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Date:   Thu, 30 Sep 2021 11:05:30 -0700
From:   Sami Tolvanen <>
Cc:     Kees Cook <>,
        Josh Poimboeuf <>,
        Peter Zijlstra <>,
        Nathan Chancellor <>,
        Nick Desaulniers <>,
        Sedat Dilek <>,,,, Sami Tolvanen <>
Subject: [PATCH v4 14/15] x86, kprobes: Fix optprobe_template_func type mismatch

The optprobe_template_func symbol is defined in inline assembly,
but it's not marked global, which conflicts with the C declaration
needed for STACK_FRAME_NON_STANDARD and confuses the compiler when
CONFIG_CFI_CLANG is enabled.

Marking the symbol global would make the compiler happy, but as the
compiler also generates a CFI jump table entry for all address-taken
functions, the jump table ends up containing a jump to the .rodata
section where optprobe_template_func resides, which results in an
objtool warning.

Use ASM_STACK_FRAME_NON_STANDARD instead to avoid both issues.

Signed-off-by: Sami Tolvanen <>
Reviewed-by: Kees Cook <>
 arch/x86/kernel/kprobes/opt.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 71425ebba98a..95375ef5deee 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -103,6 +103,7 @@ static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
 asm (
 			".pushsection .rodata\n"
+			ASM_STACK_FRAME_NON_STANDARD(optprobe_template_func)
 			".global optprobe_template_entry\n"
 #ifdef CONFIG_X86_64
@@ -154,9 +155,6 @@ asm (
-void optprobe_template_func(void);
 #define TMPL_CLAC_IDX \
 	((long)optprobe_template_clac - (long)optprobe_template_entry)
 #define TMPL_MOVE_IDX \

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