch) | |
| tree | 9b6f1803e5854e577a68959e679187e8e4c88c3c /src/arch/arm64/Kconfig | |
| parent | 93cbbbfc7f32f62b1d20027541122c17e575ced6 (diff) | |
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 <David.Milosevic@9elements.com>
Change-Id: Iae1c57f0846c8d0585384f7e54102a837e701e7e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74798
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: ron minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Diffstat (limited to 'src/arch/arm64/Kconfig')
| -rw-r--r-- | src/arch/arm64/Kconfig | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/src/arch/arm64/Kconfig b/src/arch/arm64/Kconfig index 9b89c37c10..2d71067e45 100644 --- a/src/arch/arm64/Kconfig +++ b/src/arch/arm64/Kconfig @@ -23,6 +23,20 @@ source "src/arch/arm64/armv8/Kconfig" if ARCH_ARM64 +config ARM64_CURRENT_EL + int + default 3 + range 1 3 + help + The exception level on which coreboot is started. Accepted + values are: 1 (EL1), 2 (EL2) and 3 (EL3). This option can be + used to restrict access to available control registers in case + prior firmware already dropped to a lower exception level. By default, + coreboot is the first firmware that runs on the system and should thus + always run on EL3. This option is only provided for edge-case platforms + that require running a different firmware before coreboot which drops + to a lower exception level. + config ARM64_USE_ARCH_TIMER bool default n @@ -30,7 +44,7 @@ config ARM64_USE_ARCH_TIMER config ARM64_USE_ARM_TRUSTED_FIRMWARE bool default n - depends on ARCH_RAMSTAGE_ARM64 + depends on ARCH_RAMSTAGE_ARM64 && ARM64_CURRENT_EL = 3 config ARM64_BL31_EXTERNAL_FILE string "Path to external BL31.ELF (leave empty to build from source)" |