Messages in this thread Patch in this message | | | Date | Wed, 20 Jul 2022 15:55:07 -0400 | From | Steven Rostedt <> | Subject | [PATCH] lkdtm: Keep the rodata test from causing retbleed WARNINGS |
| |
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
The rodata test checks if executable code in the .rodata section will not execute. But this also means that fix ups that the return hook code does will not be able to change this code at boot up, and this causes a warning.
By removing the RETHOOK_CFLAGS from the compilation of the rodata function makes it hidden from objtool and it will not add its return hook into the .returns section. This keeps the fix up code from trying and failing on modifying the rodata return call.
Link: https://lore.kernel.org/all/20220720125736.48164a14@gandalf.local.home/
Fixes: ee88d363d1561 ("x86,static_call: Use alternative RET encoding") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> ---
[ Note, my tests are still running with this, but it passed the test that caused the failure, so I decided to post this now. ]
arch/x86/Makefile | 1 + drivers/misc/lkdtm/Makefile | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 1f40dad30d50..2dd61d8594f4 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -25,6 +25,7 @@ endif ifdef CONFIG_RETHUNK RETHUNK_CFLAGS := -mfunction-return=thunk-extern RETPOLINE_CFLAGS += $(RETHUNK_CFLAGS) +export RETHUNK_CFLAGS endif export RETPOLINE_CFLAGS diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile index 2e0aa74ac185..fd96ac1617f7 100644 --- a/drivers/misc/lkdtm/Makefile +++ b/drivers/misc/lkdtm/Makefile @@ -16,7 +16,7 @@ lkdtm-$(CONFIG_PPC_64S_HASH_MMU) += powerpc.o KASAN_SANITIZE_rodata.o := n KASAN_SANITIZE_stackleak.o := n KCOV_INSTRUMENT_rodata.o := n -CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO) +CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO) $(RETHUNK_CFLAGS) OBJCOPYFLAGS := OBJCOPYFLAGS_rodata_objcopy.o := \ -- 2.35.1
| |