On Thu, Mar 13, 2014 at 10:11:30AM +0000, AKASHI Takahiro wrote:
> As done in arm, this change makes it easy to confirm we invoke syscall
> related hooks, including syscall tracepoint, audit and seccomp which would
> be implemented later, in correct order. That is, undoing operations in the
> opposite order on exit that they were done on entry.
>
> Signed-off-by: AKASHI Takahiro <[email protected]>
> ---
> arch/arm64/kernel/entry.S | 10 ++++-----
> arch/arm64/kernel/ptrace.c | 48
> ++++++++++++++++++++++++++++++++++----------
> 2 files changed, 41 insertions(+), 17 deletions(-)
[...]
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 6a8928b..9993a8f 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -1058,29 +1058,27 @@ long arch_ptrace(struct task_struct *child, long
> request,
> return ptrace_request(child, request, addr, data);
> }
>
> -asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
> +asmlinkage int syscall_trace_enter(struct pt_regs *regs)
> {
> unsigned long saved_reg;
>
> if (!test_thread_flag(TIF_SYSCALL_TRACE))
> return regs->syscallno;
>
> + /*
> + * A scrach register (ip(r12) on AArch32, x7 on AArch64) is
> + * used to denote syscall entry/exit:
> + * 0 -> entry
> + */
You could add an enum, like we have on ARM (ptrace_syscall_dir) for the two
directions.
> if (is_compat_task()) {
> - /* AArch32 uses ip (r12) for scratch */
> saved_reg = regs->regs[12];
> - regs->regs[12] = dir;
> + regs->regs[12] = 0;
> } else {
> - /*
> - * Save X7. X7 is used to denote syscall entry/exit:
> - * X7 = 0 -> entry, = 1 -> exit
> - */
> saved_reg = regs->regs[7];
> - regs->regs[7] = dir;
> + regs->regs[7] = 0;
This code could also be refactored so we calculated the register number
once, then avoid the if (is_compact_task()) check all over the place.
Similarly on the exit path.
Will
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