685d982112
- The biggest change is the rework of the percpu code,
to support the 'Named Address Spaces' GCC feature,
by Uros Bizjak:
- This allows C code to access GS and FS segment relative
memory via variables declared with such attributes,
which allows the compiler to better optimize those accesses
than the previous inline assembly code.
- The series also includes a number of micro-optimizations
for various percpu access methods, plus a number of
cleanups of %gs accesses in assembly code.
- These changes have been exposed to linux-next testing for
the last ~5 months, with no known regressions in this area.
- Fix/clean up __switch_to()'s broken but accidentally
working handling of FPU switching - which also generates
better code.
- Propagate more RIP-relative addressing in assembly code,
to generate slightly better code.
- Rework the CPU mitigations Kconfig space to be less idiosyncratic,
to make it easier for distros to follow & maintain these options.
- Rework the x86 idle code to cure RCU violations and
to clean up the logic.
- Clean up the vDSO Makefile logic.
- Misc cleanups and fixes.
[ Please note that there's a higher number of merge commits in
this branch (three) than is usual in x86 topic trees. This happened
due to the long testing lifecycle of the percpu changes that
involved 3 merge windows, which generated a longer history
and various interactions with other core x86 changes that we
felt better about to carry in a single branch. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core x86 updates from Ingo Molnar:
- The biggest change is the rework of the percpu code, to support the
'Named Address Spaces' GCC feature, by Uros Bizjak:
- This allows C code to access GS and FS segment relative memory
via variables declared with such attributes, which allows the
compiler to better optimize those accesses than the previous
inline assembly code.
- The series also includes a number of micro-optimizations for
various percpu access methods, plus a number of cleanups of %gs
accesses in assembly code.
- These changes have been exposed to linux-next testing for the
last ~5 months, with no known regressions in this area.
- Fix/clean up __switch_to()'s broken but accidentally working handling
of FPU switching - which also generates better code
- Propagate more RIP-relative addressing in assembly code, to generate
slightly better code
- Rework the CPU mitigations Kconfig space to be less idiosyncratic, to
make it easier for distros to follow & maintain these options
- Rework the x86 idle code to cure RCU violations and to clean up the
logic
- Clean up the vDSO Makefile logic
- Misc cleanups and fixes
* tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
x86/idle: Select idle routine only once
x86/idle: Let prefer_mwait_c1_over_halt() return bool
x86/idle: Cleanup idle_setup()
x86/idle: Clean up idle selection
x86/idle: Sanitize X86_BUG_AMD_E400 handling
sched/idle: Conditionally handle tick broadcast in default_idle_call()
x86: Increase brk randomness entropy for 64-bit systems
x86/vdso: Move vDSO to mmap region
x86/vdso/kbuild: Group non-standard build attributes and primary object file rules together
x86/vdso: Fix rethunk patching for vdso-image-{32,64}.o
x86/retpoline: Ensure default return thunk isn't used at runtime
x86/vdso: Use CONFIG_COMPAT_32 to specify vdso32
x86/vdso: Use $(addprefix ) instead of $(foreach )
x86/vdso: Simplify obj-y addition
x86/vdso: Consolidate targets and clean-files
x86/bugs: Rename CONFIG_RETHUNK => CONFIG_MITIGATION_RETHUNK
x86/bugs: Rename CONFIG_CPU_SRSO => CONFIG_MITIGATION_SRSO
x86/bugs: Rename CONFIG_CPU_IBRS_ENTRY => CONFIG_MITIGATION_IBRS_ENTRY
x86/bugs: Rename CONFIG_CPU_UNRET_ENTRY => CONFIG_MITIGATION_UNRET_ENTRY
x86/bugs: Rename CONFIG_SLS => CONFIG_MITIGATION_SLS
...
49 lines
1.0 KiB
ArmAsm
49 lines
1.0 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Common place for both 32- and 64-bit entry routines.
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*/
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#include <linux/export.h>
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#include <linux/linkage.h>
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#include <asm/msr-index.h>
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#include <asm/unwind_hints.h>
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#include <asm/segment.h>
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#include <asm/cache.h>
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#include "calling.h"
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.pushsection .noinstr.text, "ax"
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SYM_FUNC_START(entry_ibpb)
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movl $MSR_IA32_PRED_CMD, %ecx
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movl $PRED_CMD_IBPB, %eax
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xorl %edx, %edx
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wrmsr
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RET
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SYM_FUNC_END(entry_ibpb)
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/* For KVM */
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EXPORT_SYMBOL_GPL(entry_ibpb);
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.popsection
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/*
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* Define the VERW operand that is disguised as entry code so that
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* it can be referenced with KPTI enabled. This ensure VERW can be
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* used late in exit-to-user path after page tables are switched.
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*/
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.pushsection .entry.text, "ax"
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.align L1_CACHE_BYTES, 0xcc
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SYM_CODE_START_NOALIGN(mds_verw_sel)
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UNWIND_HINT_UNDEFINED
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ANNOTATE_NOENDBR
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.word __KERNEL_DS
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.align L1_CACHE_BYTES, 0xcc
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SYM_CODE_END(mds_verw_sel);
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/* For KVM */
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EXPORT_SYMBOL_GPL(mds_verw_sel);
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.popsection
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THUNK warn_thunk_thunk, __warn_thunk
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