From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@kernel.org>,
Balbir Singh <bsingharora@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>
Subject: Re: [RFC PATCH 5/5] selftest/x86: Add CET quick test
Date: Fri, 22 May 2020 08:10:14 -0700 [thread overview]
Message-ID: <cc3d7668eb7dd738a85f0b0935624496efae43be.camel@intel.com> (raw)
In-Reply-To: <20200522092848.GJ325280@hirez.programming.kicks-ass.net>
On Fri, 2020-05-22 at 11:28 +0200, Peter Zijlstra wrote:
> On Thu, May 21, 2020 at 02:17:20PM -0700, Yu-cheng Yu wrote:
>
> > +#pragma GCC push_options
> > +#pragma GCC optimize ("O0")
> > +void ibt_violation(void)
> > +{
> > +#ifdef __i386__
> > + asm volatile("lea 1f, %eax");
> > + asm volatile("jmp *%eax");
> > +#else
> > + asm volatile("lea 1f, %rax");
> > + asm volatile("jmp *%rax");
> > +#endif
> > + asm volatile("1:");
> > + result[test_id] = -1;
> > + test_id++;
> > + setcontext(&ucp);
> > +}
> > +
> > +void shstk_violation(void)
> > +{
> > +#ifdef __i386__
> > + unsigned long x = 0;
> > +
> > + ((unsigned long *)&x)[2] = (unsigned long)stack_hacked;
> > +#else
> > + unsigned long long x = 0;
> > +
> > + ((unsigned long long *)&x)[2] = (unsigned long)stack_hacked;
> > +#endif
> > +}
> > +#pragma GCC pop_options
>
> This is absolutely atrocious.
>
> The #pragma like Kees already said just need to go. Also, there's
> absolutely no clue what so ever what it attempts to achieve.
>
> The __i386__ ifdeffery is horrible crap. Splitting an asm with #ifdef
> like that is also horrible crap.
>
> This is not how you write code.
>
> Get asm/asm.h into userspace and then write something like:
>
>
> void ibt_violation(void)
> {
> asm volatile("lea 1f, %" _ASM_AX "\n\t"
> "jmp *%" _ASM_AX "\n\t"
> "1:\n\t" ::: "a");
>
> WRITE_ONCE(result[test_id], -1);
> WRITE_ONCE(test_id, test_id+1);
>
> setcontext(&ucp);
> }
>
> void shstk_violation(void)
> {
> unsigned long x = 0;
>
> WRITE_ONCE(x[2], stack_hacked);
> }
Thanks! I will change it.
Yu-cheng
next prev parent reply other threads:[~2020-05-22 15:10 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 21:17 [RFC PATCH 0/5] Update selftests/x86 for CET Yu-cheng Yu
2020-05-21 21:17 ` [RFC PATCH 1/5] x86/cet/shstk: Modify ARCH_X86_CET_ALLOC_SHSTK for 32-bit address range Yu-cheng Yu
2020-05-21 22:43 ` Kees Cook
2020-05-21 21:17 ` [RFC PATCH 2/5] selftest/x86: Enable CET for selftests/x86 Yu-cheng Yu
2020-05-21 22:44 ` Kees Cook
2020-05-21 22:58 ` Yu-cheng Yu
2020-05-21 21:17 ` [RFC PATCH 3/5] selftest/x86: Fix sigreturn_64 test Yu-cheng Yu
2020-05-21 22:47 ` Kees Cook
2020-05-21 22:48 ` Kees Cook
2020-05-21 21:17 ` [RFC PATCH 4/5] selftest/x86: Fix sysret_rip with ENDBR Yu-cheng Yu
2020-05-21 21:34 ` Thomas Gleixner
2020-05-21 22:59 ` Yu-cheng Yu
2020-05-21 21:17 ` [RFC PATCH 5/5] selftest/x86: Add CET quick test Yu-cheng Yu
2020-05-21 23:02 ` Kees Cook
2020-05-21 23:23 ` Yu-cheng Yu
2020-05-22 9:28 ` Peter Zijlstra
2020-05-22 15:10 ` Yu-cheng Yu [this message]
2020-05-22 17:22 ` Kees Cook
2020-05-22 17:27 ` Peter Zijlstra
2020-05-22 17:36 ` Kees Cook
2020-05-22 18:07 ` Yu-cheng Yu
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