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From: Dominik Brodowski <linux@dominikbrodowski.net>
To: linux-kernel@vger.kernel.org, mingo@kernel.org, x86@kernel.org
Cc: dan.j.williams@intel.com, tglx@linutronix.de, ak@linux.intel.com,
	torvalds@linux-foundation.org, luto@kernel.org
Subject: [PATCH v3 0/7] x86/entry: simplify and unify SAVE/POP_REGS
Date: Sun, 11 Feb 2018 11:49:41 +0100	[thread overview]
Message-ID: <20180211104949.12992-1-linux@dominikbrodowski.net> (raw)

The starting point for this series was the intention to interleave
the register clearing with register PUSH or MOV instructions, in order
to minimize the cost of the additional instructions required for the
register clearing. While at it, I noticed that a couple of macros in
arch/x86/entry/calling.h are unused and can be cleaned up.

Based on a preliminary version of this patch,[1] Linus suggested to
merge further codepaths and to use PUSH instead of MOV, as this should
be faster on newer CPUs.

Those who are worried about the increase in text size will find a
patch 8/7 which, based on a suggestion by Liunus, plays some trickery to
move PUSH_AND_CLEAR_REGS from the idtentry macro to the error_entry and
paranoid_entry functions. As things stand, this patch is not meant for
inclusion upstream, as it is unclear whether this additional trickery is
really worth the effort.

Changes since v2:[2] 
- update commit message to patch 6/7 to include an explanation by
  Ingo Molnar on why we should not be worried too much about the increase
  in text size
- fix objtool warning introduced in patch 6/7
- unwind hint improvements [jpoimboe@redhat.com]
- add testing-only patch 8/7

Changes since v1:[1]
- complete rework

[1] http://lkml.kernel.org/r/20180206212546.GA2026@light.dominikbrodowski.net and
    http://lkml.kernel.org/r/20180206213202.GB2026@light.dominikbrodowski.net

[2] http://lkml.kernel.org/r/20180207201517.6518-1-linux@dominikbrodowski.net

NOTE / WARNING: Please be *extremely* stringent in reviewing these
patches, *especially* concerning patch 6/7 (x86/entry: get rid of
ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS).

Dominik Brodowski (7):
  x86/entry: merge SAVE_C_REGS and SAVE_EXTRA_REGS, remove unused
    extensions
  x86/entry: merge POP_C_REGS and POP_EXTRA_REGS
  x86/entry: interleave XOR register clearing with PUSH instructions
  x86/entry: introduce PUSH_AND_CLEAN_REGS
  x86/entry: use PUSH_AND_CLEAN_REGS in more cases
  x86/entry: get rid of ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS
  x86/entry: indent PUSH_AND_CLEAR_REGS and POP_REGS properly

 arch/x86/entry/calling.h  | 118 ++++++++++++++++++----------------------------
 arch/x86/entry/entry_64.S | 109 +++++++-----------------------------------
 2 files changed, 64 insertions(+), 163 deletions(-)

-- 
2.16.1

             reply	other threads:[~2018-02-11 10:50 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-11 10:49 Dominik Brodowski [this message]
2018-02-11 10:49 ` [PATCH v3 1/7] x86/entry: merge SAVE_C_REGS and SAVE_EXTRA_REGS, remove unused extensions Dominik Brodowski
2018-02-12 10:15   ` [tip:x86/pti] x86/entry/64: Merge " tip-bot for Dominik Brodowski
2018-02-13  9:00   ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 2/7] x86/entry: merge POP_C_REGS and POP_EXTRA_REGS Dominik Brodowski
2018-02-12 10:16   ` [tip:x86/pti] x86/entry/64: Merge the POP_C_REGS and POP_EXTRA_REGS macros into a single POP_REGS macro tip-bot for Dominik Brodowski
2018-02-13  9:01   ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 3/7] x86/entry: interleave XOR register clearing with PUSH instructions Dominik Brodowski
2018-02-12 10:16   ` [tip:x86/pti] x86/entry/64: Interleave " tip-bot for Dominik Brodowski
2018-02-13  9:01   ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 4/7] x86/entry: introduce PUSH_AND_CLEAN_REGS Dominik Brodowski
2018-02-12 10:17   ` [tip:x86/pti] x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro tip-bot for Dominik Brodowski
2018-02-12 13:29     ` Denys Vlasenko
2018-02-12 13:36       ` David Laight
2018-02-12 13:43         ` Denys Vlasenko
2018-02-12 16:51       ` Linus Torvalds
2018-02-13  9:01   ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 5/7] x86/entry: use PUSH_AND_CLEAN_REGS in more cases Dominik Brodowski
2018-02-12 10:17   ` [tip:x86/pti] x86/entry/64: Use " tip-bot for Dominik Brodowski
2018-02-13  9:02   ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 6/7] x86/entry: get rid of ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS Dominik Brodowski
2018-02-12 10:18   ` [tip:x86/pti] x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros tip-bot for Dominik Brodowski
2018-02-13  9:02   ` tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 7/7] x86/entry: indent PUSH_AND_CLEAR_REGS and POP_REGS properly Dominik Brodowski
2018-02-12 10:18   ` [tip:x86/pti] x86/entry/64: Indent " tip-bot for Dominik Brodowski
2018-02-12 20:13     ` [PATCH] x86/entry/64: Remove unused icebp macro Borislav Petkov
2018-02-13  7:36       ` Ingo Molnar
2018-02-13  9:04       ` [tip:x86/pti] x86/entry/64: Remove the unused 'icebp' macro tip-bot for Borislav Petkov
2018-02-13  9:03   ` [tip:x86/pti] x86/entry/64: Indent PUSH_AND_CLEAR_REGS and POP_REGS properly tip-bot for Dominik Brodowski
2018-02-11 10:49 ` [PATCH v3 8/7] TESTING_ONLY x86/entry: reduce static footprint of idtentry Dominik Brodowski
2018-02-12  9:37   ` Ingo Molnar
2018-02-12 19:17     ` Linus Torvalds
2018-02-13 12:41       ` Ingo Molnar

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