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SubjectRe: [PATCH] arm64: make a single hook to syscall_trace() for all syscall features
On Fri, Feb 07, 2014 at 10:07:31AM +0000, AKASHI Takahiro wrote:
> Currently syscall_trace() is called only for ptrace.
> With additional TIF_xx flags introduced, it is now called in all the cases
> of audit, ftrace and seccomp in addition to ptrace.
> Those features will be implemented later, but it's safe to include them
> now because they can not be turned on anyway.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
> arch/arm64/include/asm/thread_info.h | 13 +++++++++++++
> arch/arm64/kernel/entry.S | 5 +++--
> arch/arm64/kernel/ptrace.c | 11 +++++------
> 3 files changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index 720e70b..c3df797 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h

[...]

> +#define _TIF_WORK_SYSCALL (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
> + _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)

This is called _TIF_SYSCALL_WORK on arch/arm/, any reason not to follow the
naming convention here?

> #endif /* __KERNEL__ */
> #endif /* __ASM_THREAD_INFO_H */
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 39ac630..c94b2ab 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -631,8 +631,9 @@ el0_svc_naked: // compat entry point
> enable_irq
>
> get_thread_info tsk
> - ldr x16, [tsk, #TI_FLAGS] // check for syscall tracing
> - tbnz x16, #TIF_SYSCALL_TRACE, __sys_trace // are we tracing syscalls?
> + ldr x16, [tsk, #TI_FLAGS] // check for syscall hooks
> + tst x16, #_TIF_WORK_SYSCALL
> + b.ne __sys_trace
> adr lr, ret_fast_syscall // return address
> cmp scno, sc_nr // check upper syscall limit
> b.hs ni_sys
> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> index 6a8928b..64ce39f 100644
> --- a/arch/arm64/kernel/ptrace.c
> +++ b/arch/arm64/kernel/ptrace.c
> @@ -1062,9 +1062,6 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
> {
> unsigned long saved_reg;
>
> - if (!test_thread_flag(TIF_SYSCALL_TRACE))
> - return regs->syscallno;

This doesn't look right for things like audit (where we don't want to report
the syscall if only _TIF_SYSCALL_AUDIT is set, for example).

> if (is_compat_task()) {
> /* AArch32 uses ip (r12) for scratch */
> saved_reg = regs->regs[12];
> @@ -1078,10 +1075,12 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
> regs->regs[7] = dir;
> }
>
> - if (dir)
> + if (dir) {
> tracehook_report_syscall_exit(regs, 0);
> - else if (tracehook_report_syscall_entry(regs))
> - regs->syscallno = ~0UL;
> + } else {
> + if (tracehook_report_syscall_entry(regs))
> + regs->syscallno = ~0UL;
> + }

This hunk doesn't do anything.

Will


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