Messages in this thread | | | Date | Sat, 15 Mar 2014 01:51:51 +0900 | From | AKASHI Takahiro <> | Subject | Re: [PATCH v4 2/3] arm64: split syscall_trace() into separate functions for enter/exit |
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On 03/14/2014 03:41 AM, Will Deacon wrote: > 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 <takahiro.akashi@linaro.org> >> --- >> 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.
OK, I will implement tracehook_report_syscall() as in arm.
-Takahiro AKASHI
> Will >
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