x86: Add a way to call 32-bit code from 64-bit mode
authorSimon Glass <sjg@chromium.org>
Tue, 4 Aug 2015 18:33:55 +0000 (12:33 -0600)
committerSimon Glass <sjg@chromium.org>
Wed, 5 Aug 2015 14:44:07 +0000 (08:44 -0600)
commit6f92ed8f1abfe94ee1c96c83c21f4092bb04ff63
treef487163b3e28006dbe9023ae8c6c3abfbd211461
parent7dfe8bdeef7f8a7223fb39e04faaa5c7489feb3f
x86: Add a way to call 32-bit code from 64-bit mode

The procedure to drop from 64-bit mode to 32-bit is a bit messy. Add a
function to take care of it. It requires identity-mapped pages and that
the calling code is running below 4GB.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
arch/x86/cpu/Makefile
arch/x86/cpu/call32.S [new file with mode: 0644]
arch/x86/include/asm/cpu.h