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From: Thomas Gleixner <tglx@linutronix.de>
To: David Laight <David.Laight@ACULAB.COM>,
	LKML <linux-kernel@vger.kernel.org>
Cc: "x86@kernel.org" <x86@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
	Johannes Wikner <kwikner@ethz.ch>,
	Alyssa Milburn <alyssa.milburn@linux.intel.com>,
	Jann Horn <jannh@google.com>, "H.J. Lu" <hjl.tools@gmail.com>,
	Joao Moreira <joao.moreira@intel.com>,
	Joseph Nuzman <joseph.nuzman@intel.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Juergen Gross <jgross@suse.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: RE: [patch 00/38] x86/retbleed: Call depth tracking mitigation
Date: Sun, 17 Jul 2022 21:15:44 +0200	[thread overview]
Message-ID: <87wncbwnxb.ffs@tglx> (raw)
In-Reply-To: <24673619e9e2411bb1d5f287aab2aa87@AcuMS.aculab.com>

On Sun, Jul 17 2022 at 17:56, David Laight wrote:
> From: Thomas Gleixner
>> On Sun, Jul 17 2022 at 09:45, David Laight wrote:
> I was thinking about what happens after the RSB has underflowed.
> Which is when (I presume) the BTB based speculation happens.
>
>> The intra function call in the retpoline is of course adding a RSB entry
>> which points to the speculation trap, but that gets popped immediately
>> after that by the return which goes to the called function.
>
> I'm remembering the 'active' instructions in a retpoline being 'push; ret'.
> Which is an RSB imbalance.

Looking at the code might help to remember correctly:

        call   1f
        speculation trap
1:      mov     %reg, %rsp
        ret

Thanks,

        tglx

  reply	other threads:[~2022-07-17 19:16 UTC|newest]

Thread overview: 142+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-16 23:17 [patch 00/38] x86/retbleed: Call depth tracking mitigation Thomas Gleixner
2022-07-16 23:17 ` [patch 01/38] x86/paravirt: Ensure proper alignment Thomas Gleixner
2022-07-16 23:17 ` [patch 02/38] x86/cpu: Use native_wrmsrl() in load_percpu_segment() Thomas Gleixner
2022-07-17  0:22   ` Andrew Cooper
2022-07-17 15:20     ` Linus Torvalds
2022-07-17 19:08     ` Thomas Gleixner
2022-07-17 20:08       ` Thomas Gleixner
2022-07-17 20:13         ` Thomas Gleixner
2022-07-17 21:54           ` Thomas Gleixner
2022-07-18  5:11             ` Juergen Gross
2022-07-18  6:54               ` Thomas Gleixner
2022-07-18  8:55                 ` Thomas Gleixner
2022-07-18  9:31                   ` Peter Zijlstra
2022-07-18 10:33                     ` Thomas Gleixner
2022-07-18 11:42                       ` Thomas Gleixner
2022-07-18 17:52   ` [patch 0/3] x86/cpu: Sanitize switch_to_new_gdt() Thomas Gleixner
2022-07-18 17:52   ` [patch 1/3] x86/cpu: Remove segment load from switch_to_new_gdt() Thomas Gleixner
2022-07-18 18:43     ` Linus Torvalds
2022-07-18 18:55       ` Thomas Gleixner
2022-07-18 17:52   ` [patch 2/3] x86/cpu: Get rid of redundant switch_to_new_gdt() invocations Thomas Gleixner
2022-07-18 17:52   ` [patch 3/3] x86/cpu: Re-enable stackprotector Thomas Gleixner
2022-07-16 23:17 ` [patch 03/38] x86/modules: Set VM_FLUSH_RESET_PERMS in module_alloc() Thomas Gleixner
2022-07-16 23:17 ` [patch 04/38] x86/vdso: Ensure all kernel code is seen by objtool Thomas Gleixner
2022-07-16 23:17 ` [patch 05/38] btree: Initialize early when builtin Thomas Gleixner
2022-07-16 23:17 ` [patch 06/38] objtool: Allow GS relative relocs Thomas Gleixner
2022-07-16 23:17 ` [patch 07/38] objtool: Track init section Thomas Gleixner
2022-07-16 23:17 ` [patch 08/38] objtool: Add .call_sites section Thomas Gleixner
2022-07-16 23:17 ` [patch 09/38] objtool: Add .sym_sites section Thomas Gleixner
2022-07-16 23:17 ` [patch 10/38] objtool: Add --hacks=skylake Thomas Gleixner
2022-07-16 23:17 ` [patch 11/38] objtool: Allow STT_NOTYPE -> STT_FUNC+0 tail-calls Thomas Gleixner
2022-07-16 23:17 ` [patch 12/38] x86/entry: Make sync_regs() invocation a tail call Thomas Gleixner
2022-07-16 23:17 ` [patch 13/38] x86/modules: Make module_alloc() generally available Thomas Gleixner
2022-07-16 23:17 ` [patch 14/38] x86/Kconfig: Add CONFIG_CALL_THUNKS Thomas Gleixner
2022-07-16 23:17 ` [patch 15/38] x86/retbleed: Add X86_FEATURE_CALL_DEPTH Thomas Gleixner
2022-07-16 23:17 ` [patch 16/38] modules: Make struct module_layout unconditionally available Thomas Gleixner
2022-07-16 23:17 ` [patch 17/38] module: Add arch_data to module_layout Thomas Gleixner
2022-07-16 23:17 ` [patch 18/38] mm/vmalloc: Provide huge page mappings Thomas Gleixner
2022-07-16 23:17 ` [patch 19/38] x86/module: Provide __module_alloc() Thomas Gleixner
2022-07-16 23:17 ` [patch 20/38] x86/alternatives: Provide text_poke_[copy|set]_locked() Thomas Gleixner
2022-07-16 23:17 ` [patch 21/38] x86/entry: Make some entry symbols global Thomas Gleixner
2022-07-16 23:17 ` [patch 22/38] x86/paravirt: Make struct paravirt_call_site unconditionally available Thomas Gleixner
2022-07-16 23:17 ` [patch 23/38] x86/callthunks: Add call patching for call depth tracking Thomas Gleixner
2022-07-16 23:17 ` [patch 24/38] module: Add layout for callthunks tracking Thomas Gleixner
2022-07-16 23:17 ` [patch 25/38] x86/modules: Add call thunk patching Thomas Gleixner
2022-07-16 23:17 ` [patch 26/38] x86/returnthunk: Allow different return thunks Thomas Gleixner
2022-07-16 23:17 ` [patch 27/38] x86/asm: Provide ALTERNATIVE_3 Thomas Gleixner
2022-07-16 23:17 ` [patch 28/38] x86/retbleed: Add SKL return thunk Thomas Gleixner
2022-07-16 23:17 ` [patch 29/38] x86/retpoline: Add SKL retthunk retpolines Thomas Gleixner
2022-07-16 23:17 ` [patch 30/38] x86/retbleed: Add SKL call thunk Thomas Gleixner
2022-07-16 23:18 ` [patch 31/38] x86/calldepth: Add ret/call counting for debug Thomas Gleixner
2022-07-16 23:18 ` [patch 32/38] static_call: Add call depth tracking support Thomas Gleixner
2022-07-16 23:18 ` [patch 33/38] kallsyms: Take callthunks into account Thomas Gleixner
2022-07-16 23:18 ` [patch 34/38] x86/orc: Make it callthunk aware Thomas Gleixner
2022-07-16 23:18 ` [patch 35/38] kprobes: Add callthunk blacklisting Thomas Gleixner
2022-07-16 23:18 ` [patch 36/38] x86/ftrace: Make it call depth tracking aware Thomas Gleixner
2022-07-18 21:01   ` Steven Rostedt
2022-07-19  8:46     ` Peter Zijlstra
2022-07-19 13:06       ` Steven Rostedt
2022-07-16 23:18 ` [patch 37/38] x86/bpf: Emit call depth accounting if required Thomas Gleixner
2022-07-19  5:30   ` Alexei Starovoitov
2022-07-19  8:34     ` Peter Zijlstra
2022-07-16 23:18 ` [patch 38/38] x86/retbleed: Add call depth tracking mitigation Thomas Gleixner
2022-07-17  9:45 ` [patch 00/38] x86/retbleed: Call " David Laight
2022-07-17 15:07   ` Thomas Gleixner
2022-07-17 17:56     ` David Laight
2022-07-17 19:15       ` Thomas Gleixner [this message]
2022-07-18 19:29 ` Thomas Gleixner
2022-07-18 19:30   ` Thomas Gleixner
2022-07-18 19:51     ` Linus Torvalds
2022-07-18 20:44       ` Thomas Gleixner
2022-07-18 21:01         ` Linus Torvalds
2022-07-18 21:43           ` Peter Zijlstra
2022-07-18 22:34             ` Linus Torvalds
2022-07-18 23:52               ` Peter Zijlstra
2022-07-18 21:18         ` Peter Zijlstra
2022-07-18 22:22           ` Thomas Gleixner
2022-07-18 22:47             ` Joao Moreira
2022-07-18 22:55               ` Sami Tolvanen
2022-07-18 23:08                 ` Joao Moreira
2022-07-18 23:19                 ` Thomas Gleixner
2022-07-18 23:42                   ` Linus Torvalds
2022-07-18 23:52                     ` Linus Torvalds
2022-07-18 23:57                       ` Peter Zijlstra
2022-07-19  0:03                         ` Linus Torvalds
2022-07-19  0:11                           ` Linus Torvalds
2022-07-19  0:23                             ` Peter Zijlstra
2022-07-19  1:02                               ` Linus Torvalds
2022-07-19 17:19                             ` Sami Tolvanen
2022-07-20 21:13                               ` Peter Zijlstra
2022-07-21  8:21                                 ` David Laight
2022-07-21 10:56                                   ` David Laight
2022-07-21 15:54                                 ` Peter Zijlstra
2022-07-21 17:55                                   ` Peter Zijlstra
2022-07-21 18:06                                     ` Linus Torvalds
2022-07-21 18:27                                       ` Peter Zijlstra
2022-07-21 18:32                                         ` Linus Torvalds
2022-07-21 20:22                                           ` Joao Moreira
2022-07-22  0:16                                         ` Sami Tolvanen
2022-07-22 10:23                                           ` Peter Zijlstra
2022-07-22 15:38                                             ` Sami Tolvanen
2022-07-21 22:01                                       ` David Laight
2022-07-22 11:03                                         ` Peter Zijlstra
2022-07-22 13:27                                           ` David Laight
2022-07-23  9:50                                   ` Thomas Gleixner
2022-07-19  0:01                       ` Linus Torvalds
2022-07-19  0:19                         ` Joao Moreira
2022-07-19 17:21                           ` Sami Tolvanen
2022-07-19 17:58                             ` Joao Moreira
2022-07-19  8:26                         ` David Laight
2022-07-19 16:27                           ` Linus Torvalds
2022-07-19 17:23                             ` Sami Tolvanen
2022-07-19 17:27                               ` Linus Torvalds
2022-07-19 18:06                                 ` Sami Tolvanen
2022-07-19 20:10                                   ` Peter Zijlstra
2022-07-18 22:48           ` Sami Tolvanen
2022-07-18 22:59             ` Thomas Gleixner
2022-07-18 23:10               ` Sami Tolvanen
2022-07-18 23:39               ` Linus Torvalds
2022-07-18 23:51             ` Peter Zijlstra
2022-07-20  9:00               ` Thomas Gleixner
2022-07-20 16:55               ` Sami Tolvanen
2022-07-20 19:42               ` Sami Tolvanen
2022-07-22 20:11         ` Tim Chen
2022-07-22 22:18           ` Linus Torvalds
2022-07-18 19:55 ` Thomas Gleixner
2022-07-19 10:24 ` Virt " Andrew Cooper
2022-07-19 14:13   ` Thomas Gleixner
2022-07-19 16:23     ` Andrew Cooper
2022-07-19 21:17       ` Thomas Gleixner
2022-07-19 14:45   ` Michael Kelley (LINUX)
2022-07-19 20:16     ` Peter Zijlstra
2022-07-20 16:57 ` [patch 00/38] x86/retbleed: " Steven Rostedt
2022-07-20 17:09   ` Linus Torvalds
2022-07-20 17:24     ` Peter Zijlstra
2022-07-20 17:50       ` Steven Rostedt
2022-07-20 18:07         ` Linus Torvalds
2022-07-20 18:31           ` Steven Rostedt
2022-07-20 18:43             ` Linus Torvalds
2022-07-20 19:11               ` Steven Rostedt
2022-07-20 19:36           ` Kees Cook
2022-07-20 19:43             ` Steven Rostedt
2022-07-20 21:36             ` Peter Zijlstra

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