Re: [PATCH v2 1/1] arm64: make a single hook to syscall_trace() for all syscall features

On Tue, Feb 25, 2014 at 09:14:43AM +0000, AKASHI Takahiro wrote: > Currently syscall_trace() is called only for ptrace. > With additional TIF_xx flags defined, it is now called in all the cases > of audit, ftrace and seccomp in addition to ptrace. > > Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org&gt; > Acked-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > arch/arm64/include/asm/thread_info.h | 13 ++++++++++ > arch/arm64/kernel/entry.S | 5 ++-- > arch/arm64/kernel/ptrace.c | 45 +++++++++++++++++----------------- > 3 files changed, 38 insertions(+), 25 deletions(-)

> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 6a8928b..c70133e 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -1062,31 +1062,30 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs) > { > unsigned long saved_reg; > > - if (!test_thread_flag(TIF_SYSCALL_TRACE)) > - return regs->syscallno; > - > - if (is_compat_task()) { > - /* AArch32 uses ip (r12) for scratch */ > - saved_reg = regs->regs[12]; > - regs->regs[12] = dir; > - } 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; > - } > + if (test_thread_flag(TIF_SYSCALL_TRACE)) { > + if (is_compat_task()) { > + /* AArch32 uses ip (r12) for scratch */ > + saved_reg = regs->regs[12]; > + regs->regs[12] = dir; > + } 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; > + } > > - if (dir) > - tracehook_report_syscall_exit(regs, 0); > - else if (tracehook_report_syscall_entry(regs)) > - regs->syscallno = ~0UL; > + if (dir) > + tracehook_report_syscall_exit(regs, 0); > + else if (tracehook_report_syscall_entry(regs)) > + regs->syscallno = ~0UL; > > - if (is_compat_task()) > - regs->regs[12] = saved_reg; > - else > - regs->regs[7] = saved_reg; > + if (is_compat_task()) > + regs->regs[12] = saved_reg; > + else > + regs->regs[7] = saved_reg; > + } Aren't these changes (to ptrace.c) just a giant NOP?

Will