From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit 7b6c7a877cc616bc7dc9cd39646fe454acbed48b ]
The file-wide OBJECT_FILES_NON_STANDARD annotation is used with CONFIG_FRAME_POINTER to tell objtool to skip the entire file when frame pointers are enabled. However that annotation is now deprecated because it doesn't work with IBT, where objtool runs on vmlinux.o instead of individual translation units.
Instead, use more fine-grained function-specific annotations:
- The 'save_mcount_regs' macro does funny things with the frame pointer. Use STACK_FRAME_NON_STANDARD_FP to tell objtool to ignore the functions using it.
- The return_to_handler() "function" isn't actually a callable function. Instead of being called, it's returned to. The real return address isn't on the stack, so unwinding is already doomed no matter which unwinder is used. So just remove the STT_FUNC annotation, telling objtool to ignore it. That also removes the implicit ANNOTATE_NOENDBR, which now needs to be made explicit.
Fixes the following warning:
vmlinux.o: warning: objtool: __fentry__+0x16: return with modified stack frame
Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Link: https://lore.kernel.org/r/b7a7a42fe306aca37826043dac89e113a1acdbac.165426861... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/Makefile | 4 ---- arch/x86/kernel/ftrace_64.S | 11 ++++++++--- include/linux/objtool.h | 6 ++++++ tools/include/linux/objtool.h | 6 ++++++ 4 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index c41ef42adbe8..25828e4c6237 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -36,10 +36,6 @@ KCSAN_SANITIZE := n
OBJECT_FILES_NON_STANDARD_test_nx.o := y
-ifdef CONFIG_FRAME_POINTER -OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y -endif - # If instrumentation of this dir is enabled, boot hangs during first second. # Probably could be more selective here, but note that files related to irqs, # boot, dumpstack/stacktrace, etc are either non-interesting or can lead to diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index 4ec13608d3c6..dfeb227de561 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -175,6 +175,7 @@ SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL)
jmp ftrace_epilogue SYM_FUNC_END(ftrace_caller); +STACK_FRAME_NON_STANDARD_FP(ftrace_caller)
SYM_FUNC_START(ftrace_epilogue) /* @@ -282,6 +283,7 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) jmp ftrace_epilogue
SYM_FUNC_END(ftrace_regs_caller) +STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller)
#else /* ! CONFIG_DYNAMIC_FTRACE */ @@ -311,10 +313,14 @@ trace: jmp ftrace_stub SYM_FUNC_END(__fentry__) EXPORT_SYMBOL(__fentry__) +STACK_FRAME_NON_STANDARD_FP(__fentry__) + #endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER -SYM_FUNC_START(return_to_handler) +SYM_CODE_START(return_to_handler) + UNWIND_HINT_EMPTY + ANNOTATE_NOENDBR subq $16, %rsp
/* Save the return values */ @@ -339,7 +345,6 @@ SYM_FUNC_START(return_to_handler) int3 .Ldo_rop: mov %rdi, (%rsp) - UNWIND_HINT_FUNC RET -SYM_FUNC_END(return_to_handler) +SYM_CODE_END(return_to_handler) #endif diff --git a/include/linux/objtool.h b/include/linux/objtool.h index 586d35720f13..c81ea2264ad8 100644 --- a/include/linux/objtool.h +++ b/include/linux/objtool.h @@ -141,6 +141,12 @@ struct unwind_hint { .popsection .endm
+.macro STACK_FRAME_NON_STANDARD_FP func:req +#ifdef CONFIG_FRAME_POINTER + STACK_FRAME_NON_STANDARD \func +#endif +.endm + .macro ANNOTATE_NOENDBR .Lhere_@: .pushsection .discard.noendbr diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h index 586d35720f13..c81ea2264ad8 100644 --- a/tools/include/linux/objtool.h +++ b/tools/include/linux/objtool.h @@ -141,6 +141,12 @@ struct unwind_hint { .popsection .endm
+.macro STACK_FRAME_NON_STANDARD_FP func:req +#ifdef CONFIG_FRAME_POINTER + STACK_FRAME_NON_STANDARD \func +#endif +.endm + .macro ANNOTATE_NOENDBR .Lhere_@: .pushsection .discard.noendbr