Messages in this thread |  | | Date | Fri, 25 Aug 2017 12:31:03 +0200 | From | Thomas Gleixner <> | Subject | [patch 00/41] x86: Cleanup IDT code |
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The IDT code in x86 is a convoluted mess and contains quite some bogosities.
One of the main offenders is the extra tracing IDT which has been introduced to reduce the impact of tracing on the exception vectors when tracepoints are disabled.
This results in an unholy macro mess which magically creates IDT entries by prepending the exception handler name by trace_.
For most exceptions the tracepoint overhead in the disabled case is two NOP5, which are negligible compared to the heavy work of the exception handler itself. Modern CPUs are pretty good in optimizing NOPs.
The only two handlers where the overhead matters are the pagefault handler and the reschedule IPI, where an active tracepoint introduces more extra work. These two can be handled with separate static keys which reduces the impact to a minimum.
As a result the whole tracing IDT machinery can be removed.
The second part of the series cleans up the handling of IDT/GDT/LDT/TSS descriptors to get rid of macro based initialization via the obscure raw 32bit union fields a and b.
The last part moves the setup of the IDT into a separate file, where all gate related code is moved to. The gate setup is converted to a table based mechanism so the resulting code is smaller and better understandable.
The series applies on top of
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/apic
and is available as a git branch from
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/apic
There is more cleanup to come in the near future, which aims at replacing the braindamaged vector assignment mechanics, which has quite some shortcomings.
Thanks,
tglx --- arch/x86/boot/compressed/eboot.c | 8 arch/x86/entry/entry_32.S | 20 - arch/x86/entry/entry_64.S | 26 -- arch/x86/entry/vdso/vma.c | 2 arch/x86/include/asm/desc.h | 246 +++----------------- arch/x86/include/asm/desc_defs.h | 122 +++++----- arch/x86/include/asm/entry_arch.h | 14 - arch/x86/include/asm/hw_irq.h | 20 - arch/x86/include/asm/irq.h | 4 arch/x86/include/asm/segment.h | 4 arch/x86/include/asm/trace/exceptions.h | 8 arch/x86/include/asm/trace/irq_vectors.h | 24 +- arch/x86/include/asm/traps.h | 10 arch/x86/include/asm/xen/hypercall.h | 6 arch/x86/kernel/Makefile | 3 arch/x86/kernel/apic/apic.c | 70 +---- arch/x86/kernel/apic/vector.c | 2 arch/x86/kernel/cpu/common.c | 9 arch/x86/kernel/cpu/mcheck/mce_amd.c | 16 - arch/x86/kernel/cpu/mcheck/therm_throt.c | 20 - arch/x86/kernel/cpu/mcheck/threshold.c | 16 - arch/x86/kernel/cpu/mshyperv.c | 9 arch/x86/kernel/head32.c | 4 arch/x86/kernel/head64.c | 6 arch/x86/kernel/head_32.S | 42 --- arch/x86/kernel/irq.c | 29 -- arch/x86/kernel/irq_work.c | 16 - arch/x86/kernel/irqinit.c | 102 -------- arch/x86/kernel/kvm.c | 4 arch/x86/kernel/machine_kexec_32.c | 14 - arch/x86/kernel/reboot.c | 4 arch/x86/kernel/setup.c | 4 arch/x86/kernel/setup_percpu.c | 9 arch/x86/kernel/smp.c | 81 +----- arch/x86/kernel/tls.c | 2 arch/x86/kernel/tracepoint.c | 57 +--- arch/x86/kernel/traps.c | 108 --------- arch/x86/kvm/vmx.c | 2 arch/x86/math-emu/fpu_entry.c | 11 arch/x86/math-emu/fpu_system.h | 48 +++- arch/x86/math-emu/get_address.c | 17 - arch/x86/mm/fault.c | 47 +-- arch/x86/xen/enlighten_pv.c | 14 - b/arch/x86/include/asm/trace/common.h | 16 + b/arch/x86/kernel/eisa.c | 18 + b/arch/x86/kernel/idt.c | 365 +++++++++++++++++++++++++++++++ drivers/xen/events/events_base.c | 6 47 files changed, 718 insertions(+), 967 deletions(-)
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