linux-kernel - [RFC V2 2/8] powerpc: Prepare to build with generic entry/exit framework

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Message-ID: <20250908210235.137300-4-mchauras@linux.ibm.com>
Date: Tue,  9 Sep 2025 02:32:30 +0530
From: Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com>
To: maddy@...ux.ibm.com, mpe@...erman.id.au, npiggin@...il.com,
        christophe.leroy@...roup.eu, oleg@...hat.com, kees@...nel.org,
        luto@...capital.net, wad@...omium.org, mchauras@...ux.ibm.com,
        deller@....de, ldv@...ace.io, macro@...am.me.uk, charlie@...osinc.com,
        akpm@...ux-foundation.org, bigeasy@...utronix.de,
        ankur.a.arora@...cle.com, sshegde@...ux.ibm.com, naveen@...nel.org,
        thomas.weissschuh@...utronix.de, Jason@...c4.com, peterz@...radead.org,
        tglx@...utronix.de, namcao@...utronix.de, kan.liang@...ux.intel.com,
        mingo@...nel.org, oliver.upton@...ux.dev, mark.barnett@....com,
        atrajeev@...ux.vnet.ibm.com, rppt@...nel.org, coltonlewis@...gle.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [RFC V2 2/8] powerpc: Prepare to build with generic entry/exit framework

Enabling build with generic entry/exit framework for powerpc
architecture requires few necessary steps.

Introducing minor infrastructure updates to prepare for future generic
framework handling:

- Add syscall_work field to struct thread_info for SYSCALL_WORK_* flags.
- Provide arch_syscall_is_vdso_sigreturn() stub, returning false.
- Add on_thread_stack() helper to test whether the current stack pointer
  lies within the task’s kernel stack.

No functional change is intended with this patch.

Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com>
---
 arch/powerpc/include/asm/entry-common.h | 11 +++++++++++
 arch/powerpc/include/asm/stacktrace.h   |  8 ++++++++
 arch/powerpc/include/asm/syscall.h      |  5 +++++
 arch/powerpc/include/asm/thread_info.h  |  1 +
 4 files changed, 25 insertions(+)
 create mode 100644 arch/powerpc/include/asm/entry-common.h

diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/include/asm/entry-common.h
new file mode 100644
index 0000000000000..3af16d821d07e
--- /dev/null
+++ b/arch/powerpc/include/asm/entry-common.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_PPC_ENTRY_COMMON_H
+#define _ASM_PPC_ENTRY_COMMON_H
+
+#ifdef CONFIG_GENERIC_IRQ_ENTRY
+
+#include <asm/stacktrace.h>
+
+#endif /* CONFIG_GENERIC_IRQ_ENTRY */
+#endif /* _ASM_PPC_ENTRY_COMMON_H */
diff --git a/arch/powerpc/include/asm/stacktrace.h b/arch/powerpc/include/asm/stacktrace.h
index 6149b53b3bc8e..3f0a242468813 100644
--- a/arch/powerpc/include/asm/stacktrace.h
+++ b/arch/powerpc/include/asm/stacktrace.h
@@ -8,6 +8,14 @@
 #ifndef _ASM_POWERPC_STACKTRACE_H
 #define _ASM_POWERPC_STACKTRACE_H
 
+#include <linux/sched.h>
+
 void show_user_instructions(struct pt_regs *regs);
 
+static inline bool on_thread_stack(void)
+{
+	return !(((unsigned long)(current->stack) ^ current_stack_pointer)
+			& ~(THREAD_SIZE -1));
+}
+
 #endif /* _ASM_POWERPC_STACKTRACE_H */
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
index 4b3c52ed6e9d2..834fcc4f7b543 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -139,4 +139,9 @@ static inline int syscall_get_arch(struct task_struct *task)
 	else
 		return AUDIT_ARCH_PPC64;
 }
+
+static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
+{
+	return false;
+}
 #endif	/* _ASM_SYSCALL_H */
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 2785c7462ebf7..d0e87c9bae0b0 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -54,6 +54,7 @@
 struct thread_info {
 	int		preempt_count;		/* 0 => preemptable,
 						   <0 => BUG */
+	unsigned long	syscall_work;		/* SYSCALL_WORK_ flags */
 #ifdef CONFIG_SMP
 	unsigned int	cpu;
 #endif
-- 
2.51.0