From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Andy Lutomirski <luto@kernel.org>,
Nicolai Stange <nstange@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
Petr Mladek <pmladek@suse.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Mimi Zohar <zohar@linux.ibm.com>, Juergen Gross <jgross@suse.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Nayna Jain <nayna@linux.ibm.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Joerg Roedel <jroedel@suse.de>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
live-patching@vger.kernel.org,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [RFC][PATCH v3] ftrace/x86_64: Emulate call function while updating in breakpoint handler
Date: Wed, 1 May 2019 21:17:16 +0200 [thread overview]
Message-ID: <20190501191716.GV7905@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHk-=wgMZJeMCW5MA25WFJZeYYWCOWr0nGaHhJ7kg+zsu5FY_A@mail.gmail.com>
On Wed, May 01, 2019 at 11:59:05AM -0700, Linus Torvalds wrote:
> On Wed, May 1, 2019 at 11:52 AM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > I got Peter's patch working. Here it is. What do you think?
>
> I can tell from just looking at it for five seconds that at least the
> 32-bit case is buggy.
>
> You can't look at CS(%rsp) without first also checking that you're not
> coming from vm86 mode.
Something like so then?
Index: linux-2.6/arch/x86/entry/entry_32.S
===================================================================
--- linux-2.6.orig/arch/x86/entry/entry_32.S
+++ linux-2.6/arch/x86/entry/entry_32.S
@@ -1479,6 +1479,10 @@ ENTRY(int3)
ASM_CLAC
pushl $-1 # mark this as an int
+#ifdef CONFIG_VM86
+ testl $X86_EFLAGS_VM, PT_EFLAGS(%esp)
+ jnz .Lfrom_usermode_no_gap
+#endif
testl $SEGMENT_RPL_MASK, PT_CS(%esp)
jnz .Lfrom_usermode_no_gap
.rept 6
next prev parent reply other threads:[~2019-05-01 19:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-01 15:32 Steven Rostedt
2019-05-01 18:01 ` Linus Torvalds
2019-05-01 18:52 ` Steven Rostedt
2019-05-01 18:59 ` Linus Torvalds
2019-05-01 19:17 ` Peter Zijlstra [this message]
2019-05-01 19:36 ` Linus Torvalds
2019-05-01 18:57 ` Peter Zijlstra
2019-05-01 19:00 ` Steven Rostedt
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