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Date: Thu, 27 Feb 2014 10:33:38 +0900 From: AKASHI Takahiro <takahiro.akashi@...aro.org> To: Will Deacon <will.deacon@....com> CC: "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>, "eparis@...hat.com" <eparis@...hat.com>, "rgb@...hat.com" <rgb@...hat.com>, Catalin Marinas <Catalin.Marinas@....com>, "dsaxena@...aro.org" <dsaxena@...aro.org>, "arndb@...db.de" <arndb@...db.de>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-audit@...hat.com" <linux-audit@...hat.com> Subject: Re: [PATCH v2 1/1] arm64: make a single hook to syscall_trace() for all syscall features On 02/26/2014 08:25 PM, Will Deacon wrote: > On Wed, Feb 26, 2014 at 02:00:19AM +0000, AKASHI Takahiro wrote: >> On 02/26/2014 12:00 AM, Will Deacon wrote: >>> 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@...aro.org> >>>> Acked-by: Richard Guy Briggs <rgb@...hat.com> >>>> --- >>>> 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? >> >> Umm, the purpose of this big "if" is to run the code only if TIF_SYSCALL_TRACE is set, >> and to make it easy to add additional hooks, audit and ftrace, around tracehook_report_*() >> later on. > > The existing code already checks TIF_SYSCALL_TRACE. I'd rather you added > this new code when it's actually nedded (e.g. when adding audit on top). * This patch is required only if you really merge my audit and/or ftrace patch. * Putting these changes in audit patch would impose an extra (unnecessary) dependency on ftrace patch. * Putting them both in audit and ftrace patch would cause a conflict when applying both patches. Even so, since I don't bother you on this minor issue, I will follow your comment and make changes on: * arm64: make a single hook to syscall_trace() for all syscall features * arm64: Add audit support * arm64: Add ftrace support -Takahiro AKASHI > Will > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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