[v9] arm64: entry: Convert to Generic Entry

[PATCH v9 04/16] arm64/ptrace: Refactor syscall_trace_enter/exit()

Posted by Jinjie Ruan 1 week, 5 days ago

The generic syscall entry code has the following form, which use
the input syscall work flag and syscall number:

| syscall_trace_enter(struct pt_regs *regs, long syscall,
|		      unsigned long work)
|
| syscall_exit_work(struct pt_regs *regs, unsigned long work)

In preparation for moving arm64 over to the generic entry code,
refactor syscall_trace_enter/exit() to also pass thread flags, and
get syscall number by syscall_get_nr() helper.

No functional changes.

Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/include/asm/syscall.h |  4 ++--
 arch/arm64/kernel/ptrace.c       | 25 ++++++++++++++++---------
 arch/arm64/kernel/syscall.c      |  5 +++--
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 5e4c7fc44f73..cef1d9ce6e1b 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -120,7 +120,7 @@ static inline int syscall_get_arch(struct task_struct *task)
 	return AUDIT_ARCH_AARCH64;
 }
 
-int syscall_trace_enter(struct pt_regs *regs);
-void syscall_trace_exit(struct pt_regs *regs);
+int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
+void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
 
 #endif	/* __ASM_SYSCALL_H */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 3926ce6aa268..b962cbcca11d 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2381,9 +2381,8 @@ static void report_syscall_exit(struct pt_regs *regs)
 	}
 }
 
-int syscall_trace_enter(struct pt_regs *regs)
+int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
 {
-	unsigned long flags = read_thread_flags();
 	int ret;
 
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
@@ -2396,19 +2395,27 @@ int syscall_trace_enter(struct pt_regs *regs)
 	if (secure_computing() == -1)
 		return NO_SYSCALL;
 
-	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
-		trace_sys_enter(regs, regs->syscallno);
+	/* Either of the above might have changed the syscall number */
+	syscall = syscall_get_nr(current, regs);
 
-	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
+	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);
+	}
+
+	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
 			    regs->regs[2], regs->regs[3]);
 
-	return regs->syscallno;
+	return syscall;
 }
 
-void syscall_trace_exit(struct pt_regs *regs)
+void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
 {
-	unsigned long flags = read_thread_flags();
-
 	audit_syscall_exit(regs);
 
 	if (flags & _TIF_SYSCALL_TRACEPOINT)
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index aba7ca6bca2d..ec31f82d2e9f 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -124,7 +124,7 @@ 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);
+		scno = syscall_trace_enter(regs, scno, flags);
 		if (scno == NO_SYSCALL)
 			goto trace_exit;
 	}
@@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 	}
 
 trace_exit:
-	syscall_trace_exit(regs);
+	flags = read_thread_flags();
+	syscall_trace_exit(regs, flags);
 }
 
 void do_el0_svc(struct pt_regs *regs)
-- 
2.34.1

Re: [PATCH v9 04/16] arm64/ptrace: Refactor syscall_trace_enter/exit()

Posted by Anshuman Khandual 1 week, 1 day ago

On 04/12/25 1:51 PM, Jinjie Ruan wrote:
> The generic syscall entry code has the following form, which use
> the input syscall work flag and syscall number:
> 
> | syscall_trace_enter(struct pt_regs *regs, long syscall,
> |		      unsigned long work)
> |
> | syscall_exit_work(struct pt_regs *regs, unsigned long work)
> 
> In preparation for moving arm64 over to the generic entry code,
> refactor syscall_trace_enter/exit() to also pass thread flags, and
> get syscall number by syscall_get_nr() helper.
> 
> No functional changes.
> 
> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/include/asm/syscall.h |  4 ++--
>  arch/arm64/kernel/ptrace.c       | 25 ++++++++++++++++---------
>  arch/arm64/kernel/syscall.c      |  5 +++--
>  3 files changed, 21 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> index 5e4c7fc44f73..cef1d9ce6e1b 100644
> --- a/arch/arm64/include/asm/syscall.h
> +++ b/arch/arm64/include/asm/syscall.h
> @@ -120,7 +120,7 @@ static inline int syscall_get_arch(struct task_struct *task)
>  	return AUDIT_ARCH_AARCH64;
>  }
>  
> -int syscall_trace_enter(struct pt_regs *regs);
> -void syscall_trace_exit(struct pt_regs *regs);
> +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
>  
>  #endif	/* __ASM_SYSCALL_H */
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 3926ce6aa268..b962cbcca11d 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2381,9 +2381,8 @@ static void report_syscall_exit(struct pt_regs *regs)
>  	}
>  }
>  
> -int syscall_trace_enter(struct pt_regs *regs)
> +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>  {
> -	unsigned long flags = read_thread_flags();
>  	int ret;
>  
>  	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
> @@ -2396,19 +2395,27 @@ int syscall_trace_enter(struct pt_regs *regs)
>  	if (secure_computing() == -1)
>  		return NO_SYSCALL;
>  
> -	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
> -		trace_sys_enter(regs, regs->syscallno);
> +	/* Either of the above might have changed the syscall number */
> +	syscall = syscall_get_nr(current, regs);
>  
> -	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
> +	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);
> +	}
> +
> +	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
>  			    regs->regs[2], regs->regs[3]);
>  
> -	return regs->syscallno;
> +	return syscall;

regs->syscallno still remains unchanged even if syscall is evaluated to be different ?

>  }
>  
> -void syscall_trace_exit(struct pt_regs *regs)
> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>  {
> -	unsigned long flags = read_thread_flags();
> -
>  	audit_syscall_exit(regs);
>  
>  	if (flags & _TIF_SYSCALL_TRACEPOINT)
> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> index aba7ca6bca2d..ec31f82d2e9f 100644
> --- a/arch/arm64/kernel/syscall.c
> +++ b/arch/arm64/kernel/syscall.c
> @@ -124,7 +124,7 @@ 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);
> +		scno = syscall_trace_enter(regs, scno, flags);
>  		if (scno == NO_SYSCALL)
>  			goto trace_exit;
>  	}
> @@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>  	}
>  
>  trace_exit:
> -	syscall_trace_exit(regs);
> +	flags = read_thread_flags();
> +	syscall_trace_exit(regs, flags);
>  }
>  
>  void do_el0_svc(struct pt_regs *regs)

Re: [PATCH v9 04/16] arm64/ptrace: Refactor syscall_trace_enter/exit()

Posted by Jinjie Ruan 1 week, 1 day ago


On 2025/12/8 13:48, Anshuman Khandual wrote:
> On 04/12/25 1:51 PM, Jinjie Ruan wrote:
>> The generic syscall entry code has the following form, which use
>> the input syscall work flag and syscall number:
>>
>> | syscall_trace_enter(struct pt_regs *regs, long syscall,
>> |		      unsigned long work)
>> |
>> | syscall_exit_work(struct pt_regs *regs, unsigned long work)
>>
>> In preparation for moving arm64 over to the generic entry code,
>> refactor syscall_trace_enter/exit() to also pass thread flags, and
>> get syscall number by syscall_get_nr() helper.
>>
>> No functional changes.
>>
>> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  arch/arm64/include/asm/syscall.h |  4 ++--
>>  arch/arm64/kernel/ptrace.c       | 25 ++++++++++++++++---------
>>  arch/arm64/kernel/syscall.c      |  5 +++--
>>  3 files changed, 21 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
>> index 5e4c7fc44f73..cef1d9ce6e1b 100644
>> --- a/arch/arm64/include/asm/syscall.h
>> +++ b/arch/arm64/include/asm/syscall.h
>> @@ -120,7 +120,7 @@ static inline int syscall_get_arch(struct task_struct *task)
>>  	return AUDIT_ARCH_AARCH64;
>>  }
>>  
>> -int syscall_trace_enter(struct pt_regs *regs);
>> -void syscall_trace_exit(struct pt_regs *regs);
>> +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags);
>> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
>>  
>>  #endif	/* __ASM_SYSCALL_H */
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index 3926ce6aa268..b962cbcca11d 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -2381,9 +2381,8 @@ static void report_syscall_exit(struct pt_regs *regs)
>>  	}
>>  }
>>  
>> -int syscall_trace_enter(struct pt_regs *regs)
>> +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags)
>>  {
>> -	unsigned long flags = read_thread_flags();
>>  	int ret;
>>  
>>  	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
>> @@ -2396,19 +2395,27 @@ int syscall_trace_enter(struct pt_regs *regs)
>>  	if (secure_computing() == -1)
>>  		return NO_SYSCALL;
>>  
>> -	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
>> -		trace_sys_enter(regs, regs->syscallno);
>> +	/* Either of the above might have changed the syscall number */
>> +	syscall = syscall_get_nr(current, regs);
>>  
>> -	audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
>> +	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);
>> +	}
>> +
>> +	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
>>  			    regs->regs[2], regs->regs[3]);
>>  
>> -	return regs->syscallno;
>> +	return syscall;
> 
> regs->syscallno still remains unchanged even if syscall is evaluated to be different ?

No, arm64 syscall_get_nr() returns regs->syscallno, use syscall_get_nr()
helper here to get the local "syscall" is to stay consistent with the
generic entry, without any semantic change.

 23 static inline int syscall_get_nr(struct task_struct *task,
 24 >------->------->------->------- struct pt_regs *regs)
 25 {
 26 >-------return regs->syscallno;
 27 }

> 
>>  }
>>  
>> -void syscall_trace_exit(struct pt_regs *regs)
>> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags)
>>  {
>> -	unsigned long flags = read_thread_flags();
>> -
>>  	audit_syscall_exit(regs);
>>  
>>  	if (flags & _TIF_SYSCALL_TRACEPOINT)
>> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
>> index aba7ca6bca2d..ec31f82d2e9f 100644
>> --- a/arch/arm64/kernel/syscall.c
>> +++ b/arch/arm64/kernel/syscall.c
>> @@ -124,7 +124,7 @@ 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);
>> +		scno = syscall_trace_enter(regs, scno, flags);
>>  		if (scno == NO_SYSCALL)
>>  			goto trace_exit;
>>  	}
>> @@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
>>  	}
>>  
>>  trace_exit:
>> -	syscall_trace_exit(regs);
>> +	flags = read_thread_flags();
>> +	syscall_trace_exit(regs, flags);
>>  }
>>  
>>  void do_el0_svc(struct pt_regs *regs)
> 
>