linux-kernel - [PATCH v3 3/3] x86/unwind_user: Guard unwind_user_word_size() by UNWIND

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Message-ID: <20251202150814.3505869-4-jremus@linux.ibm.com>
Date: Tue,  2 Dec 2025 16:08:13 +0100
From: Jens Remus <jremus@...ux.ibm.com>
To: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        x86@...nel.org, Steven Rostedt <rostedt@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc: Jens Remus <jremus@...ux.ibm.com>, Josh Poimboeuf <jpoimboe@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Indu Bhagat <indu.bhagat@...cle.com>,
        "Jose E. Marchesi" <jemarch@....org>,
        Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Ilya Leoshkevich <iii@...ux.ibm.com>
Subject: [PATCH v3 3/3] x86/unwind_user: Guard unwind_user_word_size() by UNWIND_USER

The unwind user framework in general requires an architecture-specific
implementation of unwind_user_word_size() to be present for any unwind
method, whether that is fp or a future other method, such as potentially
sframe.

Guard unwind_user_word_size() by the availability of the UNWIND_USER
framework instead of the specific HAVE_UNWIND_USER_FP method.

This facilitates to selectively disable HAVE_UNWIND_USER_FP on x86
(e.g. for test purposes) once a new unwind method is added to unwind
user.

Signed-off-by: Jens Remus <jremus@...ux.ibm.com>
---

Notes (jremus):
    Changes in v3:
    - Move includes into more common UNWIND_USER guard at the top of the
      source.  asm/ptrace.h is required for struct pt_regs.

 arch/x86/include/asm/unwind_user.h | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwind_user.h
index 971ffe937d50..7f1229b33d06 100644
--- a/arch/x86/include/asm/unwind_user.h
+++ b/arch/x86/include/asm/unwind_user.h
@@ -2,23 +2,11 @@
 #ifndef _ASM_X86_UNWIND_USER_H
 #define _ASM_X86_UNWIND_USER_H
 
-#ifdef CONFIG_HAVE_UNWIND_USER_FP
+#ifdef CONFIG_UNWIND_USER
 
 #include <asm/ptrace.h>
 #include <asm/uprobes.h>
 
-#define ARCH_INIT_USER_FP_FRAME(ws)			\
-	.cfa_off	=  2*(ws),			\
-	.ra_off		= -1*(ws),			\
-	.fp_off		= -2*(ws),			\
-	.use_fp		= true,
-
-#define ARCH_INIT_USER_FP_ENTRY_FRAME(ws)		\
-	.cfa_off	=  1*(ws),			\
-	.ra_off		= -1*(ws),			\
-	.fp_off		= 0,				\
-	.use_fp		= false,
-
 static inline int unwind_user_word_size(struct pt_regs *regs)
 {
 	/* We can't unwind VM86 stacks */
@@ -31,6 +19,22 @@ static inline int unwind_user_word_size(struct pt_regs *regs)
 	return sizeof(long);
 }
 
+#endif /* CONFIG_UNWIND_USER */
+
+#ifdef CONFIG_HAVE_UNWIND_USER_FP
+
+#define ARCH_INIT_USER_FP_FRAME(ws)			\
+	.cfa_off	=  2*(ws),			\
+	.ra_off		= -1*(ws),			\
+	.fp_off		= -2*(ws),			\
+	.use_fp		= true,
+
+#define ARCH_INIT_USER_FP_ENTRY_FRAME(ws)		\
+	.cfa_off	=  1*(ws),			\
+	.ra_off		= -1*(ws),			\
+	.fp_off		= 0,				\
+	.use_fp		= false,
+
 static inline bool unwind_user_at_function_start(struct pt_regs *regs)
 {
 	return is_uprobe_at_func_entry(regs);
-- 
2.51.0