Patrick Georgi (pgeorgi@google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9538
-gerrit
commit 48e75775453d4552770c06061153bb9467afb99d Author: Furquan Shaikh furquan@google.com Date: Fri Nov 21 15:35:17 2014 -0800
arm64: Add conditional read/write from/to EL3 assembly macros.
Some registers are available only at EL3. Add conditional read/write functions that perform operations only if currently we are in EL3.
BUG=chrome-os-partner:33962 BRANCH=None TEST=Compiles and boots to kernel prompt.
Change-Id: Ic95838d10e18f58867b6b77aee937bdacae50597 Signed-off-by: Patrick Georgi pgeorgi@chromium.org Original-Commit-Id: 62a0e324a00248dba92cb3e2ac2f4072d0e4e2a7 Original-Signed-off-by: Furquan Shaikh furquan@google.com Original-Change-Id: Ia170d94adb9ecc141ff86e4a3041ddbf9045bc89 Original-Reviewed-on: https://chromium-review.googlesource.com/231549 Original-Reviewed-by: Aaron Durbin adurbin@chromium.org Original-Tested-by: Furquan Shaikh furquan@chromium.org Original-Commit-Queue: Furquan Shaikh furquan@chromium.org --- src/arch/arm64/include/armv8/arch/lib_helpers.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/src/arch/arm64/include/armv8/arch/lib_helpers.h b/src/arch/arm64/include/armv8/arch/lib_helpers.h index a804747..422b81a 100644 --- a/src/arch/arm64/include/armv8/arch/lib_helpers.h +++ b/src/arch/arm64/include/armv8/arch/lib_helpers.h @@ -214,6 +214,31 @@ 104: .endm
+/* Macro to read from a register at EL3 only if we are currently at that + level. This is required to ensure that we do not attempt to read registers + from a level lower than el3. e.g. SCR is available for read only at EL3. + IMPORTANT: if EL != EL3, macro silently doesn't perform the read. +*/ +.macro read_el3 xreg sysreg + switch_el \xreg, 402f, 402f, 401f +401: + mrs \xreg, \sysreg()_el3 +402: +.endm + +/* Macro to write to a register at EL3 only if we are currently at that + level. This is required to ensure that we do not attempt to write to + registers from a level lower than el3. e.g. SCR is available to write only at + EL3. + IMPORTANT: if EL != EL3, macro silently doesn't perform the write. +*/ +.macro write_el3 sysreg xreg temp + switch_el \temp, 402f, 402f, 401f +401: + msr \sysreg()_el3, \xreg +402: +.endm + #else
#include <stdint.h>