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06947aaaf9
linux/arch/mips/include/asm
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Maciej W. Rozycki 06947aaaf9 MIPS: Implement random_get_entropy with CP0 Random 
Update to commit 9c9b415c50 [MIPS:
Reimplement get_cycles().]

On systems were for whatever reasons we can't use the cycle counter, fall
back to the c0_random register as an entropy source.  It has however a
very small range that makes it suitable for random_get_entropy only and
not get_cycles.

This optimised version compiles to 8 instructions in the fast path even in
the worst case of all the conditions to check being variable (including a
MFC0 move delay slot that is only required for very old processors):

     828:	8cf90000 	lw	t9,0(a3)
			828: R_MIPS_LO16	jiffies
     82c:	40057800 	mfc0	a1,c0_prid
     830:	3c0200ff 	lui	v0,0xff
     834:	00a21024 	and	v0,a1,v0
     838:	1040007d 	beqz	v0,a30 <add_interrupt_randomness+0x22c>
     83c:	3c030000 	lui	v1,0x0
			83c: R_MIPS_HI16	cpu_data
     840:	40024800 	mfc0	v0,c0_count
     844:	00000000 	nop
     848:	00409021 	move	s2,v0
     84c:	8ce20000 	lw	v0,0(a3)
			84c: R_MIPS_LO16	jiffies

On most targets the sequence will be shorter and on some it will reduce to
a single `MFC0 <reg>,c0_count', as all MIPS architecture (i.e. non-legacy
MIPS) processors require the CP0 Count register to be present.

The only known exception that reports MIPS architecture compliance, but
contrary to that lacks CP0 Count is the Ingenic JZ4740 thingy.  For broken
platforms like that this code requires cpu_has_counter to be hardcoded to
0 (i.e. no variable setting is permitted) so as not to penalise all the
other good platforms out there.

The asm barrier is required so that the compiler does not pull any
potentially costly (cold cache!) `cpu_data' variable access into the fast
path.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: John Crispin <blogic@openwrt.org>
Cc: Andrew McGregor <andrewmcgr@gmail.com>
Cc: Dave Taht <dave.taht@bufferbloat.net>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: Simon Kelley <simon@thekelleys.org.uk>
Cc: Jim Gettys <jg@freedesktop.org>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6702/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-05-30 18:21:30 +02:00
..
dec MIPS: DEC/SNI: O32 wrapper stack switching fixes 2014-05-13 00:29:35 +02:00
emma MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
fw MIPS: malta: malta-memory: Add support for the 'ememsize' variable 2014-03-26 23:09:20 +01:00
ip32 MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
lasat MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-ar7 Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET" 2013-07-01 15:10:58 +02:00
mach-ath79 mips: delete non-required instances of include <linux/init.h> 2014-01-24 22:39:56 +01:00
mach-au1x00 MIPS: Alchemy: remove duplicate UART register offset definitions 2014-03-31 10:16:53 +02:00
mach-bcm47xx MIPS: BCM47XX: Add Belkin F7Dxxxx board detection 2014-03-26 23:09:23 +01:00
mach-bcm63xx MIPS: BCM63XX: use linux/serial_bcm63xx.h 2014-01-23 13:02:36 +01:00
mach-cavium-octeon MIPS: Remove unnecessary platform dma helper functions 2013-10-29 21:24:40 +01:00
mach-cobalt MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-db1x00 MIPS: Alchemy: fold mach-db1xxx/db1x00 headers into board code 2014-03-26 23:09:21 +01:00
mach-dec MIPS: DECstation CPU feature overrides 2013-10-29 21:24:46 +01:00
mach-emma2rh MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-generic mips: delete non-required instances of include <linux/init.h> 2014-01-24 22:39:56 +01:00
mach-ip22 MIPS: IP22: This platform may come with either MIPS III or MIPS IV CPUs. 2014-05-23 15:10:59 +02:00
mach-ip27 MIPS: Remove unnecessary platform dma helper functions 2013-10-29 21:24:40 +01:00
mach-ip28 MIPS: Optimize current_cpu_type() for better code. 2013-09-17 18:50:53 +02:00
mach-ip32 MIPS: Remove unnecessary platform dma helper functions 2013-10-29 21:24:40 +01:00
mach-jazz mips: delete non-required instances of include <linux/init.h> 2014-01-24 22:39:56 +01:00
mach-jz4740 MIPS: jz4740: update platform data for JZ4740 usb device controller 2014-01-24 22:39:46 +01:00
mach-lantiq MIPS: Lantiq: Falcon: add cpu-feature-override.h 2013-09-03 23:22:16 +02:00
mach-lasat MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-loongson MIPS: Loongson 3: Add CPU hotplug support 2014-03-31 18:17:12 +02:00
mach-loongson1 MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-malta MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
mach-netlogic MIPS: Netlogic: Fix uniprocessor compilation 2014-05-30 16:44:55 +02:00
mach-pmcs-msp71xx MIPS: MSP71xx: Remove checks for two macros 2014-05-23 15:12:39 +02:00
mach-pnx833x MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-ralink MIPS: Ralink: Remove surviving RM9000 bits. 2014-05-23 15:12:40 +02:00
mach-rc32434 MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-rm MIPS: PMC-Sierra Yosemite: Remove support. 2012-12-13 18:15:30 +01:00
mach-sead3 MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
mach-sibyte MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mach-tx39xx MIPS: PMC-Sierra Yosemite: Remove support. 2012-12-13 18:15:30 +01:00
mach-tx49xx MIPS: PMC-Sierra Yosemite: Remove support. 2012-12-13 18:15:30 +01:00
mach-vr41xx MIPS: PMC-Sierra Yosemite: Remove support. 2012-12-13 18:15:30 +01:00
mips-boards MIPS: Malta: Setup PM I/O region on boot 2014-03-31 18:17:12 +02:00
netlogic MIPS: Add MSI support for XLP9XX 2014-05-30 16:51:02 +02:00
octeon MIPS: Octeon: Remove checks for CONFIG_CAVIUM_GDB 2014-05-23 15:12:39 +02:00
pci MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
sgi MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
sibyte MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
sn MIPS: IP27: Remove pfn_t. 2013-05-08 03:51:58 +02:00
txx9 MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
vr41xx MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
xtalk MIPS: IP27: Fix build errors with CONFIG_PCI disabled. 2013-06-21 18:07:00 +02:00
abi.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
addrspace.h MIPS: Random whitespace clean-ups 2013-11-04 18:19:20 +01:00
amon.h MIPS: APRP: Code formatting clean-ups. 2014-01-22 20:19:02 +01:00
arch_hweight.h
asm-eva.h MIPS: asm: Add wrappers for EVA/non-EVA instructions 2014-03-26 23:09:12 +01:00
asm-offsets.h
asm.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
asmmacro-32.h MIPS: Don't assume 64-bit FP registers for context switch 2014-03-26 23:09:10 +01:00
asmmacro-64.h MIPS: Support for 64-bit FP with O32 binaries 2014-01-13 23:40:56 +01:00
asmmacro.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
atomic.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
barrier.h arch: Introduce smp_load_acquire(), smp_store_release() 2014-01-12 10:37:17 +01:00
bcache.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
bitops.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
bmips.h MIPS: BMIPS: add a smp ops registration helper 2014-01-22 20:18:52 +01:00
bootinfo.h MIPS: Loongson 3: Add Lemote-3A machtypes definition 2014-03-31 18:17:12 +02:00
branch.h MIPS: Sort out mm_isBranchInstr. 2014-05-23 15:12:37 +02:00
break.h MIPS: Quit exporting kernel internel break codes to uapi/asm/break.h 2013-02-20 18:24:24 +01:00
bug.h
bugs.h
cache.h
cacheflush.h MIPS: add kmap_noncoherent to wire a cached non-coherent TLB entry 2014-05-28 16:20:14 +01:00
cacheops.h MIPS: fix case mismatch in local_r4k_flush_icache_range() 2014-01-15 14:19:42 +07:00
cevt-r4k.h
checksum.h MIPS: asm: checksum: Add MIPS specific csum_and_copy_from_user function 2014-03-26 23:09:17 +01:00
clkdev.h clk: Add common __clk_get(), __clk_put() implementations 2013-12-04 17:19:44 +01:00
clock.h MIPS: clock.h: Remove declaration of cpu_wait. 2013-05-22 01:34:25 +02:00
cmp.h MIPS: SMP: Remove plat_smp_ops cpus_done method. 2014-05-27 11:06:42 +02:00
cmpxchg.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
compat-signal.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
compat.h Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2013-03-02 07:44:16 -08:00
compiler.h
cop2.h MIPS: Netlogic: COP2 save/restore code 2013-06-13 17:46:41 +02:00
cpu-features.h MIPS: math-emu: Remove most ifdefery. 2014-05-21 11:12:58 +02:00
cpu-info.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
cpu-type.h MIPS: Remove code protected by CONFIG_SYS_HAS_CPU_RM9000. 2014-05-23 15:12:40 +02:00
cpu.h MIPS: Netlogic: Add support for XLP5XX 2014-05-30 16:50:38 +02:00
debug.h
delay.h MIPS: Make __{,n,u}delay declarations match definitions and generic delay.h 2012-10-16 22:20:03 +02:00
device.h
div64.h
dma-coherence.h MIPS: improve checks for noncoherent DMA 2014-01-22 20:43:10 +01:00
dma-mapping.h MIPS: Loongson: Add swiotlb to support All-Memory DMA 2014-03-31 18:17:12 +02:00
dma.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
ds1287.h
dsp.h MIPS: DSP: Fix DSP mask for registers. 2013-01-24 13:20:09 +01:00
edac.h
elf.h MIPS: Support for 64-bit FP with O32 binaries 2014-01-13 23:40:56 +01:00
errno.h UAPI: (Scripted) Disintegrate arch/mips/include/asm 2012-10-09 09:47:14 +01:00
exec.h Disintegrate asm/system.h for MIPS 2012-03-28 18:30:02 +01:00
fb.h
fixmap.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
floppy.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
fpregdef.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
fpu_emulator.h MIPS: math-emu: Add IEEE754 exception statistics to debugfs 2014-05-30 11:55:23 +02:00
fpu.h MIPS: math-emu: Inline fpu_emulator_init_fpu() 2014-05-23 15:12:37 +02:00
ftrace.h MIPS: ftrace: Tweak safe_load()/safe_store() macros 2014-03-19 23:18:40 +01:00
futex.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
gic.h MIPS: allow GIC clockevent device config from other CPUs 2014-05-02 16:39:11 +01:00
gio_device.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
gpio.h
gt64120.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
hardirq.h
hazards.h MIPS: Get rid of the use of .macro in C code. 2013-04-11 15:39:51 +02:00
highmem.h mips: delete non-required instances of include <linux/init.h> 2014-01-24 22:39:56 +01:00
hugetlb.h mm/hugetlb: add more arch-defined huge_pte functions 2013-04-29 15:54:33 -07:00
hw_irq.h atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
i8259.h
ide.h
idle.h MIPS: cpuidle wait instruction state 2014-05-28 16:20:34 +01:00
inst.h MIPS: MIPS16e: Support handling of delay slots. 2013-05-09 17:55:20 +02:00
io.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
irq_cpu.h MIPS: add irqdomain support for the CPU IRQ controller 2013-02-17 01:25:34 +01:00
irq_gt641xx.h
irq_regs.h
irq.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
irqflags.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
isadep.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
jazz.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
jazzdma.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
jump_label.h compiler/gcc4: Add quirk for 'asm goto' miscompilation bug 2013-10-11 07:39:14 +02:00
Kbuild locking/mcs: Allow architecture specific asm files to be used for contended case 2014-02-09 21:18:52 +01:00
kdebug.h
kexec.h MIPS: kdump: Add support 2012-12-13 16:46:47 +01:00
kgdb.h
kmap_types.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
kprobes.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
kvm_host.h MIPS: KVM: Consult HWREna before emulating RDHWR 2014-03-19 17:01:43 +01:00
linkage.h consolidate cond_syscall and SYSCALL_ALIAS declarations 2013-03-03 22:55:19 -05:00
local.h MIPS: Fix gigaton of warning building with microMIPS. 2014-03-31 18:17:12 +02:00
m48t37.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mc146818-time.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
mc146818rtc.h
mips_machine.h MIPS: move mips_{set,get}_machine_name() to a more generic place 2013-05-08 01:19:07 +02:00
mips_mt.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
mips-cm.h MIPS: CM: use __raw_ memory access functions 2014-03-31 18:17:13 +02:00
mips-cpc.h MIPS: CPC: provide locking functions 2014-05-02 16:39:14 +01:00
mipsmtregs.h MIPS: MT: define write_c0_tchalt macro 2014-05-28 16:20:22 +01:00
mipsprom.h MIPS: SNI: Fix conflicting wrapper symbols for headers. 2011-10-20 15:00:18 +01:00
mipsregs.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
mmu_context.h Merge branch 'wip-mips-pm' of https://github.com/paulburton/linux into mips-for-linux-next 2014-05-29 15:08:23 +02:00
mmu.h
mmzone.h
module.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
msa.h MIPS: Basic MSA context switching support 2014-03-26 23:09:10 +01:00
msc01_ic.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
nile4.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
paccess.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
page.h MIPS: asm: page: Allow __pa_symbol overrides 2014-03-26 23:09:18 +01:00
pci.h MIPS: PCI: Use pci_resource_to_user to map pci memory space properly 2013-09-19 00:48:48 +02:00
perf_event.h
pgalloc.h mips: handle pgtable_page_ctor() fail 2013-11-15 09:32:18 +09:00
pgtable-32.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
pgtable-64.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
pgtable-bits.h MIPS: Loongson: Add basic Loongson-3 definition 2014-03-31 18:17:12 +02:00
pgtable.h MIPS: add kmap_noncoherent to wire a cached non-coherent TLB entry 2014-05-28 16:20:14 +01:00
pm-cps.h MIPS: pm-cps: add PM state entry code for CPS systems 2014-05-28 16:20:31 +01:00
pm.h Merge branch 'wip-mips-pm' of https://github.com/paulburton/linux into mips-for-linux-next 2014-05-29 15:08:23 +02:00
pmon.h
prefetch.h
processor.h MIPS: Basic MSA context switching support 2014-03-26 23:09:10 +01:00
prom.h of: implement pci_address_to_pio as weak function 2013-10-09 20:04:06 -05:00
ptrace.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
r4k-timer.h MIPS: Synchronize MIPS count one CPU at a time 2012-08-17 10:57:28 +02:00
r4kcache.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
reboot.h
reg.h
regdef.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
rtlx.h MIPS: APRP: Code formatting clean-ups. 2014-01-22 20:19:02 +01:00
seccomp.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
setup.h MIPS: Add 8250/16550 serial early printk driver 2013-10-29 21:24:36 +01:00
sgialib.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
sgiarcs.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
shmparam.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
sigcontext.h MIPS: Save/restore MSA context around signals 2014-03-26 23:09:11 +01:00
siginfo.h UAPI: (Scripted) Disintegrate arch/mips/include/asm 2012-10-09 09:47:14 +01:00
signal.h Fix breakage in MIPS siginfo handling 2013-03-19 19:15:52 +01:00
sim.h mips: switch to generic sys_fork() and sys_clone() 2013-02-03 18:33:02 -05:00
smp-cps.h MIPS: pm-cps: add PM state entry code for CPS systems 2014-05-28 16:20:31 +01:00
smp-ops.h MIPS: SMP: Remove plat_smp_ops cpus_done method. 2014-05-27 11:06:42 +02:00
smp.h MIPS: introduce cpu_coherent_mask 2014-05-02 16:39:13 +01:00
sni.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
socket.h UAPI: (Scripted) Disintegrate arch/mips/include/asm 2012-10-09 09:47:14 +01:00
sparsemem.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
spinlock_types.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
spinlock.h MIPS: Remove redundant instructions from arch_spin_{,try}lock. 2013-04-26 17:18:24 +02:00
spram.h
stackframe.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
stackprotector.h MIPS: initial stack protector support 2013-07-01 15:10:48 +02:00
stacktrace.h MIPS: Add new unwind_stack variant 2011-06-15 14:35:33 +02:00
string.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
suspend.h PM / Hibernate: Remove arch_prepare_suspend() 2011-05-24 23:35:55 +02:00
switch_to.h MIPS: Basic MSA context switching support 2014-03-26 23:09:10 +01:00
syscall.h MIPS: Add new AUDIT_ARCH token for the N32 ABI on MIPS64 2014-05-14 01:39:54 +02:00
termios.h UAPI: (Scripted) Disintegrate arch/mips/include/asm 2012-10-09 09:47:14 +01:00
thread_info.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
time.h MIPS: MT: Remove SMTC support 2014-05-24 00:07:01 +02:00
timex.h MIPS: Implement random_get_entropy with CP0 Random 2014-05-30 18:21:30 +02:00
tlb.h MIPS: tlb: Set the EHINV bit for TLBINVF cores when invalidating the TLB 2014-01-22 20:18:59 +01:00
tlbdebug.h
tlbflush.h
tlbmisc.h MIPS: Fix Jazz 64-bit build error. 2011-12-07 22:01:45 +00:00
topology.h sched: Remove unused mc_capable() and smt_capable() 2014-03-11 12:05:45 +01:00
traps.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
txx9irq.h
txx9pio.h
txx9tmr.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
types.h UAPI: (Scripted) Disintegrate arch/mips/include/asm 2012-10-09 09:47:14 +01:00
uaccess.h MIPS: asm: uaccess: Add EVA support for str*_user operations 2014-03-26 23:09:16 +01:00
uasm.h MIPS: uasm: Add lb uasm instruction 2014-05-30 16:10:19 +02:00
unaligned.h
unistd.h compat: let architectures define __ARCH_WANT_COMPAT_SYS_GETDENTS64 2014-03-04 09:05:33 +01:00
user.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
vdso.h
vga.h MIPS: Fix VGA_MAP_MEM macro. 2013-09-18 17:13:58 +02:00
vpe.h Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus 2014-01-30 17:20:32 -08:00
war.h MIPS: Whitespace cleanup. 2013-02-01 10:00:22 +01:00
watch.h
wbflush.h