Ard Biesheuvel 07415be140 x86/decompressor: Don't rely on upper 32 bits of GPRs being preserved ... [ Upstream commit 264b82fdb4989cf6a44a2bcd0c6ea05e8026b2ac ] The 4-to-5 level mode switch trampoline disables long mode and paging in order to be able to flick the LA57 bit. According to section 3.4.1.1 of the x86 architecture manual [0], 64-bit GPRs might not retain the upper 32 bits of their contents across such a mode switch. Given that RBP, RBX and RSI are live at this point, preserve them on the stack, along with the return address that might be above 4G as well. [0] Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1: Basic Architecture "Because the upper 32 bits of 64-bit general-purpose registers are undefined in 32-bit modes, the upper 32 bits of any general-purpose register are not preserved when switching from 64-bit mode to a 32-bit mode (to protected mode or compatibility mode). Software must not depend on these bits to maintain a value after a 64-bit to 32-bit mode switch." Fixes: 194a9749c7 ("x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G") Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230807162720.545787-2-ardb@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-09-23 10:59:41 +02:00
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compressed	x86/decompressor: Don't rely on upper 32 bits of GPRs being preserved	2023-09-23 10:59:41 +02:00
tools
.gitignore
a20.c
apm.c
bioscall.S
bitops.h
boot.h	x86/boot: Wrap literal addresses in absolute_pointer()	2023-06-09 10:29:01 +02:00
cmdline.c
code16gcc.h
copy.S
cpu.c
cpucheck.c
cpuflags.c
cpuflags.h
ctype.h
early_serial_console.c
edd.c
genimage.sh
header.S
install.sh
main.c	x86/boot: Wrap literal addresses in absolute_pointer()	2023-06-09 10:29:01 +02:00
Makefile
memory.c
mkcpustr.c
mtools.conf.in
pm.c
pmjump.S	x86/boot: Annotate local functions	2023-09-23 10:59:41 +02:00
printf.c
regs.c
setup.ld
string.c
string.h
tty.c
version.c
vesa.h
video-bios.c
video-mode.c
video-vesa.c
video-vga.c
video.c
video.h