The patch titled
Subject: kmsan: disable ftrace in kmsan core code
has been added to the -mm mm-unstable branch. Its filename is
kmsan-disable-ftrace-in-kmsan-core-code.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kmsan-disable-ftrace-in-kmsan-core-code.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: kmsan: disable ftrace in kmsan core code
Date: Wed, 15 Feb 2023 14:00:57 +0100
objtool warns about some suspicous code inside of kmsan:
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_n+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_n+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_1+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_1+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_2+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_2+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_4+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_4+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_8+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_8+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_instrument_asm_store+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_chain_origin+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_poison_alloca+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_warning+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_get_context_state+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_copy_to_user+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_unpoison_memory+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_unpoison_entry_regs+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_report+0x4: call to __fentry__() with UACCESS enabled
The Makefile contained a line to turn off ftrace for the entire directory,
but this does not work. Replace it with individual lines, matching the
approach in kasan.
Link: https://lkml.kernel.org/r/20230215130058.3836177-3-arnd@xxxxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
Acked-by: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmsan/Makefile | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/mm/kmsan/Makefile~kmsan-disable-ftrace-in-kmsan-core-code
+++ a/mm/kmsan/Makefile
@@ -14,7 +14,13 @@ CC_FLAGS_KMSAN_RUNTIME := -fno-stack-pro
CC_FLAGS_KMSAN_RUNTIME += $(call cc-option,-fno-conserve-stack)
CC_FLAGS_KMSAN_RUNTIME += -DDISABLE_BRANCH_PROFILING
-CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)
+# Disable ftrace to avoid recursion.
+CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_hooks.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_instrumentation.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE)
CFLAGS_core.o := $(CC_FLAGS_KMSAN_RUNTIME)
CFLAGS_hooks.o := $(CC_FLAGS_KMSAN_RUNTIME)
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
maple_tree-reduce-stack-usage-with-gcc-9-and-earlier.patch
kasan-mark-addr_has_metadata-__always_inline.patch
kmsan-disable-ftrace-in-kmsan-core-code.patch
objtool-add-uaccess-exceptions-for-__tsan_volatile_read-write.patch
