linux-kernel - [RFC PATCH v1 10/16] s390/ptrace: Enable HAVE_USER_RA

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Message-ID: <20250710163522.3195293-11-jremus@linux.ibm.com>
Date: Thu, 10 Jul 2025 18:35:16 +0200
From: Jens Remus <jremus@...ux.ibm.com>
To: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        bpf@...r.kernel.org, x86@...nel.org,
        Steven Rostedt <rostedt@...nel.org>
Cc: Jens Remus <jremus@...ux.ibm.com>, Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrii Nakryiko <andrii@...nel.org>,
        Indu Bhagat <indu.bhagat@...cle.com>,
        "Jose E. Marchesi" <jemarch@....org>,
        Beau Belgrave <beaub@...ux.microsoft.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jens Axboe <axboe@...nel.dk>, Florian Weimer <fweimer@...hat.com>,
        Sam James <sam@...too.org>
Subject: [RFC PATCH v1 10/16] s390/ptrace: Enable HAVE_USER_RA_REG

Provide user_return_address().  Additionally provide frame_pointer().

On s390 register 11 is the preferred frame pointer (FP) register
and register 14 is the return address (RA) register in user space.

While at it convert instruction_pointer() and user_stack_pointer()
from macros to inline functions, to align their definition with
x86-64 and AArch64.

Signed-off-by: Jens Remus <jremus@...ux.ibm.com>
---
 arch/s390/Kconfig              |  1 +
 arch/s390/include/asm/ptrace.h | 25 ++++++++++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0c16dc443e2f..f4ea52c1f0ba 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -239,6 +239,7 @@ config S390
 	select HAVE_SETUP_PER_CPU_AREA
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 	select HAVE_SYSCALL_TRACEPOINTS
+	select HAVE_USER_RA_REG
 	select HAVE_VIRT_CPU_ACCOUNTING
 	select HAVE_VIRT_CPU_ACCOUNTING_IDLE
 	select HOTPLUG_SMT
diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index 0905fa99a31e..71d81280e5eb 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -212,8 +212,6 @@ void update_cr_regs(struct task_struct *task);
 #define arch_has_block_step()	(1)
 
 #define user_mode(regs) (((regs)->psw.mask & PSW_MASK_PSTATE) != 0)
-#define instruction_pointer(regs) ((regs)->psw.addr)
-#define user_stack_pointer(regs)((regs)->gprs[15])
 #define profile_pc(regs) instruction_pointer(regs)
 
 static inline long regs_return_value(struct pt_regs *regs)
@@ -230,11 +228,32 @@ static inline void instruction_pointer_set(struct pt_regs *regs,
 int regs_query_register_offset(const char *name);
 const char *regs_query_register_name(unsigned int offset);
 
-static __always_inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+static __always_inline unsigned long kernel_stack_pointer(const struct pt_regs *regs)
 {
 	return regs->gprs[15];
 }
 
+static __always_inline unsigned long instruction_pointer(const struct pt_regs *regs)
+{
+	return regs->psw.addr;
+}
+
+static __always_inline unsigned long frame_pointer(const struct pt_regs *regs)
+{
+	return regs->gprs[11];
+}
+
+static __always_inline unsigned long user_stack_pointer(const struct pt_regs *regs)
+{
+	return regs->gprs[15];
+}
+
+static __always_inline unsigned long user_return_address(const struct pt_regs *regs)
+{
+	return regs->gprs[14];
+}
+#define user_return_address user_return_address
+
 static __always_inline unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
 {
 	if (offset >= NUM_GPRS)
-- 
2.48.1