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f89451fbd2
linux-next/arch/powerpc/kernel
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Anton Blanchard f89451fbd2 powerpc: Feature nop out reservation clear when stcx checks address 
The POWER architecture does not require stcx to check that it is operating
on the same address as the larx. This means it is possible for an
an exception handler to execute a larx, get a reservation, decide
not to do the stcx and then return back with an active reservation. If the
interrupted code was in the middle of a larx/stcx sequence the stcx could
incorrectly succeed.

All recent POWER CPUs check the address before letting the stcx succeed
so we can create a CPU feature and nop it out. As Ben suggested, we can
only do this in our syscall path because there is a remote possibility
some kernel code gets interrupted by an exception that ends up operating
on the same cacheline.

Thanks to Paul Mackerras and Derek Williams for the idea.

To test this I used a very simple null syscall (actually getppid) testcase
at http://ozlabs.org/~anton/junkcode/null_syscall.c

I tested against 2.6.35-git10 with the following changes against the
pseries_defconfig:

CONFIG_VIRT_CPU_ACCOUNTING=n
CONFIG_AUDIT=n
CONFIG_PPC_4K_PAGES=n
CONFIG_PPC_64K_PAGES=y
CONFIG_FORCE_MAX_ZONEORDER=9
CONFIG_PPC_SUBPAGE_PROT=n
CONFIG_FUNCTION_TRACER=n
CONFIG_FUNCTION_GRAPH_TRACER=n
CONFIG_IRQSOFF_TRACER=n
CONFIG_STACK_TRACER=n

to remove the overhead of virtual CPU accounting, syscall auditing and
the ftrace mcount tracers. 64kB pages were enabled to minimise TLB misses.

POWER6: +8.2%
POWER7: +7.0%

Another suggestion was to use a larx to something in the L1 instead of a stcx.
This was almost as fast as removing the larx on POWER6, but only 3.5% faster
on POWER7. We can use this to speed up the reservation clear in our
exception exit code.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-09-02 14:07:30 +10:00
..
vdso32 powerpc: Rework VDSO gettimeofday to prevent time going backwards 2010-07-28 21:06:47 +02:00
vdso64 powerpc: Rework VDSO gettimeofday to prevent time going backwards 2010-07-28 21:06:47 +02:00
.gitignore powerpc: Ignore generated vmlinux.lds in git 2008-10-07 14:26:18 +11:00
align.c powerpc: Handle VSX alignment faults correctly in little-endian mode 2009-12-18 14:55:43 +11:00
asm-offsets.c powerpc: Rework VDSO gettimeofday to prevent time going backwards 2010-07-28 21:06:47 +02:00
audit.c
btext.c lmb: rename to memblock 2010-07-14 17:14:00 +10:00
cacheinfo.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
cacheinfo.h powerpc: Rewrite sysfs processor cache info code 2009-01-08 16:25:10 +11:00
clock.c
compat_audit.c
cpu_setup_6xx.S powerpc: Use names rather than numbers for SPRGs (v2) 2009-08-20 10:12:27 +10:00
cpu_setup_44x.S AMCC PPC 460SX redwood SoC platform initial framework 2009-02-14 14:41:29 -05:00
cpu_setup_fsl_booke.S powerpc/fsl-booke: Enable L1 cache on e500v1/e500v2/e500mc CPUs 2009-06-15 21:45:30 -05:00
cpu_setup_pa6t.S
cpu_setup_ppc970.S powerpc: Use LOAD_REG_IMMEDIATE only for constants on 64-bit 2008-09-15 11:08:35 -07:00
cputable.c powerpc/47x: Remove redundant line from cputable.c 2010-08-23 07:37:01 -04:00
crash_dump.c Merge commit 'gcl/next' into next 2010-08-04 10:26:03 +10:00
crash.c powerpc/kdump: Stop all other CPUs before running crash handlers 2010-08-24 15:26:27 +10:00
dbell.c powerpc/book3e: Resend doorbell exceptions to ourself 2010-07-09 16:11:19 +10:00
dma-iommu.c powerpc: Change archdata dma_data to a union 2009-09-24 15:31:43 +10:00
dma-swiotlb.c of: Merge of_platform_bus_type with platform_bus_type 2010-07-24 09:57:51 -06:00
dma.c lmb: rename to memblock 2010-07-14 17:14:00 +10:00
e500-pmu.c powerpc/perf: e500 support 2010-03-05 03:04:08 -06:00
entry_32.S powerpc/47x: Base ppc476 support 2010-05-05 09:11:10 -04:00
entry_64.S powerpc: Feature nop out reservation clear when stcx checks address 2010-09-02 14:07:30 +10:00
exceptions-64e.S powerpc/book3e: Fix single step when using HW page tables 2010-07-14 14:13:51 +10:00
exceptions-64s.S powerpc, hw_breakpoints: Implement hw_breakpoints for 64-bit server processors 2010-06-22 19:40:50 +10:00
firmware.c powerpc: Make powerpc_firmware_features __read_mostly 2010-02-09 13:56:07 +11:00
fpu.S powerpc: Use names rather than numbers for SPRGs (v2) 2009-08-20 10:12:27 +10:00
fsl_booke_entry_mapping.S powerpc/fsl-booke: Fix address issue when using relocatable kernels 2010-07-11 11:04:08 -05:00
ftrace.c Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-20 10:56:46 -07:00
head_8xx.S powerpc/8xx: Use SPRG2 and DAR registers to stash r11 and cr. 2010-04-07 18:00:34 +10:00
head_32.S KVM: PPC: Add KVM intercept handlers 2010-05-17 12:18:52 +03:00
head_40x.S powerpc: Use names rather than numbers for SPRGs (v2) 2009-08-20 10:12:27 +10:00
head_44x.S powerpc/47x: Make sure mcsr is cleared before enabling machine check interrupts 2010-08-23 07:36:58 -04:00
head_64.S powerpc: Don't use kernel stack with translation off 2010-08-31 11:35:13 +10:00
head_booke.h powerpc/booke: Add Stack Marking support to Booke Exception Prolog 2010-05-05 08:01:52 -04:00
head_fsl_booke.S powerpc/kexec: Add support for FSL-BookE 2010-05-24 21:25:32 -05:00
hw_breakpoint.c powerpc, hw_breakpoint: Tell generic code we have no instruction breakpoints 2010-06-30 13:54:58 +10:00
ibmebus.c powerpc: remove references to of_device and to_of_device 2010-07-24 09:58:21 -06:00
idle_6xx.S powerpc: Fix for getting CPU number in power_save_ppc32_restore() 2008-09-03 20:53:47 +10:00
idle_book3e.S powerpc/book3e: Add generic 64-bit idle powersave support 2010-07-14 14:13:18 +10:00
idle_e500.S powerpc: Fix for getting CPU number in power_save_ppc32_restore() 2008-09-03 20:53:47 +10:00
idle_power4.S
idle.c powerpc: Re-enable preemption before cpu_die() 2010-08-24 15:26:29 +10:00
init_task.c Use new __init_task_data macro in arch init_task.c files. 2009-09-21 06:27:08 +02:00
io.c powerpc: tiny memcpy_(to|from)io optimisation 2009-11-04 16:43:12 -07:00
iomap.c
iommu.c powerpc: Remove unused 'protect4gb' boot parameter 2010-05-21 17:31:13 +10:00
irq.c powerpc/4xx: Index interrupt stacks by physical cpu 2010-08-23 07:37:53 -04:00
isa-bridge.c [POWERPC] Remove leftover printk in isa-bridge.c 2008-05-09 20:22:59 +10:00
kgdb.c kgdb,powerpc: Replace hardcoded offset by BREAK_INSTR_SIZE 2010-08-05 09:22:22 -05:00
kprobes.c powerpc/kprobes: Remove resume_execution() in kprobes 2010-06-02 17:50:37 +10:00
l2cr_6xx.S
legacy_serial.c of/address: Clean up function declarations 2010-08-01 01:42:42 -06:00
lparcfg.c powerpc/pseries: Export data from new hcall H_EM_GET_PARMS 2010-04-07 18:00:29 +10:00
machine_kexec_32.c kexec jump: rename KEXEC_CONTROL_CODE_SIZE to KEXEC_CONTROL_PAGE_SIZE 2008-08-15 08:35:42 -07:00
machine_kexec_64.c powerpc/kexec: Fix orphaned offline CPUs across kexec 2010-07-31 15:05:22 +10:00
machine_kexec.c Merge commit 'gcl/next' into next 2010-08-04 10:26:03 +10:00
Makefile Merge branch 'next-devicetree' of git://git.secretlab.ca/git/linux-2.6 2010-08-05 15:57:35 -07:00
misc_32.S powerpc/kexec: Adds correct calling convention for kexec purgatory 2010-08-31 11:35:12 +10:00
misc_64.S powerpc: Unconditionally enabled irq stacks 2010-06-15 15:02:37 +10:00
misc.S perf: Drop the skip argument from perf_arch_fetch_regs_caller 2010-06-08 23:31:27 +02:00
module_32.c powerpc/ppc32: ftrace, dynamic ftrace to handle modules 2008-11-20 10:52:53 -08:00
module_64.c powerpc: Unify opcode definitions and support 2009-02-23 10:48:56 +11:00
module.c module: cleanup FIXME comments about trimming exception table entries. 2009-06-12 21:47:05 +09:30
mpc7450-pmu.c perf: Do the big rename: Performance Counters -> Performance Events 2009-09-21 14:28:04 +02:00
msi.c powerpc/PCI: include pci.h in powerpc MSI implementation 2009-03-25 08:54:29 -07:00
nvram_64.c arch/powerpc: Fix continuation line formats 2010-02-09 13:55:05 +11:00
of_platform.c of: remove of_default_bus_ids 2010-07-24 09:58:22 -06:00
paca.c Merge commit 'gcl/next' into next 2010-08-04 10:26:03 +10:00
pci_32.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
pci_64.c of: add 'of_' prefix to machine_is_compatible() 2010-02-09 08:33:00 -07:00
pci_dn.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
pci_of_scan.c powerpc/pci: Fix checking for child bridges in PCI code. 2010-08-24 15:28:27 +10:00
pci-common.c of/address: Clean up function declarations 2010-08-01 01:42:42 -06:00
perf_callchain.c perf: Fix inconsistency between IP and callchain sampling 2010-01-28 14:31:20 +01:00
perf_event_fsl_emb.c perf, powerpc: fsl_emb: Restore setting perf_sample_data.period 2010-08-03 10:56:45 +10:00
perf_event.c Merge branch 'linus' into perf/core 2010-07-21 21:43:06 +02:00
pmc.c powerpc: Convert pmc_owner_lock to raw_spinlock 2010-02-19 14:52:33 +11:00
power4-pmu.c perf: Do the big rename: Performance Counters -> Performance Events 2009-09-21 14:28:04 +02:00
power5-pmu.c powerpc: perf_event: Enable SDAR in continous sample mode 2009-10-28 16:13:02 +11:00
power5+-pmu.c powerpc: perf_event: Enable SDAR in continous sample mode 2009-10-28 16:13:02 +11:00
power6-pmu.c powerpc: perf_event: Enable SDAR in continous sample mode 2009-10-28 16:13:02 +11:00
power7-pmu.c powerpc: perf_event: Enable SDAR in continous sample mode 2009-10-28 16:13:02 +11:00
ppc32.h powerpc: Add VSX context save/restore, ptrace and signal support 2008-07-01 11:28:50 +10:00
ppc970-pmu.c powerpc: perf_event: Enable SDAR in continous sample mode 2009-10-28 16:13:02 +11:00
ppc_ksyms.c KVM: PPC: elide struct thread_struct instances from stack 2010-08-01 10:39:24 +03:00
ppc_save_regs.S powerpc: Prepare xmon_save_regs for use with kdump 2008-12-23 15:13:28 +11:00
proc_powerpc.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
process.c powerpc: Inline ppc64_runlatch_off 2010-08-24 15:26:30 +10:00
prom_init_check.sh powerpc: Fix compile errors in prom_init_check for gcc 4.5 2010-07-08 18:11:39 +10:00
prom_init.c powerpc: Print decimal values in prom_init.c 2010-07-31 15:05:20 +10:00
prom_parse.c of/address: Merge all of the bus translation code 2010-07-05 16:14:26 -06:00
prom.c powerpc: Fix erroneous lmb->memblock conversions 2010-07-23 12:56:57 +10:00
ptrace32.c headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
ptrace.c powerpc, hw_breakpoints: Implement hw_breakpoints for 64-bit server processors 2010-06-22 19:40:50 +10:00
reloc_64.S powerpc: Make the 64-bit kernel as a position-independent executable 2008-09-15 11:08:38 -07:00
rtas_flash.c powerpc: rtas_flash needs to use rtas_data_buf 2010-06-15 15:02:37 +10:00
rtas_pci.c powerpc/pci: Clean up direct access to sysdata by RTAS 2009-05-21 15:44:23 +10:00
rtas-proc.c powerpc: Move /proc/ppc64 to /proc/powerpc update 2010-01-15 13:26:17 +11:00
rtas-rtc.c
rtas.c Merge commit 'gcl/next' into next 2010-08-04 10:26:03 +10:00
rtasd.c powerpc/rtasd: Don't start event scan if scan rate is zero 2010-05-21 17:29:39 +10:00
setup_32.c powerpc/4xx: Index interrupt stacks by physical cpu 2010-08-23 07:37:53 -04:00
setup_64.c powerpc: Correct smt_enabled=X boot option for > 2 threads per core 2010-08-24 15:26:30 +10:00
setup-common.c powerpc: fix i8042 module build error 2010-08-06 20:49:20 -06:00
setup.h
signal_32.c powerpc/booke: Add support for advanced debug registers 2010-02-17 14:03:17 +11:00
signal_64.c powerpc: Sanitize stack pointer in signal handling code 2009-03-27 16:58:24 +11:00
signal.c powerpc, hw_breakpoint: Enable hw-breakpoints while handling intervening signals 2010-06-22 19:40:50 +10:00
signal.h powerpc: Sanitize stack pointer in signal handling code 2009-03-27 16:58:24 +11:00
smp-tbsync.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
smp.c powerpc: Silence __cpu_up() under normal operation 2010-08-24 15:26:29 +10:00
softemu8xx.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
stacktrace.c powerpc: Removed duplicated include in stacktrace.c 2008-07-28 16:30:47 +10:00
suspend.c update email address 2010-07-19 10:56:54 +02:00
swsusp_32.S powerpc/swsusp_32: Fix TLB invalidation 2010-01-15 13:20:07 +11:00
swsusp_64.c
swsusp_asm64.S powerpc: Fix 64-bit hibernation with 64k pages 2008-10-07 14:26:20 +11:00
swsusp_booke.S powerpc/fsl-booke: Add hibernation support for FSL BookE processors 2010-05-21 07:41:53 -05:00
swsusp.c powerpc/mm: Split mmu_context handling 2008-12-21 14:21:15 +11:00
sys_ppc32.c powerpc: Wire up fanotify_init, fanotify_mark, prlimit64 syscalls 2010-08-24 15:28:28 +10:00
syscalls.c Add generic sys_olduname() 2010-03-12 15:52:32 -08:00
sysfs.c powerpc: Use smt_snooze_delay=-1 to always busy loop 2010-05-21 17:31:12 +10:00
systbl_chk.c
systbl_chk.sh
systbl.S
tau_6xx.c tree-wide: fix assorted typos all over the place 2009-12-04 15:39:55 +01:00
time.c powerpc/perf_event: Reduce latency of calling perf_event_do_pending 2010-08-31 11:35:13 +10:00
traps.c powerpc/book3e: Move doorbell_exception from traps.c to dbell.c 2010-07-09 15:25:18 +10:00
udbg_16550.c trivial: fix typo "for for" in multiple files 2009-09-21 15:14:54 +02:00
udbg.c powerpc: gamecube/wii: early debugging using usbgecko 2009-12-12 22:24:31 -07:00
vdso.c lmb: rename to memblock 2010-07-14 17:14:00 +10:00
vecemu.c
vector.S powerpc: Fix usage of 64-bit instruction in 32-bit altivec code 2009-12-09 18:10:12 +11:00
vio.c powerpc: Fix bogus it_blocksize in VIO iommu code 2010-08-24 15:26:31 +10:00
vmlinux.lds.S Rename .data.read_mostly to .data..read_mostly. 2010-03-03 11:26:00 +01:00