Currently, x86, Riscv, Loongarch use the generic entry which makes
maintainers' work easier and codes more elegant. ARM64 has already
switched to the generic IRQ entry, so completely convert arm64
to use the generic entry infrastructure from kernel/entry/*.

The changes are below:
 - Remove TIF_SYSCALL_* flag, _TIF_WORK_MASK, _TIF_SYSCALL_WORK.

 - Implement arch_ptrace_report_syscall_entry/exit() with
   report_syscall_enter/exit() to do arm64-specific save/restore
   during syscall entry/exit.

 - Remove arm64 syscall_trace_enter(), syscall_exit_to_user_mode_prepare(),
   and related sub-functions including syscall_trace_exit() and
   syscall_enter_audit(), by calling generic entry's functions with
   similar functionality.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/Kconfig                    |   2 +-
 arch/arm64/include/asm/entry-common.h |  69 +++++++++++++
 arch/arm64/include/asm/syscall.h      |   7 +-
 arch/arm64/include/asm/thread_info.h  |  22 +----
 arch/arm64/kernel/debug-monitors.c    |   7 ++
 arch/arm64/kernel/ptrace.c            | 134 --------------------------
 arch/arm64/kernel/signal.c            |   2 +-
 arch/arm64/kernel/syscall.c           |   6 +-
 8 files changed, 85 insertions(+), 164 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 63e7d8a86b92..5bb8bd045ff5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -152,9 +152,9 @@ config ARM64
 	select GENERIC_CPU_DEVICES
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_EARLY_IOREMAP
+	select GENERIC_ENTRY
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_IOREMAP
-	select GENERIC_IRQ_ENTRY
 	select GENERIC_IRQ_IPI
 	select GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD
 	select GENERIC_IRQ_PROBE
diff --git a/arch/arm64/include/asm/entry-common.h b/arch/arm64/include/asm/entry-common.h
index cab8cd78f693..ae3ed608c9fa 100644
--- a/arch/arm64/include/asm/entry-common.h
+++ b/arch/arm64/include/asm/entry-common.h
@@ -11,6 +11,11 @@
 #include <asm/mte.h>
 #include <asm/stacktrace.h>
 
+enum ptrace_syscall_dir {
+	PTRACE_SYSCALL_ENTER = 0,
+	PTRACE_SYSCALL_EXIT,
+};
+
 #define ARCH_EXIT_TO_USER_MODE_WORK (_TIF_MTE_ASYNC_FAULT | _TIF_FOREIGN_FPSTATE)
 
 static __always_inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
@@ -54,4 +59,68 @@ static inline bool arch_irqentry_exit_need_resched(void)
 
 #define arch_irqentry_exit_need_resched arch_irqentry_exit_need_resched
 
+static inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
+{
+	unsigned long saved_reg;
+	int regno, ret;
+
+	/*
+	 * We have some ABI weirdness here in the way that we handle syscall
+	 * exit stops because we indicate whether or not the stop has been
+	 * signalled from syscall entry or syscall exit by clobbering a general
+	 * purpose register (ip/r12 for AArch32, x7 for AArch64) in the tracee
+	 * and restoring its old value after the stop. This means that:
+	 *
+	 * - Any writes by the tracer to this register during the stop are
+	 *   ignored/discarded.
+	 *
+	 * - The actual value of the register is not available during the stop,
+	 *   so the tracer cannot save it and restore it later.
+	 *
+	 * - Syscall stops behave differently to seccomp and pseudo-step traps
+	 *   (the latter do not nobble any registers).
+	 */
+	regno = (is_compat_task() ? 12 : 7);
+	saved_reg = regs->regs[regno];
+	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
+
+	ret = ptrace_report_syscall_entry(regs);
+	if (ret)
+		forget_syscall(regs);
+
+	regs->regs[regno] = saved_reg;
+
+	return ret;
+}
+
+#define arch_ptrace_report_syscall_entry arch_ptrace_report_syscall_entry
+
+static inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+						   int step)
+{
+	unsigned long saved_reg;
+	int regno;
+
+	/* See comment for arch_ptrace_report_syscall_entry() */
+	regno = (is_compat_task() ? 12 : 7);
+	saved_reg = regs->regs[regno];
+	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
+
+	if (!step) {
+		ptrace_report_syscall_exit(regs, 0);
+		regs->regs[regno] = saved_reg;
+	} else {
+		regs->regs[regno] = saved_reg;
+
+		/*
+		 * Signal a pseudo-step exception since we are stepping but
+		 * tracer modifications to the registers may have rewound the
+		 * state machine.
+		 */
+		ptrace_report_syscall_exit(regs, 1);
+	}
+}
+
+#define arch_ptrace_report_syscall_exit arch_ptrace_report_syscall_exit
+
 #endif /* _ASM_ARM64_ENTRY_COMMON_H */
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 6225981fbbdb..235cd0eaab47 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -114,12 +114,9 @@ static inline int syscall_get_arch(struct task_struct *task)
 	return AUDIT_ARCH_AARCH64;
 }
 
-static inline bool has_syscall_work(unsigned long flags)
+static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
 {
-	return unlikely(flags & _TIF_SYSCALL_WORK);
+	return false;
 }
 
-int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
-void syscall_exit_to_user_mode_prepare(struct pt_regs *regs);
-
 #endif	/* __ASM_SYSCALL_H */
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index f241b8601ebd..0c083be23018 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -43,6 +43,7 @@ struct thread_info {
 	void			*scs_sp;
 #endif
 	u32			cpu;
+	unsigned long		syscall_work;   /* SYSCALL_WORK_ flags */
 };
 
 #define thread_saved_pc(tsk)	\
@@ -65,11 +66,6 @@ void arch_setup_new_exec(void);
 #define TIF_UPROBE		5	/* uprobe breakpoint or singlestep */
 #define TIF_MTE_ASYNC_FAULT	6	/* MTE Asynchronous Tag Check Fault */
 #define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
-#define TIF_SYSCALL_TRACE	8	/* syscall trace active */
-#define TIF_SYSCALL_AUDIT	9	/* syscall auditing */
-#define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
-#define TIF_SECCOMP		11	/* syscall secure computing */
-#define TIF_SYSCALL_EMU		12	/* syscall emulation active */
 #define TIF_PATCH_PENDING	13	/* pending live patching update */
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_FREEZE		19
@@ -92,30 +88,14 @@ void arch_setup_new_exec(void);
 #define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_FOREIGN_FPSTATE	(1 << TIF_FOREIGN_FPSTATE)
-#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
-#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
-#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
-#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
-#define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
 #define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
-#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_32BIT		(1 << TIF_32BIT)
 #define _TIF_SVE		(1 << TIF_SVE)
 #define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_TSC_SIGSEGV	(1 << TIF_TSC_SIGSEGV)
 
-#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \
-				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
-				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
-				 _TIF_NOTIFY_SIGNAL | _TIF_SIGPENDING | \
-				 _TIF_PATCH_PENDING)
-
-#define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
-				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
-				 _TIF_SYSCALL_EMU)
-
 #ifdef CONFIG_SHADOW_CALL_STACK
 #define INIT_SCS							\
 	.scs_base	= init_shadow_call_stack,			\
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index 85fc162a6f9b..5c026b9f4a6f 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -385,11 +385,18 @@ void user_enable_single_step(struct task_struct *task)
 
 	if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP))
 		set_regs_spsr_ss(task_pt_regs(task));
+
+	/*
+	 * Ensure that a trap is triggered once stepping out of a system
+	 * call prior to executing any user instruction.
+	 */
+	set_task_syscall_work(task, SYSCALL_EXIT_TRAP);
 }
 NOKPROBE_SYMBOL(user_enable_single_step);
 
 void user_disable_single_step(struct task_struct *task)
 {
 	clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
+	clear_task_syscall_work(task, SYSCALL_EXIT_TRAP);
 }
 NOKPROBE_SYMBOL(user_disable_single_step);
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index b51b07ba37c0..9e3b39e207d1 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -42,9 +42,6 @@
 #include <asm/traps.h>
 #include <asm/system_misc.h>
 
-#define CREATE_TRACE_POINTS
-#include <trace/events/syscalls.h>
-
 struct pt_regs_offset {
 	const char *name;
 	int offset;
@@ -2312,137 +2309,6 @@ long arch_ptrace(struct task_struct *child, long request,
 	return ptrace_request(child, request, addr, data);
 }
 
-enum ptrace_syscall_dir {
-	PTRACE_SYSCALL_ENTER = 0,
-	PTRACE_SYSCALL_EXIT,
-};
-
-static int report_syscall_enter(struct pt_regs *regs)
-{
-	unsigned long saved_reg;
-	int regno, ret;
-
-	/*
-	 * We have some ABI weirdness here in the way that we handle syscall
-	 * exit stops because we indicate whether or not the stop has been
-	 * signalled from syscall entry or syscall exit by clobbering a general
-	 * purpose register (ip/r12 for AArch32, x7 for AArch64) in the tracee
-	 * and restoring its old value after the stop. This means that:
-	 *
-	 * - Any writes by the tracer to this register during the stop are
-	 *   ignored/discarded.
-	 *
-	 * - The actual value of the register is not available during the stop,
-	 *   so the tracer cannot save it and restore it later.
-	 *
-	 * - Syscall stops behave differently to seccomp and pseudo-step traps
-	 *   (the latter do not nobble any registers).
-	 */
-	regno = (is_compat_task() ? 12 : 7);
-	saved_reg = regs->regs[regno];
-	regs->regs[regno] = PTRACE_SYSCALL_ENTER;
-
-	ret = ptrace_report_syscall_entry(regs);
-	if (ret)
-		forget_syscall(regs);
-
-	regs->regs[regno] = saved_reg;
-
-	return ret;
-}
-
-static void report_syscall_exit(struct pt_regs *regs)
-{
-	int regno;
-	unsigned long saved_reg;
-
-	/* See comment for report_syscall_enter() above */
-	regno = (is_compat_task() ? 12 : 7);
-	saved_reg = regs->regs[regno];
-	regs->regs[regno] = PTRACE_SYSCALL_EXIT;
-
-	if (!test_thread_flag(TIF_SINGLESTEP)) {
-		ptrace_report_syscall_exit(regs, 0);
-		regs->regs[regno] = saved_reg;
-	} else {
-		regs->regs[regno] = saved_reg;
-
-		/*
-		 * Signal a pseudo-step exception since we are stepping but
-		 * tracer modifications to the registers may have rewound the
-		 * state machine.
-		 */
-		ptrace_report_syscall_exit(regs, 1);
-	}
-}
-
-static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
-{
-	if (unlikely(audit_context())) {
-		unsigned long args[6];
-
-		syscall_get_arguments(current, regs, args);
-		audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
-	}
-
-}
-
-int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
-{
-	int ret;
-
-	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
-		ret = report_syscall_enter(regs);
-		if (ret || (flags & _TIF_SYSCALL_EMU))
-			return NO_SYSCALL;
-	}
-
-	/* Do the secure computing after ptrace; failures should be fast. */
-	if (flags & _TIF_SECCOMP) {
-		ret = __secure_computing();
-		if (ret == -1L)
-			return NO_SYSCALL;
-	}
-
-	/* Either of the above might have changed the syscall number */
-	syscall = syscall_get_nr(current, regs);
-
-	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
-		trace_sys_enter(regs, syscall);
-
-		/*
-		 * Probes or BPF hooks in the tracepoint may have changed the
-		 * system call number as well.
-		 */
-		 syscall = syscall_get_nr(current, regs);
-	}
-
-	syscall_enter_audit(regs, syscall);
-
-	return regs->syscallno;
-}
-
-static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
-{
-	audit_syscall_exit(regs);
-
-	if (flags & _TIF_SYSCALL_TRACEPOINT)
-		trace_sys_exit(regs, syscall_get_return_value(current, regs));
-
-	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
-		report_syscall_exit(regs);
-}
-
-void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
-{
-	unsigned long flags = read_thread_flags();
-
-	rseq_syscall(regs);
-
-	if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
-		syscall_trace_exit(regs, flags);
-}
-
 /*
  * SPSR_ELx bits which are always architecturally RES0 per ARM DDI 0487D.a.
  * We permit userspace to set SSBS (AArch64 bit 12, AArch32 bit 23) which is
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 1110eeb21f57..d3ec1892b3c7 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -8,8 +8,8 @@
 
 #include <linux/cache.h>
 #include <linux/compat.h>
+#include <linux/entry-common.h>
 #include <linux/errno.h>
-#include <linux/irq-entry-common.h>
 #include <linux/kernel.h>
 #include <linux/signal.h>
 #include <linux/freezer.h>
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index a50db885fc34..5aa585111c4b 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -2,6 +2,7 @@
 
 #include <linux/compiler.h>
 #include <linux/context_tracking.h>
+#include <linux/entry-common.h>
 #include <linux/errno.h>
 #include <linux/nospec.h>
 #include <linux/ptrace.h>
@@ -68,6 +69,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
 static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 			   const syscall_fn_t syscall_table[])
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	unsigned long flags = read_thread_flags();
 
 	regs->orig_x0 = regs->regs[0];
@@ -101,7 +103,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 		return;
 	}
 
-	if (has_syscall_work(flags)) {
+	if (has_syscall_work(work)) {
 		/*
 		 * The de-facto standard way to skip a system call using ptrace
 		 * is to set the system call to -1 (NO_SYSCALL) and set x0 to a
@@ -119,7 +121,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 		 */
 		if (scno == NO_SYSCALL)
 			syscall_set_return_value(current, regs, -ENOSYS, 0);
-		scno = syscall_trace_enter(regs, regs->syscallno, flags);
+		scno = syscall_trace_enter(regs, regs->syscallno, work);
 		if (scno == NO_SYSCALL) {
 			syscall_exit_to_user_mode_prepare(regs);
 			return;
-- 
2.34.1

Hi Jinjie,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20250915]

url:    https://github.com/intel-lab-lkp/linux/commits/Jinjie-Ruan/arm64-ptrace-Split-report_syscall-into-report_syscall_enter-exit/20250916-163202
base:   next-20250915
patch link:    https://lore.kernel.org/r/20250916082611.2972008-11-ruanjinjie%40huawei.com
patch subject: [PATCH -next v6 10/10] arm64: entry: Convert to generic entry
config: arm64-randconfig-001-20250918 (https://download.01.org/0day-ci/archive/20250918/202509181742.AlhRJJjD-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 7c861bcedf61607b6c087380ac711eb7ff918ca6)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250918/202509181742.AlhRJJjD-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509181742.AlhRJJjD-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/entry/syscall-common.c:30:8: warning: attribute declaration must precede definition [-Wignored-attributes]
      30 | static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
         |        ^
   include/linux/compiler_attributes.h:55:63: note: expanded from macro '__always_inline'
      55 | #define __always_inline                 inline __attribute__((__always_inline__))
         |                                                               ^
   arch/arm64/include/asm/entry-common.h:62:19: note: previous definition is here
      62 | static inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
         |                   ^
   kernel/entry/syscall-common.c:115:8: warning: attribute declaration must precede definition [-Wignored-attributes]
     115 | static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
         |        ^
   include/linux/compiler_attributes.h:55:63: note: expanded from macro '__always_inline'
      55 | #define __always_inline                 inline __attribute__((__always_inline__))
         |                                                               ^
   arch/arm64/include/asm/entry-common.h:98:20: note: previous definition is here
      98 | static inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
         |                    ^
   2 warnings generated.


vim +30 kernel/entry/syscall-common.c

a70e9f647f501e3 Jinjie Ruan 2025-06-24  19  
204f38f88c6f9db Jinjie Ruan 2025-09-16  20  /**
204f38f88c6f9db Jinjie Ruan 2025-09-16  21   * arch_ptrace_report_syscall_entry - Architecture specific
204f38f88c6f9db Jinjie Ruan 2025-09-16  22   *				      ptrace_report_syscall_entry().
204f38f88c6f9db Jinjie Ruan 2025-09-16  23   *
204f38f88c6f9db Jinjie Ruan 2025-09-16  24   * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry().
204f38f88c6f9db Jinjie Ruan 2025-09-16  25   * Defaults to ptrace_report_syscall_entry.
204f38f88c6f9db Jinjie Ruan 2025-09-16  26   *
204f38f88c6f9db Jinjie Ruan 2025-09-16  27   * The main purpose is to support arch-specific ptrace_report_syscall_entry()
204f38f88c6f9db Jinjie Ruan 2025-09-16  28   * implementation.
204f38f88c6f9db Jinjie Ruan 2025-09-16  29   */
204f38f88c6f9db Jinjie Ruan 2025-09-16 @30  static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
204f38f88c6f9db Jinjie Ruan 2025-09-16  31  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Hi, can you make it so that this patch series support Syscall User
Dispatch? There needs to be 2 changes:

1 - Implementing arch_syscall_is_vdso_sigreturn
Here is my implementation for it:
(I checked for syscallno unlike x86, which checks if the IP exactly
matches with the VDSO sigreturn symbol. This solution seems better to me)

bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
{
	unsigned long addr, pc;

	pc = regs->pc - 4;
#ifdef CONFIG_COMPAT
	if (is_compat_task()) {
		addr = (unsigned long)current->mm->context.sigpage;
		if (pc >= addr && pc < addr + PAGE_SIZE)
			return true;
		return false;
	}
#endif
	if (regs->syscallno != __NR_rt_sigreturn)
		return false;
	addr = (unsigned long)current->mm->context.vdso;
	if (pc < addr || pc >= addr + vdso_info[VDSO_ABI_AA64].vdso_pages * PAGE_SIZE)
		return false;
	return true;
}

2 - This trick shouldn't be done if the syscall will be catched by SUD:
if (scno == NO_SYSCALL)
	syscall_set_return_value(current, regs, -ENOSYS, 0);
As the ABI could be anything.

Thanks,
-kemal

On 2025/9/16 22:46, kemal wrote:
> Hi, can you make it so that this patch series support Syscall User
> Dispatch? There needs to be 2 changes:
> 
> 1 - Implementing arch_syscall_is_vdso_sigreturn
> Here is my implementation for it:
> (I checked for syscallno unlike x86, which checks if the IP exactly
> matches with the VDSO sigreturn symbol. This solution seems better to me)
> 
> bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
> {
> 	unsigned long addr, pc;
> 
> 	pc = regs->pc - 4;
> #ifdef CONFIG_COMPAT
> 	if (is_compat_task()) {
> 		addr = (unsigned long)current->mm->context.sigpage;
> 		if (pc >= addr && pc < addr + PAGE_SIZE)
> 			return true;
> 		return false;
> 	}
> #endif
> 	if (regs->syscallno != __NR_rt_sigreturn)
> 		return false;
> 	addr = (unsigned long)current->mm->context.vdso;
> 	if (pc < addr || pc >= addr + vdso_info[VDSO_ABI_AA64].vdso_pages * PAGE_SIZE)
> 		return false;
> 	return true;
> }

Thank you! I will try to implement arch_syscall_is_vdso_sigreturn() as
this and test it. By the way, is this for supporting arm64 in wine?

> 
> 2 - This trick shouldn't be done if the syscall will be catched by SUD:
> if (scno == NO_SYSCALL)
> 	syscall_set_return_value(current, regs, -ENOSYS, 0);
> As the ABI could be anything.

This requires discussion with Catalin and Will, which may alter the
original intent.

> 
> Thanks,
> -kemal

On Çrş, Sep 17 2025 at 09:55:35 +08:00:00, Jinjie Ruan 
<ruanjinjie@huawei.com> wrote:
> Thank you! I will try to implement arch_syscall_is_vdso_sigreturn() as
> this and test it. By the way, is this for supporting arm64 in wine?
No, I don't even know if arm64 windows binaries do direct
syscalls. This is meant for some other project.
>> 
>>  2 - This trick shouldn't be done if the syscall will be catched by 
>> SUD:
>>  if (scno == NO_SYSCALL)
>>  	syscall_set_return_value(current, regs, -ENOSYS, 0);
>>  As the ABI could be anything.
>> 
> This requires discussion with Catalin and Will, which may alter the
> original intent.
Sorry, I didnt read the code carefully, syscall_user_dispatch()
already calls syscall_rollback() which should restore x0 from
orig_x0.

You can test SUD using the selftest, but you need to add these
lines at the end of handle_sigsys() in sud_test.c:

#ifdef __aarch64__
	((ucontext_t *)ucontext)->uc_mcontext.regs[0] = (unsigned int)
			((ucontext_t *)ucontext)->uc_mcontext.regs[8];
#endif

and you should define TEST_BLOCKED_RETURN in sud_benchmark.c
to make sure arch_syscall_is_vdso_sigreturn works properly

-kemal

>>