cpu/x86/64bit/mode_switch2: The reverse function to mode_switch
Add another mode_switch assembly function to call x86_64 code from
x86_32 code. This is particullary useful for BLOBs like mrc.bin or
FSP that calls back into coreboot.
The user must first wrap all functions that are to be called from
x86_32 using the macro prot2lm_wrapper. Instead of using the original
function the wrapped functions must be passed to the x86_32 BLOBs.
The assembly code assume that 0-3 32bit arguments are passed to
the wrapped function.
Tested:
- Called x86_64 code from x86_32 code in qemu.
- Booted Lenovo X220 using x86_32 MRC using x86_64 console.
Change-Id: Ib625233e5f673eae9f3dcb2d03004c06bb07b149
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79753
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/cpu/x86/64bit/Makefile.inc b/src/cpu/x86/64bit/Makefile.inc
index e1cf743..24a5a96 100644
--- a/src/cpu/x86/64bit/Makefile.inc
+++ b/src/cpu/x86/64bit/Makefile.inc
@@ -1,6 +1,7 @@
## SPDX-License-Identifier: GPL-2.0-only
all_x86-y += mode_switch.S
+all_x86-y += mode_switch2.S
# Add --defsym=_start=0 to suppress a linker warning.
$(objcbfs)/pt: $(dir)/pt.S $(obj)/config.h