x86/cmdline: Disable jump tables for cmdline.c

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 <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Link: https://lore.kernel.org/r/[email protected]
ambv · Sep 3, 2020 · aef0148 · aef0148
1 parent fc3abb5
commit aef0148
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
@@ -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