From: Ingo Molnar <mingo@kernel.org>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Alex Thorlton <athorlton@sgi.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Borislav Petkov <bp@alien8.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Denys Vlasenko <dvlasenk@redhat.com>
Subject: Re: [GIT PULL] EFI fix
Date: Tue, 17 May 2016 12:20:49 +0200 [thread overview]
Message-ID: <20160517102049.GB26924@gmail.com> (raw)
In-Reply-To: <20160517094655.GB21993@codeblueprint.co.uk>
* Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Tue, 17 May, at 10:04:34AM, Matt Fleming wrote:
> >
> > Now I'm wondering whether other users of FRAME_BEGIN/FRAME_END make
> > this same mistake. Coccinelle might be able to detect it perhaps.
>
> A quick bit of sed turned up the code in arch/x86/entry/entry_64.S,
> which looks to suffer from the same bug,
That would be arch/x86/entry/thunk_64.S, but yeah, good find!
> /* rdi: arg1 ... normal C conventions. rax is saved/restored. */
> .macro THUNK name, func, put_ret_addr_in_rdi=0
> .globl \name
> .type \name, @function
> \name:
> FRAME_BEGIN
>
> /* this one pushes 9 elems, the next one would be %rIP */
> pushq %rdi
> pushq %rsi
> pushq %rdx
> pushq %rcx
> pushq %rax
> pushq %r8
> pushq %r9
> pushq %r10
> pushq %r11
>
> .if \put_ret_addr_in_rdi
> /* 9*8(%rsp) is return addr on stack */
> movq 9*8(%rsp), %rdi
> .endif
>
> With CONFIG_FRAME_POINTER=y 9*8(%rsp) is actually the value of %rbp on
> entry, not the return address.
This seems to affect:
#ifdef CONFIG_TRACE_IRQFLAGS
THUNK trace_hardirqs_on_thunk,trace_hardirqs_on_caller,1
THUNK trace_hardirqs_off_thunk,trace_hardirqs_off_caller,1
#endif
and with TRACE_IRQFLAGS we already in most times force frame pointers, such as
when LOCKDEP is enabled:
config LOCKDEP
bool
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
...
select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
Also, unlike the efi_call() case, this thunk_64.S bug affects the quality of
debug/tracing information, not runtime correctness per se.
still all that is by accident, not by design - this bug should be fixed too.
Thanks,
Ingo
next prev parent reply other threads:[~2016-05-17 10:20 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-16 14:46 [GIT PULL] EFI fix Ingo Molnar
2016-05-16 20:05 ` Linus Torvalds
2016-05-16 20:23 ` Alex Thorlton
2016-05-16 22:40 ` Alex Thorlton
2016-05-17 6:30 ` [tip:x86/urgent] x86/efi: Fix 7-parameter efi_call()s tip-bot for Linus Torvalds
2016-05-17 9:04 ` [GIT PULL] EFI fix Matt Fleming
2016-05-17 9:46 ` Matt Fleming
2016-05-17 10:20 ` Ingo Molnar [this message]
2016-05-17 14:43 ` [PATCH] x86/asm/entry: fix stack return address retrieval in thunk Josh Poimboeuf
2016-05-17 16:31 ` Linus Torvalds
2016-05-17 16:51 ` Steven Rostedt
2016-05-17 17:21 ` Linus Torvalds
2016-05-17 17:25 ` Josh Poimboeuf
2016-05-17 18:06 ` [PATCH v2] " Josh Poimboeuf
2016-05-17 18:33 ` Linus Torvalds
2016-05-19 9:12 ` [tip:x86/urgent] x86/entry/64: Fix " tip-bot for Josh Poimboeuf
2016-05-23 12:08 ` [GIT PULL] EFI fix Matt Fleming
2016-05-23 12:33 ` Josh Poimboeuf
2016-05-24 9:03 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2019-05-18 9:17 Ingo Molnar
2019-05-19 17:45 ` pr-tracker-bot
2019-01-11 7:46 Ingo Molnar
2019-01-11 14:22 ` Ard Biesheuvel
2019-01-11 17:55 ` Linus Torvalds
2019-01-12 8:53 ` Ingo Molnar
2019-01-11 17:47 ` Linus Torvalds
2019-01-12 8:54 ` Ingo Molnar
2018-11-30 6:21 Ingo Molnar
2018-11-30 21:00 ` pr-tracker-bot
2018-07-30 17:44 Ingo Molnar
2018-07-13 19:57 Ingo Molnar
2017-06-10 8:31 Ingo Molnar
2016-04-28 17:48 Ingo Molnar
2016-04-16 9:08 Ingo Molnar
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