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From:   Lai Jiangshan <jiangshanlai@gmail.com>
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Subject: [PATCH V2 0/6] x86: don't abuse tss.sp1
Date:   Tue, 26 Jan 2021 01:34:28 +0800
Message-Id: <20210125173444.22696-1-jiangshanlai@gmail.com>
In-Reply-To: <CALCETrWPnvNr9S2hsxL+pbhNWv0OOL7tBq1XmABPjYK7zZSJbw@mail.gmail.com>
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From: Lai Jiangshan <laijs@linux.alibaba.com>

In x86_64, tss.sp1 is reused as cpu_current_top_of_stack.  But we can
directly use percpu since CR3 and gs_base is correct when it is used.

In x86_32, tss.sp1 is resued as thread.sp0 in three places in entry
code.  We have the correct CR3 and %fs at two of the places.  The last
one is sysenter.  This patchset makes %fs available earlier so that
we can also use percpu in sysenter.  And add a percpu cpu_current_thread_sp0
for thread.sp0 instead of tss.sp1

Changed from V1
	Requested from Andy to also fix sp1 for x86_32.
	Update comments in the x86_64 patch as Andy sugguested.

Lai Jiangshan (6):
  x86_64: move cpu_current_top_of_stack out of TSS
  x86_32: use percpu instead of offset-calculation to get thread.sp0
    when SWITCH_TO_KERNEL_STACK
  x86_32/sysenter: switch to the task stack without emptying the entry
    stack
  x86_32/sysenter: restore %fs before switching stack
  x86_32/sysenter: use percpu to get thread.sp0 when sysenter
  x86_32: use cpu_current_thread_sp0 instead of cpu_tss_rw.x86_tss.sp1

 arch/x86/entry/entry_32.S          | 38 +++++++++++++++++-------------
 arch/x86/include/asm/processor.h   | 12 ++--------
 arch/x86/include/asm/switch_to.h   |  9 ++-----
 arch/x86/include/asm/thread_info.h |  6 -----
 arch/x86/kernel/asm-offsets.c      |  1 -
 arch/x86/kernel/asm-offsets_32.c   | 10 --------
 arch/x86/kernel/cpu/common.c       | 12 +++++++++-
 arch/x86/kernel/process.c          |  7 ------
 arch/x86/mm/pti.c                  |  7 +++---
 9 files changed, 40 insertions(+), 62 deletions(-)

-- 
2.19.1.6.gb485710b