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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	X86 ML <x86@kernel.org>, Andy Lutomirski <luto@amacapital.net>,
	Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary
Date: Fri, 16 Mar 2018 13:38:35 -0500	[thread overview]
Message-ID: <20180316183835.2nntffoj7qottgk7@treble> (raw)
In-Reply-To: <20180316174529.GG5852@pd.tnic>

On Fri, Mar 16, 2018 at 06:45:29PM +0100, Borislav Petkov wrote:
> > You're better off getting rid of the CR2 line from __show_regs(),
> > because it can be dangerously confusing. It's not actually part of the
> > saved register state at all, it's something entirely different. It's
> > like showing the current eflags rather than the eflags saved on the
> > faulting stack.
> 
> Yeah, __show_regs() goes and gets a bunch of registers at the time
> __show_regs() runs. Which is ok for those which don't change in between
> but CR2 is special.
> 
> We probably could improve that situation by having a struct fault_regs
> or so wrapping pt_regs and adding a bunch of fields like CR2 etc. Fault
> handlers would then populate fault_regs at fault time while we're atomic
> and then hand this struct down to the printing path.
> 
> The printing path would fill out the rest and this way we won't have any
> of that monkey business anymore.
> 
> Thoughts?

It would be nice if we could save *all* the printed registers before
they get a chance to change, but I don't know how feasible that is.
Some of the registers change in entry code, like CR3 and GS.

-- 
Josh

  reply	other threads:[~2018-03-16 18:38 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 15:44 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v2 Borislav Petkov
2018-03-15 15:44 ` [PATCH 1/9] x86/dumstack: Remove code_bytes Borislav Petkov
2018-03-15 18:12   ` Josh Poimboeuf
2018-03-15 15:44 ` [PATCH 2/9] x86/dumpstack: Unexport oops_begin() Borislav Petkov
2018-03-15 15:44 ` [PATCH 3/9] x86/dumpstack: Carve out Code: dumping into a function Borislav Petkov
2018-03-15 15:44 ` [PATCH 4/9] x86/dumpstack: Improve opcodes dumping in the Code: section Borislav Petkov
2018-03-15 18:10   ` Josh Poimboeuf
2018-03-15 18:16     ` Borislav Petkov
2018-03-15 19:06       ` Josh Poimboeuf
2018-03-16 11:57       ` David Laight
2018-03-15 18:19   ` Josh Poimboeuf
2018-03-15 18:23   ` Josh Poimboeuf
2018-03-15 15:44 ` [PATCH 5/9] x86/dumpstack: Add loglevel argument to show_opcodes() Borislav Petkov
2018-03-15 15:44 ` [PATCH 6/9] x86/fault: Dump user opcode bytes on fatal faults Borislav Petkov
2018-03-15 15:44 ` [PATCH 7/9] x86/dumpstack: Add a show_ip() function Borislav Petkov
2018-03-15 18:34   ` Josh Poimboeuf
2018-03-15 18:55     ` Borislav Petkov
2018-03-15 15:44 ` [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary Borislav Petkov
2018-03-15 19:01   ` Josh Poimboeuf
2018-03-16 11:48     ` Borislav Petkov
2018-03-16 12:01       ` Josh Poimboeuf
2018-03-16 12:11         ` Borislav Petkov
2018-03-16 13:16           ` Josh Poimboeuf
2018-03-16 13:44             ` Borislav Petkov
2018-03-16 17:22       ` Linus Torvalds
2018-03-16 17:40         ` Josh Poimboeuf
2018-03-16 17:45         ` Borislav Petkov
2018-03-16 18:38           ` Josh Poimboeuf [this message]
2018-03-15 15:44 ` [PATCH 9/9] x86/dumpstack: Explain the reasoning for the prologue and buffer size Borislav Petkov
2018-03-15 18:07   ` Josh Poimboeuf
2018-03-15 18:17     ` Borislav Petkov
2018-03-15 17:51 ` [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v2 Linus Torvalds
2018-04-17 14:40   ` Borislav Petkov
2018-04-17 20:16     ` Josh Poimboeuf
2018-04-17 21:06       ` Borislav Petkov
2018-04-18 13:26         ` Josh Poimboeuf
2018-04-17 16:11 [PATCH 0/9] x86/dumpstack: Cleanups and user opcode bytes Code: section, v3 Borislav Petkov
2018-04-17 16:11 ` [PATCH 8/9] x86/dumpstack: Save first regs set for the executive summary Borislav Petkov

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