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 <[email protected]>
> Signed-off-by: Jinjie Ruan <[email protected]>
> ---
> 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)
