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From: Sami Tolvanen <samitolvanen@google.com>
To: x86@kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v3 15/16] x86, kprobes: Fix optprobe_template_func type mismatch
Date: Tue, 14 Sep 2021 12:10:44 -0700	[thread overview]
Message-ID: <20210914191045.2234020-16-samitolvanen@google.com> (raw)
In-Reply-To: <20210914191045.2234020-1-samitolvanen@google.com>

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 <samitolvanen@google.com>
---
 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"
 			"optprobe_template_func:\n"
+			ASM_STACK_FRAME_NON_STANDARD(optprobe_template_func)
 			".global optprobe_template_entry\n"
 			"optprobe_template_entry:\n"
 #ifdef CONFIG_X86_64
@@ -154,9 +155,6 @@ asm (
 			"optprobe_template_end:\n"
 			".popsection\n");
 
-void optprobe_template_func(void);
-STACK_FRAME_NON_STANDARD(optprobe_template_func);
-
 #define TMPL_CLAC_IDX \
 	((long)optprobe_template_clac - (long)optprobe_template_entry)
 #define TMPL_MOVE_IDX \
-- 
2.33.0.309.g3052b89438-goog


  parent reply	other threads:[~2021-09-14 19:11 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14 19:10 [PATCH v3 00/16] x86: Add support for Clang CFI Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 01/16] objtool: Add CONFIG_CFI_CLANG support Sami Tolvanen
2021-09-14 19:29   ` Nick Desaulniers
2021-09-14 21:01     ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 02/16] objtool: Add ASM_STACK_FRAME_NON_STANDARD Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 03/16] linkage: Add DECLARE_ASM_FUNC_SYMBOL Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 04/16] cfi: Add DEFINE_CFI_IMMEDIATE_RETURN_STUB Sami Tolvanen
2021-09-14 19:36   ` Nick Desaulniers
2021-09-14 20:32     ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 05/16] tracepoint: Exclude tp_stub_func from CFI checking Sami Tolvanen
2021-09-14 19:39   ` Nick Desaulniers
2021-09-14 19:10 ` [PATCH v3 06/16] ftrace: Use an opaque type for functions not callable from C Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 07/16] lkdtm: Disable UNSET_SMEP with CFI Sami Tolvanen
2021-09-14 19:30   ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 08/16] lkdtm: Use an opaque type for lkdtm_rodata_do_nothing Sami Tolvanen
2021-09-14 19:32   ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 09/16] x86: Use an opaque type for functions not callable from C Sami Tolvanen
2021-09-14 19:33   ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 10/16] x86/extable: Mark handlers __cficanonical Sami Tolvanen
2021-09-14 19:37   ` Kees Cook
2021-09-14 20:38     ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 11/16] x86/purgatory: Disable CFI Sami Tolvanen
2021-09-14 20:02   ` Nick Desaulniers
2021-09-14 20:30     ` Sami Tolvanen
2021-09-14 22:31       ` Nick Desaulniers
2021-09-15  6:24         ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 12/16] x86, relocs: Ignore __typeid__ relocations Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 13/16] x86, module: " Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 14/16] x86, cpu: Use LTO for cpu.c with CFI Sami Tolvanen
2021-09-14 19:44   ` Kees Cook
2021-09-14 19:46   ` Nick Desaulniers
2021-09-14 19:10 ` Sami Tolvanen [this message]
2021-09-14 19:40   ` [PATCH v3 15/16] x86, kprobes: Fix optprobe_template_func type mismatch Kees Cook
2021-09-14 19:10 ` [PATCH v3 16/16] x86, build: Allow CONFIG_CFI_CLANG to be selected Sami Tolvanen

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