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x86/cmdline: Disable jump tables for cmdline.c

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When CONFIG_RETPOLINE is disabled, Clang uses a jump table for the
switch statement in cmdline_find_option (jump tables are disabled when
CONFIG_RETPOLINE is enabled). This function is called very early in boot
from sme_enable() if CONFIG_AMD_MEM_ENCRYPT is enabled. At this time,
the kernel is still executing out of the identity mapping, but the jump
table will contain virtual addresses.

Fix this by disabling jump tables for cmdline.c when AMD_MEM_ENCRYPT is
enabled.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200903023056.3914690-1-nivedita@alum.mit.edu
This commit is contained in:
Arvind Sankar 2020-09-02 22:30:56 -04:00 committed by Ingo Molnar
parent fc3abb5325
commit aef0148f36
1 changed files with 1 additions and 1 deletions
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2
arch/x86/lib/Makefile
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@ -24,7 +24,7 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_cmdline.o = -pg
endif
CFLAGS_cmdline.o := -fno-stack-protector
CFLAGS_cmdline.o := -fno-stack-protector -fno-jump-tables
endif
inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk