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Subject[PATCH V4 0/6] x86: Don't abuse tss.sp1
Date
From: Lai Jiangshan <laijs@linux.alibaba.com>

In x86_64, tss.sp1 is reused as cpu_current_top_of_stack. We'd better
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

[V3]: https://lore.kernel.org/lkml/20210127163231.12709-1-jiangshanlai@gmail.com/
[V2]: https://lore.kernel.org/lkml/20210125173444.22696-1-jiangshanlai@gmail.com/
[V1]: https://lore.kernel.org/lkml/20210123084900.3118-1-jiangshanlai@gmail.com/

Changed from V3:
Update subjects as Borislav's imperative request. ^_^
Update changelog as Borislav suggested.
Change EXPORT_PER_CPU_SYMBOL to EXPORT_PER_CPU_SYMBOL_GPL.

Changed from V2:
Add missing "%ss:" reported by Brian Gerst.

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/entry/64: Move cpu_current_top_of_stack out of TSS
x86/entry/32: Use percpu instead of offset-calculation to get
thread.sp0 in SWITCH_TO_KERNEL_STACK
x86/entry/32: Switch to the task stack without emptying the entry
stack
x86/entry/32: Restore %fs before switching stack
x86/entry/32: Use percpu to get thread.sp0 in SYSENTER
x86/entry/32: Introduce cpu_current_thread_sp0 to replace
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 | 8 +------
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, 39 insertions(+), 62 deletions(-)

--
2.19.1.6.gb485710b

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