diff mbox series

[v5,02/15] objtool: Add ASM_STACK_FRAME_NON_STANDARD

Message ID 20211013181658.1020262-3-samitolvanen@google.com (mailing list archive)
State Changes Requested
Headers show
Series x86: Add support for Clang CFI | expand

Commit Message

Sami Tolvanen Oct. 13, 2021, 6:16 p.m. UTC 
To use the STACK_FRAME_NON_STANDARD macro for a static symbol
defined in inline assembly, we need a C declaration that implies
global visibility. This type mismatch confuses the compiler with
CONFIG_CFI_CLANG. This change adds an inline assembly version of
the macro to avoid the issue.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
---
 include/linux/objtool.h       | 6 ++++++
 tools/include/linux/objtool.h | 6 ++++++
 2 files changed, 12 insertions(+)

Comments

Kees Cook Oct. 13, 2021, 6:59 p.m. UTC | #1 
On Wed, Oct 13, 2021 at 11:16:45AM -0700, Sami Tolvanen wrote:
> To use the STACK_FRAME_NON_STANDARD macro for a static symbol
> defined in inline assembly, we need a C declaration that implies
> global visibility. This type mismatch confuses the compiler with
> CONFIG_CFI_CLANG. This change adds an inline assembly version of
> the macro to avoid the issue.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 7e72d975cb76..080e95174536 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -66,6 +66,11 @@  struct unwind_hint {
 	static void __used __section(".discard.func_stack_frame_non_standard") \
 		*__func_stack_frame_non_standard_##func = func
 
+#define ASM_STACK_FRAME_NON_STANDARD(func)				\
+	".pushsection .discard.func_stack_frame_non_standard, \"aw\"\n"	\
+	".long " __stringify(func) " - .\n"				\
+	".popsection\n"
+
 #else /* __ASSEMBLY__ */
 
 /*
@@ -127,6 +132,7 @@  struct unwind_hint {
 #define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
+#define ASM_STACK_FRAME_NON_STANDARD(func)
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
index 7e72d975cb76..080e95174536 100644
--- a/tools/include/linux/objtool.h
+++ b/tools/include/linux/objtool.h
@@ -66,6 +66,11 @@  struct unwind_hint {
 	static void __used __section(".discard.func_stack_frame_non_standard") \
 		*__func_stack_frame_non_standard_##func = func
 
+#define ASM_STACK_FRAME_NON_STANDARD(func)				\
+	".pushsection .discard.func_stack_frame_non_standard, \"aw\"\n"	\
+	".long " __stringify(func) " - .\n"				\
+	".popsection\n"
+
 #else /* __ASSEMBLY__ */
 
 /*
@@ -127,6 +132,7 @@  struct unwind_hint {
 #define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
+#define ASM_STACK_FRAME_NON_STANDARD(func)
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0