On 04/12/25 1:51 PM, Jinjie Ruan wrote:
> The generic syscall entry code has the form:
>
> | syscall_trace_enter()
> | {
> | ptrace_report_syscall_entry()
> | }
> |
> | syscall_exit_work()
> | {
> | ptrace_report_syscall_exit()
> | }
>
> In preparation for moving arm64 over to the generic entry code, split
> report_syscall() to two separate enter and exit functions to align
> the structure of the arm64 code with syscall_trace_enter() and
> syscall_exit_work() from the generic entry code.
>
> No functional changes.
>
> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
> Suggested-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
LGTM.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> v8:
> - report_syscall_enter() -> report_syscall_entry().
> - Add ptrace_save_reg() helper.
> ---
> arch/arm64/kernel/ptrace.c | 41 +++++++++++++++++++++++++++-----------
> 1 file changed, 29 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 4b001121c72d..4532e9831856 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -2317,9 +2317,10 @@ enum ptrace_syscall_dir {
> PTRACE_SYSCALL_EXIT,
> };
>
> -static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
> +static __always_inline unsigned long ptrace_save_reg(struct pt_regs *regs,
> + enum ptrace_syscall_dir dir,
> + int *regno)
> {
> - int regno;
> unsigned long saved_reg;
>
> /*
> @@ -2338,15 +2339,31 @@ static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
> * - 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] = dir;
> + *regno = (is_compat_task() ? 12 : 7);
> + saved_reg = regs->regs[*regno];
> + regs->regs[*regno] = dir;
>
> - if (dir == PTRACE_SYSCALL_ENTER) {
> - if (ptrace_report_syscall_entry(regs))
> - forget_syscall(regs);
> - regs->regs[regno] = saved_reg;
> - } else if (!test_thread_flag(TIF_SINGLESTEP)) {
> + return saved_reg;
> +}
> +
> +static void report_syscall_entry(struct pt_regs *regs)
> +{
> + unsigned long saved_reg;
> + int regno;
> +
> + saved_reg = ptrace_save_reg(regs, PTRACE_SYSCALL_ENTER, ®no);
> + if (ptrace_report_syscall_entry(regs))
> + forget_syscall(regs);
> + regs->regs[regno] = saved_reg;
> +}
> +
> +static void report_syscall_exit(struct pt_regs *regs)
> +{
> + unsigned long saved_reg;
> + int regno;
> +
> + saved_reg = ptrace_save_reg(regs, PTRACE_SYSCALL_EXIT, ®no);
> + if (!test_thread_flag(TIF_SINGLESTEP)) {
> ptrace_report_syscall_exit(regs, 0);
> regs->regs[regno] = saved_reg;
> } else {
> @@ -2366,7 +2383,7 @@ int syscall_trace_enter(struct pt_regs *regs)
> unsigned long flags = read_thread_flags();
>
> if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
> - report_syscall(regs, PTRACE_SYSCALL_ENTER);
> + report_syscall_entry(regs);
> if (flags & _TIF_SYSCALL_EMU)
> return NO_SYSCALL;
> }
> @@ -2394,7 +2411,7 @@ void syscall_trace_exit(struct pt_regs *regs)
> trace_sys_exit(regs, syscall_get_return_value(current, regs));
>
> if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
> - report_syscall(regs, PTRACE_SYSCALL_EXIT);
> + report_syscall_exit(regs);
>
> rseq_syscall(regs);
> }