Messages in this thread Patch in this message | | | From | "Hook, Gary" <> | Subject | [PATCH 2] x86/mm/mem_encrypt: Disable all instrumentation for SME early files | Date | Mon, 29 Apr 2019 22:22:58 +0000 |
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Enablement of AMD's Secure Memory Encryption feature is determined very early after start_kernel() is entered. Part of this procedure involves scanning the command line for the parameter 'mem_encrypt'.
To determine intended state, the function sme_enable() uses library functions cmdline_find_option() and strncmp(). Their use occurs early enough such that we can't assume that any instrumentation subsystem is initialized. For example, making calls to a KASAN-instrumented function before KASAN is set up will result in the use of uninitialized memory and a boot failure.
When AMD's SME support is enabled, conditionally disable instrumentation of these dependent functions in lib/string.c and arch/x86/lib/cmdline.c.
Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption") Reported-by: Li RongQing <lirongqing@baidu.com> Signed-off-by: Gary R Hook <gary.hook@amd.com> --- arch/x86/lib/Makefile | 16 ++++++++++++++++ lib/Makefile | 14 ++++++++++++++ 2 files changed, 30 insertions(+)
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index 140e61843a07..b5b932124280 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -6,6 +6,22 @@ # Produces uninteresting flaky coverage. KCOV_INSTRUMENT_delay.o := n +ifdef CONFIG_AMD_MEM_ENCRYPT +# +# Early boot use of cmdline; don't instrument it +# +KCOV_INSTRUMENT_cmdline.o := n + +KASAN_SANITIZE_cmdline.o := n + +ifdef CONFIG_FUNCTION_TRACER +CFLAGS_REMOVE_cmdline.o = -pg +endif + +nostackp := $(call cc-option, -fno-stack-protector) +CFLAGS_cmdline.o := $(nostackp) +endif + inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk inat_tables_maps = $(srctree)/arch/x86/lib/x86-opcode-map.txt quiet_cmd_inat_tables = GEN $@ diff --git a/lib/Makefile b/lib/Makefile index 3b08673e8881..07d71662f6b2 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -17,6 +17,20 @@ KCOV_INSTRUMENT_list_debug.o := n KCOV_INSTRUMENT_debugobjects.o := n KCOV_INSTRUMENT_dynamic_debug.o := n +ifdef CONFIG_AMD_MEM_ENCRYPT +# +# Early boot use of cmdline, don't instrument it +# +KASAN_SANITIZE_string.o := n + +ifdef CONFIG_FUNCTION_TRACER +CFLAGS_REMOVE_string.o = -pg +endif + +nostackp := $(call cc-option, -fno-stack-protector) +CFLAGS_string.o := $(nostackp) +endif + lib-y := ctype.o string.o vsprintf.o cmdline.o \ rbtree.o radix-tree.o timerqueue.o xarray.o \ idr.o int_sqrt.o extable.o \
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